WO2003057823A2 - Epitope synchronization in antigen presenting cells - Google Patents

Epitope synchronization in antigen presenting cells Download PDF

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Publication number
WO2003057823A2
WO2003057823A2 PCT/US2002/035582 US0235582W WO03057823A2 WO 2003057823 A2 WO2003057823 A2 WO 2003057823A2 US 0235582 W US0235582 W US 0235582W WO 03057823 A2 WO03057823 A2 WO 03057823A2
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Prior art keywords
epitope
cell
epitopes
cells
antigen
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PCT/US2002/035582
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English (en)
French (fr)
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WO2003057823A3 (en
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John J. L. Simard
David C. Diamond
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Mannkind Corporation
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Priority claimed from US10/026,066 external-priority patent/US20030215425A1/en
Application filed by Mannkind Corporation filed Critical Mannkind Corporation
Priority to AU2002365187A priority Critical patent/AU2002365187A1/en
Priority to JP2003558125A priority patent/JP2005514029A/ja
Priority to EP02804113A priority patent/EP1451305A4/en
Publication of WO2003057823A2 publication Critical patent/WO2003057823A2/en
Publication of WO2003057823A3 publication Critical patent/WO2003057823A3/en

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    • C—CHEMISTRY; METALLURGY
    • C07—ORGANIC CHEMISTRY
    • C07K—PEPTIDES
    • C07K14/00—Peptides having more than 20 amino acids; Gastrins; Somatostatins; Melanotropins; Derivatives thereof
    • C07K14/435—Peptides having more than 20 amino acids; Gastrins; Somatostatins; Melanotropins; Derivatives thereof from animals; from humans
    • C07K14/705—Receptors; Cell surface antigens; Cell surface determinants
    • C07K14/70503—Immunoglobulin superfamily
    • C07K14/7051—T-cell receptor (TcR)-CD3 complex
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
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    • A61K39/0011—Cancer antigens
    • A61K39/001184—Cancer testis antigens, e.g. SSX, BAGE, GAGE or SAGE
    • A61K39/001189—PRAME
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    • A61K39/001151—Apoptosis related proteins, e.g. survivin or livin p53
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    • A61K2039/53—DNA (RNA) vaccination

Definitions

  • the invention disclosed herein relates to methods and compositions for inducing an antigen presenting cell to present a particular target cell-specific epitope, thereby promoting an effective cytotoxic T cell response to the target cell.
  • the invention further relates to the identification of target cell epitopes and epitope clusters, and also to epitope-encodmg vectors that can be used to generate immunologically active pharmaceutical compositions. These compositions, when administered, can stimulate the immune system of a subject to mount an immune response against a target cell displaying the target antigen.
  • the invention is therefore useful in the treatment and prevention of neoplastic and viral disease.
  • the neoplastic disease state commonly known as cancer is thought to generally result from a single cell growing out of control.
  • the uncontrolled growth state typically results from a multi- step process m which a series of cellular systems fail, resulting in the genesis of a neoplastic cell.
  • the resulting neoplastic cell rapidly reproduces itself, forms one or more tumors, and eventually may cause the death of the host.
  • neoplastic cells are largely exempt from the host's immune system.
  • immune surveillance the process in which the host's immune system surveys and localizes foreign materials, a neoplastic cell will appear to the host's immune surveillance machinery as a "self cell. Viruses and the Immune System
  • virus infection involves the expression of clearly non-self antigens
  • many virus infections are successfully dealt with by the immune system with minimal clinical sequela.
  • a variety of vaccine approaches have been successfully used to combat various diseases. These approaches include subunit vaccines consisting of individual proteins produced through recombinant DNA technology. Notwithstanding these advances, the selection and effective administration of minimal epitopes for use as viral vaccines has remained problematic.
  • the immune system functions to discriminate molecules endogenous to an organism ("self molecules) from material exogenous or foreign to the organism ("non-self molecules).
  • the immune system has two types of adaptive responses to foreign bodies based on the components that mediate the response: a humoral response and a cell-mediated response.
  • the humoral response is mediated by antibodies, while the cell-mediated response involves cells classified as lymphocytes.
  • Recent anticancer and antiviral strategies have focused on mobilizing the host immune system as a means of anticancer or antiviral treatment or therapy.
  • the immune system functions in three phases to protect the host from foreign bodies: the cognitive phase, the activation phase, and the effector phase.
  • the cognitive phase the immune system recognizes and signals the presence of a foreign antigen or invader in the body.
  • the foreign antigen can be, for example, a cell surface marker from a neoplastic cell or a viral protein.
  • An array of effector cells implements an immune response to an invader.
  • One type of effector cell, the B cell generates antibodies targeted against foreign antigens encountered by the host. In combination with the complement system, antibodies direct the destruction of cells or organisms bearing the targeted antigen.
  • Another type of effector cell is the natural killer cell (NK cell), a type of lymphocyte having the capacity to spontaneously recognize and destroy a variety of virus infected cells as well as malignant cell types. The method used by NK. cells to recognize target cells is poorly understood.
  • T cell Another type of effector cell, the T cell, has members classified into three subcategories, each playing a different role in the immune response.
  • Helper T cells secrete cytokines which stimulate the proliferation of other cells necessary for mounting an effective immune response, while suppressor T cells down-regulate the immune response.
  • a third category of T cell, the cytotoxic T cell (CTL) is capable of directly lysing a targeted cell presenting a foreign antigen on its surface.
  • CTL cytotoxic T cell
  • the Major Histocompatibility Complex and T Cell Target Recognition T cells are antigen specific immune cells that function in response to specific antigen signals.
  • B lymphocytes and the antibodies they produce are also antigen specific entities. However, unlike B lymphocytes, T cells do not respond to antigens in a free or soluble form. For a T cell to respond to an antigen, it requires the antigen to be bound to a presenting complex known as the major histocompatibility complex (MHC).
  • MHC major histocompatibility complex
  • MHC complex proteins provide the means by which T cells differentiate native or "self cells from foreign cells. There are two types of MHC, class I MHC and class II MHC. T Helper cells
  • CD4 + predominately interact with class II MHC proteins
  • cytolytic T cells CD8 + predominately interact with class I MHC proteins.
  • MHC complexes are transmembrane proteins with a majority of their structure on the external surface of the cell. Additionally, both classes of MHC have a peptide binding cleft on their external portions. It is in this cleft that small fragments of proteins, native or foreign, are bound and presented to the extracellular environment.
  • APCs antigen presenting cells
  • MHC restriction it is the mechanism by which T cells differentiate "self from "non-self cells. If an antigen is not displayed by a recognizable MHC complex, the T cell will not recognize and act on the antigen signal.
  • T cells specific for the peptide bound to a recognizable MHC complex bind to these MHC-peptide complexes and proceed to the next stages of the immune response.
  • neoplastic cells are largely ignored by the immune system.
  • a great deal of effort is now being expended in an attempt to harness a host's immune system to aid in combating the presence of neoplastic cells in a host.
  • One such area of research involves the formulation of anticancer vaccines.
  • neoplastic cells are derived from and therefore are substantially identical to normal cells on a genetic level, many neoplastic cells are known to present tumor-associated antigens (TuAAs). In theory, these antigens could be used by a subject's immune system to recognize these antigens and attack the neoplastic cells. Unfortunately, neoplastic cells appear to be ignored by the host's immune system.
  • TuAAs tumor-associated antigens
  • 5,993,828 describes a method for producing an immune response against a particular subunit of the Urinary Tumor Associated Antigen by administering to a subject an effective dose of a composition comprising inactivated tumor cells having the Urinary Tumor Associated Antigen on the cell surface and at least one tumor associated antigen selected from the group consisting of GM-2, GD-2, Fetal Antigen and Melanoma Associated Antigen. Accordingly, this patent describes using whole, inactivated tumor cells as the immunogen m an anticancer vaccine. Another strategy used with anticancer vaccines involves administering a composition containing isolated tumor antigens.
  • MAGE-A1 antigemc peptides were used as an immunogen (See Chaux, P., et al , "Identification of Five MAGE-A1 Epitopes Recognized by Cytolytic T Lymphocytes Obtained by In Vitro Stimulation with Dendritic Cells Transduced with MAGE-A1," J. Immunol., 163(5):2928-2936 (1999)).
  • MAGE-A1 peptides for vaccination, although the effectiveness of the vaccination regimes was limited The results of some of these trials aie discussed in Vose, J M , "Tumor Antigens Recognized by T Lymphocytes," 10" 1 European Cancer Conference, Day 2, Sept 14, 1999.
  • Schemberg, et al. treated 12 chiomc myelogenous leukemia (CML) patients already receiving mterferon (IFN) or hydroxyurea with 5 injections of class I-associated bcr-abl peptides with a helper peptide plus the adjuvant QS-21.
  • CML chiomc myelogenous leukemia
  • IFN mterferon
  • hydroxyurea with 5 injections of class I-associated bcr-abl peptides with a helper peptide plus the adjuvant QS-21.
  • Scheibenbogen, et al. immunized 18 patients with 4 HLA class I restricted tyrosinase peptides, 16 with metastatic melanoma and 2 adjuvant patients.
  • Vaccine strategies to protect against viral diseases have had many successes. Perhaps the most notable of these is the progress that has been made against the disease small pox, which has been driven to extinction. The success of the polio vaccine is of a similar magnitude.
  • Viral vaccines can be grouped into three classifications: live attenuated virus vaccines, such as vaccinia for small pox, the Sabin poliovirus vaccine, and measles mumps and rubella; whole killed or inactivated virus vaccines, such as the Salk poliovirus vaccine, hepatitis A virus vaccine and the typical influenza virus vaccines; and subunit vaccines, such as hepatitis B. Due to their lack of a complete viral genome, subunit vaccines offer a greater degree of safety than those based on whole viruses. The paradigm of a successful subunit vaccine is the recombinant hepatitis B vaccine based on the viruses envelope protein.
  • the present invention is directed to methods and compositions for inducing an antigen presenting cell to present a particular target cell-specific epitope, thereby promoting a prolonged, directed cytotoxic T cell response to the target cell.
  • a vaccine including a housekeeping epitope derived from an antigen associated with a target cell.
  • the target cell may be a neoplastic cell.
  • the neoplastic cell can be any transformed cell associated with solid tumors or lymphomas such as leukemia, carcinoma, lymphoma, astrocytoma, sarcoma, glioma, retinoblastoma, melanoma, Wilm's tumor, bladder cancer, breast cancer, colon cancer, hepatocellular cancer, pancreatic cancer, prostate cancer, lung cancer, liver cancer, stomach cancer, cervical cancer, testicular cancer, renal cell cancer, and brain cancer.
  • the target cell can be infected by an intracellular parasite.
  • the intracellular parasite may be a virus such as an adenovirus, cytomegalovirus, Epstein-Barr virus, herpes simplex virus, human herpesvirus 6, varicella-zoster virus, hepatitis viruses, papilloma virus, parvovirus, polyomavirus, measles virus, rubella virus, human immunodeficiency virus (HIV), or human T cell leukemia virus.
  • the intracellular parasite may be a bacterium, protozoan, fungus, or a prion.
  • the intracellular parasite can be Chlamydia, Listeria, Salmonella, Legionella, Brucella, Coxiella, Rickettsia, Mycobacterium, Leishmania, Trypanasoma, Toxoplasma, and
  • the housekeeping epitope can be derived from an antigen associated with the target cell.
  • the antigen can be MelanA (MART-I), gplOO (Pmel 17), tyrosinase, TRP-1, TRP-2, MAGE-1, MAGE-3, BAGE, GAGE-1, GAGE-2, CEA, RAGE, NY-ESO, SCP-1, Hom Mel-40, PRAME, p53, H-Ras, HER-2/neu, BCR-ABL, E2A-PRL, H4-RET, IGH-IGK, MYL-RAR, Epstein Barr virus antigens, EBNA, human papillomavirus (HPV) antigens E6 and E7, TSP-180, MAGE-4, MAGE-5, MAGE-6, pl85erbB2, pl80erbB-3, c-met, nm-23Hl, PSA, TAG-72-4, CAM 17.1, NuMa, K-ras, ⁇ -Cat
  • the antigen can be a virus-associated antigen.
  • the antigen can be a parasite-associated antigen.
  • the housekeeping epitope may include or encode a polypeptide of about 6 to about 23 amino acids in length.
  • the polypeptide is 9 or 10 amino acids in length.
  • the polypeptide may be a synthetic polypeptide.
  • the vaccine additionally includes buffers, detergents, surfactants, anti-oxidants, or reducing agents.
  • the housekeeping epitope includes a nucleic acid.
  • the housekeeping epitope is specific for at least one allele of MHC. The allele can encode types Al, A2, A3, Al l, A24, A26, A29, B7, B8, B14, B18, B27, B35, B44, B62, B60, or B51.
  • the vaccine may include an immune epitope.
  • the immune epitope is derived from a second antigen associated with the target cell.
  • the first antigen and the second antigen may be the same or different.
  • the housekeeping epitope is specific for a first allele of MHC
  • the immune epitope is specific for a second allele of MHC.
  • the first allele and second allele may be the same or different.
  • the vaccine includes an epitope cluster (see below) that includes the immune epitope.
  • the epitope cluster can be derived from a second antigen associated with the target cell.
  • the first antigen and the second antigen may be the same or different.
  • the epitope cluster includes or encodes a polypeptide having a length of at least 10 amino acids but less than about 60 amino acids.
  • the length of the polypeptide of the epitope cluster is less than about 80%, 50%>, or 20%) of the length of the second antigen.
  • the vaccine further includes a second housekeeping epitope derived from a second antigen associated with a second target cell.
  • the first antigen and the second antigen can be the same.
  • the first and second antigen are different.
  • the first and second target cell may be the same or different.
  • the vaccine of the present invention may advantageously include a nucleic acid construct that encodes a housekeeping epitope derived from an antigen associated with a target cell.
  • the target cell is a neoplastic cell.
  • the neoplastic cell can be any transformed cell associated with solid tumors or lymphomas such as leukemia, carcinoma, lymphoma, astrocytoma, sarcoma, glioma, retinoblastoma, melanoma, Wilm's tumor, bladder cancer, breast cancer, colon cancer, hepatocellular cancer, pancreatic cancer, prostate cancer, lung cancer, liver cancer, stomach cancer, cervical cancer, testicular cancer, renal cell cancer, and brain cancer.
  • the target cell can be a cell infected by an intracellular parasite.
  • the intracellular parasite may be a virus.
  • the virus may be an adenovirus, cytomegalovirus, Epstein-Barr virus, herpes simplex virus 1, herpes simplex virus 2, human herpesvirus 6, varicella-zoster virus, hepatitis B virus, hepatitis D virus, papilloma virus, parvovirus B 19, polyomavirus BK, polyomavirus JC, hepatitis C virus, measles virus, rubella virus, human immunodeficiency virus (HIV), human T cell leukemia virus I, or human T cell leukemia virus II.
  • the intracellular parasite is a bacterium, protozoan, fungus, or prion.
  • the intracellular parasite can be Chlamydia, Listeria, Salmonella, Legionella, Brucella, Coxiella, Rickettsia, Mycobacterium, Leishmania, Trypanasoma, Toxoplasma, and Plasmodium.
  • the antigen of the vaccine including a nucleic acid construct may be MelanA (MART-I), gplOO (Pmel 17), tyrosinase, TRP-1, TRP-2, MAGE-1, MAGE-3, BAGE, GAGE-1, GAGE-2, CEA, RAGE, NY-ESO, SCP-1, Hom/Mel-40, PRAME, p53, H-Ras, HER-2/neu, BCR-ABL, E2A- PRL, H4-RET, IGH-IGK, MYL-RAR, Epstein Barr virus antigens, EBNA, human papillomavirus (HPV) antigens E6 and E7, TSP-180, MAGE-4, MAGE-5, MAGE-6, pl85erbB2, pl80erbB-3, c- met, nm-23Hl, PSA, TAG-72-4, CAM 17.1, NuMa, K-ras, ⁇ -Catenin, CDK4, Mum-1
  • the housekeeping epitope preferably encodes a polypeptide of about 6 to about 23 amino acids in length. More preferably, the housekeeping epitope encodes a polypeptide of 9 to 10 amino acids in length.
  • the housekeeping epitope is specific for at least one allele of
  • the allele can encode type Al, A2, A3, Al 1, A24, A26, A29, B7, B8, B14, B18, B27, B35,
  • the vaccine includes an immune epitope.
  • the immune epitope may be derived from a second antigen associated with the target cell.
  • the first antigen and second antigen may be the same or different.
  • the housekeeping epitope is specific for a first allele of MHC and the immune epitope is specific for a second allele of MHC.
  • the first allele and the second allele may be the same or different.
  • the vaccine with a nucleic acid construct additionally includes an epitope cluster.
  • the epitope cluster includes an immune epitope.
  • the epitope cluster is derived from a second antigen associated with the target cell.
  • the first antigen and the second antigen may be the same or different.
  • the epitope cluster includes or encodes a polypeptide having a length of at least 10 amino acids and less than about 60 amino acids.
  • the epitope cluster includes or encodes a polypeptide with a length less than about 80%> of the length of the second antigen.
  • the length of the polypeptide is less than about
  • the length of the polypeptide is less than about 20% of the length of the second antigen.
  • the vaccine including a nucleic acid construct further includes a second housekeeping epitope, wherein the second housekeeping epitope is derived from a second antigen associated with a second target cell.
  • the first antigen and the second antigen can be the same or different.
  • the first target cell and the second target cell are different.
  • the invention provides a nucleic acid construct including a first coding region, wherein the first coding region includes a first sequence encoding at least a first polypeptide, wherein the first polypeptide includes a first housekeeping epitope derived from a first antigen associated with a first target cell.
  • the first coding region can further include a second sequence encoding at least a second polypeptide, wherein the second polypeptide includes an second epitope derived from a second antigen associated with a second target cell.
  • the first polypeptide and the second polypeptide can contiguous or non-contiguous.
  • the second epitope can be a housekeeping epitope or an immune epitope.
  • the first antigen and the second antigen can be the same or different; likewise, the first and second target cells can be the same or different.
  • the target cell can be a neoplastic cell, such as, for example, leukemia, carcinoma, lymphoma, astrocytoma, sarcoma, glioma, retinoblastoma, melanoma, Wilm's tumor, bladder cancer, breast cancer, colon cancer, hepatocellular cancer, pancreatic cancer, prostate cancer, lung cancer, liver cancer, stomach cancer, cervical cancer, testicular cancer, renal cell cancer, or brain cancer.
  • a neoplastic cell such as, for example, leukemia, carcinoma, lymphoma, astrocytoma, sarcoma, glioma, retinoblastoma, melanoma, Wilm's tumor, bladder cancer, breast cancer, colon cancer, hepatocellular cancer, pancreatic cancer, prostate cancer, lung cancer, liver cancer, stomach cancer, cervical cancer, testicular cancer, renal cell cancer, or brain cancer.
  • the first antigen can be, for example, MART- 1 /MelanA, gplOO (Pmel 17), tyrosinase, TRP-1 , TRP-2, MAGE-1, MAGE-3, BAGE, GAGE-1, GAGE-2, pl5, NY-ESO, products of an SSX gene family member, CT-7, and products of an SCP gene family member.
  • MART- 1 /MelanA gplOO (Pmel 17)
  • tyrosinase TRP-1 , TRP-2, MAGE-1, MAGE-3, BAGE, GAGE-1, GAGE-2, pl5, NY-ESO, products of an SSX gene family member, CT-7, and products of an SCP gene family member.
  • the target cell can be infected by a virus such as, for example, adenovirus, cytomegalovirus, Epstein-Barr virus, herpes simplex virus 1 and 2, human herpesvirus 6, varicella-zoster virus, hepatitis B virus, hepatitis D virus, papillomavirus, parvovirus B19, polyomavirus BK, polyomavirus JC, hepatitis C virus, measles virus, rubella virus, human immunodeficiency virus (HIV), human T-cell leukemia virus I, or human T-cell leukemia virus II.
  • the target cell can likewise be infected by a bacterium, a protozoan, a fungus, a prion, or any other intracellular parasite, examples of which are
  • Chlamydia Listeria, Salmonella, Legionella, Brucella, Coxiella, Rickettsia, Mycobacterium, Leishmania, Trypanasoma, Toxoplasma, and Plasmodium.
  • the construct typically includes a first promoter sequence operably linked to the first coding region.
  • the promoter can be, for example, cytomegalovirus (CMV), SV40 and retroviral long terminal repeat (LTR).
  • CMV cytomegalovirus
  • LTR retroviral long terminal repeat
  • the promoter can be a bidirectional promoter, and/or a second promoter sequence can be operably linked to a second coding region.
  • the nucleic acid construct can further include a poly-A sequence operably linked to the first coding region, the second coding region, or both.
  • the nucleic acid construct can also include an internal ribosome entry site (IRES) sequence, a ubiquitin sequence, an autocatalytic peptide sequence, enliancers, nuclear import sequences, immunostimulatory sequences, and expression cassettes for cytokines, selection markers, reporter molecules, and the like.
  • the first polypeptide can be about 7 to 15 amino acids in length, and is preferably 9 or 10 amino acids in length.
  • the second polypeptide can be 9 or 10 amino acids in length, or it can be an epitope cluster between about 10 and about 75 amino acids in length. The first epitope and second epitopes can bind the same or different alleles of MHC.
  • inventions include a vaccine that includes any of the foregoing nucleic acid construct embodiments; a method of treating an animal by administering such a vaccine; and a method of making the vaccine.
  • inventions disclosed herein relate to the identification of epitope cluster regions that are used to generate pharmaceutical compositions capable of inducing an immune response from a subject to whom the compositions have been administered.
  • One embodiment of the disclosed invention relates to an epitope cluster, the cluster being derived from an antigen associated with a target, the cluster including or encoding at least two sequences having a known or predicted affinity foi an MHC receptor peptide binding cleft, wherein the cluster is a fragment of the antigen
  • the target is a neoplastic cell
  • the target may be a cell infected by an intracellular parasite
  • the mtiacellular parasite can be a virus, a bacterium or a protozoan
  • the target is a pathogenic agent
  • the pathogenic agent can include a virus, a bacterium, a fungus, a protozoan, a prion, a toxin, or a venom
  • the MHC receptor may be a class I HLA receptor.
  • the MHC receptor can be a class II HLA receptor.
  • the cluster includes or encodes a polypeptide having a length, wherein the length is at least 10 ammo acids.
  • the length of the polypeptide may be less than about 75 ammo acids.
  • an antigen having a length wherein the cluster consists of or encodes a polypeptide having a length, wherein the length of the polypeptide is less than about 80% of the length of the antigen.
  • the length of the polypeptide is less than about 50% of the length of the antigen.
  • the length of the polypeptide is less than about 20% of the length of the antigen
  • Anothei embodiment of the disclosed invention relates to a method of identifying an epitope cluster including the steps of. providing a sequence of an antigen associated with a target cell, scoring candidate peptides within the sequence, based on known or predicted affinity for an
  • MHC receptor peptide binding cleft to identify putative MHC epitopes; and identifying a region within the antigen, wherein the region includes at least two of the putative MHC epitopes, and wherein the region comprises a higher density of putative MHC epitopes than a density of putative
  • the MHC epitopes m the antigen as a whole.
  • Another embodiment relates to an epitope cluster.
  • the cluster can be derived from an antigen associated with a target.
  • the cluster can include or can encode at least two sequences having a known or predicted affinity for an MHC receptor peptide binding cleft.
  • the cluster can be a fragment of the antigen, for example.
  • the cluster can have the structure:
  • X is any amino acid naturally occurring in protein sequence
  • -1) are strings of such amino acids of length 'a' and '
  • -l) represents the number of amino acids between P2 N and P ] ;
  • P2 is a first primary anchor and second residue of a first epitope
  • P2 N is a first primary anchor and second residue of an Nth epitope
  • P i is a last primary anchor and C-terminal residue of the first epitope
  • P N is a last primary anchor and C-terminal residue of the Nth epitope
  • 2 N Nc, N indicating the Nth epitope of the cluster and Nc the total number of epitopes in the cluster
  • a N and b N defining the positional relationship between the 1 st and Nth epitope.
  • (Nc/Lc) can be > (Np/Lp), the cluster and antigen each having a length, where Lc is the length of the cluster, Lp is the length of the antigen, and Np is the total number of epitopes in the antigen.
  • inventions relate to an isolated polypeptide comprising the epitope cluster according to the structure as described above and herein, wherein the amino acid sequence consists of not more than about 80% of the amino acid sequence of the antigen, for example.
  • embodiments also relate to a vaccine or an immunotherapeutic product that include the isolated polypeptide.
  • the isolated polypeptide can be encoded by an isolated polynucleotide, for example.
  • a vaccine or immunotherapeutic product can include the polynucleotide.
  • the polynucleotide can be DNA, for example.
  • the polynucleotide can be RNA, for example.
  • a method of treating an animal by administering to an animal a vaccine including a first housekeeping epitope, wherein the housekeeping epitope is derived from a first antigen associated with a first target cell is similarly contemplated by the present invention.
  • the administering step includes a mode of delivery that is transdermal, intranodal, perinodal, oral, intravenous, intradermal, intramuscular, intraperitoneal, or mucosal.
  • the method of treating an animal may additionally include an assaying step to deteimine a characteristic indicative of a state of the target cells.
  • the assaying step may further include a first assaying step and a second assaying step, wherein the first assaying step precedes the administering step, and the second assaying step follows the administering step.
  • the characteristic determined in the first assaying step is compared with the characteristic determined in the second assaying step to obtain a result.
  • the result can be a diminution in number of target cells, a loss of mass or size of a tumor comprising target cells, or a decrease in number or concentration of an intracellular parasite infecting target cells.
  • the target cell is a neoplastic cell.
  • the neoplastic cell can be any transformed cell associated with solid tumors or lymphomas such as leukemia, carcinoma, lymphoma, astrocytoma, sarcoma, glioma, retinoblastoma, melanoma, Wilm's tumor, bladder cancer, breast cancer, colon cancer, hepatocellular cancer, pancreatic cancer, prostate cancer, Lung cancer, liver cancer, stomach cancer, cervical cancer, testicular cancer, renal cell cancer, and brain cancer.
  • the target cell is infected by an intracellular parasite.
  • the intracellular parasite may be a virus.
  • the virus can be adenovirus, cytomegalovirus, Epstein-Barr virus, herpes simplex virus
  • the intracellular parasite may be a bacterium, protozoan, fungus, or a prion.
  • the intracellular parasite is Chlamydia, Listeria, Salmonella,
  • the antigen is MelanA (MART-I), gplOO (Pmel 17), tyrosinase, TRP-1, TRP-2, MAGE-1, MAGE-3, BAGE, GAGE-1, GAGE-2, CEA, RAGE, NY- ESO, SCP-1, Hom/Mel-40, PRAME, p53, H-Ras, HER-2/neu, BCR-ABL, E2A-PRL, H4-RET,
  • the antigen is associated with a virus or viral infection.
  • the antigen is an antigen associated with non-viral intracellular parasites.
  • the housekeeping epitope may include or encode for a polypeptide of about 6 to about 23 amino acids in length. Preferably, the polypeptide is 9 or 10 amino acids in length.
  • the polypeptide may be synthetic.
  • the vaccine may additionally include buffers, detergents, surfactants, anti-oxidants, or reducing agents.
  • the housekeeping epitope may advantageously include a nucleic acid. Preferably, the housekeeping epitope is specific for at least one allele of
  • the allele can encode types Al, A2, A3, Al l, A24, A26, A29, B7, B8, B14, B18, B27, B35, B44, B62, B60, or B51.
  • the method of treating an animal further includes an immune epitope.
  • the immune epitope may be derived from a second antigen associated with the target cell.
  • the first antigen and the second antigen are the same.
  • the housekeeping epitope can be specific for a first allele of MHC, and the immune epitope can be specific for a second allele of MHC.
  • the first allele and the second allele may be the same or different.
  • the vaccine includes an epitope cluster that includes the immune epitope.
  • the epitope cluster may be derived from a second antigen associated with the target cell.
  • the first antigen and the second antigen are the same.
  • the epitope cluster may include or encode a polypeptide having a length of at least 10 amino acids and less than about 60 amino acids.
  • the epitope cluster includes or encodes a polypeptide having a length less than about 80%) of the length of the second antigen.
  • the length of the polypeptide can be less than about 50% of the length of the second antigen. In still another aspect, the length of the polypeptide can be less than about 20% of the length of the second antigen.
  • the method of treating an animal may further include a second housekeeping epitope, wherein the second housekeeping epitope is derived from a second antigen associated with a second target cell.
  • the first antigen and the second antigen may be the same or different.
  • the first target cell and the second target cell may be the same or different.
  • a method of treating an animal including administering to an animal a vaccine comprising a nucleic acid construct is also contemplated by the present invention.
  • the nucleic acid construct advantageously encodes a housekeeping epitope.
  • the housekeeping epitope may be derived from a first antigen associated with a first target cell.
  • a method of making a vaccine includes the steps of selecting a housekeeping epitope by identifying epitopes that are or could be produced from a particular antigen source by housekeeping proteasomes wherein the housekeeping epitope is derived from a first antigen associated with a first target cell, making a vaccine including the housekeeping epitope, and preparing a vaccine composition that includes or encodes the selected housekeeping epitope.
  • the vaccine made in accordance with the aforementioned method is likewise provided by the present invention.
  • the vaccine can be administered to treat an animal.
  • a method of treating an animal with the vaccine is similarly contemplated.
  • inventions disclosed herein are directed to the identification of epitopes that are useful for generating vaccines capable of inducing an immune response from a subject to whom the compositions have been administered, particularly those epitopes most useful in the vaccine embodiments of the invention.
  • One embodiment of the invention relates to a method of epitope discovery comprising the step of selecting an epitope from a population of peptide fragments of an antigen associated with a target cell, wherein the fragments have a known or predicted affinity for a major histocompatibility complex class I receptor peptide binding cleft, wherein the epitope selected corresponds to a proteasome cleavage product of the target cell.
  • Another embodiment of the invention relates to a method of discovering an epitope comprising the steps of: providing a sequence from a target cell, wherein the sequence encodes or comprises a protein expressed in the target cell; identifying a population of peptide fragments of the protein, wherein members of the population of peptide fragments have a known or predicted affinity for a major histocompatibility complex class I receptor peptide binding cleft; selecting the epitope from the population of peptide fragments, wherein the epitope corresponds to a product of a proteasome active in the target cell.
  • One aspect of this embodiment relates an epitope discovered by the aforementioned method. Another aspect of this embodiment relates to a vaccine comprising the discovered epitope. Still another aspect of the invention relates to a method of treating an animal, comprising administering to the animal the aforementioned vaccine.
  • One embodiment of the disclosed invention relates to a method of epitope discovery comprising the steps of: providing a neoplastic cell and a sequence, wherein the sequence comprises or encodes an antigen associated with the neoplastic cell; identifying a population of peptide fragments of the antigen, wherein the population of peptide fragments is predicted to have an affinity for a major histocompatibility complex class I receptor peptide binding cleft; selecting an epitope from the population of peptide fragments, wherein the epitope is determine by in vitro analysis to be a proteasome cleavage reaction product of a proteasome active in the neoplastic cell.
  • One aspect of this embodiment relates an epitope discovered by the aforementioned method. Another aspect of this embodiment relates to a vaccine comprising the discovered epitope. Still another aspect of the invention relates to a method of treating an animal, comprising administering to the animal the aforementioned vaccine.
  • Another embodiment of the disclosed invention relates to a method of epitope discovery comprising the step of selecting an epitope from a population of peptide fragments of an antigen associated with a target in a host, wherein the fragments have a known or predicted affinity for a major histocompatibility complex class I or II receptor peptide binding cleft of the host, wherein the epitope selected corresponds to a product of proteolytic cleavage of the antigen in a cell of the host.
  • One aspect of this embodiment relates an epitope discovered by the aforementioned method. Another aspect of this embodiment relates to a vaccine comprising the discovered epitope. Still another aspect of the invention relates to a method of treating an animal, comprising administering to the animal the aforementioned vaccine. Another embodiment relates to an isolated T cell expressing a T cell receptor specific for an MHC-peptide complex including a first housekeeping epitope.
  • the housekeeping epitope can be derived from a first antigen associated with a first target cell, for example.
  • a T cell clone can include the T cell, for example.
  • a polyclonal population of T cells can include the T cell, for example.
  • the T cell can be produced by an in vitro immunization, for example.
  • the T cell of can be isolated from an immunized animal, for example.
  • the method can include, for example, combining the T cell as described herein with a pharmaceutically acceptable adjuvant, carrier, diluent, excipient, and the like.
  • the T cell can be originally obtained from a donor, for example.
  • the donor can be an intended recipient of the immunotherapeutic, for example.
  • the donor can be immunologically na ⁇ ve with respect to the first antigen.
  • the donor can have been previously exposed to the first antigen, for example.
  • the donor can be vaccinated with the housekeeping epitope prior to donation, for example.
  • the method of making an adoptive immunotherapeutic can further include the step of culturing the T cell in vitro.
  • the T cell can be stimulated to grow by exposure to the MHC-peptide complex, for example.
  • the T cell can be stimulated to grow by exposure to cytokines, and the like, for example.
  • the culture further can include a pAPC, an adjuvant, a combination thereof, and the like.
  • the pAPC can be a dendritic cell, for example.
  • the adjuvant can be, for example, GM-CSF, G-CSF, IL-2, IL-12, BCG, tetanus toxoid, osteopontin/ETA-1, CD40 ligand, a CTLA-4 blockade agent, and the like.
  • embodiments of the invention relate to the use of the T cell, as described herein in the manufacture of a medicament for use in adoptive immunotherapy.
  • Other embodimetns relate to a method of treating an illness comprising administering to a recipient the T cell as described herein.
  • Another embodiment relates to a method of treating an illness comprising administering to a recipient the immunotherapeutic made according to the methods described herein.
  • Figure 1 depicts schematically the parts of a cell involved in protein processing by the proteasome and epitope presentation.
  • Figure 2 is a comparison of the housekeeping proteasome and the immune proteasome.
  • Figure 3 depicts schematically epitope synchronization between infected cells and pAPCs.
  • Figure 4 shows presentation of different epitopes by pAPCs and tumor cells.
  • Figure 5 shows presentation of different epitopes by pAPCs and infected cells.
  • Figure 6 depicts presentation by tumor cells of both housekeeping and immune epitopes due to induction by IFN-gamma.
  • Figure 7 shows an attack of virally infected cells by T cells induced to recognize a housekeeping epitope.
  • Figure 8 shows a dual attack against both housekeeping and immune epitopes.
  • Figure 9 is a positional plot of the predicted HLA-A*0201 epitopes in tyrosinase.
  • Figure 10A is a depiction of the components of plasmid pVAX-EPl-IRES-EP2-ISS-NIS.
  • Figure 1 OB is a depiction of the components of plasmid pVAX-EPl-IRES-EP2.
  • Figure 11 is a depiction of the components of plasmid pVAX-EP2-UB-EPl.
  • Figure 12 is a depiction of the components of plasmid pVAX-EP2-2A-EPl.
  • Figure 13 depicts the results of a flow cytometry assay verifying HLA binding by Melan-A epitopes.
  • Figure 14 depicts the results of a flow cytometry assay verifying HLA binding by Tyrosinase peptide 207-216.
  • Figure 15 depicts the sequence of Melan-A (SEQ ID NO: 1), showing clustering of class I HLA epitopes.
  • Figure 16 depicts the sequence of SSX-2 (SEQ ID NO: 2), showing clustering of class I
  • Figure 17 depicts the sequence of NY-ESO (SEQ ID NO: 3), showing clustering of class I HLA epitopes.
  • Figure 18 depicts the sequence of Tyrosinase (SEQ ID NO: 4), showing clustering of class I HLA epitopes predicted by the BIMAS-NIH/Parker algorithm above the line of sequence and by the SYFPEITHI/Rammensee algorithm below.
  • Embodiments of the present invention provide epitopes, vaccines, and therapeutic methods for directing an effective immune response against a target cell.
  • a primary basis of the invention is the novel and unexpected discovery that many target cells display epitopes that are different from the epitopes displayed by professional antigen presenting cells (pAPCs). Because of this difference, the pAPCs direct T cells against epitopes that are not present on the target cells, and the T cells therefore fail to recognize the target cells.
  • the methods and medicaments of the present invention can cause pAPCs to display the same epitopes that are present on target cells, resulting in
  • Embodiments of the invention disclosed herein further provide methods for identifying epitopes of target antigens that can be used to generate immunologically effective vaccines. Such vaccines can stimulate the immune system to recognize and destroy target cells displaying the selected epitopes.
  • Embodiments of the invention are particularly useful in the treatment and prevention of cancers and of infections of cells by intracellular parasites, as well as in the treatment or prevention of conditions associated with other pathogens, toxins, and allergens.
  • targets are particularly elusive to the immune system.
  • targets are many kinds of cancer, as well as cells infected by intracellular parasites, such as, for example, viruses, bacteria, and protozoans.
  • a great deal of research has been done to identify useful antigens and epitopes for generating an effective immune response against such targets, with little success.
  • This disclosure provides a basis for the efficient discovery of a new generation of effective epitopes effective against such elusive targets.
  • the invention disclosed herein makes it possible to select epitope sequences with true biological relevance.
  • an epitope For an epitope to have biological significance, e.g., to function in stimulating an immune response, it must have an affinity for the binding cleft of a major histocompatibility complex (MHC) receptor peptide.
  • MHC major histocompatibility complex
  • the methods of the disclosed invention permit the vaccine designer to ignore peptides that, despite predicted high binding affinity for MHC, will never be useful because they cannot be presented by target cells.
  • methods and teachings disclosed herein provide a major advance in vaccine design, one that combines the power of antigen sequence analysis with the fundamental realities of immunology.
  • the methods taught herein allow for the simple and effective selection of meaningful epitopes for creation of MHC class I or class II vaccines using any polypeptide sequence corresponding to a desired target.
  • ECRs epitope cluster regions
  • embodiments of the invention relate to identifying epitope clusters for use in generating immunologically active compositions directed against target cell populations, and for use in the discovery of discrete housekeeping epitopes and immune epitopes.
  • numerous putative class I MHC epitopes may exist in a single target-associated antigen (TAA).
  • TAA target-associated antigen
  • Such putative epitopes are often found in clusters (ECRs), MHC epitopes distributed at a relatively high density within certain regions in the amino acid sequence of the parent TAA.
  • ECRs include multiple putative epitopes with potential useful biological activity in inducing an immune response, they represent an excellent material for in vitro or in vivo analysis to identify particularly useful epitopes for vaccine design. And, since the epitope clusters can themselves be processed inside a cell to produce active MHC epitopes, the clusters can be used directly in vaccines, with one or more putative epitopes in the cluster actually being processed into an active MHC epitope.
  • the use of ECRs in vaccines offers important technological advances in the manufacture of recombinant vaccines, and further offers crucial advantages in safety over existing nucleic acid vaccines that encode whole protein sequences. Recombinant vaccines generally rely on expensive and technically challenging production of whole proteins in microbial fermentors.
  • ECRs offer the option of using chemically synthesized polypeptides, greatly simplifying development and manufacture, and obviating a variety of safety concerns.
  • the ability to use nucleic acid sequences encoding ECRs, which are typically relatively short regions of an entire sequence allows the use of synthetic oligonucleotide chemistry processes in the development and manipulation of nucleic acid based vaccines, rather than the more expensive, time consuming, and potentially difficult molecular biology procedures involved with using whole gene sequences. Since an ECR is encoded by a nucleic acid sequence that is relatively short compared to that which encodes the whole protein from which the ECR is found, this can greatly improve the safety of nucleic acid vaccines.
  • nucleic acid vaccines An important issue in the field of nucleic acid vaccines is the fact that the extent of sequence homology of the vaccine with sequences in the animal to which it is administered determines the probability of integration of the vaccine sequence into the genome of the animal.
  • a fundamental safety concern of nucleic acid vaccines is their potential to integrate into genomic sequences, which can cause deregulation of gene expression and tumor transformation.
  • the Food and Drug Administration has advised that nucleic acid and recombinant vaccines should contain as little sequence homology with human sequences as possible. In the case of vaccines delivering tumor-associated antigens, it is inevitable that the vaccines contain nucleic acid sequences that are homologous to those which encode proteins that are expressed in the tumor cells of patients.
  • a housekeeping epitope includes peptide fragments produced by the active proteasome of a peripheral cell.
  • a basis for the present invention is the discovery that any antigen associated with a target cell can be processed differentially into two distinguishable sets of epitopes for presentation by the class I major histocompatibility complex (MHC) molecules of the body.
  • MHC major histocompatibility complex
  • Immunotopes are presented by pAPCs and, also generally in peripheral cells that are acutely infected or under active immunological attack by interferon (IFN) secreting cells.
  • IFN interferon
  • housekeeping epitopes are presented by all other peripheral cells including, generally, neoplastic (cancerous) cells and chronically infected cells. This mismatch, or asynchrony, in presented epitopes underlies the persistence and advance of cancers and chronic infections, despite the presence of a functioning immune system in the host. It is thus essential to bring about synclironization of epitope presentation between the pAPC and the target cell in order to provoke an effective, cytolytic T lymphocyte (CTL)- mediated immune response.
  • CTL cytolytic T lymphocyte
  • Synchronization can be accomplished most reliably by providing the pAPC with a housekeeping epitope. Often a more robust response can be achieved by providing more than a single epitope. Additionally, once an effective immune response against the target cells has been established, secretion of IFN may lead to expression of the immune proteasome, thereby switching epitope presentation to immune epitopes. For this reason, among others, it can also be advantageous to include immune epitopes, in addition to housekeeping epitopes, in vaccines developed according to the above referenced disclosure. It can be of further utility to provide immune epitopes in the form of an ECR. Embodiments of the invention provide expression vectors encoding housekeeping epitopes and/or immune epitopes in a variety of combinations.
  • Preferred expression constructs encode at least one epitope capable of stimulating a cellular immune response directed against a target cell.
  • target cells are neoplastic cells.
  • target cells are any intracellularly infected host cell.
  • Intracellular infective agents include persistent viruses and any other infectious organism that has an intracellular stage of infection.
  • the nucleic acid constructs of some embodiments are directed to enhancing a subject's immune system and sensitizing it to the presence of neoplastic cells within the host. In other embodiments, the nucleic acid constructs facilitate the eradication of persistent viral infections as well as cells infected with intracellular parasites.
  • PROFESSIONAL ANTIGEN-PRESENTING CELL a cell that possesses T cell costimulatory molecules and is able to induce a T cell response.
  • Well characterized pAPCs are dendritic cells, B cells, and macrophages.
  • PERIPHERAL CELL - a cell that is not a pAPC.
  • HOUSEKEEPING PROTEASOME - a proteasome normally active in peripheral cells, and generally not present or not strongly active in pAPCs.
  • IMMUNE PROTEASOME - a proteasome normally active in pAPCs; the immune proteasome is also active in some peripheral cells in infected tissues.
  • epitopes according to this definition include but are not necessarily limited to a polypeptide and a nucleic acid encoding a polypeptide, wherein the polypeptide is capable of stimulating an immune response.
  • epitopes according to this definition include but are not necessarily limited to peptides presented on the surface of cells non- covalently bound to the pocket of class I MHC, such that they can interact with T cell receptors.
  • MHC EPITOPE - a polypeptide having a known or predicted affinity for a mammalian class I major histocompatibility complex (MHC) molecule.
  • MHC mammalian class I major histocompatibility complex
  • HLA EPITOPE - a polypeptide having a known or predicted affinity for a human class I major histocompatibility complex (MHC) molecule.
  • MHC major histocompatibility complex
  • a housekeeping epitope is defined as a polypeptide fragment that is an MHC epitope, and that is displayed on a cell in which housekeeping proteasomes are predominantly active.
  • a housekeeping epitope is defined as a polypeptide containing a housekeeping epitope according to the foregoing definition, that is flanked by one to several additional amino acids.
  • a housekeeping epitope is defined as a nucleic acid that encodes a housekeeping epitope according to either of the foregoing definitions.
  • an immune epitope is defined as a polypeptide fragment that is an MHC epitope, and that is displayed on a cell in which immune proteasomes are predominantly active.
  • an immune epitope is defined as a polypeptide containing an immune epitope according to the foregoing definition, that is flanked by one to several additional amino acids.
  • an immune epitope is defined as a polypeptide including an epitope cluster sequence, having at least two polypeptide sequences having a known or predicted affinity for a class I MHC.
  • an immune epitope is defined as a nucleic acid that encodes an immune epitope according to any of the foregoing definitions.
  • TARGET CELL - a cell to be targeted by the vaccines and methods of the invention.
  • target cells include but are not necessarily limited to: a neoplastic cell and a cell harboring an intracellular parasite, such as, for example, a virus, a bacterium, or a protozoan.
  • TUMOR-ASSOCIATED ANTIGEN (TuAA) - a TAA, wherein the target cell is a neoplastic cell.
  • Epitopes presented by class I MHC on the surface of either pAPCs or peripheral cells are produced by digestion of proteins within those cells by proteasomes. Wlder it has been reported that the proteasomes of pAPCs are not identical to the proteasomes of peripheral cells, the significance of this difference has been heretofore unappreciated.
  • This invention is based on the fact that when pAPCs and peripheral cells process a given TAA, the proteasomes active in the pAPCs generate epitope fragments that are different from the epitope fragments generated by the proteasomes that are active in the peripheral cells.
  • proteasomes that are predominantly active in pAPCs are referred to herein as “immune proteasomes” while the proteasomes that are normally active in peripheral cells are referred to herein as “housekeeping proteasomes.”
  • CTL responses are induced by pAPCs, by definition they target immune epitopes rather than housekeeping epitopes and thus fail to recognize target cells, which are therefore able to persist in the body.
  • This fundamental "epitope compartmentalization" of the cellular immune response is the reason that some neoplastic cells can persist to form tumors; it is also the reason that some viruses and intracellular parasites can chronically infect cells without being eradicated by the immune system.
  • infectious agents normally they cause the expression of immune proteasomes in the cells they infect. This results in the production of epitopes on the cell surface that are identical to those being presented by pAPCs to the immune system.
  • Epitope synchronization in this context means that the pAPCs are made to present housekeeping epitopes, resulting in CTLs that can recognize the housekeeping epitopes displayed on target cells, and thereby attack and eliminate the target cells.
  • embodiments of the invention are useful for treating neoplastic diseases including solid tumors and lymphomas. Additional embodiments of the invention have application in treating persistent viral infections as well as parasitic infections in which the infective agent has an intracellular stage of infection. Appropriate administration of housekeeping epitopes corresponding to such target cells can activate a specific, cytotoxic T cell response against the target cells.
  • the present invention is directed to treating neoplastic diseases.
  • Cancers are caused by the progressive, unregulated growth of the progeny of a single abnormal cell.
  • the term "cancer” as used herein includes neoplastic diseases, neoplastic cells, tumors, tumor cells, malignancies and any transformed cell, including both solid tumors and diffuse neoplastic disease.
  • cancer cells generally have been thought to escape detection and destruction by the immune system because cancer cells contain the same genetic material as other non- cancerous cells of the body. The genetic identity or similarity of cancer cells and healthy cells in the body supposedly causes the difficulty of distinguishing cancer cells from normal cells, and the immune system is therefore unable to mount an effective immune response, as evidenced by the persistence of cancer cells in the body.
  • TuAAs tumor associated antigens
  • TILs tumor infiltrating lymphocytes
  • TILs in vitro.
  • the failure of TILs to control cancer results from a difference in the epitopes produced and presented by the cells which induce CTL activity, the pAPC, and the desired target cells, i.e., those of the tumor.
  • CTL activity the epitopes produced and presented by the cells which induce CTL activity, the pAPC, and the desired target cells, i.e., those of the tumor.
  • proteasomes all cells contain proteasomes to degrade proteins. These proteasomes, which comprise about 1 % of the total protein content of the cell, serve to regulate protein half-life in the cell.
  • proteasomes In the course of protein degradation, proteasomes generate the vast majority of peptide fragments involved in Class 1 antigen presentation, and the proteasome cleavage patterns affect the availability of antigenic epitopes for presentation on Class I molecules ( Figure 1). Thus MHC epitopes are produced by the proteasomal activity of cells. However, the proteolytic activity in pAPCs, as compared to peripheral cells, is markedly different.
  • the pAPCs contain a proteasome that constitutively incorporates subunits that are typically only expressed in peripheral cells during infection or after exposure to various cytokines, particularly interferon (IFN), as part of a cellular immune response.
  • IFN interferon
  • the immune and housekeeping proteasomes have the capacity to cleave proteins at similar but distinct locations.
  • the immune proteasome incorporates several subunits that distinguish it from its housekeeping counterpart. These immune subunits include LMP2, LMP7, and MECL1, which replace the catalytic subunits of the housekeeping proteasome, and PA28 and PA28B, which serve a regulatory function (Figure 2).
  • LMP2, LMP7, and MECL1 which replace the catalytic subunits of the housekeeping proteasome
  • PA28 and PA28B which serve a regulatory function
  • IFN- ⁇ is produced by T lymphocytes, where it is involved in promoting the induction of cellular immune responses and, as noted above, induces expression of the immune proteasome.
  • IFN is also produced by virtually any other cell under one condition: in the event that the cell becomes infected by a pathogen.
  • viral infection typically causes IFN production by the infected cell, which in turn induces the cell to convert from a housekeeping proteasome configuration to an immune proteasome configuration.
  • TuAAs are useful targets of a tumor-specific T cell response to the extent that they are not displayed on the surface of normal cells, or are overexpressed by the tumor cells, or are otherwise strongly characteristic of tumor cells. Numerous TuAAs are known and are readily available to those of skill in the art in the literature or commercially.
  • peripheral target cells including tumor cells, and some cells infected by a virus or other intracellular parasite (all of which express the housekeeping proteasome), necessarily display different epitope signals than the epitope signals that T cells are conditioned by pAPCs to recognize.
  • pAPCs intracellular parasite
  • T lymphocyte responses are primed against TuAA that have been processed by the pAPC.
  • CTLs found among TILs are hopelessly targeting class I TuAAs that were present on the pAPC, but not on the tumor cells ( Figure 4).
  • the behavior of tumor cells in the body namely migration, antigen shedding, induction of inflammatory responses, etc., results in strong immune responses.
  • the present invention is directed to the treatment and prevention of intracellular infection by various pathogens.
  • pathogens include, but are not limited to: any viruses, bacteria, protozoa, prions or other organisms that have an intracellular stage of infection in the host.
  • Viral antigen presentation by the pAPCs begins with the digestion of viral antigens into peptides by the proteasome. After the proteasome digests the protein into peptides, some of the peptides are loaded onto the class I complex in the endoplasmic reticulum and transported to the cell surface. At the cell surface, the class I-peptide complex is recognized by T cell receptors on the surface of CTLs and the infected cells are killed.
  • Other mechanisms by which certain viruses may elude the immune system have also been proposed, including "immunologically privileged" sites of viral infection and antigenic variation in key viral peptides. While these models may explain the persistence of certain viruses, the concept of epitope synchronization, or conversely, epitope compartmentalization, provides a solution. Namely, this concept provides a basis for vaccines to direct an effective cellular immune response against any virus or other intracellular parasite that eludes the immune system by blocking immune proteasome expression in the host cells, or otherwise preventing effective epitope synchronization between infected cells and the pAPCs. (Figure 5).
  • the proteasome in infected tissue typically switches from the housekeeping configuration to an immune configuration. Infection thus has the effect of aligning the infected cell, in terms of the antigen repertoire it displays on its surface, with that of the pAPCs involved in stimulating the immune response against the virus or other intracellular pathogen.
  • virally infected cells or parasitically infected cells are induced to express an immune proteasome, rather than the housekeeping proteasome, the result is "epitope synchronization" between the infected cells and the pAPCs, and subsequent eradication of the infected cells by CTL.
  • viruses such as adenovirus, cytomegalovirus, Epstein-Barr virus, herpes simplex virus 1, herpes simplex virus 2, human herpesvirus 6, varicella-zoster virus, hepatitis B virus, hepatitis D virus, papilloma virus, parvovirus B19, polyomavirus BK, polyomavirus JC, hepatitis C vims, measles vims, rubella virus, human immunodeficiency virus (HIV), human T cell leukemia vims I, and human T cell leukemia virus II; bacteria such as Chlamydia, Listeria, Salmonella, Legionella, Brucella, Coxiella, Rickettsia, Mycobacterium; and protozoa such as Leishmania, Trypanasoma, Toxoplasma, and Plasmodium.
  • viruses such as adenovirus, cytomegalovirus, Epstein-Barr virus, herpes simplex virus 1, her
  • the vaccines and methods of preferred embodiments of the present invention thus represent, essentially, a "reverse" epitope synchronization, causing the pAPCs to display housekeeping epitopes to address situations in which target cells do not display immune epitopes. ( Figures 6 and 7). Certain embodiments also provide a second wave of epitope synchronization by inducing pAPCs to display both housekeeping epitopes and immune epitopes corresponding to a selected target cell.
  • Preferred embodiments of the present invention are directed to vaccines and methods for causing a pAPC or population of pAPCs to present housekeeping epitopes that correspond to the epitopes displayed on a particular target cell.
  • the housekeeping epitope is a TuAA epitope processed by the housekeeping proteasome of a particular tumor type.
  • the housekeeping epitope is a virus-associated epitope processed by the housekeeping proteasome of a cell infected with a virus. This facilitates a specific T cell response to the target cells.
  • Concurrent expression by the pAPCs of multiple epitopes can drive a CTL response effective against target cells as they display either housekeeping epitopes or immune epitopes.
  • Figure 8 By having both housekeeping and immune epitopes present on the pAPC, this embodiment can optimize the cytotoxic T cell response to a target cell.
  • the pAPCs can continue to sustain a CTL response to the immune-type epitope when the tumor cell switches from the housekeeping proteasome to the immune proteasome with induction by IFN, which, for example, may be produced by tumor-infiltrating CTLs.
  • immunization of a patient is with a vaccine that includes a housekeeping epitope.
  • Many preferred TAAs are associated exclusively with a target cell, particularly in the case of infected cells.
  • many preferred TAAs are the result of deregulated gene expression in transformed cells, but are found also in tissues of the testis, ovaries and fetus.
  • useful TAAs are expressed at higher levels in the target cell than in other cells.
  • TAAs are not differentially expressed in the target cell compared to other cells, but are still useful since they are involved in a particular function of the cell and differentiate the target cell from most other peripheral cells; in such embodiments, healthy cells also displaying the TAA may be collaterally attacked by the induced T cell response, but such collateral damage is considered to be far preferable to the condition caused by the target cell.
  • preferred antigens include TuAAs.
  • protein antigens suitable for use include differentiation antigens such as MelanA (MART-I), gplOO (Pmel 17), tyrosinase, TRP-1, TRP-2, and tumor-specific multilineage antigens such as MAGE-1, MAGE-3, BAGE, GAGE-1, GAGE-2, CEA, RAGE, NY-ESO, SCP-1, Hom/Mel-40 and PRAME.
  • differentiation antigens such as MelanA (MART-I), gplOO (Pmel 17), tyrosinase, TRP-1, TRP-2, and tumor-specific multilineage antigens such as MAGE-1, MAGE-3, BAGE, GAGE-1, GAGE-2, CEA, RAGE, NY-ESO, SCP-1, Hom/Mel-40 and PRAME.
  • TuAAs include overexpressed oncogenes, and mutated tumor-suppressor genes such as p53, H-Ras and HER-2/neu.
  • TuAAs resulting from chromosomal rranslocations such as BCR-ABL, E2A-PRL, H4-RET, IGH-IGK, MYL-RAR and viral antigens such as Epstein Barr virus antigens EBNA, and the human papillomavirus (HPV) antigens E6 and E7 are included.
  • Other useful protein antigens include but are not limited to TSP-180, MAGE-4, MAGE-5, MAGE-6, pl85erbB2, pl80erbB-3, c-met, nm-23Hl, PSA, TAG-72-4, CAM 17.1,
  • the TAA is an antigen specific for a vims. See Table 2.
  • the TAA is an antigen specific for a non-viral intracellular parasite.
  • parasite-specific antigens include nucleotides, proteins, or other gene products associated with the intracellular parasite . Suitable nucleotides or proteins can be found at the NCBI Taxonomy Database located at http://www.ncbi.nlm.nih.gov/Taxonomy/tax.html/ . More detailed descriptions of gene products for parasites and other pathogens are provided at this web site.
  • Proteolytic Processing of Antigens Epitopes that are displayed by MHC on target cells or on pAPCs are cleavage products of larger protein antigen precursors.
  • protein antigens are digested by proteasomes resident in the cell. See Figure 1. Intracellular proteasomal digestion typically produces peptide fragments of about 3 to 23 amino acids in length. Additional proteolytic activities within the cell, or in the exttaceUular milieu, can trim and process these fragments further. Processing of MHC II epitopes occurs via intracellular proteases from the lysosomal/endosomal compartment.
  • Vaccine design that focuses entirely on MHC affinity is fundamentally flawed. The mere fact that a peptide has MHC binding affinity does not ensure that such a peptide will make for a functional immunogen.
  • the peptide To provide an epitope capable of eliciting an effective immune response against a TAA, the peptide must have MHC binding affinity and be the product of cellular peptide generating systems.
  • the methods of the disclosed invention utilize both MHC binding affinity analysis and antigen processing analysis protocols to identify new epitopes of interest.
  • Embodiments of the invention combine an analysis of MHC binding with an analysis of proteolytic processing to identify epitopes that have both of the essential properties of a useful epitope: MFIC affinity and correct proteolytic processing. Peptides having both of these properties are strong candidates for vaccines and immunotherapies. Peptides lacking either of these properties are unlikely to have any significant opportunity to function as effective epitopes.
  • Embodiments of the invention are capable of identifying epitopes derived from TAAs for use in vaccines.
  • the target antigens can be derived from neoplastic cells, cells infected with a virus or other intracellular parasite, or cells infected with other pathogenic agents such as bacteria, fungi, protozoans, viruses, prions, toxins, venoms, allergens, and the like.
  • embodiments of the method can be applied to virtually any protein sequence, to identify therein epitopes capable of generation by proteolysis and capable of binding to MHC. Accordingly, the invention is not limited to any particular target or medical condition, but instead encompasses discovery of biologically relevant MHC epitopes from any useful source.
  • the TAA is characteristic of a neoplastic cell and is thus defined as a tumor-associated antigen (TuAA).
  • Preferred TuAAs include: differentiation antigens such as MelanA (MART-1), gplOO (Pmel 17), tyrosinase, TRP-1, TRP-2, MAGE-1, MAGE-3, BAGE, GAGE-1, GAGE-2, pi 5; overexpressed embryonic antigens generally; overexpressed oncogenes and mutated tumor-suppressor genes such as p53, Ras, HER-2/neu; unique tumor antigens resulting from chromosomal translocations such as BCR-ABL, E2A-PRL, H4-RET, IGH- IGK, MYL-RARl and viral antigens, such as Epstein Barr virus antigens (EBVA) and the human papillomavirus (HPV) antigens E6 and E7.
  • differentiation antigens such as MelanA (MART-1),
  • PSA prostate specific antigen
  • PSCA prostate stem cell antigen
  • MAAT-1 MAAT-1
  • GP-100 GP-100
  • TSP-180 MAGE-4
  • MAGE- 5 MAGE-6
  • RAGE P 185erbB-2
  • P 185erbB-3 c-met
  • nm-23Hl TAG-72
  • CA 19-9 CA 72-4
  • CAM 17.1 NuMa, K-ras, ⁇ -Catenin, CDK4, Mum-1 , pi 5, and pl6.
  • Other target antigens are also contemplated.
  • TuAAs TuAAs
  • differential hybridization including the use of microarrays; subtractive hybridization cloning; differential display, either at the level of mRNA or protein expression; EST sequencing; and SAGE (sequential analysis of gene expression).
  • Differential display of proteins involves, for example, comparison of two-dimensional polyacrylamide gel electrophoresis of cell lysates from tumor and no ⁇ al tissue, location of protein spots unique or overexpressed in the tumor, recovery of the protein from the gel, and identification of the protein using traditional biochemical or mass spectrometry sequencing techniques.
  • An additional technique for identification of TuAAs is the SEREX technique, discussed in Tureci, O., Sahin, U., and Pfreundschuh, M., "Serological analysis of human tumor antigens: molecular definition and implications", Molecular Medicine Today, 3:342, 1997.
  • TAA fragments within the TAA with a known or predicted affinity for MHC are identified.
  • the amino acid sequence of a TAA can be analyzed by a number of different techniques with which to identify peptide fragments having a known or predicted affinity for the MHC peptide binding cleft.
  • TAA fragments are analyzed for their predicted ability to bind to the MHC peptide binding cleft using a computer algorithm.
  • Each allele of MHC specifies a particular epitope binding domain.
  • the candidate peptides can be screened for predicted affinity thereto.
  • NIH Parker
  • NIH Parker
  • peptides with an infinite retention time would be selected.
  • peptides with a retention time of 25 minutes or more would be selected to indicate a binding sequence.
  • a retention time of 15 minutes or more would be selected to indicate a binding sequence.
  • a retention time of 10 minutes or more would be selected to indicate a binding sequence. Retention times of 9, 8, 7, 6, 5, 4, 3, 2, and 1 minute are also contemplated.
  • the initial population of peptide fragments can be narrowed to include only those peptides having an actual or predicted affinity for the selected allele of MHC.
  • peptide candidates for this analysis can include every possible sequence of about 6 to 24 contiguous amino acids from the entire protein sequence of the TAA.
  • the sequences can be from about 7 to 20 amino acids in length. In a more preferred embodiment, the sequences can be from about 8 to 15 amino acids in length.
  • sequence analysis to identify fragments with predicted affinity for MHC I a most preferred embodiment analyzes all possible sequences of 9 or 10 contiguous amino acid fragments of the TAA. Analysis of the MHC affinity of the fragments can be conducted in vitro or via computer analysis of the fragments. Selected common alleles of MHC I, and their approximate frequencies, are reported in the tables 3-5 below. Table 3. Estimated gene frequencies of HLA- A antigens
  • Tables 3, 4, and 5 derived from HLA Gene and Haplotype Frequencies in the North American Population: The National Marrow Donor Program Donor Registry, Mori, M. et al.
  • a preliminary step of the disclosed method is to select from among the original population of peptide fragments a subpopulation of peptides with an actual or predicted MHC affinity.
  • the selected fragments are analyzed further to detemiine which can be produced by a cell under in vivo conditions that could result in binding of the peptide to the selected MHC allele.
  • All peptides that meet both criteria of MHC affinity and correct proteolytic processing are designated as "discovered epitopes.”
  • a variety of methods are available for determining which peptide fragments can be produced by proteolytic processing in vivo. These methods include elution of peptides from solubilized MHC and intact cells, computer sequence analysis of the proteolytic cleavage motifs, and in vitro analysis of actual peptide fragments produced by cellular proteolytic machinery.
  • a series of synthetic peptides centrally containing either individual or clustered candidate peptide sequences can be generated.
  • Such peptides typically range in length from about 10 to about 75 amino acids.
  • the synthetic peptide is between about 20 and 60 amino acids in length.
  • the cluster is between about 30 and 40 amino acids in length.
  • peptide fragments containing candidate peptides can be generated in vitro through protease digestion or chemical cleavage of the TAA or fragments thereof.
  • Protease digestion to prepare such fragments of TAAs can employ a wide variety of known proteases, including but not limited to proteasome proteases, trypsin, ⁇ -chymotrypsin, bromelain, clostripain, elastase, endoproteinases, exoproteinases, proteinase K, ficin, papain, pepsin, plasmin, fhermolysin, thrombin, trypsin, cathepsins, and others. Chemical methods can also be used to generate peptide candidates.
  • Suitable chemicals or chemical reactions for cleaving peptide bonds include mild acid cleavage, cyanogen bromide, hydroxylamine, iodosobenzoic acid, 2-Nitro-5- fhiocyanobenzoate, and the like.
  • the unfragmented TAA can be used, although the use of a particularly large initial sequence can complicate the analysis.
  • proteasome digestion is used to estimate cellular epitope generation.
  • immune and housekeeping proteasomes are purified for in vitro use in order to assess the antigenic repertoire generated naturally from the two kinds of proteasomes.
  • proteasomes are prepared by affinity purification from cell extracts.
  • a cell lysate is prepared using standard techniques. The lysate is cleared by ultracentrifugation if eryfhrocytes are not the original source material. The prepared cell lysate is then purified from other cellular components using any one of a number of purification techniques including various forms of chromatography.
  • affinity chromatography is used to purify the proteasomes.
  • the cell lysate is applied to an affinity column containing a monoclonal antibody (mAb) against one of the proteasomal subunits.
  • mAb monoclonal antibody
  • the column is then washed to purify the bound proteasomes from other cellular material.
  • the bound proteasomes are then eluted from the column.
  • the eluate is characterized in terms of protein content and proteolytic activity on a standard substrate.
  • Cleavage analysis using both housekeeping and immune proteasomes yields class I epitopes from various TAA.
  • the epitopes that are presented by pAPCs correspond to cleavage products of the immune proteasome, while the epitopes presented by tumors and by many cells chronically infected with intracellular parasites correspond to cleavage products of the housekeeping proteasome.
  • the digest is performed, the particular molecular species produced are identified. In a prefei ⁇ ed embodiment, this is accomplished by mass spectrometry. This allows the rapid identification of natural peptide fragments that are produced by either of the two kinds of proteasomes.
  • cleavage of the target antigen or fragments thereof by immune and housekeeping proteasomes, or by endosomal/lysosomal proteases (see below), is predicted by computer modeling based on cleavage motifs of the relevant proteolytic activities.
  • class I MFIC is loaded primarily with proteasomally derived peptides as it initially folds in the endoplasmic reticulum
  • the binding cleft of class II MHC is blocked by the so-called invariant chain (Ii) in this compartment.
  • Loading of peptide for class II MHC takes place primarily in the endosomal compartment, utilizing peptides generated by endosomal and lysosomal proteases.
  • preparations of proteases from endosomal and/or lysosomal fractions can be substituted for the proteasomes.
  • a variety of methods to accomplish this substitution are described in the literature. For example, Kido & Ohshita, Anal. Biochem., 230:41-7 (1995); Yamada, et al., J. Biochem. (Tokyo), 95:1155-
  • class I epitopes it is preferred that the type of proteasome expressed by the cell be determined, for example, by western blotting.
  • the MHC epitopes produced can then be eluted from either solubilized and purified MHC as described in Falk, K. et al. Nature 351:290, 1991, or directly from the intact cell as described in U.S. Patent 5,989,565. Eluted fragments are then identified by mass spectrometty.
  • the molecular species detected by mass spectrometty are compared with the candidate peptides predicted above.
  • class I epitopes species that are as long as, or longer than, a candidate peptide and share its C-terminus are desired; N-terminal trimming of at least up to 25 amino acids can occur independently of the proteasome (Craiu, A. et al. Proc. Natl. Acad. Sci. USA 94: 10850-55, 1997).
  • Class II MHC is highly tolerant in terms of the length of the peptides it will bind, so the absence of cleavage in the middle of the epitope becomes the primary criterion, rather than generation of a correct end.
  • a selected digestion product is then synthesized and used as a standard in an analytic method such as HPLC versus an aliquot of the digest. This provides a further check on the identity of the digestion product and allows its yield to be determined. In rare cases more than one potential product may have similar enough masses and chemical characteristics that they may not be reliably differentiated by these methods. In such cases the HPLC peak can be collected and subjected to direct sequencing to confirm identity.
  • the epitope is synthesized and tested for its ability to bind a MHC receptor.
  • cells displaying the MHC I receptor can be used to measure the binding affinity of candidate peptides labeled with a radionuclide.
  • Another preferred approach measures the ability of a peptide to bind to an MFIC I receptor using a cell culture-based assay.
  • cells lacking transporters associated with antigen processing (TAP) are used to detemiine whether or not a candidate peptide has the ability to bind to the MHC I receptor.
  • TAP transporters associated with antigen processing
  • MHC I is thus reduced or abolished.
  • the cell is flooded with exogenous peptide that can bind to the MHC I cleft, expression of the receptor is restored. This can be monitored by several means such as RIA, FACS, and the like.
  • TAP TAP " cells, one of skill in the art can screen large numbers of potential candidate peptides for receptor binding without having to perform detailed binding affinity analysis.
  • the analysis methods of the various embodiments of the invention are useful in examining candidate peptides generated in a variety of ways.
  • the described analysis can be used in evaluating multiple candidate peptides generated through in vitro methods or by computational analysis, to identify those candidate sequences that have MHC receptor binding characteristics.
  • Preferred candidate peptides in this embodiment of the invention are those that are already known to be products of proteolytic production by housekeeping and/or immune proteasomes. Both in vivo cleavage products and in vitro cleavage products that are shown or predicted to bind to MHC are properly designated as "discovered epitopes.” Epitope clusters for use in connection with this invention are disclosed herein.
  • ECRs are Processed into MHC-Binding Epitopes in pAPCs
  • Tire immune system constantly surveys the body for the presence of foreign antigens, in part through the activity of pAPCs.
  • the pAPCs endocytose matter found in the extracellular milieu, process that matter from a polypeptide form into shorter oligopeptides of about 3 to 23 amino acids in length, and display some of the resulting peptides to T cells via the MHC complex of the pAPCs.
  • a tumor cell upon lysis releases its cellular contents, including various proteins, into the extracellular milieu. Those released proteins can be endocytosed by pAPCs and processed into discrete peptides that are then displayed on the surface of the pAPCs via the MHC.
  • the scavenger receptors on pAPC can take-up naked nucleic acid sequences or recombinant organisms containing target nucleic acid sequences. Uptake of the nucleic acid sequences into the pAPC subsequently results in the expression of the encoded products.
  • these products can be presented as
  • MHC epitopes for recognition by T cells For recognition by T cells.
  • MHC-binding epitopes are often distributed unevenly throughout a protein sequence in clusters.
  • Embodiments of the invention are directed to identifying epitope cluster regions (ECRs) in a particular region of a target protein.
  • ECRs epitope cluster regions
  • Candidate ECRs are likely to be natural substrates for various proteolytic enzymes and are likely to be processed into one or more epitopes for MHC display on the surface of an pAPC.
  • ECRs can be administered as vaccines, resulting in a high probability that at least one epitope will be presented on MHC without requiring the use of a full length sequence.
  • Identifying putative MHC epitopes for use in vaccines often includes the use of available predictive algorithms that analyze the sequences of proteins or genes to predict binding affinity of peptide fragments for MHC. These algorithms rank putative epitopes according to predicted affinity or other characteristics associated with MHC binding. Exemplary algorithms for this kind of analysis include the Rammensee and NIFI (Parker) algorithms. However, identifying epitopes that are naturally present on the surface of cells from among putative epitopes predicted using these algorithms has proven to be a difficult and laborious process. The use of ECRs in an epitope identification process can enormously simplify the task of identifying discrete MHC binding epitopes.
  • ECR polypeptides are synthesized on an automated peptide synthesizer and these ECRs are then subjected to in vitro digests using proteolytic enzymes involved in processing proteins for presentation of the epitopes. Mass spectrometry and/or analytical HPLC are then used to identify the digest products and in vitro MHC binding studies are used to assess the ability of these products to actually bind to MHC. Once epitopes contained in ECRs have been shown to bind MHC, they can be incorporated into vaccines or used as diagnostics, either as discrete epitopes or in the context of ECRs.
  • ECR electrospray cyclopentase
  • the simplicity of using chemically synthesized ECRs enables the analysis and identification of large numbers of epitopes, while greatly reducing the time and expense of the process as compared to other currently used methods.
  • the use of a defined ECR also greatly simplifies mass spectrum analysis of the digest, since the products of an ECR digest are a small fraction of the digest products of a whole protein.
  • nucleic acid sequences encoding ECRs are used to express the polypeptides in cells or cell lines to assess which epitopes are presented on the surface.
  • a variety of means can be used to detect the epitope on the surface. Preferred embodiments involve the lysis of the cells and affinity purification of the MHC, and subsequent elution and analysis of peptides from the MFIC; or elution of epitopes from intact cells; (Falk, K. et al. Nature 351:290, 1991, and U.S. Patent 5,989,565, respectively).
  • a sensitive method for analyzing peptides eluted in this way from the MHC employs capillary or nanocapillary HPLC ESI mass spectrometry and on-line sequencing.
  • TAAs from which ECRs may be defined include those from TuAAs, including oncofetal, cancer-testis, deregulated genes, fusion genes from errant translocations, differentiation antigens, embryonic antigens, cell cycle proteins, mutated tumor suppressor genes, and overexpressed gene products, including oncogenes.
  • ECRs may be derived from virus gene products, particularly those associated with viruses that cause chronic diseases or are oncogenic, such as the herpes viruses, human papilloma viruses, human immunodeficiency virus, and human T cell leukemia virus.
  • ECRs may be derived from gene products of parasitic organisms, such as Trypanosoma, Leishmania, and other intracellular or parasitic organisms.
  • TuAA include ⁇ -fetoprotein, carcinoembryonic antigen (CEA), esophageal cancer derived NY-ESO-1, and SSX genes, SCP-1, PRAME, MART- 1 /MelanA (MART-1), gplOO (Pmel 17), tyrosinase, TRP-1, TRP-2, MAGE-1, MAGE-2, MAGE-3, BAGE, GAGE-1, GAGE-2, pl5; overexpressed oncogenes and mutated tumor-suppressor genes such as p53, Ras, HER-2/neu; unique tumor antigens resulting from chromosomal translocations such as BCR-ABL, E2A-PRL, H4-RET, IGH-IGK, MYL-RAR1 and viral antigens, EBNA1, EBNA2, HPV-E6, -E7; prostate specific antigen (PSA), prostate stem cell antigen (PSCA), MAAT-1, GP-100, T
  • TuAAs a variety of methods are available and well known in the art to identify genes and gene products that are differentially expressed in neoplastic cells as compared to normal cells. Examples of these techniques include differential hybridization, including the use of microarrays; subtractive hybridization cloning; differential display, either at the level of mRNA or protein expression; EST sequencing; and SAGE (sequential analysis of gene expression). These nucleic acid techniques have been reviewed by Carulli, J.P. et al., J. Cellular Biochem Suppl. 30/31:286-
  • Differential display of proteins involves, for example, comparison of two-dimensional poly-acrylamide gel electrophoresis of cell lysates from tumor and normal tissue, location of protein spots unique or overexpressed in the tumor, recovery of the protein from the gel, and identification of the protein using traditional biochemical- or mass spectrometry-based sequencing.
  • An additional technique for identification of TAAs is the Serex technique, discussed in T ⁇ reci, O.,
  • identification of ECRs involves two main steps: (1) identifying good putative epitopes; and (2) defining the limits of any clusters in which these putative epitopes are located.
  • There are various preferred embodiments of each of these two steps and a selected embodiment for the first step can be freely combined with a selected embodiment for the second step.
  • the methods and embodiments that are disclosed herein for each of these steps are merely exemplary , and are not intended to limit the scope of the invention in any way. Persons of skill in the art will appreciate the specific tools that can be applied to the analysis of a specific TAA, and such analysis can be conducted in numerous ways in accordance with the invention.
  • Preferred embodiments for identifying good putative epitopes include the use of any available predictive algorithm that analyzes the sequences of proteins or genes to predict binding affinity of peptide fragments for MHC, or to rank putative epitopes according to predicted affinity or other characteristics associated with MHC binding.
  • available exemplary algorithms for this kind of analysis include the Rammensee and NTH (Parker) algorithms.
  • good putative epitopes can be identified by direct or indirect assays of MHC binding.
  • a cutoff point in terms of the score reported by the prediction software or in terms of the assayed binding affinity.
  • such a cutoff is absolute.
  • the cutoff can be based on the measured or predicted half time of dissociation between an epitope and a selected MHC allele.
  • embodiments of the cutoff can be any half time of dissociation longer than, for example, 0.5 minutes; in a prefei ⁇ ed embodiment longer than 2.5 minutes; in a more preferred embodiment longer than 5 minutes; and in a highly stringent embodiment can be longer than 10, or 20, or 25 minutes.
  • the good putative epitopes are those that are predicted or identified to have good MHC binding characteristics, defined as being on the desirable side of the designated cutoff point.
  • the cutoff can be based on the measured or predicted binding affinity between an epitope and a selected MHC allele.
  • the absolute cutoff can be simply a selected number of putative epitopes.
  • the cutoff is relative. For example, a selected percentage of the total number of putative epitopes can be used to establish the cutoff for defining a candidate sequence as a good putative epitope. Again the properties for ranking the epitopes are derived from measured or predicted MHC binding; the property used for such a determination can be any that is relevant to or indicative of binding. In preferred embodiments, identification of good putative epitopes can combine multiple methods of ranking candidate sequences. In such embodiments, the good epitopes are typically those that either represent a consensus of the good epitopes based on different methods and parameters, or that are particularly highly ranked by at least one of the methods.
  • TAA The regions with the highest density of the characteristic, or with a density above a certain selected cutoff, are designated as ECRs.
  • ECRs The regions with the highest density of the characteristic, or with a density above a certain selected cutoff, are designated as ECRs.
  • Various embodiments of the invention employ different characteristics for the density analysis. For example, one preferred characteristic is simply the presence of any good putative epitope (as defined by any appropriate method). In this embodiment, all putative epitopes above the cutoff are treated equally in the density analysis, and the best clusters are those with the highest density of good putative epitopes per amino acid residue. In another embodiment, the preferred characteristic is based on the parameter(s) previously used to score or rank the putative epitopes.
  • a putative epitope with a score that is twice as high as another putative epitope is doubly weighted in the density analysis, relative to the other putative epitope.
  • Still other embodiments take the score or rank into account, but on a diminished scale, such as, for example, by using the log or the square root of the score to give more weight to some putative epitopes than to others in the density analysis.
  • the various embodiments of the invention can be used alone or in combination to identify those ECRs that are most useful for a given application. Iterative or parallel analyses employing multiple approaches can be beneficial in many cases. ECRs are tools for increased efficiency of identifying true MHC epitopes, and for efficient "packaging" of MHC epitopes into vaccines. Accordingly, any of the embodiments described herein, or other embodiments that are evident to those of skill in the art based on this disclosure, are useful in enhancing the efficiency of these efforts by using ECRs instead of using complete TAAs in vaccines and vaccine design.
  • an ECR can be any fragment of a TAA with elevated epitope density.
  • an ECR can include a region up to about 80% of the length of the TAA.
  • an ECR can include a region up to about 50% of the length of the TAA. In a more preferred embodiment, an ECR can include a region up to about 30 % of the length of the TAA. And in a most preferred embodiment, an ECR can include a region of between 5 and 15% of the length of the TAA.
  • the ECR can be defined in terms of its absolute length. Accordingly, by this definition, the minimal cluster for 9-mer epitopes includes 10 amino acid residues and has two overlapping 9-mers with 8 amino acids in common. In a preferred embodiment, the cluster is between about 15 and 75 amino acids in length. In a more preferred embodiment, the cluster is between about 20 and 60 amino acids in length. In a most preferred embodiment, the cluster is between about 30 and 40 amino acids in length.
  • ECR identification can employ a simple density function such as the number of epitopes divided by the number of amino acids spanned by the those epitopes. It is not necessarily required that the epitopes overlap, but the value for a single epitope is not significant. If only a single value for a percentage cutoff is used and an absolute cutoff in the epitope prediction is not used, it is possible to set a single threshold at this step to define a cluster.
  • an ECR is defined in one embodiment as any region containing two or more predicted epitopes for which this ratio exceeds 2, that is, any region with twice the average density of epitopes. In other embodiments, the region is defined as an ECR if the ratio exceeds 1.5, 3, 4, or 5, or more.
  • ECR average number of peptides per amino acid in a target protein to calculate the presence of an ECR highlights densely populated ECRs without regard to the score/affinity of the individual constituents. This is most appropriate for use of score-based cutoffs.
  • an ECR with only a small number of highly ranked candidates can be of more biological significance than a cluster with several densely packed but lower ranking candidates, particularly if only a small percentage of the total number of candidate peptides were designated as good putative epitopes.
  • This sum of scores method is more sensitive to sparsely populated clusters containing high scoring epitopes. Because the wide range of scores (i.e. half times of dissociation) produced by the BIMAS-NIH/Parker algorithm can lead to a single high scoring peptide dwarfing the contribution of other potential epitopes, the log of the score rather than the score itself is preferably used in this procedure. Various other calculations can be devised under one or another condition. Generally speaking, the epitope density function is constt ⁇ icted so that it is proportional to the number of predicted epitopes, their scores, their ranks, and the like, within the putative cluster, and inversely proportional to the number of amino acids or fraction of protein contained within that putative cluster.
  • the function can be evaluated for a window of a selected number of contiguous amino acids. In either case the function is also evaluated for all predicted epitopes in the whole protein. If the ratio of values for the putative cluster (or window) and the whole protein is greater than, for example, 1.5, 2, 3, 4, 5, or more, an ECR is defined.
  • An epitope cluster is a segment of a protein, and as such is a string of amino acids connected by peptide bonds. Within the protein of which it is a segment its termini are half peptide bonds. As an isolated macromolecule it generally has the terminal amino and carboxylate groups of other polypeptides, but whatever blocking groups or other modifications that are made to the termini do not alter the characteristic structure of the epitope cluster. While any cluster has an amino acid sequence, it is not directly defined by that sequence. Rather a cluster is defined by the arrangement of epitopes, pertaining to a particular MHC molecule, within a protein sequence.
  • FIG. 9 An illustration of the clustering of epitopes within a protein, Figure 9, is a positional plot of the predicted HLA-A*0201 epitopes in tyrosinase.
  • the specific sequence infomiation has been generalized to symbols to illustrate the density and positioning of epitopes in this protein or any segment of it, which shows where the clusters are and where they are not.
  • Such a plot can be derived from a knowledge and predictive analysis of the protein sequence (see Example 24: Tables 21-24 and Figure 18), but can also be derived empirically. For example, by creating an ordered set of 9-mer fragments of tyrosinase and testing each fragment for HLA-A*0201 binding, a plot very similar to Fig. 9 can be obtained.
  • the clusters can be identified without any reference to the underlying sequence. Knowledge of the sequence facilitates and increases the usefulness of the clusters, but it is not directly determinant of them.
  • -1)-P ,-Xa-P where: X is any amino acid naturally occurring in a protein sequence, and each occurrence of X in the formula can indicate an amino acid that is different from or the same as any other X in the formula; a indicates the number of amino acids between P2, and P2 2 ; b represents the relative positions of P2 2 and P ,; Xa and X(
  • P2 is the first primary anchor and second residue of the first epitope
  • P2 2 is the first primary anchor and second residue of the second epitope
  • P i is the last primary anchor and C-terminal residue of the first epitope; and P 2 is the last primary anchor and C-terminal residue of the second epitope.
  • anchor residues The identity of the anchor residues is a specific subset of the possibilities for X, depending on the binding motif of the MHC type to which the cluster pertains. Binding motifs for a variety of MHC types are well known in the art, and some examples are discussed below. In particular, primary and auxiliary anchors and other favored residues for many MHC molecules from a variety of species are reported in "MHC Ligands and Peptide Motifs," incorporated by reference above. These data form the basis of the prediction algorithm used by SYFPEITHI and those data related to class I HLA have been extracted and are presented in Table 6.
  • Class I FILA coefficient tables used by the BIMAS-NIFI/Parker algorithm also revealing anchor, preferred, and disfavored residues, are presented in Table(s) 7-1 to 7-41. These Tables are provided as illustrative examples of the kind of useful information that is accessible to those of skill in the art; the Tables are not presented as a complete list of such information.
  • Epitopes that are 8 or 10 amino acids in length are also commonly found.
  • the length of the cluster, Lc, is then 4+2a+b.
  • 'a' and 'b' can take on any value in the specified ranges.
  • specification of anchor residues can lead to excluded structures.
  • P2 can be defined as X adjacent to (on the amino side of) the preferred P3 residues, which are D and E in the example of HLA- A 1.
  • the binding motif for HLA-B 8 has primary anchors at both P3 and P5, in addition to P , preferring K or R at those positions.
  • P2 as the first residue in the sequence X-K7R-X-K/R, the template above can still be used.
  • Ever more complex motif definitions, incorporating secondary anchors and ultimately including the matrix definitions can thus be accommodated, depending upon the preferences and goals of the practitioner. Table 6.
  • Anchor or auxiliary anchor R L R I L Residues K Y H L
  • Anchor or auxiliaiy anchor R L Residues F HLA-B*35 Position
  • an indexing scheme can be devised to iteratively apply the definition to each successive pair of epitopes in a cluster of any size.
  • the formula can be adapted so that it can be iteratively applied to the first epitope in combination with each successive member of the epitope cluster, as follows:
  • N indicates the Nth epitope of the cluster
  • Nc indicates the total number of epitopes in the cluster
  • a N and b N define the positional relationship between the 1 st and Nth epitope, similarly to a and b above;
  • Lc 4 + 2a Nc + b Nc .
  • epitope clusters comprising epitopes of a single length sharing known or predicted affinity for a particular MHC molecule. This can be called a proximity cluster.
  • the general definition of an epitope cluster disclosed above requires that the density of epitopes within the cluster be greater than the average density of epitopes in the whole protein. Thus, this density requirement can be expressed as (Nc/Lc) > (Np/Lp), where Np is the total number of epitopes in the protein and Lp is the length of the protein.
  • the protein sequence can be used to identify putative epitopes with known or predicted affinity to the MHC peptide binding cleft.
  • Tests of peptide fragments can be conducted in vitro, or using the sequence can be computer analyzed to determine MHC receptor binding of the peptide fragments.
  • peptide fragments based on the amino acid sequence of the target protein are analyzed for their predicted ability to bind to the MHC peptide binding cleft. Examples of suitable computer algorithms for this purpose include the Rammensee/SYFPEITHI and the NIH (Parker) sites referenced in the discussion of epitope discovery above.
  • the initial population of peptide fragments can be narrowed to include only putative epitopes having an actual or predicted affinity for the selected allele of MHC. Selected common alleles of MHC, and their approximate frequencies, are reported in the tables 3-5 above.
  • vaccine design can take into account the MFIC I genotype of the patient, so as to deliver epitopes having suitable binding affinities for a particular patient's MHC allele(s). Since a patient may be homozygous or heterozygous for the relevant locus, in some embodiments of the invention, epitopes optimal for a single MHC I allele are preferred, while in other embodiments, epitopes corresponding to different MHC alleles may be preferred.
  • a partial list of major class I MHC types, each generally encoded by multiple alleles, and their approximate frequencies, are reported in Table 8.
  • the pAPCs are provided with a housekeeping epitope and an epitope cluster.
  • the epitope cluster is a peptide or nucleic acid sequence that contains or encodes at least two sequences having a known or predicted affinity to MHC I. While it is preferable that the housekeeping epitope be provided to the pAPCs in a state that is fully processed or as a precursor that is engineered in such a way so that it can be processed in the pAPC to be an effective housekeeping epitope, the immune epitope can be processed from a larger precursor by the pAPCs. This is because the immune proteasome is constitutively active in the pAPC, and is fully competent to process an appropriate precursor of presumably any length into a "correct" immune epitope.
  • Potential epitopes are commonly but not always found in clusters in discrete segments of a TAA containing multiple epitopes for the purpose of providing an immune epitope. Simply providing the pAPC with a polypeptide containing a cluster of potential epitopes, or a nucleic acid encoding a cluster, or a recombinant organism expressing the cluster enables the pAPC to produce at least one appropriate immune epitope. Since epitope clusters generally contain potential epitopes for more than one class I MHC allele, in many embodiments a single cluster can be used to produce immune epitopes useful with more than one class I MHC allele.
  • a patient is inoculated with a vaccine that includes housekeeping epitopes derived from a selected TAA.
  • the housekeeping epitope can be a polypeptide or a nucleic acid encoding a polypeptide, or a recombinant organism engineered to express the discrete epitope.
  • embodiments of the invention include vaccines that additionally have one or more other housekeeping epitopes, or one or more immune epitopes, or any combination thereof.
  • Such epitopes can be derived from the same TAA, or they can be derived from different TAAs.
  • a preferred embodiment of the present invention includes a method of administering a vaccine including a housekeeping epitope to induce a therapeutic immune response.
  • the vaccine is administered to a patient in a manner consistent with the standard vaccine delivery protocols that are well known in the art.
  • Methods of administering epitopes of TAAs include, without limitation, transdermal, intranodal, perinodal, oral, intravenous, intradermal, intramuscular, intraperitoneal, and mucosal administration.
  • a particularly useful method of vaccine delivery to elicit a CTL response is disclosed in PCT Publication No. WO 99/01283, entitled "A METHOD OF
  • a vaccine to induce a specific T cell response to a target cell is likewise included in a preferred embodiment of the present invention.
  • the vaccine contains a housekeeping epitope in a concentration effective to cause a pAPC or populations of pAPCs to display housekeeping epitopes.
  • the vaccine can include a plurality of housekeeping epitopes or one or more housekeeping epitopes optionally in combination with one or more immune epitopes.
  • Formulations of the vaccine contain peptides and/or nucleic acids in a concentration sufficient to cause pAPCs to present the epitopes.
  • the formulations preferably contain epitopes in a total concentration of about l ⁇ g-lmg/lOO ⁇ l of vaccine preparation.
  • Conventional dosages and dosing for peptide vaccines and/or nucleic acid vaccines can be used with the present invention, and such dosing regimens are well understood in the art.
  • a single dosage for an adult human may advantageously be from about 1 to about 5000 ⁇ l of such a composition, administered one time or multiple times, e.g., in 2, 3, 4 or more dosages separated by 1 week, 2 weeks, 1 month, or more.
  • such a composition is administered continuously, directly into a lymph node, tlirough the use of an insulin pump, at a rate of at least 1 ⁇ l per hour over several days.
  • Such administration can be repeated periodically to maintain the CTL response as is more fully described in PCT
  • compositions and methods of the invention disclosed herein further contemplate incorporating adjuvants into the formulations in order to enhance the performance -of the vaccines.
  • adjuvants to the formulations is designed to enhance the delivery or uptake of the epitopes by the pAPCs.
  • the adjuvants contemplated by the present invention are known by those of skill in the art and include, for example, GM-CSF, G-CSF, IL-2, IL-12, BCG, tetanus toxoid, osteopontin/ETA-1, CD40 ligand and CTLA-4 blockade agents.
  • housekeeping epitope-reactive T cells can be administered to a patient as an adoptive immunotherapy.
  • T cells can be most readily obtained by in vitro immunization, using cells from a na ⁇ ve donor, though using the patient as donor can also be feasible.
  • Techniques for in vitro immunization are known in the field, for example, Stauss et al., Proc. Natl. Acad. Sci. USA 89:7871-7875, 1992; Kawakami et al., J. Immunol. 154:3961-3968, 1995; Salgaller et al. Cancer Res. 55:4972-4979, 1995; Tsai et al., J. Immunol.
  • T cells Once generated, sufficient numbers of such T cells can be obtained by expansion in vitro through stimulation with the vaccines of this invention and/or cytokines (see for example Kurokawa, T. et al., Int. J. Cancer 91:749-746, 2001).
  • These T cells can constitute a clone or a polyclonal population recognizing one or more epitopes.
  • mice and 10 to 10 in humans typically, on the order of 10 to 10 cells are transferred in mice and 10 to 10 in humans.
  • Clones and otherwise more enriched populations generally require the transfer of fewer cells.
  • the epitopes recognized can be • housekeeping epitopes or a combination of housekeeping and immune epitopes. It is also envisioned that genetic engineering can be used to express cloned. TCRs in a cell line suitable for use in adoptive immuno therapy. Examples of sources from which useful TCRs can be cloned include the T cells described above, and HLA-transgenic mice immunized with the vaccines of this invention. Additional variations will be apparent to one of skill in the art.
  • Adoptive immunotherapy refers to a therapeutic approach for treating cancer or infectious diseases, for example, in which immune cells are administered to a host with the aim that the cells mediate either directly or indirectly specific immunity to tumor cells and/or antigenic components or regression of the tumor or treatment of infectious diseases, as the case may be. See U.S. Pat. Nos.
  • cancers responsive to adoptive immunotherapy include, but are not limited to, human sarcomas and carcinomas, e.g., fibrosarcoma, myxosarcoma, liposarcoma, chondrosarcoma, osteogenic sarcoma, chordoma, angiosarcoma, endotheliosarcoma, lymphangiosarcoma, lymphangioendotheliosarcoma, synovioma, mesothelioma, Ewing's tumor, leiomyosarcoma, rhabdomyosarcoma, colon carcinoma, pancreatic cancer, breast cancer, ovarian cancer, prostate cancer, squamous cell carcinoma, basal cell carcinoma, adenocarcinoma, sweat gland carcinoma, sebaceous gland carcinoma, papillary carcinoma, papillary adenocarcinomas, cystadenocarcinoma, medullary carcinoma, bronchogenic carcinoma, renal cell carcinoma, hepatoma,
  • acute lymphocytic leukemia and acute myelocytic leukemia myeloblastic, promyelocytic, myelomonocytic, monocytic and eiythroleukemia
  • chronic leukemia chronic myelocytic (granulocytic) leukemia and chronic lymphocytic leukemia
  • polycythemia vera lymphoma (Hodgkin's disease and non-Hodgkin's disease), multiple myeloma, Waldenstrom's macroglobulinemia, heavy chain disease, and the like.
  • Adoptive immunotherapy includes passive immunotherapy, which can involve the delivery of biologic reagents with established tumor-immune reactivity (such as effector cells or antibodies) that can directly or indirectly mediate anti Lumor effects and do not necessarily depend on an intact host immune system.
  • Embodiments of the instant invention related to the use of effector cells, including T cells such as CTL with specificity for epitopes.
  • the epitopes can include immune epitopes and more preferably housekeeping epitopes.
  • the use of autologous T lymphocytes in adoptive immunotherapy circumvents the issue of whom to select as the donor of the immune cells for adoptive transfer.
  • T cells used in adoptive immunotherapy have the capacity to specifically kill tumor cells as well as to proliferate and persist after transfer and therefore can completely eliminate all residual tumor cells or newly emerging tumor cells.
  • T cells can be activated ex vivo in a polyclonal manner and then reinfused to the patient where they respond directly to tumor or to tumor antigen presented by APC in the patient.
  • a prefeired method of procuring adequate numbers of T-cells for adoptive immunotherapy is to isolate and clonally expand antigen-specific T-cells in vitro. Culture conditions for expanding single antigen-specific T-cells to several billion in number with retention of antigen recognition in vivo are well known in the art.
  • Immunoreactive polypeptides may be used to rapidly expand antigen-specific T cell cultures in order to generate sufficient number of cells for immunotherapy.
  • antigen-presenting cells such as dendritic, macrophage, monocyte, fibroblast, or B-cells, may be pulsed with immunoreactive polypeptides, or polynucleotide sequence(s) may be introduced into antigen presenting cells, using a variety of standard techniques well known in the art.
  • APCs may be transfected or transduced with a polynucleotide sequence, wherein said sequence contains a promoter region appropriate for increasing expression, and can be expressed as part of a recombinant virus or other expression system.
  • viral vectors may be used to transduce an antigen presenting cell, including pox vims, vaccinia virus, and adenovirus; also, antigen presenting cells may be transfected with polynucleotide sequences by a variety of means, including gene-gun technology, lipid-mediated delivery, electroporation, osmotic shock, and particulate delivery mechanisms, resulting in efficient and acceptable expression levels as determined by one of ordinary skill in the art.
  • the effect of adoptive immunotherapy on development and progression of diseases can be monitored by any methods known to one skilled in the art, including but not limited to, measuring: a) delayed hypersensitivity as an assessment of cellular immunity; b) activity of cytolytic T- lymphocytes in vitro; c) levels of tumor specific antigens, e.g., carcinoembryonic (CEA) antigens; d) changes in the morphology of tumors using techniques such as a computed tomographic (CT) scan; e) changes in levels of putative biomarkers of risk for a particular cancer in individuals at high risk; and f) changes in the morphology of tumors using a sonogram.
  • CT computed tomographic
  • the vaccines can include a recombinant organism, such as a virus, bacterium or parasite, genetically engineered to express an epitope in a host.
  • a recombinant organism such as a virus, bacterium or parasite
  • genetically engineered to express an epitope in a host for example, Listeria monocytogen.es, a gram-positive, facultative intracellular bacterium, is a potent vector for targeting TuAAs to the immune system.
  • this vector can be engineered to express a housekeeping epitope to induce therapeutic responses. The normal route of infection of this organism is through the gut and can be delivered orally.
  • an adenovirus (Ad) vector encoding a housekeeping epitope for a TuAA can be used to induce anti-virus or anti-tumor responses.
  • Bone marrow-derived dendritic cells can be transduced with the virus construct and then injected, or the virus can be delivered directly via subcutaneous injection into an animal to induce potent T-cell responses.
  • Another embodiment employs a recombinant vaccinia virus engineered to encode amino acid sequences corresponding to a housekeeping epitope for a TAA.
  • Vaccinia viruses carrying constructs with the appropriate nucleotide substitutions in the form of a minigene construct can direct the expression of a housekeeping epitope, leading to a therapeutic T cell response against the epitope.
  • nucleic acid constructs useful as vaccines in accordance with the present invention are disclosed herein.
  • the present invention provides nucleic acid constructs for use as therapeutic vaccines.
  • the constructs include a coding region having a sequence that encodes a polypeptide.
  • the polypeptide is an epitope of a TAA.
  • the target cell is a neoplastic cell and the polypeptide is an epitope or precursor of an epitope of a TuAA.
  • the target cell is any cell infected with an intracellular parasite.
  • parasite as used herein includes any organism or infective agent such as a virus that has an intracellular stage of infection within the host.
  • viruses such as adenovirus, cytomegalovirus, Epstein- Ban- virus, herpes simplex virus 1, herpes simplex virus 2, human herpesvirus 6, varicella-zoster virus, hepatitis B virus, hepatitis D virus, papilloma virus, parvovirus B19, polyomavirus BK, polyomavirus JC, hepatitis C virus, measles virus, rubella virus, human immunodeficiency virus (HIV), human T cell leukemia virus I, and human T cell leukemia virus II; bacteria such as
  • Chlamydia Listeria, Salmonella, Legionella, Brucella, Coxiella, Rickettsia, Mycobacterium; and protozoa such as Leishmania, Trypanasoma, Toxoplasma, and Plasmodium.
  • the polypeptide(s) encoded by the nucleic acid construct can include a housekeeping epitope of a TAA.
  • the nucleic acid construct encodes a plurality of housekeeping epitopes. When the construct encodes such a plurality, the multiple epitopes can all correspond to different segments of a single TAA, or they can correspond to different TAAs.
  • the nucleic acid construct contains a housekeeping epitope and an immune epitope. In another prefeired embodiment, the nucleic acid construct contains a housekeeping epitope and an epitope cluster region.
  • the vaccine can stimulate a cellular immune response against target cells presenting either epitope—that is, the immune response can recognize the housekeeping epitopes displayed initially by the target cells, and then can also recognize the immune epitopes presented by the target cells after induction by IFN.
  • the nucleic acid construct can further include a third or fourth sequence, or more, with such sequences encoding a third or fourth epitope, or additional epitopes, respectively.
  • Such epitopes can be derived from a single TAA or from two or more different TAAs, and can be housekeeping or immune epitopes on any combination.
  • the constructs can be designed to encode epitopes corresponding to any other proteasome activities that may play a role in processing antigens in any target cell or pAPC.
  • the encoded MHC epitopes are preferably about 7-15 amino acids in length, and more preferably, 9 or 10 amino acids in length. While the generally preferred peptide size for MHC I binding is 9 amino acids, shorter and longer peptides may also in some cases bind MHC I. Likewise, many peptides much longer than 9 amino acids can be trimmed by exopeptidases or other proteases resident in the cell, to produce fragments that bind MHC I very effectively.
  • the size of a peptide containing an immune epitope sequence is not critical, so long as the sequence includes the epitope.
  • the immune proteasome resident in the pAPC, in combination with trimming exopeptidases and other proteases, in its normal function correctly processes full length TAAs to produce immune epitopes.
  • the nucleic acid sequence encoding the immune epitope can actually encode a much larger precursor, including the complete
  • TAA TAA
  • TuAAs and other TAAs suitable for use in the present invention include but are not limited to: differentiation antigens such as MelanA (MART-I), gplOO (Pmel 17), tyrosinase, TRP-1, TRP-2, and tumor-specific multilineage antigens such as MAGE-1, MAGE-3, BAGE, GAGE- 1 , GAGE-2, CEA, RAGE, NY-ESO, SCP- 1 , Hom/Mel-40 and PRAME.
  • differentiation antigens such as MelanA (MART-I), gplOO (Pmel 17), tyrosinase, TRP-1, TRP-2, and tumor-specific multilineage antigens such as MAGE-1, MAGE-3, BAGE, GAGE- 1 , GAGE-2, CEA, RAGE, NY-ESO, SCP- 1 , Hom/Mel-40 and PRAME.
  • TuAAs include overexpressed oncogenes, and mutated tumor-suppressor genes such as p53, H-Ras and HER-2/neu. Additionally, unique TuAAs resulting from chromosomal translocations such as BCR-ABL, E2A-PRL, FI4-RET, IGH-IGK, MYL-RAR and viral antigens such as Epstein Ban- virus antigens EBNA, and the human papillomavirus (FIPV) antigens E6 and E7 are included.
  • chromosomal translocations such as BCR-ABL, E2A-PRL, FI4-RET, IGH-IGK, MYL-RAR and viral antigens such as Epstein Ban- virus antigens EBNA, and the human papillomavirus (FIPV) antigens E6 and E7 are included.
  • TSP-180 TSP-180, MAGE-4, MAGE-5, MAGE- 6, RAGE, NY-ESO, P 185erbB2, pl 80erbB-3, c-met, nm-23Hl, PSA, TAG-72-4, CAM 17.1, NuMa, K-ras, ⁇ -Catenin, CDK4, Mum-1, and pi 6.
  • TuAAs and pathogen-related antigens are known and available to those of skill in the art in the literature or commercially.
  • the TAA is an antigen specific for a virus. See Table 2 above.
  • the TAA is an antigen specific for a non-viral inh-acellular parasite.
  • parasite-specific antigens include nucleotides, proteins, or other gene products associated with the intracellular parasite . Suitable nucleotides or proteins can be found at the NCBI Taxonomy Database located at http://www.ncbi.nlm.nih.gov/Taxonomy/tax.html/ . More detailed descriptions of gene products for parasites and other pathogens are provided at this web site.
  • Particularly preferred peptides are about 7 - 15 amino acids in length.
  • An extensive listing of peptides having MHC binding motifs is provided in Han-Georg Rammensee, Jutta Bachmann, and Stefan Stevanovic, "MHC Ligands and Peptide Motifs," Springer-Verlag, Gennany, (1997) Austin, Texas.
  • the epitopes encoded by the constructs have affinity to one or more MHC I alleles.
  • the construct can encode epitopes conesponding to different MHC I alleles.
  • Prefeired nucleic acid constructs include at least one promoter sequence that is operably linked to the 5 ' end of the coding region of the construct. It will be appreciated by those of skill in the art that any promoter active in mammalian cells can be employed. Prefeired promoter sequences include, but are not limited to, the CMV promoter, the SV40 promoter, and retroviral LTR promoter sequences, and can also include EF-1A, UbC, ⁇ -actin promoters. In some embodiments, the constructs can include two or more promoters that are operably linked to the 5' end of different polypeptide-encoding sequences.
  • the constructs can employ enhancers, nuclear import sequences, immunostimulatory sequences, and expression cassettes for cytokines, selection markers, reporter molecules, and the like.
  • immunostimulatory, or other modulatory sequences can be attached to the vector via a stably hybridized PNA peptide nucleic acid.
  • the nucleic acid constructs of the present invention also include a poly-A sequence that is operably linked to a 3' end of the coding region. A nucleic acid construct that includes a nuclear import sequence and an immunostimulatory sequence is depicted in
  • the nucleic acid constructs encode an mRNA that is translated as a single polypeptide and then cleaved.
  • the polypeptide consists of a linear array of epitopes, wherein the first (N-teiminal) sequence is one or more immune epitopes or epitope clusters, and the second (C-terminal) sequence is a housekeeping epitope, such that the correct C-terminus of the housekeeping epitope is specified by the teirnination codon, and all other HLA epitope termini are determined by proteasomal processing and exopeptidase trimming.
  • Strategies for the construction of vectors able to rely on such immunoproteasomal processing and trimming for the liberation of housekeeping useful as vaccines in accordance with the present invention are disclosed in Provisional U.S. Patent Application No.60/336,968, entitled
  • the nucleic acid construct encodes an amino acid sequence wherein an immune epitope or an epitope cluster is linked to a ubiquitin sequence.
  • the ubiquitin sequence is similarly linked to a housekeeping epitope. The presence of ubiquitin between the epitopes facilitates efficient delivery of the immune epitope to the proteasome for epitope processing.
  • the ubiquitin sequence (with or without an N-terminal spacer to ensure the integrity of the preceding peptide) is located in frame between the first and second sequence, or between any other epitope-encoding sequences.
  • Sequencel-Ubiquitin-Sequence2 polypeptide is rapidly (co-translationally) cleaved at the Ubiquitin-Sequence2 junction by
  • ubiquitin serves primarily as a signal that targets protein for degradation by the proteasome. It is among the most conserved proteins in eukaryotes, with only three conservative amino acid substitutions between yeast and human. Although the precise sequence of ubiquitin may vary somewhat, the sequence of the preferred embodiment is represented by SEQ ID NO: 5. Ubiquitin is a 76 amino acid long polypeptide having two crucial features: 1) a C-ten inal Gly residue, involved in the conjugation of ubiquitin to the Lys side chain of protein substrates and 2) a Lys residue, at position 48, for the formation of multi-ubiquitin chains.
  • Ubiquitin genes are unique in the sense that all of them are synthesized as fusions to other polypeptides, including other ubiquitins.
  • yeast S. cerevisiae four ubiquitin genes have been identified: whereas the first three (UBI1-3) are fused to ribosomal proteins, the fourth gene (UBI4) is synthesized as a fusion of five identical repeats of the ubiquitin sequence.
  • UBI1 the first three
  • UBI4 the fourth gene
  • functional free ubiquitin is naturally produced after co-translational proteolytic processing by ubiquitously expressed ubiquitin-specific hydrolases.
  • Such a natural organization has been exploited by generating C-terrninal fusions between a single ubiquitin moiety and any desired polypeptide.
  • Ubiquitin can exist in two conformations: the first one is described above and consists of a linear fusion of a single ubiquitin to any desired polypeptide, in which the C-terminal Gly of ubiquitin is linked, via a peptide bond to the N-terminal amino acid of the polypeptide of choice.
  • the second involves the conjugation of a ubiquitin moiety to a protein substrate, via a Gly-Lys bond formation.
  • the COOH group of the ubiqutin Gly is linked to the ⁇ (epsilon) side chain of a solvent exposed Lys of the substrate (or another ubiquitin moiety).
  • the ubiquitin signal for the degradation of the substrate is associated with the second conformation.
  • Sequence2 typically is not targeted to the proteasome. Accordingly, the Sequence2 position is preferably used for a fully processed epitope, or one needing only N-teiminal trimming, typically a housekeeping epitope.
  • the ubiquitin moiety remaining attached to Sequence 1 in the construct described above can be polyubiquitinated at Lys48, thereby targeting that fragment to the proteasome for processing, and resulting in the liberation of the epitope contained in Sequence 1.
  • the nucleic acid constructs of the present invention may include autoproteolytic peptide-encoding sequences. Such sequences are located between the first and second sequences or between any other epitope-encoding sequences.
  • autoproteolytic sequences include the inteins; also included are the 3C pr0 and 2A p ⁇ ° proteases of picoinaviruses, including polioviruses and other enteroviruses, rhinoviruses, cardioviruses, and apthoviruses, and the equivalent cornoviridae proteases. These proteases catalyze the post- translational cleavage of the large precursor polyprotein made by this family of viruses.
  • the autocatalytic protein sequence is inserted between two or more epitopes.
  • the sequence is inserted after two or more epitopes, but the cleavage signal is found between the epitopes such that they are cleaved into two or more fully functional epitopes.
  • the type of protease is not important, it is only important that the appropriate cleavage signal be available for the correct processing of the epitopes.
  • cleavage sites and the sequences of the autocatalytic proteins are known (recently reviewed by Seipelt, J. et al., Virus Research 62: 159-168, 1999) they can easily be used for construction of a vector which produces a polyprotein or biprotein. Briefly, 3C pro predominantly recognizes a Q-G site as a cleavage signal although other closely adjacent positions can be important. Also the 3C P '° of some of these viruses adhere less closely to this general pattern, providing for a greater degree of flexibility in design.
  • 2A P '° can be used much the same way with the understanding that the cleavage site, while favoring G-P, is somewhat more variable among these viruses. It must also be considered that its expression can lead to a shutdown of host cell protein synthesis with a rapidity and completeness that depend on the virus strain from which it was denved. Stuctly speaking, the 2 A proteins from cardioviruses and aptho viruses (i.e., Foot-and-
  • Mouth Disease Virus are not proteases, but rather prevent peptide bond fonnation at their C-termini without causing a termination of translation (Ryan, M.D., et al., Bioorgamc Chemistry 27 55-79, 1999) Thus by positioning these 2A proteins between epitopes one can cause scission within a single reading frame.
  • the 2A protein from FMDV is very small, only 18 ammo acids, making it particularly well suited to multiple epitope expression.
  • the nucleic acid constructs encode an mRNA that is translated as two or more polypeptides
  • the transcript can contain one or more internal ribosome entry site (IRES) sequences that are located between the first and second sequence or between any other epitopc-encod g sequences.
  • IRES sequences are naturally used by picornaviruses to dnect internal cap-independent translation of mRNA. Such IRES sequences can also allow independent translation of two oi more consecutive open reading frames from the same messenger RNA.
  • the IRES sequences of various constructs may vary, the IRES sequence of one prefened embodiment is provided in SEQ ID NO: 6. The C-termmus of each epitope expressed is detenmned by termination codons.
  • sequence encoding the housekeeping epitope can precede the IRES sequence and the sequence encoding the immune epitope can be linked to the other end of the IRES sequence.
  • Such vectors can also usefully encode two or more housekeeping epitopes. They can further allow the combination of the various single polypeptide constricts described above, m order to productively express multiple epitopes. See Figures 9A and 9B.
  • the nucleic acid constructs encode two or more mRNA transcripts Each of these transcripts may encode single epitopes or any of the dual or multiple epitope transcripts described m the embodiments above. Two or more transcripts can be the result of using multiple promoters. Those of skill in the art will recognize that use of more than one copy of a single promoter can lead to instability of the plasmid during propagation. Thus it will generally be preferable to use two (or more) different promoters.
  • Two or more transcripts can also be the result of using bidirectional promoters.
  • Bidirectional promoters can be found in a wide variety of organisms. Examples of such promoters include PDGF-A from human, pcbAB and pcbC from Penicillium chrysogenum, neurotropic JC virus, and BRCA1 from mouse, dog and human.
  • PDGF-A from human
  • pcbAB and pcbC from Penicillium chrysogenum
  • neurotropic JC virus and BRCA1 from mouse, dog and human.
  • the dipeptidylpeptidase IV promoter was shown to stimulate transcription from both sides with a similar efficiency.
  • Rat mitochondrial chaperonins 60 and 10 are linked head to head and share a bidirectional promoter. Accordingly, various working bidirectional promoters have been identified, sequenced, and cloned in such a way that they can be used in a nucleic acid construct to express two genes.
  • the nucleic acid constructs contain bidirectional promoters such as, for example, those listed above, linked to a nucleic acid sequence encoding a housekeeping epitope or precursor thereof.
  • the nucleic acid constrict contains bidirectional promoters linked to nucleic acid sequences encoding a plurality of housekeeping epitopes.
  • the nucleic acid constructs comprise bidirectional promoters linked to nucleic acid sequences encoding a housekeeping epitope and an immune epitope, or to an epitope cluster region.
  • the bidirectional promoter may be positively or negatively regulated.
  • the bidirectional promoter may express the plurality of epitopes in comparable amounts or some may be expressed at higher levels than the others.
  • one epitope can be inducible and the other constitutive. In this way, a temporal regulation of epilope expression can be achieved, wherein one epitope is expressed early in the h-eatment and the other expressed later.
  • a direct method for determining housekeeping epitope presentation on pAPCs involves the purification of pAPCs from an animal after administration of an epitope.
  • pAPCs may be harvested from PBMC, splenocytes or lymph node cells, using monoclonal antibodies against specific markers present on pAPCs and affinity purification, such as with the use of monoclonal antibodies fixed to magnetic beads.
  • the optimal time for such harvest is variable, and can depend on the animal vaccinated, the nature of the vaccine, and other factors including dosing, site of administration, pharmacokinetics, and the like. Crude blood or splenoctye preparation can be enriched for pAPCs using this technique.
  • the enriched pAPCs can then be used in a proliferation assay against a T cell clone that has been generated and is specific for the housekeeping epitope of interest.
  • the pAPCs are coincubated with the T cell clone and the T cells are monitored for proliferation activity, such as by measuring the incorporation of radiolabeled thymidine by T cells. Proliferation indicates that T cells specific for the housekeeping epitope are being stimulated by that epitope ⁇ the pAPCs.
  • the following examples are intended for illustration purposes only, and should not be construed as limiting the scope of the invention in any way.
  • Example 1 Proteolytic characterization of an HLA epitope as a housekeeping epitope or an immune epitope
  • a synthetic peptide of 13 amino acids or more is prepared, containing the candidate HLA epitope centrally.
  • Proteasomes are prepared from cells expressing each type of proteasome, for example red blood cells and Raji cells for housekeeping and immune proteasomes, respectively.
  • the peptide is digested with the proteasome preparations and the resultant fragments identified by mass spectrometry. If one of those fragments is co-C- terminal with the HLA epitope, and is produced in significant yield in the preparation containing a housekeeping proteasome, then the HLA epitope is a housekeeping epitope.
  • Synthetic or recombinant polypeptides are constricted which encompass the HLA epitope and at least two residues proximal to its temiini. These residues added to the ends of a particular HLA epitope are to ensure that the proteasome complex encounters a processing environment similar to that found within the cell, hence increasing the likelihood that it performs its proteolytic functions normally. Additional residues normally found proximal to the ends of the FILA epitope can be added if necessary to help increase the solubility of the peptides.
  • HLA epitopes present solubility difficulties due to their high hydrophobicity. Certain peptides can be extremely di fficult to purify because they will not dissolve in normal chromatographic eluents, or they can be very difficult to use once purified because they will not dissolve in the digestion buffers. This problem can be avoided by carefully choosing which part of the sequence surrounding the HLA epitope to include in a particular peptide consfruct, or by extending the sequence as mentioned in the preceding paragraph. If there are no residues proximal to the ends of the HLA epitope that can help increase the solubility, a short hydrophilic sequence can be added instead (e.g. -EAEAE). This is added at least three to five residues past the end of the HLA epitope to maintain a natural terminal cleavage site for the proteasome.
  • -EAEAEAE short hydrophilic sequence
  • peptides are synthesized on an Applied Biosystems 433A Peptide Synthesizer using standard Fmoc solid phase synthesis methodologies.
  • the synthesizer is equipped with a conductivity feedback monitoring system which allows for increased reaction times for sequences that contain stretches of residues that are difficult to deprotect and/or difficult to couple.
  • the peptides are cleaved from their support with trifluoroacetic acid in the presence of appropriate scavengers, precipitated with ether, and then lyophilized.
  • the crude peptides are then purified on a preparative diphenyl HPLC column after first developing a gradient using a similar analytical diphenyl FIPLC system.
  • the major HPLC fractions from the first preparative injection of the peptide are analyzed by elecfrospray mass spectrometry to identify the target compound.
  • the corresponding peaks from subsequent injections are collected, pooled and lyophilized, and a sample is taken to verify retention time and chromatographic purity by analytical HPLC.
  • These purified peptides are then ready for digestion by the proteasome preparation.
  • the purified peptides are then dissolved in an appropriate buffer to a concentration of about 1 mM and added to approximately 2 volumes of the proteasome preparations.
  • Replicate digests are prepared: one for mass spectrometry analysis and one for HPLC analysis, and an additional digest is prepared using a positive control peptide to verify proper functioning of the proteasome preparation used.
  • MLLAVLYCLLWSFQTS SEQ ID NO: 7
  • HSYTTAEEAAGITILTYJLGVL SEQ ID NO: 8
  • EAASSSSTLVEVTLGEVPAAESPD SEQ ID NO: 9
  • EFLWGPRALVETSYVKVLHHMVKI SEQ ID NO: 10
  • APEEKIWEELSVLEVFEGR MLLAVLYCLLWSFQTS (SEQ ID NO: 7); HSYTTAEEAAGITILTYJLGVL (SEQ ID NO: 8); EAASSSSTLVEVTLGEVPAAESPD (SEQ ID NO: 9); EFLWGPRALVETSYVKVLHHMVKI (SEQ ID NO: 10); APEEKIWEELSVLEVFEGR
  • Peptide FLWGPRALVETSYVK (SEQ ID NO: 13) is suitable as a control peptide for housekeeping proteasome assays. These are allowed to incubate in parallel at 37°C for a period of time and then the digestion is stopped by the addition of dilute tifluoroacetic acid and the samples frozen on dry ice. One replicate and a positive control are sent for analysis using a Lasermat 2000 (Finnigan Mat, LTD, U.K.). Matrix Assisted Laser Desorption Ionization - Time Of Flight (MALDI-TOF) mass spectrometry, and the others are set aside for HPLC.
  • MALDI-TOF Matrix Assisted Laser Desorption Ionization - Time Of Flight
  • HLA epitope encompassing peptide is of the sequence:
  • the program would identify all of the following sequences as being potentially useful, and would assign each a molecular weight.
  • the corresponding peptide is synthesized, purified, identified by mass spec omet-y and then subjected to analytical HPLC to establish both a standard retention time and an approximate mass to peak area ratio.
  • the reserve digest is then diluted in an appropriate solvent and injected using the same analytical HPLC method. If the digest gives a peak in good yield that has the same retention time as that of the standard, it is almost certain that it is due to the presence of that sequence in the digest. If there is any ambiguity due to the possible generation of other fragments that would give the same or similar mass spectrometry results, the suspect component can be collected and set aside for C-terminal sequencing to confirm identity.
  • Raji cells a Burkitt's lymphoma cell line, were obtained from ATCC, (American Type Culture Collection, Manassas, VA). The cells were grown using standard cell culture methods and stimulated with INF-Gamma (100-500U/ml) (Pharmingen, San Diego, CA). Expression of immune proteasome subunits was confirmed separately by immunohistochemsitry on the culture, and SDS-PAGE on a sample of the cell lysate. The cells were collected by centrifugation, washed with PBS and stored at -70° C until use.
  • INF-Gamma 100-500U/ml
  • proteasomes at a concentration of 4mg/ml, were then aliquotted and stored at -20° C until use.
  • the proteasomes were tested for activity and specificity by digestion of a fluorogenic substate or a control peptide yielding known fragments.
  • MLLAVLYCLLWSFQTS SEQ ID NO: 21
  • HSYTTAEEAAGITILTVILGVL SEQ ID NO: 22
  • EAASSSSTLVEVTLGEVPAAESPD SEQ ID NO: 23
  • EFLWGPRALVETSYVKVLHHMVKI SEQ ID NO: 24
  • APEEKIWEELSVLEVFEGR SEQ ID NO: 25
  • ELMEVDPIGHLYIFAT SEQ ID NO: 26.
  • Underlined residues indicate proteolytic cleavage sites.
  • FLWGPRALVETSYVK (SEQ ID NO: 27) is suitable as a control peptide for housekeeping proteasome assays.
  • ELISA enzyme-linked immunosorbant assay
  • the supernatant was passed over a protein G sepharose column (Amersham Pharmacia Biotech Piscataway, NJ).
  • the column was washed with PBS and the antibody was eluted in a
  • the optical density of the eluate fractions was measured at 280 nm, and the positive factions were collected.
  • the antibody was dialyzed against 2L of PBS for 2 days at 4° C and stored until use.
  • the antibody was bound to CNBr-aclivated Sepharose 4B (Amersham Phannacia biotech, Piscataway, NY).
  • the antibody-Seph ros complex was washed alternately 5-7 times with 0.1M sodium acetate saline, pH 4 and 0.1 M sodium borate saline, pH 8 and finally suspended in Tris buffered saline (TBS), pH 8.
  • TBS Tris buffered saline
  • a population of candidate MHC I binding peptides generated from the amino acid sequence of human carcinoembryonic antigen precursor (CEA) (GENBANK ACCESSION P06731), was produced using an algorithm. The particular algorithm is available at
  • the table above arbitrarily cuts off scores below 15.
  • the algorithm can produce scores of less than 15.
  • Example 4 Digestion of peptide precursors using immune and housekeeping proteasomes to detenriine fragments produced by proteolytic digestion
  • MS MALDI-TOF mass spectroscopy
  • An optional desalting step can be performed on the digests prior to MS analysis using the ZIP-TIP method (Millipore, Boston, MA).
  • the ZIP TIP is a specially designed pipet tip which contains a bed of spherical silica resin. The sample is bound to the tip, which is pre-equilibrated with 0.1% TFA, and then eluted with 50% Acetonitrile 0.1% TFA elution buffer.
  • Example 5 Identification and quantitation of relevant proteolytic fragments by HPLC and mass spectrometry
  • the amino acid sequence of a protein of interest is entered into a computer, and the algorithm of Rammensee, et al., is used to generate 9- or 10-amino-acid-long sequences predicted to bind a particular HLA receptor. The algorithm also ranks these predicted epitopes according to how well they match the binding motif.
  • Synthetic peptides containing the sequence of the identified potential epitopes are then constructed to encompass the epitope candidate sequence and at least 3-5 residues proximal to its temiini.
  • the residues added to the ends of a particular epitope candidate are to ensure that the proteasome complex encounters a processing environment similar to that found within the cell, hence increasing the likelihood that it performs its proteolytic functions nonrially. Additional residues normally found proximal to the ends of the epitope candidate may be added if necessary to help increase the solubility of the peptides.
  • Peptides are synthesized on an Applied Biosystems 433A Peptide Synthesizer (Applied
  • the synthesizer is equipped with a conductivity feedback monitoring system which allows for increased reaction times for sequences that contain stretches of difficult to deprotect and difficult to couple residues.
  • the peptides are cleaved from their support with trifluoroacetic acid in the presence of appropriate scavengers, precipitated with ether and then lyophilized. The crude peptides are then dissolved in a suitable solvent at 0.5 mg/ml.
  • the gradients used vary from 0-40% acetonitrile for hydrophillic to 30-70% acetonitrile for hydrophobic peptides.
  • the peptides are subsequently purified on a Varian Prostar HPLC system (Varian, Inc., Palo Alto, CA) using similar gradients and semi-preparative versions of the above-mentioned columns (Machery Nagel # 715802, and Vydac 219TP510).
  • the major HPLC fractions from the first preparative injection of the peptide are analyzed using a MALDI-TOF mass spectrometer to identify the desired component.
  • Immune or housekeeping proteasome complexes are isolated by the method of Levy, (Morel, S., et al., Immunity 12: 107-117 (2000), and the references cited therein) described above.
  • the purified peptide is dissolved in an appropriate buffer to a concentration of about 1 to 2 mM and added to approximately 2 volumes of the proteasome preparation.
  • the buffer chosen must solvate the peptide without interfering with the digestion process.
  • An additional digest is prepared using the positive control peptide described above to verify proper functioning of the proteasome preparation used.
  • each digest was mixed with an equal volume of the matrix solution (10 mg/ml dihydroxybenzoic acid in 70% EtOH, pH 2-3) directly on the sample slide and allowed to air dry at about 40°C.
  • the samples were then analyzed on a LaseimatTM MALDI-TOF mass spectrometer (Thermo Bioanalysis, Santa Fe, NM)that was calibrated with suitable molecular weight standards.
  • the computer programs (either "Peptide” software, (Lighthouse Data), or “Dynamo” (ThermoBioanalysis Ltd., U.K.)) developed for the proteasome assay generates the sequence and molecular weight of all the possible fragments that satisfy both requirements of having the con-ect C-terminus of any predicted epitope, and of containing the full length of that epitope or longer.
  • the coirespondi ⁇ g peptide was synthesized, purified, identified by MALDI- TOF and then subjected to reverse phase analytical HPLC to establish a standard retention time and an approximate mass to peak area ratio. These procedures are directly analogous to those described above. A replicate proteasome digest was then diluted in an appropriate solvent and analyzed using the same analytical HPLC method. When the digest gives a peak in good yield that has the same retention time as that of the standard, it is almost certain that it is due to the presence of that sequence in the digest.
  • the suspect component can be collected and set aside for sequencing to confirm identity.
  • the analytical HPLC also importantly provides relatively accurate quantitation of the peptide product in the digest, which allows determination of whether a given peptide is a minor or a major product of the digest, which indicates whether the epitope is efficiently produced by the proteasome. Using the above method, housekeeping epitopes were identified.
  • Figure 13 shows the results of a flow cytometry assay to verify HLA binding by these epitopes. This assay is discussed in Example 6.
  • Example 6 Determine the MHC binding ability of selected peptides Binding of a candidate epitope to HLA-A2.1 was assayed according to the method of
  • T2 cells which express empty or unstable MHC molecules on their surface, were washed twice and suspended at 5xl0 6 cells/ml in serum-free complete Iscove's modified Dulbecco's medium (IMDM). ⁇ 2 microglobulin (Sigma,
  • tyrosinase 207- 216 FLPWHRLFLL SEQ ID NO: 85
  • HLA-B44 binding peptide AEMGKYSFY SEQ ID NO: 87
  • the fluorescence obtained from the negative control was similar to the signal obtained when no peptide was used in the assay.
  • Positive and negative control peptides were chosen from Table 18.3.1 in Current Protocols in Immunology p. 18.3.2, John Wiley and Sons, New York, 1998.
  • Example 7 Elution of HLA epitopes from tumors, tissue samples, immortalized cell lines, or tumor cell lines
  • HLA epitopes Rather than generating HLA epitopes with in vitro proteolysis, they can be identified after elution from the HLA of tumors, tissue samples, tumor cell lines or other immortalized cell lines using mass spectrometry methods. While a variety of such methods can be used, one of the most powerful methods of identifying epitopes from the surface of cells involves capillary or nanocapillary HPLC ESI mass spectrometry and on-line sequencing, as described in the published literature. Elution procedures for sol ⁇ bilized HLA and intact cells are also described in Falk, K. et al. Nature 351 :290, 1991 and in U.S. Patent 5,989,565, respectively.
  • proteasome expression can be assessed preferably by western blotting, which is described in detail below, and can also be assessed by RT-PCR, immunohistochemishy, or in situ hybridization.
  • Another assay to distinguish between housekeeping epitopes and immune epitopes is to test the ability of anti-peptide CTL to kill cells expressing the TAA in question.
  • IFN can be used to induce expression of the immune proteasome (assuming • it is not already constitutively expressed) and CTL recognition of the induced and uninduced cells can be compared.
  • proteasome type should be confirmed, e.g., by western blotting. If the IFN-induced cells are killed preferentially, the peptide constitutes an immune epitope. If the non-induced cells are killed preferentially, the peptide constitutes a housekeeping epitope.
  • Some epitopes can be produced by both proteasomes at differing efficiencies, and in such cases cytolytic activity is observed against both populations. Such epitopes are classified as housekeeping epitopes since they are present on peripheral target cells.
  • Example 9 The use of human peripheral blood mononuclear cells (PBMCs) or tumor infiltrating lymphocytes (TILs) to identify housekeeping epitopes
  • PBMCs peripheral blood mononuclear cells
  • TILs tumor infiltrating lymphocytes
  • TILs isolated from patient biopsies, or PBMCs from blood of donors or patients can be used to identify housekeeping epitopes using methods that are commonly described in the published literature. To identify housekeeping epitopes, the target cells used to test for active killing by PBMCs or TILs are confirmed to express only the housekeeping proteasomes, and not to express at significant levels the immune proteasome.
  • PBMCs from donor blood are stimulated in vitro using a panel of peptide antigens with predicted affinity for the class I HLA allele expressed on the blood cells being used. Each PBMC sample is stimulated with a specific class I peptide antigen for one week, preferably with the combination of cytokines such as IL-2 or IL-12 to enhance the activity of the T cells.
  • This stimulation is repeated at least three times to induce clonal expansion of T cells specific against the peptide.
  • a standard chromium release assay is performed using target cells that are known to express the protein containing the epitope and exclusively the housekeeping proteasome. Evidence of killing of the target cells as measured by chromium release indicates that the peptide used to stimulate the PBMCs is present as a housekeeping epitope on the surface of the target cell. Tumors expressing this protein are thus candidate targets for a vaccine containing the epitope.
  • Example 10 Identification of housekeeping and/or immune proteasomes by western blotting
  • Horse anti mouse for monoclonal antibodies
  • Vector Labs Cat. No. BA-2000 1 :1000 9. Wash the membrane as in step 3. 10. Incubate the membrane in 5 ml of ABC (Vector Laboratories, Cat. No. PK-6100) in PBS-T for 30 min:
  • Tris- buffered saline 2.42g Tris base (20mM) 8g sodium chloride ( 137mM)
  • Example 1 1 . Preparation of a housekeeping epitope peptide vaccine
  • a sequence identified to be a housekeeping epitope is synthesized using a commercial peptide synthesizer.
  • Peptides of interest are formulated in different ways and administered alone, or in combination with adjuvants, such as CFA, IF A, or melacine, or with cytokines, such as IL-2, IL-12, or GM-CSF in order to achieve the effect of stimulating T cells against the epitope in animals.
  • Peptides are also formulated with controlled release substances, such as PLGA microspheres or other biodegradable substances, which alter the phamiacokinetics of the peptide and can also improve immunogenicity.
  • Peptides are also formulated for oral delivery using such substances to facilitate priming of the immune response through uptake into GALT (gut-associated lymphoid tissues).
  • Peptide are also adhered to minute gold particles so that they can be delivered using a "gene gun.”
  • Peptides are synthesized using either FMOC or tBOC solid phase synthesis methodologies. After synthesis, the peptides are cleaved from their supports with either t-ifluoroacetic acid or hydrogen fluoride, respectively, in the presence of appropriate protective scavengers. After removing the acid by evaporation, the peptides are extracted with ether to remove the scavengers and the crude, precipitated peptide is then lyophilized. Purity of the crude peptides is deteraiined by HPLC, sequence analysis, amino acid analysis, counterion content analysis and other suitable means. If the crude peptides are pure enough (greater than or equal to about 90% pure), they can be used as is.
  • the peptides are purified using one or a combination of the following: re-precipitation; reverse-phase, ion exchange, size exclusion or hydrophobic interaction chromatography; or counter-current distribution.
  • GMP-grade peptides are formulated in a parenterally acceptable aqueous, organic, or aqueous-organic buffer or solvent system in which they remain both physically and chemically stable and biologically potent.
  • buffers or combinations of buffers or combinations of buffers and organic solvents are appropriate.
  • the pH range is typically between 6 and 9.
  • Organic modifiers or other excipients can be added to help solubilize and stabilize the peptides. These include detergents, lipids, co-solvents, antioxidants, chelators and reducing agents.
  • sucrose or mannitol or other lyophilization aids can be added.
  • Peptide solutions are sterilized by membrane filtration into their final container-closure system and either lyophilized for dissolution in the clinic, or stored until use.
  • a formulation containing peptide in aqueous buffer with an antimicrobial agent, an antioxidant, and an immunomodulating cytokine was injected continuously over several days into the inguinal lymph node using a miniature pumping system developed for insulin delivery (MiniMed; Northridge, CA). This infusion cycle was selected in order to mimic the kinetics of antigen presentation during a natural infection. Additional embodiments to this mode of vaccine delivery useful in accordance with the present invention are disclosed in PCT Publication No. WO 99/01283; U.S. Patent Application No. 09/380,534, entitled A METHOD OF INDUCING A CTL
  • a peptide formulation is delivered using contolled PLGA microspheres, which alter the pha ⁇ nacokinetics of the peptide and improve immunogenicity. This formulation is injected or taken orally.
  • a peptide formulation is prepared wherein the peptide is adhered to gold microparticles.
  • the particles are delivered in a gene gun, being accelerated at high speed so as to penetrate the skin, carrying the particles into dermal tissues that contain pAPCs.
  • a peptide formulation is inhaled as an aerosol, for uptake into appropriate vascular or lymphatic tissue in the lungs.
  • Example 13 Preparation of a nucleic acid vaccine
  • pVAXl Invitrogen, Carlsbad, CA
  • pVAXl kanamycin resistance gene
  • CMV promoter a CMV promoter
  • a suitable E. coli strain was then transfected with the plasmid and plated out onto selective media. Several colonies were grown up in suspension culture and positive clones were identified by restriction mapping. The positive clone was then grown up and aliq ⁇ otted into storage vials and stored at -70°C.
  • a mini-prep (QIAprep Spin Mini-prep: Qiagen, Valencia, CA) of the plasmid was then made from a sample of these cells and automated fluorescent dideoxy sequence analysis was used to confirm that the constrict had the desired sequence.
  • Further nucleic acid vaccine vectors and fo ⁇ riulations are described in the foregoing sections of this specification, and in Examples 18-20 below. Certain modifications of the plasmid backbone useful in conjunction with large-scale production of the plasmid, as in vaccine manufacture, are provided in U.S. Patent Application No. 09/715,835, entitled AVOIDANCE OF UNDESIRABLE REPLICATION INTERMEDIATES IN PLASMID PROPAGATION, filed on November 16, 2000.
  • a nucleic acid vaccine is injected into a lymph node using a miniatre pumping system, such as the MiniMed insulin pump.
  • a nucleic acid constructs fonmilated in an aqueous buffered solution containing an antimicrobial agent, an antioxidant, and an immunomodulating cytokine is delivered over a several day infusion cycle in order to mimic the kinetics of antigen presentation during a natural infection. Additional embodiments to this mode of vaccine delivery useful in accordance with the present invention are disclosed in PCT Publication No. WO 99/01283 and U.S. Patent Application No. 09/776,232.
  • the nucleic acid construct is delivered using contolled release substances, such as PLGA microspheres or other biodegradable substances. These substances are injected or taken orally.
  • the nucleic acid vaccine is given using oral delivery, priming the immune response through uptake into GALT tissues.
  • the nucleic acid vaccine is delivered using a gene gun, wherein the nucleic acid vaccine is adhered to minute gold particles.
  • Nucleic acid constricts can also be inhaled as an aerosol, for uptake into appropriate vascular or lymphatic tissue in the lungs.
  • Class I tetramer analysis is used to determine T cell frequency in an animal before and after administration of a housekeeping epitope.
  • Clonal expansion of T cells in response to an epitope indicates that the epitope is presented to T cells by pAPCs.
  • the specific T cell frequency is measured against the housekeeping epitope before and after administration of the epitope to an animal, to detemiine if the epitope is present on pAPCs.
  • An increase in frequency of T cells specific to the epitope after administration indicates that the epitope was presented on pAPC.
  • pAPCs are harvested from PBMCs, splenocytes, or lymph node cells, using monoclonal antibodies against specific markers present on pAPCs, fixed to magnetic beads for affinity purification.
  • Crude blood or splenoctye preparation is enriched for pAPCs using this technique.
  • the enriched pAPCs are then used in a proliferation assay against a T cell clone that has been generated and is specific for the housekeeping epitope of interest.
  • the p APCs are coincubated with the T cell clone and the T cells are monitored for proliferation activity by measuring the incorporation of radiolabeled thymidine by T cells. Proliferation indicates that T cells specific for the housekeeping epitope are being stimulated by that epitope on the pAPCs.
  • Example 16 Assay for effectiveness of housekeeping epitopes as anticancer treannent
  • Suirogate endpoints or survival are used to determine the effectiveness of epitope synchronization vaccines in cancer treatment.
  • a useful suirogate endpoint is the determination of T cell frequency against the housekeeping epitope used in immunization.
  • Patients developing elevated T cell frequencies against specific TuAA epitopes used in tumor immunotherapy have significantly better survival compared to patients immunized by the same epitope but not developing increased T cell frequency to the epitope.
  • Tetramer analysis, ELISPOT analysis, or limiting dilution analysis are used to assess T cell frequency to a housekeeping epitope before and after immunization with the epitope, indicating the anticancer effectiveness of a housekeeping epitope in a vaccine.
  • T cells from these animals are used in a standard chromium release assay using human tumor targets or targets engineered to express the same class I MHC. T cell killing of the targets indicates that stimulation of T cells in a patient would be effective at killing a tumor expressing a similar TuAA.
  • Example 17 Identification of Unique Housekeeping Epitopes
  • Epitopes useful in the vaccines and methods of the present invention can be readily identified as disclosed herein.
  • three unique housekeeping epitopes that are not produced by pAPCs have been identified as follows:
  • Immune or housekeeping proteasome complexes are isolated.
  • the purified peptide is dissolved in an appropriate buffer to a concentration of about 1 to 2 mM and added to approximately 2 volumes of the proteasome preparation.
  • the buffer chosen must solvate the peptide without interfering with the digestion process.
  • An additional digest is prepared using the positive control peptide described above to verify proper functioning of the proteasome preparation used. These are incubated at 37°C for periods of up to 120 minutes and then the digestion is stopped by the addition of dilute trifluoroacetic acid; the samples are analyzed immediately by mass spectrometry, or they are frozen on dry ice until analysis.
  • the digest reaction can also be halted by putting samples on ice for immediate analysis by mass spectrometry.
  • each digest was mixed with an equal volume of the matrix solution (10 mg/ml dihydroxybenzoic acid in 70% EtOH, pH 2-3) directly on the sample slide and allowed to air diy at about 40°C.
  • the samples were then analyzed on a LasermatTM MALDI-TOF mass spectrometer that was calibrated with suitable molecular weight standards.
  • the computer program developed for the proteasome assay generates the sequence and molecular weight of all the possible fragments that satisfy both requirements of having the coirect C-terminus of any predicted epitope, and of containing the full length of that epitope or longer.
  • the suspect component can be collected and set aside for sequencing to confii ⁇ n identity. Using the above method, housekeeping epitopes were identified.
  • Binding of a candidate epitope to HLA-A2.1 was assayed according to the method of Stauss et al., (Proc Natl Acad Sci USA 89(17):7871-5 (1992)). T2 cells, which express empty or unstable MHC molecules on their surface, were washed twice and suspended at 5x10 6 cells/ml in serum-free complete Iscove's modified Dulbecco's medium (IMDM). ⁇ 2 microglobulin (Sigma,
  • tyrosinase 207-216 FLPWHRLFLL SEQ ID NO: 85
  • HLA-B44 binding peptide AEMGKYSFY SEQ ID NO: 87
  • the fluoresence obtained from the negative control was similar to the signal obtained when no peptide was used in the assay.
  • Positive and negative contol peptides were chosen from Table 18.3.1 in Current Protocols in Immunology p. 18.3.2, John Wiley and Sons, New York, 1998.
  • the starting plasmid for this construct is pVAXl purchased from Invihrogen. (Carlsbad, CA) Epitope EP1 and EP2 were synthesized by GIBCO BRL (Rockville, MD). IRES was cut out from pIRES purchased from Clontech (Palo Alto, CA). See Figure 10B. Procedure:
  • the starting plasmid for this construct was pVAX-EPl-IRES-EP2 .(Example 18).
  • ISS immunonostimulatory sequence
  • SEQ ID NO: 89 introduced to this construct is AACGTT
  • NIS standing for nuclear import sequence
  • SEQ ID NO: 88 used is the SV40 72bp repeat sequence.
  • ISS-NIS was synthesized by GIBCO BRL. See Figure 10 A.
  • the starting plasmid for this construct is pVAXl (Invitrogen).
  • EP2 and EP1 were synthesized by GIBCO BRL. Wild type Ubiquitin cDNA encoding the 76 amino acids in the construct was cloned from yeast. See Figure 11. Procedure: 1 Perform RT-PCR using yeast mRNA. Primers were designed to amplify the complete coding sequence of yeast Ubiquitin;
  • Examples 21-24 all concern the prediction of 9-mer epitopes presented by HLA-A2.1, although the procedure is equally applicable to any HLA type, or epitope length, for which a predictive .algorithm or MHC binding assay is available.
  • This melanoma tumor-associated antigen is 118 amino acids in length.
  • 16 are given a score 16 by the SYFPEITHI/Rammensee algoritlim. (See Table 10). These represent 14.5% of the possible peptides and an average epitope density on the protein of 0.136 per amino acid. Twelve of these overlap, covering amino acids 22-49 of SEQ ID NO: 1 resulting in an epitope density for the cluster of 0.428, giving a ratio, as described above, of 3.15.
  • Another two predicted epitopes overlap amino acids 56-69 of SEQ ID NO: 1, giving an epitope density for the cluster of 0.143, which is not appreciably different than the average, with a ratio of just 1.05. See Figure 15.
  • This melanoma tumor-associated antigen is 188 amino acids in length. Of the 180 possible 9-mers, 1 1 are given a score 16 by the SYFPEITHI/Rammensee algorithm. (See Table
  • This tumor-associated antigen is 180 amino acids in length. Of the 172 possible 9- mers, 25 are given a score 16 by the SYFPEITHI/Rammensee algorithm. (See Table 17). Like Melan-A above, these represent 14.5% of the possible peptides and an average epitope density on the protein of 0.136 per amino acid. However the distribution is quite different. Nearly half the protein is empty with just one predicted epitope in the first 78 amino acids. Unlike Melan-A where there was a very tight cluster of highly overlapping peptides, in NY-ESO the overlaps are smaller and extend over most of the rest of the protein.
  • One set of 19 overlapping peptides covers amino acids 108-174 of SEQ ID NO: 3, resulting in a ratio of 2.04.
  • Another 5 predicted epitopes cover 79-104 of SEQ ID NO: 3, for a ratio of just 1.38. (See Table 18).
  • Example 24 ECRs in Tyrosinase (SEQ ID NO: 4)
  • This melanoma tumor-associated antigen is 529 amino acids in length. Of the 521 possible 9-mers, 52 are given a score 16 by the SYFPEITHI/Rammensee algorithm. (See Table 21). These represent 10% of the possible peptides and an average epitope density on the protein of 0.098 per amino acid. There are 5 groups of overlapping peptides containing 2 to 13 predicted epitopes each, with ratios ranging from 2.03 to 4.41, respectively. There are an additional 7 groups of overlapping peptides, containing 2 to 4 predicted epitopes each, with ratios ranging from 1.20 to 1.85, respectively. The 17 peptides in the region 444-506 of SEQ ID NO: 4, including the 13 overlapping peptides above, constitutes a cluster with a ratio of 2.20. (See Table 22).

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EP1853289A2 (en) * 2005-01-31 2007-11-14 Vaxinnate Corporation Novel polypeptide ligands for toll-like receptor 2 (tlr2)
EP1996232A2 (en) * 2006-03-01 2008-12-03 Janssen Pharmaceutica, N.V. CANCER TREATMENT COMBINING LYMPHODEPLETING AGENT WITH CTLs AND CYTOKINES
JP2010523141A (ja) * 2007-04-11 2010-07-15 コンセホ ナシオナル デ インベスティガシオネス シェンティフィサス イ テクニカス （コニセト） 細胞株、黒色腫の治療のためにそれを含む組成物、組成物の製造手順および治療方法
EA034800B1 (ru) * 2007-07-27 2020-03-23 Имматикс Байотекнолоджиз Гмбх Пептид, связывающийся с мнс-i, индуцирующий цтл и стимулирующий антиопухолевые иммунные ответы

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GB201408255D0 (en) * 2014-05-09 2014-06-25 Immatics Biotechnologies Gmbh Novel immunotherapy against several tumours of the blood, such as acute myeloid leukemia (AML)
EP4219524A3 (en) * 2016-04-06 2023-10-18 immatics biotechnologies GmbH Novel peptides and combination of peptides for use in immunotherapy against aml and other cancers

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Cited By (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP1853289A2 (en) * 2005-01-31 2007-11-14 Vaxinnate Corporation Novel polypeptide ligands for toll-like receptor 2 (tlr2)
EP1853289A4 (en) * 2005-01-31 2008-04-09 Vaxinnate Corp NOVEL POLYPEPTIDE LIGANDS FOR THE GREAT ARTICLE RECEPTOR 2
EP1996232A2 (en) * 2006-03-01 2008-12-03 Janssen Pharmaceutica, N.V. CANCER TREATMENT COMBINING LYMPHODEPLETING AGENT WITH CTLs AND CYTOKINES
EP1996232A4 (en) * 2006-03-01 2010-08-04 Janssen Pharmaceutica Nv TREATMENT OF CANCER ASSOCIATED WITH LYMPHODEPPLER AGENT TO CTL AND CYTOKINES
US7993638B2 (en) 2006-03-01 2011-08-09 Janssen Pharmaceutica Nv Cancer treatment combining lymphodepleting agent with CTLs and cytokines
AU2007222080B2 (en) * 2006-03-01 2012-08-16 Janssen Pharmaceutica N.V. Cancer treatment combining lymphodepleting agent with CTLs and cytokines
JP2010523141A (ja) * 2007-04-11 2010-07-15 コンセホ ナシオナル デ インベスティガシオネス シェンティフィサス イ テクニカス （コニセト） 細胞株、黒色腫の治療のためにそれを含む組成物、組成物の製造手順および治療方法
EA034800B1 (ru) * 2007-07-27 2020-03-23 Имматикс Байотекнолоджиз Гмбх Пептид, связывающийся с мнс-i, индуцирующий цтл и стимулирующий антиопухолевые иммунные ответы

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