WO2008147186A1 - P53 peptide vaccine - Google Patents

Abstract

The invention relates to a peptide derived from p53 that could be used as a vaccine against cancer.

Description

P53 PEPTIDE VACCINE

Field of the invention The present invention relates to the field of medicine and immunology. In particular it relates to an improved p53 peptide vaccine.

Background of the invention

In this application p53, is taken as a representative example of an ubiquitously expressed self-antigen known to be associated with cancer. The strategy used to design a vaccine against p53 could be applied to design a vaccine against any other ubiquitously expressed self-antigen known to be associated with cancer. The nuclear phosphoprotein p53 is a tumor suppressor protein that is ubiquitously expressed at low levels in normal tissues, including thymus, spleen and lymphohematopoetic cells (Rogerl A et al, Milner J et al, Terada N et al). The normal half-life of wild-type p53 is less than 30 minutes. Following ubiquitination, the wild- type (WT) p53 protein is rapidly degraded by proteasomes (Honda R et al, Momand J et al, Shkedy D et al). Proteasome-mediated digestion of p53 may lead to the generation of peptides that are presented by class I MHC molecules. Recognition of these class I MHC bound wild-type p53 derived peptides at the surface of thymic APC by immature thymic T-cells with high avidity for the class I MHC-peptide complex will result in negative selection (Allen PM et al, Ashton-Rickardt PG et al, Kappler JW et al). As a consequence, the peripheral T-cell repertoire will not contain functional p53- specific class I MHC-restricted T-cells. Theobald et al. elegantly showed that CTL specific for the naturally processed peptide p53₁₈₇-₁₉₇ were deleted from the repertoire in WTρ53 mice but not in p53-/- mice (Theobald M et al, 1997), demonstrating that negative selection of high avidity p53 -specific CTL can occur in the thymus. Paradoxically, class I MHC-restricted CTL able to recognize endogenously processed WTp53 at the surface of tumor cells, have been detected in both mice and man (Theobald M et al 1997, Macagno A, et al, Mayordomo JI et al, Barfoed AM et al, Chikamatsu K et al, Eura M et al, Houbiers JG et al, Ropke M et al) suggesting that functional p53 -specific class I MHC-restricted CTL can escape from tolerance induction. Several p53 vaccines have already been developed. For example, WO 00/75336 discloses polyepitopic peptides derived from p53 having the capacity to be degraded by the proteasome and to associate with high affinity to class I MHC molecules. Such properties are supposed to be essential for inducing an immune response against p53. More likely, T-cells responding to this type of peptides have either been deleted in the thymus, are tolerized in the periphery or are of low T-cell receptor affinity to mediate an effective anti-tumor response (Theobald M & Offringa R. 2003, and Morgan et al.) Thus, it is to be expected that such peptides derived from an ubiquitously expressed self-antigen, such as p53, will not be able to trigger a strong and effective immune response in vivo.

Therefore, there is still a need for new and improved p53 vaccines, which does not have all the drawbacks of existing p53 vaccines.

Description of the invention

The present invention is based on the surprising finding that in order to induce an efficient anti p53 response, a peptide derived from p53 should be inefficiently processed by the proteasome and/or exhibit low to intermediate capacity to stably form cell surface class I MHC-peptide complexes and/or a peptide exhibits a low to intermediate MHC binding affinity. Preferably, a peptide derived from p53 should be inefficiently processed by the proteasome and/or exhibit low to intermediate capacity to stably form cell surface class I MHC-peptide complexes. We have found that escape of self-specific T-cells from negative selection in the thymus may occur through low-avidity interactions between the TCR and MHC. Indeed, WTp53-specific CTL that recognizes their cognate peptide have been detected in WTp53-mice but with a 10-fold lower avidity than CTL obtained from p53-/- mice (Theobald M et al, 1997 and Hernandez J et al). Furthermore, a disparity between so- called household proteasomes and immunoproteasomes in the generation of certain peptide epitopes may allow positive selection by thymic epithelium but failure to delete these cells by a lack of presentation of these MHC-peptide complexes by thymic APC. Dendritic cells constitutively express immunoproteasomes (Kloetzel PM & Ossendorp 2004) and high levels of immunoproteasomes have been detected in the thymus (Zanelli E et al, and Stohwasser R et al). Morel et al. demonstrated that human CTL recognizing the melanoma antigen Melan-A as well as CTL that recognized a novel ubiquitously expressed protein did not recognize APC carrying immunoproteasomes whereas they were capable of recognizing cells expressing household proteasomes. Failure to present enough class I MHC-molecules presenting the same peptide may also allow T-cells to survive thymic selection (Sebzda E et al). A modest surface expression of certain class I MHC-restricted peptides can be achieved by several, not mutually exclusive, mechanisms: 1) to low expression or to low turn-over of proteins in the cell resulting in the generation of insufficient numbers of epitopes that allow recognition by CTL (Vierboom MP et al), 2) peptides with only a weak binding affinity for MHC may lose the competition with peptides with better MHC-binding properties and as such are scarcely expressed at the cell surface, 3) peptides with only a weak capacity to stably bind to class I MHC may form class I MHC-peptide complexes at the cell surface which quickly disintegrate and as such are not stimulatory to T-cells anymore (van der Burg SH et al 1996) and 4) proteosomal generation of CTL epitopes may be insufficient to generate effective numbers of MHC-peptide complexes.

Peptide

Therefore, in a first aspect, there is provided a peptide derived from a protein that is ubiquitously expressed self-antigen and known to be associated with cancer, said peptide comprising an epitope exhibiting a low to intermediate capacity to form stable class I MHC-peptide complexes at the cell surface and/or being inefficiently processed by a proteasome and/or exhibiting a low to intermediate MHC binding affinity. Preferably, a peptide comprises an epitope exhibiting a low to intermediate capacity to form stable class I MHC-peptide complexes at the cell surface and/or being inefficiently processed by a proteasome.

In the context of the invention, "exhibiting a low to intermediate MHC binding affinity" preferably means that the relative binding affinity of an epitope contained in a peptide is comprised between 5 and 50 μM. More preferably, the relative binding affinity is comprised between 10 and 50 μM, even more preferably between 15 and 50 μM. The relative binding affinity is preferably assessed by a competition based cellular binding assay as previously described (van der Burg SH 1995) (see also example 1). The affinity of a given epitope present within a peptide is expressed as the epitope concentration to inhibit 50% (IC50) of the binding of a reference epitope. The length of the epitope is generally comprised between 8 and 12 amino acids in length and is typically selected based on typical anchor residues for HLA-A*0101, A*0301, A*l 101 and A*2401 (Rammensee HG et al). Preferred peptides are the ones as described in example 1. In the context of the invention, "exhibiting a low to intermediate MHC binding affinity" is preferably measured by measuring the stability for binding to MHC as described in (van der Burg SH et al 1996).

Stability of other peptide-HLA complexes was preferably determined as follows. Peptide binding was performed at 4⁰C and 20°C and IC₅₀ were determined. Peptides of >50% of the initial complexes was lost within 2 hours were considered unstable. Stable peptides displayed IC₅₀ at 20⁰C that deviated <2 times of the IC₅₀ at 4°C. Peptides that displayed IC₅₀ at 2O⁰C of more than twice the IC₅₀ at 4°C but IC_5O<15μM were considered to bind with intermediate stability. The rest was designated as unstable peptide binding. In the context of the invention, "being inefficiently processed by a proteasome" preferably means that within the first hour of digestion by a proteasome less than 1% of total digested peptide is found. The processing by a proteasome is preferably assessed by incubating a purified proteasome, more preferably a human proteasome with a peptide comprising the potential CTL epitope (30 amino acid length approximately) in a proteasome digestion buffer during at least one hour at 37⁰C. The reaction is subsequently stopped by adding trifluoroacetic acid. Analysis of the digested peptides is performed with electrospray ionization mass spectrometry (see example 1). Even more preferably, the human proteasome is an immunoproteasome from B-LCL JY cells (Kessler JH et al. 2001). The sequence of a peptide used in the present invention is not critical as long as it is derived from a protein ubiquitously expressed self-antigen and known to be associated with cancer and as long as the peptide comprises an epitope exhibiting a low capacity to form stable class I MHC at the cell surface and/or which is inefficiently processed by a proteasome and/or exhibiting a low to intermediate MHC binding affinity. Preferably, a peptide comprises an epitope exhibiting a low capacity to form stable class I MHC at the cell surface and/or which is inefficiently processed by a proteasome Accordingly, a peptide is preferably used, which comprises a contiguous amino acid sequence derived from the amino acid sequence of a protein ubiquitously expressed self-antigen and know to be associated with cancer.

In the context of the invention, a protein is ubiquitously expressed. Preferably, a protein is ubiquitously expressed when it is broadly expressed. Broadly preferably means that its expression is detectable by means of arrays or Northern in at least 5 distinct types of tissues including the thymus, more preferably at least 7, including the thymus and even more preferably at least 10, including the thymus . A protein is preferably said to be associated with cancer in the following illustrating and non-limitative cases: a protein is over-expressed and/or is mutated and/or is aberrantly expressed in a given tissue of cancer patients by comparison with the corresponding tissue of a subject not having cancer. An aberrantly expressed protein may be de novo expressed in a tissue wherein it is normally not expressed. A mutated protein may be a splice variant. A mutated protein may further be produced as an aberrant fusion protein as a result of a translocation.

Examples of proteins that are ubiquitously expressed self-antigens known to be associated with cancer are p53, MDM-2, HDM2 and other proteins playing a role in p53 pathway, molecules such as survivin, telomerase, cytochrome P450 isoform IBl, Her-2/neu, and CD 19 and all so-called house hold proteins. In a preferred embodiment, the protein is p53, more preferably human p53.

The amino acid sequence of human p53 is depicted in SEQ ID No.l Preferably, the length of the contiguous amino acid sequence derived from the protein, preferably p53 is no more than 45 amino acids and comprises at least 19 contiguous amino acids derived from the amino acid sequence of a protein, preferably p53. The length of the contiguous amino acid sequence derived from a protein, preferably p53 comprised within the peptide, preferably is comprised between 19-45, 22-45, 22-40, 22-35, 24-43, 26-41, 28-39, 30-40, 30-37, 30-35, 32-35 33-35, 31-34 amino acids. In another preferred embodiment, a peptide comprises 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, or 45 or more than 45 contiguous amino acid residues of a protein, preferably p53. The skilled person will therefore understand that a peptide of the invention is distinct from a p53 protein, preferably from the human p53. In another preferred embodiment, a peptide of the invention consists of any of the contiguous amino acid sequences from a protein, preferably p53 as defined herein. A peptide of such length used in the invention may be easily synthesized. In a preferred embodiment, an antigen present in a peptide derives from a protein, preferably p53 or an immunogenic part, derivative and/or analogue thereof. This peptide should meet the activities as earlier defined herein (a peptide comprises an epitope displaying a low to intermediate capacity to form stable cell-surface expressed class I MHC-peptide complexes and/or being inefficiently processed by a proteasome and/or exhibiting a low to intermediate MHC binding affinity. Preferably, a peptide comprises an epitope displaying a low to intermediate capacity to form stable cell- surface expressed class I MHC-peptide complexes and/or being inefficiently processed by a proteasome). An immunogenic part, derivative and/or analogue of a protein, preferably p53 comprises the same immunogenic capacity in kind not necessarily in amount as said protein itself. A derivative of such a protein can be obtained by preferably conservative amino acid substitution.

In a preferred embodiment, when the protein is p53, several epitopes displaying a low to intermediate capacity to form stable cell-surface expressed class I MHC-peptide complexes have already been identified and are presented in table 5. In this preferred embodiment, a peptide of the invention comprises any of these HLA Al, A2, A3, Al 1 and/or A24 type epitopes: Al : 229-236 and/or A2 149-157 and/or

A3: 101-110, 112-120, 113-120, 117-126, 154-163, 156-163, 360-370, 363-372, 373- 381, 376-386 and/or Al l : 101-110, 112-120, 283-291, 311-319, 311-320, 312-319, 363-370, ,374-382 and/or

A24: 340-348.

Alternatively or in combination with the previous preferred embodiment, in another preferred embodiment, when the protein is p53, epitopes which are inefficiently processed by a proteasome have already been identified and are presented in table 5. In this preferred embodiment, a peptide of the invention comprises any of these HLA Al, A2, A3 and/or Al l type epitopes: Al : 117-126, 196-205, 229-236 and/or A2: 264-272 and/or

A3: 101-110, 154-163, 154-164, 156-163, 156-164, 172-181, 376-386 and/or

Al l: 101-110, 156-164, 311-319, 311-320, 312-319, 374-382.

Alternatively or in combination with one or two of the previous preferred embodiments, in a preferred embodiment, when the protein is p53, several epitopes exhibiting a low to intermediate MHC binding affinity have already been identified and are presented in table 5. In this preferred embodiment, a peptide of the invention comprises any of these HLA Al, A2, A3, and/or Al 1 type epitopes: Al: 117-126, 196-205, 205-214, 229-236, 229-236, and/or A2: 113-122, 149-157, 264-272, 322-330, and/or

A3: 112-120, 113-120, 117-126, 154-163, 156-163, 172-181, 360-370, 363-372, 373- 381 and/or Al l: 112-120, 283-291, 363-370, 374-382.

In an even more preferred embodiment, first two preferred embodiments are combined to define several epitopes, when the protein is p53, said epitopes displaying a low to intermediate capacity to form stable cell-surface expressed class I MHC-peptide and being inefficiently processed by a proteasome. In this even more preferred embodiment, a peptide of the invention comprises any of these HLA Al, A3, and/or Al l type epitopes: Al: 229-236 and/or

A3: 101-110, 154-163, 156-163, 376-386 and/or Al l: 101-110, 311-319, 311-320, 312-319, 374-382. Within this even more preferred embodiment, epitopes Al: 229-236, A3: 154-163, 156- 163 and/or Al 1 : 374-382 are most preferred since each of these also exhibits a low to intermediate MHC binding affinity.

In one embodiment, a p53 peptide does not consist of or comprise an HLA- A2.1 type epitope. In this embodiment, preferably a p53 peptide does not consist of or comprise an epitope exhibiting a low to intermediate MHC binding affinity. In a more preferred embodiment, when the protein is p53, the peptide is selected from the following peptides, each peptide comprises or consists of or overlaps with any of the following sequences: p53 86-115, p53 102-131, p53 142-171, p53 157-186, p53 190-219, p53 224-248, p53 225-254, p53 257-286, p53 273-302, p53 305-334, p53 353-382 and p53 369-393.

Even more preferably, when the protein is p53, the peptide is selected from the following peptides, each peptide comprises or consists of or overlaps with any of the following sequences: p53 142-171, p53 157-186, p53 190-219, p53 224-248, p53 225- 254, p53 241-270, p53 257-286 and p53 273-302. In the context of the invention, overlapping means that the sequence of the peptide partially or completely overlaps with a given sequence. Preferably, overlapping means partially overlapping. Partially preferably means that the overlap is of one or more amino acids at the N-terminus and/or at the C-terminus of the peptide sequence, more preferably of two or more amino acids at the N-terminus and/or at the C-terminus, or more. It is also preferred that the overlap is of one or more amino acids at the N- terminus and/or two or more amino acids at the C-terminus of the peptide sequence or vice versa. The skilled person will understand that all kinds of overlaps are encompassed by the present invention as long as the obtained peptide exhibits the desired activity as earlier defined herein. Even more preferably, the peptide does not consist of p53 102-137, p53 106-137, p53 149-169, p53 129-156, p53 187-212, p53 187-220, p53 187-205, p53 187-234, p53 226-243 or p53 226-264. Each of these p53 peptides is known from the prior art to exhibit a high MHC binding affinity and/or is efficiently processed by a proteasome

Composition

In a second aspect of the invention, there is provided a composition comprising one or more of the peptides as defined herein above. Preferably the composition comprises at least two or at least three or at least four, or at least five, or at least six or more of such peptides. Preferred compositions include at least two of, or at least three of or the following peptides: p53 142-171, p53 157-186, p53 190-219, p53 224-248, p53 225-254, p53 241-270, p53 257-286 and p53 273-302, p53 305-334, p53 353-382 and p53 369-393. More preferred compositions further include p53 86-115 and/or p53 102-131. In yet other preferred embodiments, the composition comprises at least one of the following pools of peptides, wherein each peptide comprises or consists of or overlaps with the following sequences: pool 1: p53 190-219, p53 206-235, p53 224-248, pool 2: p53 142-171, p53 157-186, 174-203, pool 3: p53 225-254, p53 241-270, p53 257-286, p53 273-302, p53 289-318, p53 305- 334, p53 321-350, p53 337-366, p53 353-382 and p53 369-393, pool 4: p53 102-131, p53 126-155, pool 5: p53 70-90, p53 86-115.

The art currently knows many ways of generating a peptide. The invention is not limited to any form of generated peptide as long as the generated peptide comprises, consists or overlaps with any of the given sequences and had the required activity as earlier defined herein. By way of example, a peptide present in the composition may be obtained from a protein, preferably p53 synthesized in vitro or by a cell, for instance through an encoding nucleic acid. A peptide may be present as a single peptide or incorporated into a fusion protein. A peptide may further be modified by deletion or substitution of one or more amino acids, by extension at the N- and/or C-terminus with additional amino acids or functional groups, which may improve bio-availability, targeting to T-cells, or comprise or release immune modulating substances that provide adjuvant or (co)stimulatory functions. The optional additional amino acids at the N- and/or C-terminus are preferably not present in the corresponding positions in the amino acid sequence of the protein it derives from, preferably p53 amino acid sequence.

Accordingly, in a further aspect a peptide of the invention and a composition of the invention as herein defined are for use as a medicament.

In a further preferred embodiment, a peptide or a peptide composition further comprises a pharmaceutical excipient and/or an immune modulator. Any known inert pharmaceutically acceptable carrier and/or excipient may be added to the composition. Formulation of medicaments, and the use of pharmaceutically acceptable excipients are known and customary in the art and for instance described in Remington; The Science and Practice of Pharmacy, 21^nd Edition 2005, University of Sciences in Philadelphia. A peptids of the invention is preferably soluble in physiologically acceptable watery solutions (e.g. PBS) comprising no more than 35 decreasing to 0%; 35, 20, 10, 5 or 0% DMSO. In such a solution, a peptide is preferably soluble at a concentration of at least 0.5, 1, 2, 4, or 8 mg peptide per ml. More preferably, a mixture of more than one different peptides of the invention is soluble at a concentration of at least 0.5, 1, 2, 4, or 8 mg peptide per ml in such solutions.

Any known immune modulator, may be added to the composition. Preferably, the immune modulator is an adjuvant. More preferably, the composition comprises a peptide as earlier defined herein and at least one adjuvant. Preferably, the adjuvant is an oil-in-water emulsion such as incomplete Freunds Adjuvants, Montanide ISA51 (Seppic, France), Montanide 720 (Seppic, France). This type of medicament may be administered as a single administration. Alternatively, the administration of a peptide as earlier herein defined and/or an adjuvant may be repeated if needed and/or distinct peptides and/or distinct adjuvants may be sequentially administered.

Particularly preferred adjuvants are those that are known to act via the Toll-like receptors. Adjuvants that are capable of activation of the innate immune system, can be activated particularly well via Toll like receptors (TLR' s), including TLR' s 1 - 10 and/or via a RIG-I (Retinoic acid-inducible gene-1) protein and/or via an endothelin receptor. Compounds capable of activating TLR receptors and modifications and derivatives thereof are well documented in the art. TLRl may be activated by bacterial lipoproteins and acetylated forms thereof, TLR2 may in addition be activated by Gram positive bacterial glycolipids, LPS, LPA, LTA, fimbriae, outer membrane proteins, heatshock proteins from bacteria or from the host, and Mycobacterial lipoarabinomannans. TLR3 may be activated by dsRNA, in particular of viral origin, or by the chemical compound poly(I:C). TLR4 may be activated by Gram negative LPS, LTA, Heat shock proteins from the host or from bacterial origin, viral coat or envelope proteins, taxol or derivatives thereof, hyaluronan containing oligosaccharides and fibronectins. TLR5 may be activated with bacterial flagellae or flagellin. TLR6 may be activated by mycobacterial lipoproteins and group B Streptococcus heat labile soluble factor (GBS-F) or Staphylococcus modulins. TLR7 may be activated by imidazoquinolines and derivatives. TLR9 may be activated by unmethylated CpG DNA or chromatin - IgG complexes. In particular TLR3, TLR4, TLR7 and TLR9 play an important role in mediating an innate immune response against viral infections, and compounds capable of activating these receptors are particularly preferred for use in the invention. Particularly preferred adjuvants comprise, but are not limited to, synthetically produced compounds comprising dsRNA, poly(I:C), unmethylated CpG DNA which trigger TLR3 and TLR9 receptors, IC31, a TLR9 agonist, IMSAVAC, a TLR4 agonist. In another preferred embodiment, the adjuvants are physically linked to a peptide as earlied defined herein. Physical linkage of adjuvants and costimulatory compounds or functional groups, to the HLA class I and HLA class II epitope comprising peptides provides an enhanced immune response by simultaneous stimulation of antigen presenting cells, in particular dendritic cells, that internalize, metabolize and display antigen. Another preferred immune modifying compound is a T cell adhesion inhibitor, more preferably an inhibitor of an endothelin receptor such as BQ-788 (Buckanovich RJ et al,, Ishikawa K, PNAS (1994) 91:4892). BQ-788 is N-cis- 2,6-dimethylpiperidinocarbonyl-L-gamma-methylleucyl-D - 1 - methoxycarbonyltryptophanyl-D-norleucine. However any derivative of BQ-788 or modified BQ-788 compound is also encompassed within the scope of this invention.

Furthermore, the use of APC (co)stimulatory molecules, as set out in WO99/61065 and in WO03/084999, in combination with a peptide present in the medicament used in the invention is preferred. In particular the use of 4-1 -BB and/or CD40 ligands, agonistic antibodies or functional fragments and derivates thereof, as well as synthetic compounds with similar agonistic activity are preferably administered separately or combined with a peptide present in the medicament to subjects to be treated in order to further stimulate the mounting an optimal immune response in the subject.

In a preferred embodiment, the adjuvant comprises an exosome, a dendritic cell, monophosphoryl lipid A and/or CpG nucleic acid.

Therefore in a preferred embodiment, a medicament comprises a peptide or a composition as earlier defined herein and an adjuvant selected from the group consisting of: oil-in water emulsions (Montanide ISA51, Montanide ISA 720), an adjuvant known to act via a Toll-like receptor, an APC-costimulatory molecule, an exosome, a dendritic cell, monophosphoryl lipid A and a CpG nucleic acid.

In another preferred embodiment, to promote the presentation of a peptide by a professional antigen presenting cell or dendritic cells, the medicament comprising a peptide further comprises a DC-activating agent.

Ways of administration are known and customary in the art are for instance described in Remington; The Science and Practice of Pharmacy, 21^st Edition 2005, University of Sciences in Philadelphia. Peptide, peptide compositions and pharmaceutical compositions and medicaments of the invention are preferably formulated to be suitable for intravenous or subcutaneous, or intramuscular administration, although other administration routes can be envisaged, such as mucosal administration or intradermal and/or intracutaneous administration, e.g. by injection. Intradermal administration is preferred herein. Advantages and/or preferred embodiments that are specifically associated with intradermal administration are later on defined in a separate section entitled "intradermal administration".

It is furthermore encompassed by the present invention that the administration of at least one peptide and/or at least one composition of the invention may be carried out as a single administration. Alternatively, the administration of at least one peptide and/or at least one composition may be repeated if needed and/or distinct peptides and/or compositions of the invention may be sequentially administered.

Any way of administration of the composition or medicament of the invention may be used. The composition or medicament of the invention may be formulated to be suitable for intravenous or subcutaneous, or intramuscular administration, although other adminstration routes may be envisaged, such as mucosal or intradermal and/or intracutaneous administrations, e.g. by injection.

In addition a preferred embodiment comprises delivery of a peptide, with or without additional immune stimulants such as TLR ligands and/or anti CD40/anti-4-l BB antibodies in a slow release vehicle such as mineral oil (e.g. Montanide ISA 51) or PLGA. Alternatively, a peptide of the invention may be delivered by intradermally, e.g. by injection, with or without immune stimulants (adjuvants). Preferably for intradermal delivery a peptide of the invention is administered in a composition consisting of the peptides and one or more immunologically inert pharmaceutically acceptable carriers, e.g. buffered aqueous solutions at physiological ionic strength and/or osmolarity (such as e.g. PBS).

Use of a peptide In a further aspect of the invention, there is provided a use of a peptide as earlier defined herein derived from a ubiquitously expressed self-antigen known to be associated with cancer, said peptide exhibiting a low to intermediate capacity to form stable cell surface expressed class I-MHC complexes and/or being inefficiently processed by a proteasome and/or exhibiting a low to intermediate MHC binding affinity for the manufacture of a medicament for the treatment or prevention of cancer. Preferably, the protein is p53. Preferably, a peptide exhibits a low to intermediate capacity to form stable cell surface expressed class I-MHC complexes and/or is inefficiently processed by a proteasome. Preferred peptides for use in the treatment or prevention of cancer are as already defined herein above.

All preferred features of the medicament manufactured for this use have already been defined earlier herein. In a preferred embodiment, the medicament which is used further comprises an inert pharmaceutically acceptable carrier and/or an adjuvant. In a preferred embodiment, the medicament, which is a vaccine, is administered to a human or animal. In a more preferred embodiment, the human or animal is suffering from or at risk of suffering from a cancer, wherein the protein the peptide derives from is associated with. More preferably, the protein is p53, even more preferably human p53. Even more preferably, cancer associated with p53 are selected among the following list: lung, colon, esophagus, ovary, pancreas, skin, gastric, head and neck, bladder, sarcoma, prostate, hepatocellular, brain, adenal, breast, endometrium, mesothelioma, renal, thyroid, hematologic, carcinoid, melanoma, parathyroid, cervix, neuroblastoma, Wilms, testes, pituitary and pheochromocytoma cancers. Other preferred proteins have been already cited herein. Preferably, said disease such as cancer is at least in part treatable or preventable by inducing and/or enhancing said immune response using a peptide of the invention.

A method of the invention is therefore very suited for providing a subject with immunity against any ubiquitously expressed self protein known to be associated with cancer and/or for enhancing said immunity. Methods of the invention are suitable for any purpose that other immunization strategies are used for. Of old immunizations are used for vaccination purposes, i. e. for the prevention of cancer. However, methods of the invention are not only suitable for preventing cancer. Methods can also be used to treat existing cancer, of course with the limitations that the cancer is treatable by inducing and/or enhancing antigen specific T cell immunity.

Method

In a further aspect, the invention provides a method for designing a peptide derived from a protein ubiquitously expressed self-antigen associated with cancer, said peptide comprising an epitope exhibiting a low to intermediate capacity to form stable cell surface expressed class I-MHC complexes and/or being inefficiently processed by a proteasome and/or exhibiting a low to intermediate MHC binding affinity and said peptide being suitable for the manufacture of a medicament for the treatment or prevention of cancer. Preferred peptide comprises an epitope exhibiting a low to intermediate capacity to form stable cell surface expressed class I-MHC complexes and/or being inefficiently processed by a proteasome. AU features of this method have already been explained herein. To identify such a peptide the skilled person could follow the strategy as illustrated in the examples: an epitope exhibiting a low to intermediate MHC binding affinity may be identified by measuring the relative binding affinity as earlier defined herein. The capacity of an epitope to form a low/intermediate stable cell surface expressed class I- MHC complexes may be measured as earlier defined herein. Finally, the inefficiently processing of a peptide by a proteasome may be assessed as earlier defined herein.

Intradermal administration

In a preferred embodiment, a peptide or a composition comprising a peptide or a medicament used in the invention all as defined herein are formulated to be suitable for intradermal administration or application. Intradermal is known to the skilled person. In the context of the invention, intradermal is synonymous with intracutaneous and is distinct from subcutaneous. A most superficial application of a substance is epicutaenous (on the skin), then would come an intradermal application (in or into the skin), then a subcutaneous application (in the tissues just under the skin), then an intramuscular application (into the body of the muscle). An intradermal application is usually given by injection. An intradermal injection of a substance is usually done to test a possible reaction, allergy and/or cellular immunity to it. A subcutaneous application is usually also given by injection: a needle is injected in the tissues under the skin.

In another further preferred embodiment, a medicament or composition or peptide used in the invention does not comprise any adjuvant such as Montanide ISA-51, it means the formulation of the medicament (or composition or peptide) is more simple: an oil- water based emulsion is preferably not present in a medicament (or composition or peptide) used. Accordingly, a medicament (or composition or peptide) used in the invention does not comprise an adjuvant such as Montanide ISA-51 and/or does not comprise an oil-in-water based emulsion. Therefore, in a preferred embodiment, a medicament (or composition or peptide) used in the invention is a buffered aqueous solutions at physiological ionic strength and/or osmolarity, such as e.g. PBS (Phosphate Buffer Saline) comprising or consisting of one or more peptide as defined earlier herein. The skilled person knows how to prepare such a solution.

A medicament (or composition or peptide) as used in the invention has another advantage, which is that by intradermally administering low amounts of a peptide as earlier herein defined, an immunogenic effect may still be achieved. The amount of each peptide used is preferably ranged between 1 and 1000 μg, more preferably between 5 and 500 μg, even more preferably between 10 and 100 μg.

In another preferred embodiment, a medicament (or composition) comprises a peptide as earlier defined herein and at least one adjuvant, said adjuvant being not formulated in an oil-in water based emulsion and/or not being of an oil-in-water emulsion type as earlier defined herein. This type of medicament may be administered as a single administration. Alternatively, the administration of a peptide as earlier herein defined and/or an adjuvant may be repeated if needed and/or distinct peptides and/or distinct adjuvants may be sequentially administered. It is further encompassed by the present invention that a peptide of the invention is administered intradermally whereas an adjuvant as defined herein is sequentially administered. An adjuvant may be intradermally administered. However any other way of administration may be used for an adjuvant.

The intradermal administration of a peptide is very attractive since the injection of the vaccine is realized at or as close by as possible to the site of the disease resulting in the local activation of the disease draining lymph node, resulting in a stronger local activation of the immune system. In a preferred embodiment, the intradermal administration is carried out directly at the site of the lesion or disease. At the site of the lesion is herein understood to be within less than 5, 2, 1, 0.5, 0.2 or 0.1 cm from the site of the lesion.

Upon intradermally administering a medicament as defined herein, not only Th2 but also ThI responses are triggered. This is surprising since it was already found that cutaneous antigen priming via gene gun lead to a selective Th2 immune response (Alvarez D. et al, 2005). Furthermore, the immune response observed is not only restricted to the skin as could be expected based on (Alvarez D. et al, 2005). We demonstrate that specific T cells secreting IFNγ circulate through the secondary lymph system as they are detected in the post challenged peripheral blood.

Another crucial advantage of a medicament (or composition or peptide) of the invention is that relatively low amounts of a peptide may be used, in one single shot, in a simple formulation and without any adjuvant known to give undesired side-effects as Montanide IS A-51. Without wishing to be bound by any theory, we believe that the intradermal peptide(s) used in the invention specifically and directly targets the epidermal Langerhans cells (LC) present in the epithelium. Langerhans cells are a specific subtype of DC which exhibit outstanding capacity to initiate primary immune responses (Romani N. et al 1992). These LC may be seen as natural adjuvants recruited by the medicament used in the invention. In another preferred embodiment, the invention relates to the use of a peptide as defined herein for the manufacture of a medicament for the treatment or prevention of a disease as defined herein, wherein the medicament is for intradermal administration as earlier defined and wherein in addition a same and/or distinct peptide as defined herein is further used for the manufacture of a medicament for the treatment or prevention of the same disease, wherein the medicament is for subcutaneous administration.

A medicament for intradermal administration has already been defined herein. A peptide used for subcutaneous adminstration may be the same as the one used for intradermal administration and has already been defined herein. The skilled person knows how to formulate a medicament suited for subcutaneous administration. Preferably, a medicament suited for subcutaneous adminstration comprises a peptide as already herein defined in combination with an adjuvant. Preferred adjuvants have already been mentioned herein. Other preferred adjuvants are of the type of an oil-in water emulsions such as incomplete Freund's adjuvant or IFA, Montanide ISA-51 or Montanide ISA 720 (Seppic France). In a further preferred embodiment, a medicament suited for subcutaneous administration comprises one or more peptides, an adjuvant both as earlier defined herein and an inert pharmaceutically acceptable carrier and/or excipients all as earlier defined herein. Formulation of medicaments, and the use of pharmaceutically acceptable excipients are known and customary in the art and for instance described in Remington; The Science and Practice of Pharmacy, 21^nd Edition 2005, University of Sciences in Philadelphia. The second medicament used in the invention is formulated to be suitable for subcutaenous administration.

In this preferred embodiment, a medicament suited for intradermal administration may be simultaneously administered with a medicament suited for subcutaneous administration. Alternatively, both medicaments may be sequentially intradermally and subsequently subcutaneously administered or vice versa (first subcutaneous administration followed by intradermal administration). In this preferred embodiment as in earlier preferred embodiment dedicated to the intradermal administration, the intradermal and/or subcutaneous administration of a peptide as earlier herein defined and/or of an adjuvant may be repeated if needed and/or of distinct peptides and/or of distinct adjuvants may be sequentially intradermally and/or subcutaneously administered. It is further encompassed by the present invention that a peptide of the invention is administered intradermally and/or subcutaneously whereas an adjuvant as defined herein is sequentially administered. The adjuvant may be intradermally and/or subcutaneously administered. However any other way of administration may be used for the adjuvant.

We expect the combination of an intradermal and a subcutaneous administration of a medicament (or a composition or a peptide) according to the invention is advantageous. DC in the epidermis are clearly different from DC in the dermis and in the subcutis. The intracutaneous (intradermal) immunization will cause antigen processing and activation of epidermal DC (Langerin-positive langerhans cells) that through their dendritic network are in close contact with the keratinocytes. This will also optimally activate inflammatory pathways in the interactions between Langerhans cell and keratinocytes, followed by trafficking of antigen loaded and activated Langerhans cell to the skin-draining lymph nodes.

The subcutaneous administration will activate other DC subsets, that will also become loaded with antigen and travel independently to the skin- draining lymph nodes. Conceivably, the use of a medicament which may be administered both intradermally and subcutaneously may lead to a synergistic stimulation of T-cells in these draining nodes by the different DC subsets.

In this document and in its claims, the verb "to comprise" and its conjugations is used in its non-limiting sense to mean that items following the word are included, but items not specifically mentioned are not excluded. In addition the verb "to consist" may be replaced by "to consist essentially of meaning that a peptide or a composition as defined herein may comprise additional component(s) than the ones specifically identified, said additional component(s) not altering the unique characteristic of the invention. In addition, reference to an element by the indefinite article "a" or "an" does not exclude the possibility that more than one of the element is present, unless the context clearly requires that there be one and only one of the elements. The indefinite article "a" or "an" thus usually means "at least one". All patent and literature references cited in the present specification are hereby incorporated by reference in their entirety. The following examples are offered for illustrative purposes only, and are not intended to limit the scope of the present invention in any way

Brief description of the drawings

Figure 1. Proteasomal cleavage products

Figure 2. Explanation of the mechanism of formation of the proteasomal cleavage products.

Figure 3. Flow chart of phase I and II of the clinical trial in ovarian cancer patient as presented in example 2 and in colon cancer patient as presented in example 3. For ovarian cancer patient, fours shots of vaccine are used, whereas for colon cancer patient, two shots of vaccine are used. For colon cancer patient, the skin biopsy was carried out at the second vaccine site.

Figure 4. P53 -peptide specific responses in clinical trial of ovarian cancer patients as measured by proliferation assay (n=8).A-F) Vaccine induced response (*) if post- vaccination sample > lOOOcpm & proliferation index > 3 and if post- vaccination cpm value > 2x pre-vaccination cpm value. G) Responses to memory recall mix (MRM). Light grey bars: pre-vaccination, black bars: post- vaccination.

Figure 5. P53-peptide specific responses in clinical trial of colon cancer patients as measured by proliferation assay and cytokine production. The p53-specific proliferative capacity (A and C) and cytokine production (B and D) of 2 male patients with colorectal cancer is shown before and after vaccination with p53-long peptide vaccine. Patients were vaccinated twice with overlapping p53 peptides covering the amino acid sequence 70-248 (indicated by the pools of 2 peptide: V70-115, V102-155, V142-203, Vl 90-248). Patients PBMC were also tested against the N-terminal region of p53 (aa 1- 78) and C-terminal region of p53 (aa 241-393). Figure 6. P53-peptide specific responses as measured by IFN-γ ELISPOT (n=7) in ovarian cancer patients.

A-F) Vaccine induced response (*) if {mean number of spots - (mean number of spots in medium + 2SD) > 10 spots} AND post- vaccination value > 2x pre-vaccination value. Light grey bars: pre-vaccination, black bars: post-vaccination.

Figure 7. P53-peptide specific responses in skin biopsies of vaccination sites obtained from ovarian cancer patients as measured by proliferation assay (n=7). Biopsies are taken three weeks after the last vaccination from the last injection site. A- D) Vaccine induced response (*) if counts per minute > 1000 and proliferation index >

3.

Figure 8. Vaccine-induced p53-specific T-cells can migrate into areas where p53 antigen is present and recognize naturally processed and presented p53 protein.

A biopsy of the second vaccine site of a patient with colorectal cancer was taken and skin-infiltrating T-cells were expanded. The skin-infiltrating T-cells were tested against several pools of p53 peptides (indicated by the number of the first and last amino acid of the amino acid sequence of the p53 protein that is covered by the pool of peptides used) as well as p53 protein and control protein. The bars indicate the mean and standard deviation of triplicate wells.

Figure 9. Vaccination with p53-SLP vaccine induces T-cell memory responses and antigen-spreading in patients with colorectal cancer. PBMC isolated pre-vaccination, after 2 vaccinations and at 6 months (#1) or 9 months (#2) after vaccination were tested for the presence of p53 -specific T-cells in a proliferation assay by stimulating the PBMC for 6 days with several pools of p53 peptides (indicated by the number of the first and last amino acid of the amino acid sequence of the p53 protein that is covered by the pool of peptides used). The bars indicate the mean and standard deviation of 8-wells. Figure 10. Responses in ovarian cancer patients to individual p53 synthetic long peptides as measured by proliferation assay after four immunisations. Positive response (*) if > 1000 cpm & proliferation index > 2.

Figure 11. P53-peptide specific responses in skin biopsies of vaccination sites obtained from ovarian cancer patients as measured by proliferation assay. Biopsies from the last injection site were obtained from 17 ovarian cancer patients three weeks after the last vaccination. Insufficient numbers of lymphocytes for proliferation assay could be cultured from two biopsies (015 & 020). Positive response (*) if counts per minute > 1000 and proliferation index > 3.

Figure 12. P53-specific T-cell responses as measured by proliferation assay before the first and after the last vaccination as well as after subsequent chemotherapy in ovarian cancer patients . Post-chemotherapy samples were obtained 12 months (009) resp. 9 months (019) after the last vaccination and at least one month after the last chemotherapy. Vaccine-induced response (*) if cpm > 1000 & S.I. > 3 and if the cpm after vaccination / chemotherapy was > 2 the pre- vaccination value.

Figure 13. Serum CA- 125 levels in ovarian cancer patients before, during and after vaccination. Missing values: 04 visit 4/5/FU; 05 visit 3/4/5/FU; 11 visit FU

Figure 14: An overview of the number, day of appearance and injected antigen that induced a positive skin reactions in the group of 19 healthy donors (HD). Skin reactions were considered positive when papules greater then 2 mm in diameter arose no less then 2 days after injection. The indicated layout is used for the 8 peptide pools, the first and last amino acid in the protein of the peptide pool used is indicated. The layout printed in bold indicates at least one positive reaction within this timeframe; a filled square represents a new developed, positive skin reaction to the indicated peptide pool.

Figure 15. Detection of HPV 16 specific T cells by IFNγ ELIspot in the pre-challenge blood sample of healthy donors is significantly correlated with the appearance of an early (<13 days) positive skin reaction to the recognized peptide pool (p= 0.0003, two tailed Fisher's Extract test). Specific responses were calculated by subtracting the mean number of spots + 2xSD of the medium control from the mean number of spots in experimental wells. The number of specific spots per 100.000 PBMC is given. Responses were considered positive if peptide pool specific T cell frequencies were > 5 in 100.000 PBMCs.

Figure 16. A. Association between the appearance of a positive skin reaction and the simultaneous detection (IFNγ ELIspot) of circulating HPV 16 specific T cells in the post-challenge blood sample of healthy donors (p < 0.0001, two tailed Fisher's exact test). From a total of 88 skin tests, 39 were positive. Twenty-five of these 39 reactions were associated with a positive reaction in ELIspot (T cell frequency > 5 in 100.000 PBMCs). Of the 49 skin test sites that did not show a skin reaction, 10 were associated with a positive ELIspot.

Figure 17. A. HPV 16 specific T cell responses detected by IFNγ ELIspot in the post-challenge blood sample of healthy donors displaying a positive skin reaction. The mean number of spots per 100.000 PBMCs are depicted. Memory response mix (MRM) was used as a positive control. The filled bar indicates the positive skin reaction site of which a punch biopsy was taken and put in to culture. B. T lymphocytes exfiltrating from punch biopsies were, after a 14- to 28 day period of cytokine driven expansion, tested for their capacity to proliferate upon stimulation with monocytes pulsed with peptides (10 μg/ml) —as injected in the skin test- or with protein (20 μg/ml). Phytohemagglutinine (PHA) served as a positive control. Proliferation was measured by [³H]thymidine incorporation and a proliferative response was defined specific as the stimulation index (SI) > 3. Healthy donor 17 (HD 17) is an example of a positive skin reaction site consisting of non specific T cells.

C. Supernatants of the proliferative responses in B were analysed for the presence of IFNγ, interleukin 4 (IL4), IL5 and tumor necrosis factor α, IL2, ILlO (not shown) by cytometric bead array. Cutoff values were based on the standard curves of the different cytokines (100 pg/ml IFNγ and 20 pg/ml for the remaining cytokines). Antigen-specific cytokine production was defined as a cytokine concentration above cutoff level and >2x the concentration of the medium control. Healthy donor 15 (HD 15) displays a high background level of IL5, but is increased >2x after antigen stimulation. Figure 18.

T cell culture of the skin biopsy of pool 4 (Eo_41-65, Eo_55-S0, Eo_7J-95 ) of healthy donor 15 (HDl 5) consists of both HPV 16 specific CD4+ and CD8+ T cells. The specificity of the culture was tested in an intracellular cytokine staining (ICS) against the protein (20 μg/ml) and the peptides (10 μg/ml) corresponding with the injected skin test. Remarkably, in 3 out of 4 biopsies CD8+ HPV16-specific T cells were detected.

Examples

Example 1 : Relation between HLA binding, proteasomal digestion and tolerance

A modest surface expression of certain class I MHC-restricted peptides can be achieved by several, not mutually exclusive, mechanisms: 1) to low expression or to low turnover of proteins in the cell resulting in the generation of insufficient numbers of epitopes that allow recognition by CTL (Vierboom MP et al), 2) peptides with only a weak binding capacity for MHC may lose the competition with peptides with better MHC-binding properties and as such are scarcely expressed at the cell surface, and 3) proteosomal generation of CTL epitopes may be insufficient to generate effective numbers of MHC-peptide complexes. As part of normal cell regulation, p53 protein is targeted for proteasome-mediated degradation and shortage of protein entering the proteasome is therefore not likely to play an important role in the escape of negative selection. We have, therefore, analyzed the binding capacity of p53 derived peptides as well as the capacity of immunoproteasomes and household proteasomes to generate these peptides in vitro.

Results and discussion

From a large set of peptides that were selected based on the presence of so-called major anchor residues for HLA-A*0101, HLA-A*0301, HLA-A* 1101 and HLA-A*2401, 43 peptides were found to bind with intermediate to high affinity (Table 1). These peptides and 7 HLA-A* 0201 binding peptides (Houbiers JG et al, Nijman HW et al, Theobald M et al 1995) were further in vitro analyzed for both the stability of binding van der Burd SH et al 1995 and 1996) as well as for the liberation of the exact C-terminus by immunoproteasomes and household proteasomes (Kessler JH et al 2001) (Table 1). In general, the results obtained with both types of proteasomes were comparable. Except for the peptides p53i ₁₀-₁₂₀, p53π 1-120, p53112-120, and p53113-120 binding to both HLA- A*0301 and/or HLA-A* 1101 and carrying the same C-terminal lysine, no disparity in epitope generation between the household and immunoproteasomes was detected (Table 1). At present, 5 different CTL epitopes in p53 have been identified (Table 2). Four of these epitopes were restricted by HLA-A*0201 and one by HLA-A*2401. Peptide binding analysis revealed that peptide p53_264-272 displayed intermediate binding affinity and peptide p53i_49-i₅₇ displayed a weak capacity to form stable peptide- HLA-A*0201 complexes, the other 4 peptides displayed a good and stable binding to their restricting HLA molecules. Interestingly, proteasomal cleavage analysis of 30 residue long precursor peptides demonstrated that only two (p53_149-157 and p53_187-197) out of these five peptides were efficiently generated by both household and immunoproteasomes (Figure 1). For peptide p53_264-272 a fragment corresponding to the part after C-terminal cleavage was found after 4 hours of digestion, but the peptide itself or N-terminally extended pre-cursors were not detected (Figure 1). Recently, it was demonstrated that pre-cursor peptides could be detected after in vitro digestion by 2OS proteasomes, albeit at trace amounts (Theobald M et al 1998) . Taken together, there are two epitopes p53_65-73 and p53_125-134 which display good binding capacity but are not/inefficiently processed by 2OS proteasomes whereas a third peptide (p53_149-157) is well processed by both types of proteasomes but demonstrates a weak capacity to form stable peptide- HLA complexes. Furthermore, p53_264-272 binds with intermediate affinity to HLA- A* 0201 but is not well processed by proteasomes (Table 2). Most likely, the number of MHC-peptide complexes formed by these peptides at the surface of thymic APC is insufficient to delete the corresponding p53 -specific CTL, allowing these cells to egress into the periphery. The one peptide (p53 _J87-197) that displays good binding capacity to HLA-A* 0201, forms stable peptide-HLA complexes and is well generated by both immunoproteasomes and household proteasomes (Table 2) induced T-cell tolerance (Theobald M et al 1997), as was expected. Bearing this in mind, it will be interesting to find out whether the other inefficiently processed peptides, presented in table 1, which bind to either HLA-A*0101, HLA-A*0301, HLA-A*1101 or HLA-A*2401, form genuine CTL epitopes.

We recently reported on the identification of CTL epitopes in the cancer associated self-antigen PRAME (Kessler JH et al 2001). Comparison of the binding capacity and liberation of the C-terminus by proteasomes of p53- and PRAME-derived peptides reveals that the PRAME peptides are well processed whereas the p53-derived CTL epitopes are not (Table 2). PRAME is expressed in a variety of tumors, testis and at low levels in normal endometrium but is not expressed in the thymus and as a result PRAME-specifϊc CTL are not deleted in the thymus. Together these data suggest that the combination of stable peptide binding and proteasomal liberation of exact C-termini may lead to accurate prediction of CTL epitopes for which CTL will be available (e.g. viral antigens, tumor antigens such as PRAME) whereas for ubiquitously expressed antigens such as p53 it may reveal to which peptides tolerance will exist.

It has now been well established that CTL epitopes may be generated via alternative processing pathways (Benham AM et al, Glas R et al, Geier E et al, Reimann J et al) and that this results in HLA-class I molecules containing peptides with diverse carboxy termini and from proteins dispersed throughout the cell (Luckey CJ et al 1998). A wide variety of tumors display enhanced expression levels of p53, due to mutations in the p53 gene or other genes of the p53 regulatory pathway, as a result of decreased proteasomal digestion (Honda R et al). Interestingly, the expression of the dominant HLA-A* 0201 -restricted influenza matrix CTL epitope is enhanced when cells are treated with proteasome inhibitors (Luckey CJ et al 1998). Furthermore, it was demonstrated that 50-60% of normal expression levels of HLA- A* 0201 molecules reappeared at surface despite the presence of proteasome inhibitors (Luckey CJ et al 2001). This suggests that proteins that are not/less well degraded by proteasome are more likely to be processed by other ways. This may mean that over-expression of p53 results in an enhanced expression of (amongst others HLA-A* 0201 -restricted) CTL epitopes generated via other routes than the proteasome (figure 2). Activation of p53- specific CTL may occur after uptake of tumor-derived p53 by peripheral APC. This results in the presentation of p53 -peptides in the MHC class II pathway (van der Brug SH et al 2001 and Tilkin AF et al ) and may also lead to presentation in MHC class I (Reimann J et al)(figure 2).

Concluding remarks

We recently demonstrated that the efficient liberation of the exact C-terminus of putative CTL epitopes present in 25-30 amino acid long precursor peptides by 2OS proteasomes, accurately identified natural processed peptides for which CTL are present in the peripheral blood (Kessler JH et al 2001). With respect to ubiquitously expressed antigens that as part of their normal regulation are degraded by the proteasome, some necessary differentiations should be made. A combination of a high capacity to form stable MHC peptide complexes and an efficient liberation by proteasomal digestion renders a peptide to induce tolerance. In contrast, peptides handicapped by either one of these two may form natural targets for CTL that made it to the periphery.

Material and Methods Peptides, peptide binding and stabilization assays

Peptides 8-11 residues in length were selected based on typical anchor residues for HLA-A*0101, A*0301, A*l 101 and HLA-A*2401 (Rammensee HG et al). The capacity of peptides to bind was tested in a competition based cellular binding assay as previously described (van der Burg SH et al 1995). FL-labeled reference peptides were synthesized as Cys-derivative (van der Burg SH et al 1995). Fluorescence labeled reference peptides used were: YLEPAC(FL)AK (HLA-A*0101) and KVFPC(FL)ALINK (HLA-A* 1101) (Sette A et al), KVFPC(FL)ALINK (HLA- A*0301) (van der Burg SH et al 1995) and RYLKC(FL)QQLL (A*2401) (Dai LC et al). B-cell lines used are: CAA (A⁺OlOl), EKR (A*0301), BVR (A*l 101), VIJF (A*2401). The relative binding capacity of the peptides is expressed as the peptide concentration to inhibit 50% (IC₅₀) of the binding of the reference peptide. Affinity is categorized as follows: good IC₅₀<5μM, intermediate IC₅₀=5-15μM, and low IC₅₀>15- 50μM. Peptide stabilization for HLA-A* 0201 was performed as previously described (van der Burg SH et al, 1996). Peptides of >50% of the initial complexes was lost within 2 hours were considered unstable. Stability of other peptide-HLA complexes was determined as follows. Peptide binding was performed at 4°C and 20°C and IC_5O were determined. Stable peptides displayed IC₅₀ at 20°C that deviated <2 times of the IC₅₀ at 4°C. Peptides that displayed IC₅₀ at 20°C of more than twice the IC₅₀ at 4°C but IC_5O<15μM were considered to bind with intermediate stability. The rest was designated as unstable peptide binding.

In vitro proteasome mediated digestions and mass-spectrometry 2OS immuno-proteasomes were purified from a mouse B-cell line (RMA) and a human B-LCL cell line (JY) and 2OS household proteasomes were purified from human tumor cell line (HeLa) as described (Kessler JH et al 2001). To assess kinetics, digestions were performed with different incubation periods as indicated. Briefly, peptides containing the (potential) CTL epitopes (30 mers, 20 μg) were incubated with 1 μg of purified proteasome at 37⁰C for 1 h, 4 h and 24 h in 300 μl proteasome digestion buffer, trifluoroacetic acid (30 μl) was added to stop the digestion and samples were stored at -20 C before mass spectrometric analysis. Electrospray ionization mass spectrometry was performed on a hybrid quadrupole time-of-flight mass spectromter, a Q-TOF (Micromass), equipped with an on-line nanoelectrospray interface with an approximate flow rate of 250 nL/min as described (Kessler JH et al 2001). The peaks in the mass spectrum were searched in the digested precursor peptide using the Biolynx/proteins software (Micromass) supplied with the mass spectrometer. The intensity of the peaks in the mass spectra was used to establish the relative amounts of peptides generated after proteasome digestion. The relative amounts of the peptides are given as a percentage of the total amount of peptide digested by the proteasome at the indicated incubation time. Major cleavage sites are defined as more than >1% of total digested peptide within the first hour.

Example 2: Vaccination study with p53 peptides in ovarian cancer patients- Immunological results in 7 vaccinated patients Objectives of the trial

2.1 General Objectives Primary objective:

-To evaluate the safety and tolerability of a p53 specific "long peptide" vaccine in combination with a defined adjuvant with known mode of action (Montanide ISA)

(phase I part of the study)

-To evaluate the immunogenicity of a p53 specific "long peptide" vaccine in combination with a defined adjuvant with known mode of action (Montanide ISA)

(phase II part of the study)

2.2 End-points

Primary endpoint of the phase I study is safety and tolerability

Primary endpoint of the phase II study is immunogenicity (p53 specific T cell responses) 2.3. Trial Design

A phase I / II vaccination study was performed in patients with ovarian cancer, using 10 overlapping p53 peptides in combination with an adjuvant with a sustained dendritic cell activating ability (Montanide-ISA-51). The flow chart phase is given in figure 3.

2.4. Patient Selection criteria

2.4.1. Inclusion Criteria - Histological proven epithelial ovarian carcinoma

- At least 4 weeks after termination of first line treatment (debulking surgery and platinum based chemotherapy)

Rising CAl 25 serum levels after first line treatment and no measurable disease according to the RECIST (Response Evaluation Criteria in Solid Tumours) criteria (Therasse P et al).

- Rising CA125 serum levels after first line treatment with measurable disease according to the RECIST (Response Evaluation Criteria in Solid Tumours) criteria (Therasse P et al) but not willing or otherwise not fit to receive second line chemotherapy. A rising in CAl 25 is known as a prognostic marker for ovarian cancer (Ferrandina G et al, Goonewardene et al and Rustin et al).

Age 18 years or older , an expected life expectancy of at least 3 months

- Absence of any psychological, familial, sociological or geographical condition potentially hampering compliance with the study protocol and follow-up schedule; those conditions should be discussed with the patient before registration in the trial

Before patient registration/randomization, written informed consent must be given according to Good Clinical Practice (GCP), and national/local regulations. - Performance status 0 to 2 (WHO scale)

- Adequate hepatic, renal, and bone marrow function as defined: INR < 1.5 ;WBC > 3.0 x 109/L thrombocytes > 100 x 109/L ;hemoglobin > 6.0 mmol/1.

2.4.2, Exclusion Criteria - Pregnancy and / or breast feeding.

- Other malignancies (previous or current), except basal or squamous cell carcinoma of the skin.

- High dose of immunosuppressive agents.

Prior therapy with a biological response modifier. - Uncontrolled hypertension, unstable angina pectoris, arrhythmias requiring treatment or myocardial infarction within the preceding 3 months.

Uncontrolled congestive heart failure or severe cardiomyopathy.

- Signs or symptoms of CNS metastases. Severe neurological or psychiatric disorders.

2.4.3 Withdrawal criteria

- progressive disease necessitating other forms of anti-tumor therapy

- unacceptable toxicity (gr 3-4 toxicity due to vaccination persisting for more than 2 weeks) - patient refusal

- lost to follow-up

2.5. Therapeutic regimens, expected toxicity.

Most Th and CTL responses recognize peptides within the residues 70-251 of the p53 protein. Therefore the vaccine encompasses this region of the p53 protein. The peptides used are given in table 3.

The clinical grade peptides for vaccination are prepared in the Peptide Laboratory, section IGFL, department of Clinical Pharmacy and Toxicology, Leiden University Medical Center. Technical details on production processes or product are described in the relevant IMPD. The p53 peptides are 9 30-mers, and 1 25-mer overlapping each other by 15 residues (see table 3). This set of 10 peptides is expected to contain the possible CTL epitopes for all class I alleles as well as the possible T-helper epitopes for all class II alleles. Montanide-ISA-51 is used as an adjuvant: Montanide ISA 51 or purified incomplete Freund's adjuvant is composed of 10±2%(w/w) mannide oleate (Montanide 80) in 90±2%(w/w) Drakeol 6VR, a pharmaceutical-grade mineral oil. Montanide ISA 51 is marketed as a sterile, pyrogen-free adjuvant for human use by Seppic (Paris, France). Long term (35 years) monitoring of 18000 patients - that received incomplete Freund's adjuvanted vaccine - and 22000 controls, did not show a significant difference in death rate due to cancer: 2.18% and 2.43% for vaccines with and without adjuvant, respectively.

2.6. Dosage and treatment overview A phase I vaccination study at first in 5 patients with rising CAl 25 levels is performed. The dose of peptides consists of 300 μg/peptide. This dose is chosen based on prior clinical trials of peptide vaccination (Rosenberg SA et al, Hersey P et al) and results from the phase I/II HPV E6/E7 long peptide trial performed at LUMC (unpublished data) .Vaccination is carried out 4 times with a 3 weeks interval with clinical and immunological evaluation in between.. The vaccine is injected deep subcutaneously, at four different sites, in a dose of 300 μg per peptide in DMSO/20mM phosphate buffer pH 7.5/Montanide ISA-51 adjuvant. The first injection is in the right upper arm, the second in the left upper arm, the third in the left upper leg and the fourth and last in the right upper leg. Prior to vaccination, mononuclear blood cells (PBMC; stored in 10 % DMSO in liquid nitrogen) and serum is isolated for evaluation of the baseline immune status towards p53 prior to vaccination. The effect of vaccination on p53 immunity is tested in PBMC and serum samples taken 2 weeks after the second- and final (booster) vaccination. T cell responses against the individual peptides in the vaccine are measured. In addition, a skin biopsy is taken from the fourth vaccination site, 2 weeks after vaccination, to isolate infiltrating T-cells. These T-cells are tested with respect to their specificity and polarization.

If no grade 3 or 4 toxicity occurs in any of the 5 patients entered in the phase I study the phase II vaccination study is started. If one patient experiences unexpected grade 3 or 4 toxicity, the number of patients in the phase I will be expanded to 10. It should be noted that in previous peptide vaccination studies no or minor toxicity occurred. Due to the relative good general condition normally encountered in these patients, this patient group is ideal to test the immunogenicity of the vaccine in a classical phase II trial. At first 14 patients are entered in this phase II study. P53 specific T cell responses before and after vaccination are compared. If no responders (response arbitrarily defined as > 30% increase p53 specific T cell responses) are found among the first 19 patients the study is discontinued because of apparent lack of immunogenicity of the vaccine. In case of responses the total number of patients in the study depends on the number of observed responses.

Vaccination in the phase I / II study is started 3 months after the last first line chemotherapy course and continued for a total of 4 vaccinations spaced by 3 weeks. If the phase II vaccination shows no results in terms of positive T cell responses, this approach will be discontinued.

2.7. Supportive care in case of toxicity

In case of skin toxicity, systemic antihistamines or topical steroids are allowed. Patients are not allowed to receive growth factors for myelosuppression. Analgetics are allowed.

2.8. Concomitant therapy

No other chemotherapy, immunotherapy, hormonal agents (excluding topical steroids for skin rashes), radiation therapy, experimental drugs, radiotherapy, and/or surgery are allowed while patients are on study. Any disease progression necessitating other forms of anti-tumor therapy is a cause for patient's withdrawal from the study. Systemic corticosteroids are not permitted during the study. Patients should receive full supportive care.

2.9 Clinical evaluation, laboratory tests and follow-up

2.9.1 Before treatment start

Less than 14 days before registration within the trial the following parameters are required to recorded:

- relevant medical history including date of first diagnosis, histological type, concurrent diseases, and any concurrent use of medication. - Physical examination including WHO performance, height, weight, vital signs, base-line clinical symptoms.

- Electrocardiogram (ECG) and urine analysis to exclude an asymptomatic cystitis

- Hematology: hemoglobin, thrombocytes, WBC. - Biochemistry: serum creatinine, INR, bilirubin, ASAT, ALAT, LDH, INR,

When the patient is registered within the trial, study treatment starts within 7 days after inclusion.

2.9.2. During treatment Less than 28 days before start of vaccination (300 ml), during vaccination (3 x 50 ml) and approximately 14 days after the last vaccination (300 ml) PBMC are collected to measure p53 specific T cell responses.

Two weeks after the last vaccination a punch biopsy is taken from the fourth vaccination site. Immediately before administration of each vaccination, 10 to 14 days after the last administration of the vaccine, the following examinations are carried out: (1) physical examination including neurological evaluation, vital signs, O₂-saturation and ECG before and three-four hours after each vaccination. (2) Evaluation of all adverse events (worst grade of events occurring during this vaccination should be recorded), as well as weight and WHO performance, (3) Hematology and biochemistry including hemoglobin, thrombocytes, WBC, serum creatinine, INR, bilirubin, ASAT, ALAT, LDH and INR. (4) Any concomitant medication.

2.9.3. After the end of treatment (Follow-up) If the patient has not progressed after vaccination, the extent of disease is recorded every 3 months following the same procedures as during treatment. In case of progression, the patients are followed for survival every 3 months. Initiation of any form of other anti-tumor treatment is recorded. Table 4 summarizes the whole vaccination and analysis process.

Toxicity evaluation is recorded during vaccination. Hematology and biochemistry including hemoglobin, thrombocytes, WBC, serum creatinine, INR, bilirubin, ASAT, ALAT, LDH and INR. 2.10. Immuno-monitoring

At five different time points during the study PBMC are collected: before vaccination (300 ml), and after each vaccination (3 x 50 ml) and after the last vaccination (300 ml). PBMC and serum is isolated. Evaluation of the p53 -specific T cell responses in vaccinated subjects of the phase I/II study is carried out as follows:

Positive CD4+ T helper cell responses after vaccination are defined by: a) Significantly increased (a vaccination induced reaction is considered positive when the proliferation index of post- vaccination samples is at least twice as high as the proliferation index of pre-vaccination samples and the proliferation index of post- vaccination samples should at least be 2 and/or b) Significantly increased IFNγ production of PBMC, that have been stimulated twice with peptide in vitro, against p53 peptides as measured by ELISA following 1 day culture, and/or c) A significantly increased percentage of CD4+ PBMC that produce IFNγ upon a 6 hour in vitro stimulation with p53 peptides in the presence of brefeldin A, utilizing tricolor intracellular FACS staining with antibodies against CD4, the early activation marker CD69 and IFNγ, and/or d) A significantly increased number of antigen-specific T cells that produce IFNγ, IL-4 or IL-10 as measured in the ELISPOT assay in which a frequency of > 1/10,000 PBMC is considered positive and a twofold increase in the number of spots between pre-vaccination and post- vaccination is chosen as a positive response to the vaccine.

2.11. Statistical consideration

2.11.2. Analysis

Patients not satisfying the inclusion criteria are ineligible. Patients not evaluated because of withdrawal or for other reasons (e.g. patients refusal, lost to follow-up, protocol violation) are clearly indicated. A total of 19 full evaluable patients need to be entered in the study with a maximum of 20% drop-out, this number might increase to 23 patients).

The p53 specific immune response of the vaccine measured before and after the vaccinations will be compared by Sign test (2-sided, 5% significance level). Response rates and rates of grade 3-4 toxicity encountered during vaccination will be estimated and the 95% exact confidence limits calculated. Time to progression will be computed by Kaplan-Meier curves and will be compared to a historical control group by the logrank test.

2.12. Translational research

The following analyses are performed:

The p53 -specific T-cell response is analyzed using freshly isolated PBMC for p53- specific proliferation. The cytokines (IFNγ, TNFα, IL-IO, IL-5, IL-4, IL-2) that are specifically produced upon this antigenic stimulation are tested by the cytokine bead array (according to the protocol of the manufacturer Becton-Dickinson). PBMC freshly isolated before, during and after the fourth vaccination, are tested. Responses are classified as ThI (IFNγ, TNFα), Th2 (IL-4, IL-5, IL-IO), ThO (IFNγ, IL-4, IL-5, IL-10) or impaired with respect to cytokine production (no production). The presence of high numbers of p53 -specific T-cells in the peripheral blood may not in all cases lead to the migration of these T-cells to the vaccine injection site, despite the presence of peptide antigen. The success or failure of T-cells to migrate into the skin may be a reflection of what goes on at the site of disease. Therefore, 2 weeks after the last vaccination a biopsy is taken from the fourth vaccination site. T-cells that have infiltrated the vaccination site are isolated from the biopsy. The specificity, polarization and type of the infiltrating T-cells is tested by cytokine bead array (protocol of manufacturer) and by FACS.

2.13. Results 2.13.1. Proliferation assay

Figure 4 depicts the proliferation assay carried out as indicated. It demonstrates that the vaccine containing peptides covering p53_70-248 is able to induce an immune response in most patients. Clearly, peptides derived from the region of p53₁₀2-2₄8 most efficiently induce a T cell response after vaccination as measured by proliferation after in vitro stimulation with pools of vaccine peptides (Fig. 4b-d). The first pool of vaccine peptides, covering p53_70-101j hardly induces T cell proliferation after in vitro stimulation (Fig. 4a). T cells isolated from vaccinated patients were also stimulated with peptides that were not present in the vaccine. This concerned peptides covering the N-terminal and the C-terminal region of the p53 protein. As shown by Fig. 4f, the N-terminal region is able to induce a T cell response in some ovarian cancer patients. This could indicate that the vaccine is very efficient at inducing killer T cells, eventually resulting in epitope spreading. On the other hand, the C-terminal region of p53 in these patients does not induce a measurable T cell response.

2.13.2. IFNγ ELISPOT

The vaccine was considered to induce a positive response if:

-the mean number of spots - (mean number of spots in medium +2SD)>10 spots -post- vaccination SI>= twice the prevaccination SI. The results are depicted in figure 6. This assay shows similar results compared to the proliferation assay: The vaccine peptides derived from the p53io₂-24₈ region have induced T cells specific for epitopes contained in that area (Fig 6b-d), whereas the peptides derived from the p53_7O-ioi region do not (Fig 6a). Moreover, this assay further confirms that the principal of epitope spreading might take place in some patients (Fig 6f).

Example 3: Vaccination study with p53 peptides in colorectal cancer patients- Immunological results in 2 vaccinated patients

The principle of the study is similar as in example 2 (see also figure 3). The differences being that in this study, patients only received two vaccinations (instead of four).

The p53-specifϊc proliferative capacity (figure 5A and C) and cytokine production (figure 5 B and D) of 2 male patients with colorectal cancer is shown before and after vaccination with p53-long peptide vaccine. Patients were vaccinated twice with overlapping p53 peptides covering the amino acid sequence 70-248 (indicated by the pools of 2 peptide: V70-115, V102-155, V142-203, V190-248). Patients PBMC were also tested against the N-terminal region of p53 (aa 1-78) and C-terminal region of p53 (aa 241-393). Note that in both cases, vaccination results in the activation of T-cell reactivity against the C-terminal region (outside the vaccine) too, indicative for epitope-spreading of the immune response following vaccination. P53-specific proliferation is associated with the production of IFNγ, IL-IO and IL-5, as measured by Cytokine bead Array (CBA). Example 4: Vaccination study with p53 peptides in colorectal cancer patients- Immunological responses in 9 vaccinated patients

Table 6 shows an overview of p53 specific T cell responses in colorectal cancer patients that have been vaccinated twice with the p53 SLP vaccine. In conclusion, all patients exhibited a p53 specific T cell response. The peptides that seem to be the most immunogenic are located in the most N-terminal portion of the p53 protein as present in the vaccine (aa 190-248): 8 out of 9 patients responded against these peptides. However, also peptides derived from aa 102-155 and 142-203 are able to induce p53 specific responses (6 out of 9 patients respond to one or more peptides derived from these regions). Clearly, the C-terminal portion of p53 seems to be less immunogenic. Importantly, peptides derived from the N-terminal portion of p53 which was not present in the p53 SLP vaccine still were able to induce a T cell response in vitro. This phenomenon is known as antigen spreading and occurs through stimulation of T-cells by DC that have taken up tumor-derived p53 released by dying tumor cells. As this is observed after vaccination only it is indicative for an effective vaccine-induced antitumor response.

To determine whether the p53 SLP vaccine is able to induce p53 specific T cells that can migrate to areas where the p53 antigen is presented, vaccine sites were isolated and skin-infiltrating T cells were expanded. Figure 8 shows the results from 1 patient with colorectal cancer. T cells have migrated to the vaccine site and are mostly specific for vaccine peptides 5-10 (aa 142-248). Furthermore, also peptides encoding the N- terminal portion of the p53 protein (aa 241-393) can be recognized by infiltrating T cells, while this part of the protein is not present in the p53-SLP vaccine. Again evidence for antigen spreading after effective vaccination. Importantly, the results also show that vaccine induced T cells that have migrated to the area of antigen presentation can also recognize cells that have processed whole p53 protein. This indicates that the natural processing pathway processes p53 protein into epitopes that can be recognized by the vaccine induced T cells. This implies that tumor cells that also process whole p53 protein in a natural manner can also be recognized and lysed by these T cells. To determine whether the vaccinated colon carcinoma patients were also able to induce a memory T cell response, PBMC isolated before and after 2 vaccinations and after 6 or 9 months were tested for the presence of p53 specific T cells. In figure 9, shows that the p53-specific T-cell responses which were not present before vaccination and induced after 2 vaccinations were still present in the circulation of the tested patients at 6-9 months after vaccination which is indicative for p53-specific memory T-cell responses. Moreover, both patients display a response to amino acids 241-393 of the p53-protein after 2 vaccinations and even at 6 months of follow up (#1), indicating that T cells induced as a result of epitope spreading were also still present.

Example 5: Vaccination study with p53 peptides in ovarian cancer patients- Immunological results in all (18) vaccinated patients

Table 7 summarizes immunological and clinical responses of all ovarian cancer patients treated with the p53-SLP vaccine.

Immunological Responses

In 100% of the ovarian cancer patients receiving all four immunizations (N=I 8), vaccine-induced p53 -specific responses against the vaccine peptides were present at two or more time points (I-IV) after immunization as measured by IFN-γ ELISPOT (Table 8). Vaccine-induced p53-specific responses were directed against at least two of the vaccine peptide pools in all ovarian cancer patients. After four immunizations, circulating IFN-y secreting p53 -specific T-cells could be detected in 61.1% (11/18) of patients. Vaccine-induced p53 -specific proliferative responses against the vaccine peptides were observed in 82.4% (14/17) of ovarian cancerpatients (Table 9). As depicted in figure

12, proliferative responses against the vaccine peptides could still be demonstrated 9-12 months after the last immunization, even though patients had since been treated with chemotherapy. Furthermore, also in the ovarian cancer patients, p53-specific responses against the first (aa 1-78) and the last (aa 241-393) portion of the p53-protein not covered by the vaccine peptides, were observed in 11.8% (2/17) and 23.5% (4/17) of the patients respectively after four immunizations (Table 9). Figure 10 illustrates the proliferative capacity of PBMC in response to ex- vivo stimulation with single vaccine peptides as analyzed in 7 patients with ovarian cancer after four immunizations.

Responses were observed to all peptides, except for vaccine peptide 1 (aa70-99).

To analyze the capacity of p53 -specific T-cells to migrate to sites where p53 antigen is presented, a proliferation assay was performed with lymphocytes cultured from skin biopsies taken at the fourth injection site (n=17). Insufficient numbers of lymphocytes could be cultured from the skin biopsies of two patients (P 15 and P20). P53-specific responses were observed in lymphocytes cultured from skin biopsies in 52.9% (9/17) of patients. Most responses were observed against vaccine peptide p8-plθ (aa 190-248)

(Figure 11). Importantly, all patients with p53 -specific responses in lymphocytes cultured from skin biopsies also showed vaccine-induced p53 -specific responses in

PBMC as analyzed by proliferation assay (Table 7), although responses were not always directed against the same epitopes.

P53-autoantibodies were present in 40% (8/20) of the patients before immunization.

After one or more immunizations, p53 -autoantibodies were present in 45% (9/20) of patients. A vaccine-induced increase in p53 -autoantibody titer was detected in 15%

(3/20) of the patients (Table 7).

Clinical Responses

Because of rapidly progressive disease, two patients received only two immunizations (P04, P 12). Clinical responses of the remaining 18 ovarian cancer patients were evaluated based on CA- 125 levels and evaluation of CT scans according to the RECIST and GCIG criteria (Table 10). One patient had a partial response as measured by CA- 125 (P05), and six patients had stable CA-125 levels (P02, P03, P06, P09, P17, P21, P23) (Figure 13). Two of these patients (11.1%) also had stable disease on CT-scan (P17, P23). In both patients, vaccine-induced p53-specific responses were detected in PBMC. P23 also showed p53-specific responses in lymphocytes cultured from the skin biopsy. The other patients (16/18; 88.9%) were classified as having progressive disease. All patients with progressive disease had developed new lesions since their last CT-scan.

Example 6. Demonstration of the advantage of intradermal administration of a vaccine peptide In this example, peptides were derived from a HPV protein are used in an intradermal vaccine. The advantages of an intradermal vaccine as demonstrated herein are generalisable to any other peptides, among other derived from a protein that is ubiquitously expressed self-antigen and known to be associated with cancer, such as p53.

Materials and methods Study design

A cross-sectional pilot study to analyse HPV 16 E2-, E6-, and E7-specific T-cell responses as measured by intradermal injection of pools of clinical grade HPV 16 peptides in the upper arm was performed in patients with HPV-related disorders of the cervix and in healthy individuals. Since a delayed type hypersensitivity reaction represents a memory T-cell response, there was no prerequisite for HPVlό-positivity at the time of analysis. Subjects

A group of nineteen healthy individuals (HD) participated in this study after providing informed consent. The group of healthy individuals displayed a median age of 31 years old (range, 20-51 years) and was comprised of 80 % women and 20 % males. Peripheral blood mononuclear cells (PBMCs) were obtained from all subjects immediately before administration of the skin test. The late appearance of positive skin tests in healthy individuals resulted in the isolation of a second blood sample from 11 of 19 healthy volunteers. The study design was approved by the Medical Ethical Committee of the Leiden University Medical Centre. DTH Skin test Skin tests, based on Delayed Type Hypersensitivity reactions (DTH), can be used as a sensitive and simple method for in vivo measurement of HPV-specific cellular immune responses (Hopfl R et al, 2000; Hopfl R et al, 1991). The skin test preparations consisted of 8 pools of long clinical-grade synthetic peptides spanning the whole HPV 16 E6 and E7 protein and the most immunogenic regions of HPV 16 E2 protein (de Jong A et al, 2004). These clinical grade peptides were produced in the interdivisional GMP-Facility of the LUMC. Each pool of the skin test consisted of 2 or 3 synthetic peptides, indicated by the first and last amino acid of the region in the protein covered by the peptides. Pool 1: E2_31-6o, E2_46-75, Pool 2: E2_301-330, E2_316-345, Pool 3: Eo_1-31, E6i9- so, Pool 4: Eo_41-65, Eo_55-80, Eo_71-95, Pool 5: Eo_85-109, Eo_91-122, Pool 6: E6_109-i₄₀, Eo_127-158, Pool 7: E7i.35, E7_22-56, Pool 8: E7_43-77, E7_64-98. The sequence of E2, E6, and E7 of HPV16 is respectively represented by SEQ ID NO:22, 23, and 24. Per peptide pool 0.05 ml of 0.2 mg/ml peptides in 16% DMSO in 20 mM isotonic phosphate buffer (10 μg/peptide) was injected intracutaneously. The pools of peptides and a negative control (dissolvent only) were injected separately at individual skin test sites of the upper arm. Skin test sites were inspected at least three times, at 72 hours and 7 days after injection (Hopfl R et al 2000, 2001) of the peptides and at 3 weeks following the first report of a very late skin reaction in one of the first healthy subjects. Reactions were considered positive when papules greater than 2 mm in diameter arose no less than 2 days after injection. From positive skin reaction sites punch biopsies (4 mm) were obtained, cut in small pieces and cultured in IMDM containing 10% human AB serum, 10 % TCGF and 5 ng/ml IL7 and IL 15 to allow the emigration of lymphocytes out of the skin tissue . After 2 to 4 weeks of culture the expanded T cells were harvested and tested for their HPV-specific reactivity.

Antigen for in vitro immune assays

A set of peptides, similar to the peptides used in the skin test, were used for T - cell stimulation assays and IFNγ-ELISPOT assays. The four HPV 16 E2 peptides consisted of 30-mer peptides overlapping 15 residues, HPV 16 E6 consisted of 32-mers and HPV 16 E7 of 35-mers, both overlapping 14 residues. The peptides were synthesized and dissolved as previously described (van der Burg SH et al, 1999). Notably, in the IFNγ ELISPOT assays peptide pool 4 and 5 slightly differed from the peptide pools used in the skin test, pool 4 contained peptides Eo_37-68, Eo_55-86, Eo_73-104 and pool 5 comprised peptides Eo_73-104, Eo_91-122. Memory response mix (MRM 50x), consisting of a mixture of tetanus toxoid (0,75 Limus βocculentius/m\; National Institute of Public Health and Environment, Bilthoven, The Netherlands), Mycobacterium tuberculosis sonicate (5 μg/ml; generously donated by Dr. P. Klatser, Royal Tropical Institute, Amsterdam, The Netherlands), and Candida albicans (0.15mg/ml, HAL Allergenen Lab., Haarlem, The Netherlands) was used as a positive control. Recombinant HPV 16 E2, E6 and E7 proteins were produced in recombinant Escherichia coli as described previously (van der Burg SH et al, 2001). Analysis of Antigen-specific Th Cells by IFNγ ELISPOT

The presence of HPV 16-specific Th Cells was analyzed by ELISPOT as described previously (van der Burg SH et al, 2001) Briefly, fresh PBMCs were seeded at a density of 2 x 10⁶ cells/well of a 24-well plate (Costar, Cambridge, MA) in 1 ml of IMDM (Bio Whittaker, Venders, Belgium) enriched with 10% human AB serum, in the presence or absence of the indicated HPV 16 E2, E6 and E7 peptide pools. Peptides were used at a concentration of 5μg/ml/peptide. After 4 days of incubation at 37⁰C, PBMCs were harvested, washed, and seeded in four replicate wells at a density of 10⁵ cells per well in lOOμl IMDM enriched with 10% FCS in a Multiscreen 96-well plate (Millipore, Etten-Leur, The Netherlands) coated with an IFNγ catching antibody

(Mabtech AB, Nacha, Sweden). Further antibody incubations and development of the ELISPOT was performed according to the manufacturer's instructions (Mabtech). Spots were counted with a fully automated computer-assisted-video-imaging analysis system (Bio Sys). Specific spots were calculated by subtracting the mean number of spots + 2xSD of the medium control from the mean number of spots in experimental wells (van der Burg SH et al, 2001). T cell proliferation assay

T-cell cultures of the skin biopsies were tested for recognition of the specific peptides and protein in a 3 -day proliferation assay (van der Burg SH et al, 2001). Briefly, autologous monocytes were isolated from PBMCs by adherence to a flat-bottom 96- well plate during 2 h in X- vivo 15 medium (Cambrex) at 37°C. The monocytes were used as APCs, loaded overnight with 10 μg/ml peptide and 20 μg/ml protein. Skin test- infiltrating-lymfocytes were seeded at a density of 2-5 x 10⁴ cells/well in IMDM suplemented with 10% AB serum. Medium alone was taken along as a negative control, phytohemagglutinine (0,5 μg/ml) served as a positive control. Proliferation was measured by [³H]thymidine (5 μCi/mmol) incorporation. A proliferative response was defined specific as the stimulation index (SI) > 3. Supernatants of the proliferation assays were harvested 48 hours after incubation for the analysis of antigen-specific cytokine production. Analysis of cytokines associated with HPV16-specific proliferative responses The simultaneous detection of six different ThI and Th2 cytokines: IFNγ, tumor necrosis factor α, interleukin 2 (IL2), IL4, IL5 and ILlO was performed using the cytometric bead array (Becton Dickinson) according to the manufacturer's instructions. Cut-off values were based on the standard curves of the different cytokines (100 pg/ml IFNγ and 20 pg/ml for the remaining cytokines). Antigen-specific cytokine production was defined as a cytokine concentration above cutoff level and >2x the concentration of the medium control (de Jong A et al, 2004). Intracellular Cytokine Staining (ICS)

The specificity and character of the T cell cultures derived from positive skin reaction sites was tested by ICS as reported previously (de Jong A et al, 2005). Briefly, skin test infiltrating lymphocytes were harvested, washed and suspended in IMDM + 10% AB serum and 2-5 x 10⁴ cells were added to autologous monocytes that were pulsed overnight with 50 μl peptide (10 μg/ml) or protein (20 μg/ml) in X vivo medium.

Medium alone was taken along as a negative control, phytohemagglutinine (0,5 μg/ml) served as a positive control. Samples were simultaneously stained with FITC-labelled mouse-antihuman IFNγ (0.5 g/ml, BD PharMingen), PE-labelled mouse-antihuman IL5 (0,2 mg/ml, BD PharMingen), APC-labelled anti-CD4 (BD Bioscience) and PerCP-labelled anti-CD8 (BD Bioscience). After incubation at 4°C, the cells were washed, fixed with 1% paraformaldehyde and analyzed by flow cytometry (FACSscan, BD Biosciences) Statistical Analysis Fisher's Exact test (2-tailed) was used to analyze the relationship between the detection of IFNγ-producing HPV-specific T-cells in PBMC, the presence of a skin test reaction or the presence of HPV-specific T-cells in skin biopsies, as well as differences between patients and healthy controls with respect to the size or the number of the skin reactions within these groups. Statistical analyzes were performed using Graphpad Instat Software (version 3.0) and Graphpad Prism 4.

Results

Skin reactions to intracutaneous injection with HPV 16 E2, E6- and E7 peptides We studied skin reactions in healthy subjects after intracutaneous injection with HPV 16 E2, -E6 and -E7 peptides. Positive skin reactions appeared as flat reddish papules of 2 to 20 mm of diameter, arising within 2 to 25 days after injection. A positive skin reaction was detected in 46 of the 152 skin tests in the healthy volunteers. Over all, each peptide-pool in the skin test could give rise to a positive skin reaction. Most frequently reactions against E2_31-75 (10 out of 19 subjects), Eo_37-104 (9/16) and ET_43-98 (7/19) were observed in the control group. This reaction pattern resembles that of what we previously observed in PBMC (de Jong A et al, 2002; Welters et al, 2003) (Figure 14). These skin reactions corresponded with the presence of a peptide specific T cell response as detected in the PBMC of these individuals (data not shown). Skin reactions in healthy donors are associated with higher frequencies of HPV 16-specific T-cells in the peripheral blood.

In order to compare the results of the skin test with the presence of circulating HPV 16- specific type 1 T cells, an IFNγ ELIspot assay was performed with PBMCs collected before the intradermal peptide-challenge was given. In 5 out of 19 healthy volunteers we were able to detect a HPV 16-specific immune response by IFNγ-ELIspot. The detection of > 5 circulating HPV 16-specific T-cells per 100.000 PBMC in the pre- challenge blood sample of healthy individuals was associated with an early (< 13 days) positive skin reaction to the same peptide sequence (p= 0.0003, two tailed Fisher's exact test; Figure 15). No HPV 16-specific circulating T-cells were detected in the pre- challenge blood sample healthy donors to peptides that induced a late positive skin reaction (14 to 25 days). This suggests that the frequency of circulating antigen-specific cells determine the delay time for skin reactions to appear.

In order to assess the frequency of HPV-specific T-cells at the time that a late skin reaction appeared additional blood samples from 11 healthy volunteers were collected. In these individuals 39 out of 88 skin tests were positive. In 25 of the 39 positive skin reactions and in 10 of 49 negative skin reactions > 5 HPV 16-specific T-cells were detected per 100.000 PBMC. At this point a significant correlation was found between the detection of circulating HPV-specific IFNγ-producing T-cells in the post- challenged blood sample and the presence of a skin reaction (p < 0.0001, Fisher^'s exact test; Figure 16). This shows that the frequency of HPV 16-specific T cells in the blood of healthy volunteers is significantly higher following an intradermal challenge with HPV 16 peptide and indicates that intracutaneous injection of peptide antigens enhances the number of HPV 16-specific T cells in the blood of healthy volunteers. Biopsies of positive skin reaction sites consist of both Thl/Th2- CD4+ and CD8+ HPV16-specifϊe T cells.

Approximately 25% of the positive skin reactions of healthy volunteers were not associated with the detection of HPV 16-specific IFNγ-producing T-cells in the blood, suggesting that other, non IFNγ-producing types of T-cells may infiltrate the skin after intradermal injection of HPV 16 peptides.

In order to characterize the cells in a positive skin reaction site punch biopsies were taken. In total, 8 biopsies were taken from different positive skin reaction sites of 7 healthy controls and cultured with a cocktail of cytokines that allowed the outgrowth of T-cells in vitro without antigenic stimulans. In 7 of 8 cases, T-cells ex-filtrated the tissue and expanded within 3-4 weeks. The expanded T-cells were tested for their specificity in a short term proliferation assay. Figure 17 shows examples of T-cell cultures that specifically proliferated upon stimulation with autologous monocytes pulsed with the pool of peptides, also injected in this site during the skin test (HD2, HDlO, HD 15) as well as to monocytes pulsed with HPV 16 E6 protein (Figure 17AB). This indicates that these T-cells were capable of recognizing their cognate HLA- peptide complexes after the antigen was naturally processed and presented. Analysis of the supernatants of these proliferative T-cell cultures revealed a mixed Thl/Th2 cytokine profile in that the HPV16-specific T-cells produced IFNγ, IL-4 and IL-5 (Figure 17C).

In each case that HPV-specific T-cells were detected in the biopsy culture (4 out of 8) this coincided with the detection of circulating HPV16-specific IFNγ-producing T-cells in the post-challenge blood sample by ELIspot (compare Figures 17A and B). In 3 of the other 4 positive skin reaction biopsies (HD2, HD 17, HD 18) the T-cells did not respond to HPV 16 peptides (Figure 17; HD 17) and in one case no T-cells ex-filtrated the tissue at all (HD 13). In these 4 cases we were not able to detect circulating HPV 16- specific IFNγ-producing T-cells in the post-challenge blood sample. Co-staining of the biopsy-T cells by CD4 and CD8 cell surface markers showed that not only HPV 16-sρecific CD4⁺ but also HPV 16-specific CD8⁺ T cells infiltrated the skin site upon intradermal challenge with HPV 16 peptide (Figure 18). Overall, in 3 out of 4 biopsies infiltrated by HPVl 6-specific T-cells, we were able to detect HPV 16- specific CD8⁺ T cells. The CD8⁺ T cells isolated from the biopsy (pool 6) of HD2 responded to both overlapping peptides of the injected skin test: HPV16 E6₁₀9_-140 and Eo_127-158 (data not shown), while the CD8⁺ T cells of both subjects HD15 and HD16 responded to HPV16 E6_37-68 (see example for HD15, Fig 18). Taken together, the population of immune cells migrating into the skin upon an intradermal challenge with HPV 16 peptides comprises HPVl 6-specific CD4⁺ ThI-, Th2- and CD8⁺ cytotoxic T cells. This infiltration is paralleled by the appearance of circulating HPV16-specific IFNγ-producing T-cells in the blood.

Discussion Skin tests are commonly used as a simple assay for in vivo measurement of cell mediated immunity. We have validated the use of the skin test assay for the measurement of HPV 16 specific cellular immune response against the early antigens E2, E6 and E7 in vivo by comparing the results with that of parallel measurements of T cell reactivity by in vitro assays. In the group of healthy volunteers early skin reactions appeared between 4 to 12 days after intradermal antigen challenge. In these individuals, known to display HPV 16 specific type 1 T cell responses in vitro (de Jong A et al, 2002;Welters et al, 2003), the appearance of an early skin reaction (within 13 days) was significantly associated with the detection of IFNγ-producing HPV16-specifϊc T cells at a frequency of at least 1 per 20.000 PBMC (Figure 15, p<0.001). The same cut-off criteria for a positive reaction in the IFNγ ELIspot assay are recommended by Jeffries et al (Jeffries DJ et al, 2006), who used mathematical tools to define the appropriate cut-off of the ELISPOT in relation to Mantoux-tests. The low number of circulating memory T cells (Figure 15) may explain why the skin reactions appear somewhat delayed compared to classical DTH tests. The T cells need to be boosted or reactivated and start to divide before enough cells are produced to cause a local inflammatory reaction: the positive skin test. Indeed, at the time a positive skin reaction appears, a higher frequency of HPV16-specific ThI responses can be detected in the peripheral blood (Figure 16).

Historically it has been postulated that the ThI cell induce DTH responses, however, several studies have now shown that also Th2 cells infiltrating the skin test sites (Wang S et al, 1999;Woodfolk JA et al, 2001). Similarly, this study shows that the positive skin test sites of healthy volunteers contain both ThI and Th2 type HPV 16- specific T cells (Figures 17 and 18). In addition, positive skin reactions may also be the result of the influx of non-specific T cells as became evident from two in depth studies of positive skin test sites used to assay the specific immune response following vaccination of patients with renal cell cancer or melanoma (Bleumer I et al, 2007). Also this study showed that a number of positive skin test sites from healthy subjects were infiltrated with T-cells that did not respond to the injected HPV 16 antigens. So far, the reason for a-specific positive skin reactions remains unclear. Unexpectedly, we observed the majority of skin reactions in healthy individuals to appear 2 to 3 weeks after intradermal injection of the antigen. While, these late positive skin reactions were not correlated with detection of circulating HPV-specifϊc CD4⁺ memory T cells in pre- challenge blood (Figure 15) the immunological constitution of these skin test sites are similar to that of classic DTH tests (Platt JL et al, 1983; Poulter LW et al, 1982) and comprised of HPVlό-specific CD4⁺ ThI- and Th2- cells as well as HPVlό-specific CD8⁺ T cells (Figure 17 and 18). We hypothesize that these reactions might be the result of T cell priming. This has also been noted in 29% of patients whom underwent a 2-step tuberculin skin testing protocol and whom were only positive at the second test round (Akcay A et al, 2003). In general, vaccine-induced T cell responses peak at 10 to 14 days after vaccination and not at three weeks. However, one should bear in mind that in such protocol a higher antigen dose as well as strong adjuvants are injected. It is therefore reasonable to assume that the T cell responses induced by intradermal challenge develop more slowly and peak at a later period. Since the intradermal peptide challenge in healthy volunteers results in the induction of both HPVlό-specific CD4⁺ and CD8⁺ T cells it, therefore, should be considered as a single, low dose vaccination. The main objective of this pilot study was to validate the use of the HPV 16 specific skin test to detect type 1 immune responses in vivo. In healthy volunteers, a positive skin reaction within 13 days is indeed correlated with the presence of circulating IFNγ- producing memory T cells as detected by the IFNγ ELIspot in vitro. Importantly, we also observed discrepancies between the outcomes obtained by skin test and ELIspot. In a number of cases HPVlό-specific circulating IFNγ-producing T cells were detected in the post-challenge blood samples but without a concomitant skin reaction and vice versa (Figure 16), and this may be considered as a false negative or false positive result. In order to fully understand the impact of this on the interpretation of the detection of type 1 immunity against HPV, we have begun a field trial in a large group of HPV positive patients and healthy volunteers in Indonesia. Table 1 HLA binding and C-terminal cleavage by proteasomes ofprotential CTL epitopes.

Peptide Binding Proteasomal Cleavage of C-terminus

Affinity Stability IP (RMA) IP (JY) HH (HeLa)

HLA-A*0101

117-126 GTAKSVTCTY intermediate 196-205 RVEGNLRVEY intermediate 205-214 YLDDRNTFRH intermediate 226-234 GSDCTTIHY high 229-236 CTTIHYNY intermediate

HLA-A*0201³ 24- 32 KLLPENNVL intermediate NT + + + 65- 73 RMPEAAPPV high 6h - - - 113-122 FLHSGTAKSV low 6h + + + 149-157 STPPPGTRV low <2 h + + + 187-197 GLAPPQHLIRV high 6h + + + 264-272 LLGRNSFEV intermediate 6h - - - 322-330 PLDGEYFTL intermediate ? + + +

HLA-A*0301

101-110 KTYQGSYGFR high +/- 110-120 RLGFLHSGTAK high + + + 111-120 LGFLHSGTAK high +/- + + 112-120 GFLHSGTAK intermediate - + + 113-120 FLHSGTAK intermediate +/- + + 117-126 GTAKSVTCTY intermediate - +/- + +/- 122-132 VTCTYSPALNK intermediate + 124-132 CTYSPALNK high + 129-139 ALNKMFCQLAK high + 132-139 KMFCQLAK high + 154-163 GTRVRAMAIY intermediate - 154-164 GTRVRAMAIYK high + 156-163 RVRAMAIY intermediate - 156-164 RVRAMAIYK high + 172-181 WRRCPHHER intermediate + 360-370 GGSRAHSSHLK intermediate - 361-370 GSRAHSSHLK high + 363-370 RAHSSHLK high + 363-372 RAHSSHLKSK intermediate 363-373 RAHSSHLKSKK high + 373-381 KGQSTSRHK intermediate +/ 376-386 STSRHKKLMFK high +/

HLA-A*1101 101-110 KTYQGSYGFR high 111-120 LGFLHSGTAK high + 112-120 GFLHSGTAK intermediate - 124-132 CTYSPALNK high + 132-139 KMFCQLAK high + 156-164 RVRAMAIYK high + 311-319 NTSSSPQPK high 311-320 NTSSSPQPKK high +/ 312-319 TSSSPQPK high 283-291 RTEEENLRK intermediate 363-370 RAHSSHLK intermediate +/ 374-382 GQSTSRHKK intermediate +/

HLA-A*2401

18- 26 TFSDLWKLL high + 102-111 TYQGSYGFRL high + 106-113 SYGFRLGF high + 106-114 SYGFRLGFL high +/ 125-134 TYSPALNKMF high + 204-212 EYLDDRNTF high + 340-348 MFRELNEAL high +/

¹ Affinity of peptide binding is categorized as follows: good IC₅₀<5μM, intermediate IC₅o=5-15μM, and low IC₅₀>15-50μM.

To determine the stability of the peptide-MHC complex, peptide binding was performed at 4°C and 20⁰C and IC₅₀ were determined.

Stable peptides displayed IC₅₀ at 20⁰C that deviated <2 times of the IC₅₀ at 4°C. Peptides that displayed

IC₅₀ at 20⁰C of more than twice the IC₅₀ at 4⁰C but IC₅o<15μM were considered to bind with intermediate stability.

The rest was designated as unstable peptide binding.

² Proteasome cleavage of C-terminus. 30 residue long peptides were digested by both mouse (RMA- cells) and human (B-LCL JY) derived immunoproteasomes (IP) and human (HeLa cells) derived household (HH) proteasomes.

³ HLA-A*0201 binding peptides. Peptide binding capacity was previously determined by (16, 24, 25). Peptide stability Table 2 Relation between peptide binding, proteasomal digestion and tolerance.

Sequence and HLA- Restriction Tolerance Peptide Binding Proteasomal Cleavage of Naturally processed CTL epitopes of C-terminus

HLA- WTp53 p53-/- IP IP HH

Position Sequence restriction Human mice mice Affinity Stability (RMA) (JY) (HeLa)

RMPEAAPPV HLA-A*0201 NO high 6h -

P53 65-73 - P53 149-157 STPPPGTRV HLA-A'0201 NO low <2 h + + +

P53 187-197 GLAPPQHLIRV HLA-A*0201 YES NO high 6h + + +

P53 125-134 TYSPALNKMF HLA-A*2401 NO high + - -

P53 264-272 LLGRNSFEV HLA-A*0201 NO intermediate 6h - -

PRA 100-108 VLDGLDVLL HLA-A*0201 NO intermediate 2.5h +

PRA 142-151 SLYSFPEPEA HLA-A*0201 NO high 3h +

PRA 300-309 ALYVDSLFFL HLA-A*0201 NO high >4h +

PRA 425-433 SLLQHLIGL HLA-A*0201 NO high >4h +

Table 3 10 p53 peptides used in the phase I/ II vaccination study

Table 4: whole vaccination and analysis process in ovarian cancer patients

Table 5: Analysis of the affinity and stability of the epitopes for HLA binding as well as proteasome processing of some preferred peptides

Table 6: Summary of p53-specific T-cell responses of patients with colorectal cancer vaccinated twice with the p53-SLP vaccine.

'The number of the first and last amino acid of the amino acid sequence of the p53 protein that is covered by the pool of peptides used is depicted. The columns with the first and last amino acid in bold depict the parts of the p53 protein tat are used in the vaccine. 2 A plus-sign indicates that this patient displayed a vaccine-induced p53 -specific T-cell response to this pool of p53 peptides.

Table 7. Cellular and humoural vaccine-induced T-cell responses and clinical responses to p53-SLP vaccine in ovarian cancer patients Patient Vaccine-induced T-cell Vaccine-induced T-cell p53-specific T-cell p53-specific Clinical Response responses in PBMC (IFN- responses in PBMC responses in antibodies after γ ELlSPOT)¹ (proliferation assay)² lymphocytes from skin immunisation⁴ biopsies³ CA-125⁶ CT⁷

POl + + + - PD PD

P02 H- + + SD PD

P03 + + + (4.8)⁵ SD PD

P04 na na na - na⁸ na⁸

P05 - + + + PR PD

P06 - + + SD PD

P08 + + - PD PD

P09 - + SD PD

PI l + nt na - PD PD

P12 na na na - na⁸ na⁸

P13 + + + + (2 9) PD PD

P14 - - PD PD

P15 - nt + PD PD

P17 - 4 - SD SD

P18 + + + PD PD

P19 + + + + (2 5) PD PD

P20 - + nt - PD PD

P21 + + - SD PD

P22 + + + - PD PD

P23 + + + + SD SD

¹ Vaccme-mduced T cell responses after 4 immunisations as measured by IFN-γ ELISPOT - no vaccine-induced response, + a vaccine- induced response. ²Vaccine-induced T-cell responses after 4 immunisations as measured by proliferation assay. - no vaccine-induced response, + a vaccine-induced response ³P53 -specific responses in lymphocytes cultured from skm biopsies as measured by proliferation assay - no p53-specific T-cell reactivity, +- p53-specific T-cell reactivity.⁴Serum p53 IgQ titers after immunisation as measured by quantitative ELISA. - no p53-specific antibodies, + p53-specific antibodies.⁵The fold of vaccine-induced increase in p53-specific antibody titer ⁶CA- 125 levels evaluated according to GCIG criteria. ⁷ CT scan evaluated according to RECIST criteria ^s Patient no evaluated by CA- 125 level or CT scan due to clinically evident rapidly progressive disease na = not available nt = not terminated Table 8. Vaccine-induced p53-specific immune responses in PBMC of ovarian cancer patients immunised with the p53-SLP vaccine as analysed by IFN-γ ELISPOT

Patient After one vaccination (I) After two vaccinations (II) After three vaccinations (III) After four vaccinations (IV)

vac pi- vac p3- vac p5- vac p8- vac pi- vac p3- vac p5- vac p8- vac pi- vac vac vac p8- vac p8- p2² p4 p7 plO p2 p4 p7 plO p2 p3-p4 p₅-p7 plO pl-p2 p3-p4 p5-p7 plO

POl 62 )3 17 106 14 33 20 - 56 P02 28 - - - 21 - 66 27 P03 52 37 166 29 15 81 - 43 58 132 15 20 57 P04 na na na na na na na na P05 19 19 11 - - 29 18 P06 12 47 22 - - - 21 P08 110 131 241 220 76 130 200 303 42 113 44 219 59 32 156 P09 31 38 55 - 10 18 20 - 14 12 - PIl 71 120 138 - - 78 - - - 35 - 28 - P12 26 - 67 73 na na na na na na na na na na na na P13 65 65 81 37 83 133 144 16 125 93 49 21 P14 60 - 22 - - 12 48 - - P15 18 - - 22 20 - 14 P17 63 46 21 - - 52 20 P18 88 106 120 - 41 61 45 60 41 13 - P19 183 94 75 60 - 23

P20 - - - 34 11 - 28 10 - 53

P21 22 119 100 178 88 81 32 33 38 32 12 16

P22 14 80 257 367 21 5577 220011 229955 7777 221177 334455 64

P23 50 106 21 _ 35 - 20 55 22 13

'Patients analysed for p53-specific responses before and after every immunisation (time points I-IV) by IFN-γ ELISPOT. ²The pool of p53 vaccine peptides used to stimulate patient-derived PBMC in vitro for 4 days. ³OnIy vaccine-induced ρ53-specific responses are shown (see definition in Material and Methods). Responses are depicted as number of specific spots per 10⁵ PBMC (mean of experimental wells - (mean + 2xSD) of medium control). - = no vaccine-induced p53-specific response; na = PBMC were not available.

'Ji

00

Table 9. Vaccine-induced p53-specific T-cell responses after four immunisations in freshly isolated PBMC of ovarian cancer patients immunised with the p53-SLP vaccine as analysed by proliferation assay.

Vaccine peptides Non- vaccine peptides

Patient¹ vac pl-p2² vac p3-p4 vac p5-p7 vac p8-plθ pl-p4 pl6-p24

POl - 13³ 6.8 6.4 - -

P02 - - - 15.8 - -

P03 - 24 14.5 5.3 - -

P05 - 3.9 2.5 3.3 - -

P06 - - - 3.4 - -

P08 - - 4.4 7.8 - 4.0

P09 - - - - - -

PI l nt nt nt nt nt nt

P13 - 2.3 4.9 3 - -

P14 - - - - - -

P15 - - - - - -

P17 - - - 7.1 - -

P18 2.3 3.1 - - - -

P19 - 16.5 7.4 - - -

P20 3.7 5.1 - 2.4 - -

P21 6.9 25.4 4.6 8.0 6.4 5.4

P22 - - 67.6 14.0 - 22.3

P23 6.4 3.2 - - 3.6 2.1

Total 4 (23.5%) 8 (47.1%) 8 (47.1%) 11 (64.7%) 2 (11.8%) 4 (23.5%)

¹ Patients analysed for p53-specific responses before and after four immunisations by proliferation assay. ²The pool ofp53 peptides (vaccine peptides or non-vaccine peptides) used to stimulate patient-derived PBMC in vitro for 6 days. Proliferation was measured by ³H-thymidine incorporation. ³ Responses are depicted as the mean of p53-induced proliferation after four immunisations divided by the mean of p53-induced proliferation before immunisation. A response > 2 was considered a vaccine-induced response. Otherwise the response was considered negative (-). nt = not tested. Table 10. Clinical Responses to p53-SLP immunotherapy after four immunisations according to serum CA- 125 levels and CT scan in ovarian cancer patients. Patient Target lesions¹ Non-target lesions¹ New Lesions¹ CA- 125² Overall Best Reponse²

001 PD Yes PD PD

002 PD Yes SD PD

003 PD PD Yes SD PD

004 ND ND ND ND ND*

005 Yes PR PD

006 PD Yes SD PD

008 Yes PD PD

009 PD No SD PD

011 PD Yes PD PD

012 ND ND ND ND ND*

013 PD PD Yes PD PD

014 PD Yes PD PD

015 Yes PD PD

017 No SD SD

018 PD Yes PD PD

019 Yes PD PD

020 PD Yes PD PD

021 PD PD Yes SD PD

022 SD Yes PD PD

023 SD No SD SD

¹ Evaluated according to RECIST criteria; Evaluated according to GCIG criteria. PD = progressive disease; SD = stable disease; PR = partial response; ND = dot done * clinically progressive after 2 immunisations

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Claims

Claims

1. Use of a peptide derived from an ubiquitously expressed self-protein known to be associated with cancer, said peptide exhibiting a low to intermediate capacity to form stable cell surface expressed class I-MHC complexes, and/or being inefficiently processed by a proteasome and/or exhibiting a low to intermediate MHC binding affinity for the manufacture of a medicament for the treatment or prevention of the disease.

2. Use of a peptide according to claim 1 , wherein the peptide exhibits a low to intermediate capacity to form stable cell surface expressed class I-MHC complexes and/or is inefficiently processed by a proteasome

3. A use according to claim 1 , wherein the MHC binding affinity of an epitope contained in the peptide is comprised between 5 and 50 μM.

4. A use according to claim 1 or 3, wherein the epitope contained in the peptide displayed a low to intermediate capacity to form stable class I-MHC complexes as defined by the IC₅₀ at 20°C of more than twice the IC₅₀ at 4°C but IC_5O<15μM MHC binding affinity of an epitope as assessed in the competition based cellular binding assay as described in example 1.

5. A use according to any one of claim 1 -4, wherein less than 1 % of digested peptides are found after one hour of digestion of the peptide by a proteasome.

6. A use according to any one of claims 1 to 5, wherein the protein is an oncoprotein, preferably p53 and the disease is preferably a cancer.

7. A use according to claim 6, wherein the peptide comprises or consists of or overlaps with any of the following sequences: p53 86-115, p53 102-131, p53 142-171, p53 157-186, p53 190-219, p53 224-248, p53 225-254, p53 241-270, p53 257-286 and p53 273-302.

8. A use according to claim 7, wherein the peptide comprises or consists of or overlaps with any of the following sequences: p53 142-171, p53 157-186, p53 190-219, p53 224-248.

9. A use according to claim 7 or 8, wherein an additional peptide is present, which peptide comprises or consists of or overlaps with any of the following sequences: p53 70-90, p53 126-155, p53 174-203, p53 206-235.

10. A use according to any one of claims 1-9, wherein the medicament further comprises an inert pharmaceutically acceptable carrier and/or an adjuvant.

11. A peptide derived from a protein ubiquitously expressed self-protein and known to be associated with cancer, said peptide exhibiting a low to intermediate capacity to form stable cell surface expressed class I-MHC complexes and/ or being inefficiently processed by a proteasome and/or exhibiting a low to intermediate MHC binding affinity.

12. A peptide according to claim 11 , wherein said peptide exhibits a low to intermediate capacity to form stable cell surface expressed class I-MHC complexes and/ or is inefficiently processed by a proteasome.

13. A peptide according to claim 11 , wherein the MHC binding affinity of an epitope contained in the peptide is comprised between 5 and 50 μM.

14. A peptide according to any one of claims 11 to 13, wherein the epitope contained in the peptide displayed a low to intermediate capacity to form stable class I-MHC complexes as defined by the IC₅₀ at 20°C of more than twice the IC₅₀ at 4°C but IC_5O<15μM MHC binding affinity of an epitope as assessed in the competition based cellular binding assay as described in example 1.

15. A peptide according to any one of claim 11 to 14, wherein less than 1% of digested peptides are found after one hour of digestion of the peptide by a proteasome.

16. A peptide according to any one of claims 11 to 15, wherein the protein is an oncoprotein, preferably p53 and the disease is preferably a cancer.

17. A peptide according to claim 16, wherein the peptide comprises or consists or overlaps with the following peptides selected from: p53 86-115, p53 102-131, p53 142- 171, p53 157-186, p53 190-219, p53 224-248, p53 225-254, p53 241-270, p53 257-286 and p53 273-302.

18. A peptide according to claim 17, wherein the peptide comprises or consists or overlaps with the following peptides selected from: p53 142-171, p53 157-186, p53

190-219 and p53 224-248.

19. A peptide composition comprising at least two peptides of claim 17 or 18, and optionally any of a peptide comprising or consisting or overlapping with the following peptides selected from: p53 70-90, p53 126-155, p53 174-203 and p53 206-235.

20. A peptide composition according to claim 19, wherein the peptide composition further comprises a pharmaceutical excipient and/or an immune modulator.

21. A peptide according to any one of claims 11 to 18 or the peptide composition according to claim 19 or 20 for use as a medicament.

22. Method for designing a peptide derived from a protein ubiquitously expressed self-protein (antigen) known to be associated with cancer, said peptide exhibiting a low to intermediate capacity to form stable cell surface expressed class I-MHC complexes and/or being inefficiently processed by a proteasome and/or exhibiting a low to intermediate MHC binding affinity and said peptide being suitable for the manufacture of a medicament for the treatment or prevention of cancer.

23. A method according to claim 22, wherein the peptide exhibits a low to intermediate capacity to form stable cell surface expressed class I-MHC complexes and/or is inefficiently processed by a proteasome.