CA2190261C - Method of immunomodulation by means of adoptive transfer of antigen-specific cytotoxic t-cells - Google Patents

Abstract

A method for the production of antigen-specific cytotoxic T-cells (CTLs) by incubating a T cell-containing cell preparation with sai d antigen and isolating said antigen-specific CTLs, characterized by i) activa ting proliferation of CTLs in the cell preparation by in cubation with the antigen; ii) selectively transferring a vector into the proliferati ng CTLs, said vector containing a marker gene by means o f which marked and non-marked cells can be separated; and iii) separating the transf ected antigen-specific CTLs on the basis of said marker gene, is useful for immunomodulation.

Description

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1 ~~~~61 Method of immunomodulation by means of adoptive transfer of antigen-specific cytotoxic T-cells The invention is concerned with a method for the production, and the use of, antigen-specific cytotoxic T-cells (CTLs), and a process for the production of a therapeutic agent using such T-cells, as well as a cornposition of CTLs suitable for use as a therapeutic agent.
Adoptive transfer of antigen-specific T-cells causes in animal models an efficient immunity and is, therefore, a therapeutic method for the treatment of viral infections and tumors.
In immunosuppressed patients, reactivation Burin~; ctwonic infections, for example by cytomegalovirus, Epstein Ban Virus or viruses from the hepatovints groups, leads to life-threatening syndromes. This affects predominantly patients who have undergone transplantation of bone marrow or transplantation of solid organs, patients subjected to chemotherapy or radiotherapy, and HIV-infected patients.
Epstein Ban Virus (EBV) is a human herpes virus l:hat nomally replicates in epithelial cells of oropharingeal tract, and is able to immortalize B-lymphocytes in vitro. In the immunocompetent host, EBV is the causing agent of infectious mononucleosis. It is however associated with several human cancers in vivo, such as Burkitt's lymphoma, nasopharingeal carcinoma, and B-cell lymphomas in immunodeficient patients: primary immunodeficiencies, HIV-infected patients, organ transplants recipients, and patients treated with immunosuppressive dings for autoimmune diseases (Hanto et al., 1985 (l); Forman et al., 1987 (2j;
Zutter et al., 1988 (3); Kamel et al., 1993 (a)). The occurrence of these EBV-induced lymphoproliferations is in the majority of cases related to the degree of immunosuppression (Horowitz et al., 1990 (23)).

W O 95/31208 ~ , ' ;~J ~ J ~ PCT/EP94101573 i _2_ In the normal host, EBV-induced lymphoid proliferations are controlled by EBV-specific and MHC-restricted T-lymphocytes, able to be cytotoxic toward EBV-transformed cells (Royston et al., 1975 (i); Rickinson et al., 1980 (6J), by MHC-unrestricted cytotoxic T-lymphocytes (Duncombe et al., 1992 (7)) and by antibodies directed toward specific viral antigens. On the contrary, in the immunodeficient patient the proliferation of these EBV-induced cells can progress without control. It is supposed that these conditions are at their beginning of polyclonal origin. However, with the persistence of the immunosuppression, clones can become neoplastic, consequently configurating the occurrence of a true EBV-induced lymphoma (Hanto et al., 1985 (7)).
Many works have pointed on the fact that the removal of drug-induced immunosuppression, as in the case of solid organ recipients, could be sufficient for a spontaneous remission of this condition. If the immunosuppression persists, however, an overt neoplasm develops. Cases of EBV-induced BLPD (B-cell lymphoproliferative disorders) following bone marrow transplantation have been described (Zutter et al., 1988 (3~; Shapiro et al., 1988 (8)). The probability of developing such a proliferation is strictly related to the features of the bone marrow transplant performed. Sporadic reports of EBV-induced BLPD have been described in the setting of T-cell depleted bone marrow transplantation or in vivo use of anti-thymocyte globulin (Zutter et al., 1988 (3~; Shapiro et al., 1988 (8)).
Differently than in drug-induced immunosuppression of solid organ recipients, in bone marrow transplant recipients the removal of pharmacologic immunosuppression administered for GVHD (Fer-rara et al., 1991 (31~; Jadus et al., 1992 (32)) or bone marrow rejection cannot be done with the objective of a fast immunologic reconstitution (Zutter et al., 1988 (3); Shapiro et al., 1988 (8)).
For this reason, the prognosis of EBV-induced BLPD in the setting of BMT has up to now been dramatically severe.
Since limited number of specific cytotoxic T-lymphocytes are required for controlling EBV-transformed B-lymphocytes in normal individuals, the administration of donor lymphocytes for the occurrence of BLPD in recipients of T-cell depleted bone marrow transplants could control this severe complication __. ~y0 95/31208 2 ~ ~' J L ~~ 1 PCT/EP94I01573 by providing to the patient donor immunity against EBV (Kernan et al., 1989 ~l0)). However, potential risks are represented by the development of a severe GVHD, that could by itself, and by the immunosu;ppressive drugs used for its treatment, be responsible for a relapse of EBV-induced disease.
It was shown by Riddell et al. (199?) (12) that by the adoptive transfer of cloned T-cells specific for CMV, antiviral immunity in immunodeficient humans could be restored. In this study, CD3+, CD8+, CD4- CTL clones which are specific for a CMV antigen were generated from three CMV seropositive bone marrow donors and propagated in vitro for 5 to 12 weeks before adoptive transfer.
These clones were representative of the Class I MHC-restricted immunodominant protective CTL response. During T cell transfer with these CTLs the patients received as prophylaxis for graft-versus-host disease immunosuppressive therapy with Cyclosporine A and Prednisone.
However, this method suffers from the drawback than, in order to obtain specific CTLs, individual clones have to be selected and propagated over a period of at least five to six weeks. Moreover, the CTL clones so obtained are directed in each case against one certain epitope of a virus antigen and are restricted for only one MHC class. Another drawback occurring in therapeutic use is the necessity of an additional immunosuppressive therapy. Especially in the case of patients suffering from AIDS, or patients who had to previously undergo chemotherapy or radiotherapy, such therapy is however not the treatment to be recommended.
The object of the invention is to avoid these drawba<;ks and provide an efficient method for the production of antigen-specific CTLs which are suitable for use, and efficient, as therapeutic agents, without requiring a long period of production or involving serious side effects.
The subject-matter of the invention is a method for the production of antigen-specific cytotoxic T-cells (CTLs), preferably CD8+ CTLs, by incubating a T-cell-containing cell preparation with said antigen and isolating said antigen-specific CTLs, characterized by W095/31208 ~ ~ ~ PCT/EP94/01573 Z~ ~tJOU~

i) activating proliferation of CTLs in the cell preparation by incubation with the antigen;
ii) selectively transferring a vector into the proliferating CTLs, said vector containing a marker gene by means of which marked and non-marked cells can be separated; and iii) separating the transfected antigen-specific CTLs on the basis of said marker gene.
An essential advantage of this method lies in obviating the need to select individual CTL clones in a time-consuming procedure; according to the method described here, CTLs can be obtained and separated by means of marker gene transfer followed by positive selection for a genetic marker. Furthermore, the so prepared CTL preparation contains at least two, but preferably a plurality of CTLs which present different epitopes of the antigens in the MHC complex. Here both CD4+ (MHC Class II restricted) and CD8+ (MHC Class I restricted) CTLs are obtained. In a preferred embodiment, the ratio of CD8+ CTLs and CD4+
CTLs can be controlled by interleukin-2 at predetermined concentrations, and by addition over a predetermined period. Preferably, the CTL preparation contains an excess of CD8+. It is also preferred to prepare, by applying suitable measures, a CD4- CTL preparation (using, e.g., a cytokine additive).
As T-cell preparation there can be employed both an autologous and an allogenic preparation. Though this is not required, prior to carrying out the method according to the invention, the T-cells can be enriched or separated from other cells, and this enriched preparation can be used for the method of the invention.
As T-cells there are used preferably T-cells from an allogenic donor (of the suitable HLA type). Preferably, there is used a blood preparation which has been purified (e.g. by means of a Ficoll~~ gradient) so as to be free from any other blood cells. A preparation of this type is usually termed "buffy coat".

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'" W095/31208 ~ ~ ~ PCT/EP94/01573 As vectors, there are preferred viral vectors which can act as a gene-delivery system in the transduction of cells. As viral vectors, there are preferred retroviruses, adenoviruses, adeno-associated viruses and herpes viruses.
Retroviral vectors are the best characterized viral vectors for gene transfer and have been employed in initial gene therapy protocols (Mulligan in Nobel Symposium 80: Etiology of human diseases at the DNA level (Lindsten and Petterson, eds. 143-189, Raven Press). Adenoviral vectors may be also attractive because they are structurally stable and can be prepared at high titer (Berkner in Current Topics in Microbiology and Immunology 158 (1992), Muzyczka, N.
(ed.) 36-66, Springer Verlag). Vectors derived from the non-pathogenic human adeno-associated virus (AAV) are also promising tools for human gene transfer (Muzyczka, supra, 97-129).
Since retroviral vectors infect almost exclusively dividing cells, positive selection of transduced cells allows a significant enrichment of antigen-specific lymphocytes. Therefore, retroviral vectors are preferred.
In a preferred embodiment of the invention, as an antigen there are used viral antigens, such as antigens of CMV, HBV, EBV, HIV, HSV and HCV.
Depending on the basic disease, also other antigens specific for various viruses, bacteria or monocellular pathogenic organisms could be used. It is also preferred to use complete inactivated viruses, pans of viruses, isolated antigens, or preferably antigen-presenting cells as antigens. For example, patient tumor cells, infected cell lines or infected cells of the patients are useful. The use of viruses or parts thereof offers the advantage that not only one type of antigen-specific CTLs is generated but a lot of different CTLs which are directed to different antigens of the virus and/or different epitopes of the viruses. It is also prefewed to use a combination of two or more virus antigens or viruses as antigens.
As the vector gene, genes coding for molecules presented at the surface of cells, such as, e.g., receptors, are preferred. In the case of blood cells, the LNGFR
receptor is preferred (Bordignon et al., 1994 ~l8)).

Immunomodulation means transient transfer of antigen-specific T-cells for the stimulation of the immune response of the patient against tumor cells or infected cells.
These gene-modified CTLs contain preferably, in addition, a suicide gene (which expresses after induction a substance which causes directly or by mediators the death of the infected cell; e.g. WO 92/08796) for in vi.vo specific elimination of these cells after successful treatment. For this purpose, there is preferably applied the thymidine-kinase gene, which confers to the transduced CTLs in vivo sensitivity to the drug Gancyclovir for in vivo specific elimination of cells potentially responsible for GVHD. If, for example, the patients develop signs of acute GVHD with increasing liver function enzymes and a positive skin biopsy, it is preferred to administer i.v. two doses of about 10 mg/kg of the drug Gancyclovir. This results in a reduction of marked lymphocytes only to a minor extent.
Preferred types of gene-modified CTLs are shown in Fig. 1.
The diphtheria toxin gene is also preferred as a suicide gene, which is described in WO 92/05262 (36). For the in vivo specific elimination of the CTLs after a GVHD it is also possible to induce a cell apoptosis. It is thus preferred to use a modified FAS-receptor and a dose of a related ligand.
The strategy according to the invention may find a wide application in adoptive immunotherapy approaches where a very large number of donor lymphocytes are utilized, for example in controlling relapsing leukemic cells after alto-BMT
{Kolb et al., 1990 (25); Riddel et al., 1992 (26); Cullis et al., 1992 (27);
Klingemann et al., 1991 (28); Helg et al., 1993 (29); Bar et al., 1993 (30)).
An additional advantage of the positive selection of antigen-specific cells through vector infection and positive sorting of vector-gene-expressing cells is the production of a population of donor lymphocytes containing a higher frequency of tumor-specific cells, while at the same time reducing the number of alloreactive cells potentially causing GVHD. It is noteworthy to consider that this °~ WO 95/31208 PCT/EP94/01573 technique may find application in other forms of adoptive immunotherapy of tumors expressing known tumor associated antigens (Traversari et al., 1992 (33J;
van der Bruggen et al., 1991 (34)).
In a preferred embodiment of the invention, IL-2 is added at a concentration of from 10 to 50 units/105 cells, preferably at about 10 I:o 25 units/about 105 cells.
In a further embodiment of the invention, it is preferred to add, in addition, at a concentration of about 5 units/105 cells.
Surprisingly it was found that for the production of vector-transduced antigen-specific CTLs it is prefe~Ted to cultivate in the presence of IL-2 the lymphocytes after activation of the proliferation of the CTLs with the antigen for 2 to 30 days, preferably 2 to 10 days, before infecting the proliferating CTLs with the vector.
After the infection with said vector, cells will be cultivated also in the presence of IL-2 for another period of 2 to 4 days. Then the selection on the basis of the marker gene is carried out and the (preferably CD8+) CTLs are isolated.
The infection of T-cells with viral vectors can be accomplished by co-cultivation of vector virus-producing cells with said T-cells wuth supernatant from vector virus-producing cells or by infection with purified viruses.
It is also preferred to use tumor cell-specific antigens, tumor cells or cells presenting such antigens, for the activation of T-cells. An example hereof is the MAGE-antigen which is specific for a part of the malignant melanomas or a part of the mastocarcinomas (van der Bruggen et al., 1991 (3-i)).
The invention is further illustrated by the figure and the examples set forth below.

WO 95/31208 ~ ~ '~ ~ 2 ~ ~PCT/EP94/01573 _g-REFERENCES
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8 Shapiro RS, McClain K, Frizzera G. et al: Epstein-Barr Virus Associated B cell lymphoproliferative disorders following bone marrow transplantation. Blood 1988;71:1234-1243.
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Abundant expression of EBER 1 small nuclear RNA in nasopharyngeal carcinoma. Am. J. Pathol. 1991; 138:1461-1469.

W 0 95/31208 ~ ~ ~/ ~~ ~ U ~ PCT/EP94/01573 10_ 17 McCann S.R. Lawler M. Mixed chimaerism; detection and significance following BMT. Bone Marrow Transpl. 1993; 17:91-94.
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Bordignon: Retroviral vector mediated gene transfer into human peripheral blood lymphocytes for human gene therapy. Blood 83 (1994) 1988-1997 19 Langhorne J. and Fischer-Lindahl K.: Limiting dilution analysis of precursors of cytotoxic T-lymphocytes. J. Imrnunol. Methods 11:221 (1981).
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21 Taswell C.: Limiting dilution assay for the determnination of immunocompetent cell frequencies. I Data analysis. J. Immunol.
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22 Ridell et al., Science 1992, 257:238-241 23 Horowitz M.M., Gale R.P., Sondel B.M., Goldman J.M., Kersey J., Kolbe H.J., Rimm A.A., Ringden O, Rozman C., Speck B., Truitt R.L., Zwaan F.E., Bortin M.M. Graft-versus-leukemia reactions after bone marrow transplantation. Blood 1990, 75:555-562.
24 Markowitz D., et al., J. Virol. 1988, 62:1120-1124 25 Kolb HJ, Mittermuller J, Clemm Ch, Holler E, Ledderose G, Brehm G, Heim M, Wilmanns W: Donor leukocyte transfusions for treatment of recurrent chronic myelogenous leukemia in marrow transplant patients. Blood 1990, 76: 2462-2465.
26 Riddel S.R., Watanabe K.S., Goodrich J.M., f_i C.R., Agha M.E., Greenberg P.D. Restoration of viral immunity in immunodeficient humans by the adoptive transfer of T-cell clones. Science 1992, 257:238-241.
27 Cullis JO, Jiang YZ, Schwarer AP, Hughes TP, Barrett AJ, Goldman JM: Donor leukocyte infusions for chronic myeloid leukemia in relapse after allogeneic bone marrow transplantation Blood 1992, 79:

W095/31208 2 ~ f~ lJ 2 U ~ PCT/EP94/01573 28 Klingemann HG, Phillips GL: Immunotherapy after bone marrow _ transplantation Bone Marrow Transplantation 1991, 8: 73-81.
29 Helg C, Roux E, Beris P, Cabrol C, Wacher P, Darbellay R, Wyss M, Jeannet M, Chapuis B, Roosnek E.: Adoptive immunotherapy for rccurrent CML after BMT. Bone Marrow Transplantation 1993, 12:
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35 Markowitz D., et al., Virolobry 1988, 167:400-40ti 21 ~>0251 Example 1 Mixed lymphocyte tumor culture (MLTC) for production of vector-transduced antigen-specific CTLs On day 0: autologous PBLs were resuspended in Iscove's medium supplemented with L-arginine (0.55 mM), L-asparagine (0.24 mM), L-glutamine ( 1.5 mM) in the presence of 10 % human serum (HS). HS was pooled A B and O Serum from healthy donors, decomplemented (56°C, 30 min), and sterilized.
One million responder PBL were mixed in multi-dish 24 wells with 10~
stimulator autologous tumor cells expressing EBV antigens, irradiated ( 10,000 rads are enough for the tumor cell lines used till now) in a final volume of 2 ml of the above-described medium, in the presence of 20 ng/ml r-hu-IL4 (5 U). Higher concentrations induce IL-2 production and block the activity of exogenous IL-2, thus inhibiting cytotoxicity.
On day 3: r-hu-IL2 was added at the final concentration of 10 - 25 units/ml and infectious viruses were added. On day 7: responder lymphocytes were collected, centrifuged, counted and resuspended in fresh medium. Lymphocytes 3 - 5 x 105 were restimulated in 24-well plates with 105 irradiated tumor cells in 2 ml of the same medium containing 10 - 25 units/ml of IL-2 and 20 ng/ml of IL-4. On day 14: responder lymphocytes were restimulated as at day 7, or cloned by limiting dilution. MLTC responder lymphocytes were cloned by limiting dilution in 96-well microtiter plates (round-bottomed wells). 10, 3, 1 and 0.3 responder cells were seeded in 100 pl of medium containing 50 units/ml of IL-2, 3000 iwadiated (10,000 rads) tumor cells and 5 x 104 irradiated (6000 rads) allogeneic PBLs as feeder cells. On day 21: clones were restimulated by adding in 100 pl of medium containing 50 units/ml of IL-2, 3000 irradiated (10,000 rads) tumor cells and 5 x 104 irradiated (6000 rads) allogeneic PBLs as feeder cells. The frequency of EBV-specific donor lymphocytes, after exposure to irradiated EBV-infected autologous B-cells, and positive sorting of vector transduced lymphoctes increased of over 100 folds.

This time kinetic is providing the highest efficiency of production of gene-transduced, highly cytotoxic CTLs.
Example 2 Preparation of the infectious viruses Vector DNAs were converted to corresponding viruses by a tr~sfection protocol. Briefly, vector DNA was transfected into the psi2 ecotropic packaging line (Mann et al., Cell 33 (1983) 153) by standard calcium phosphate co-precipiptation. 48 hrs after transfection psi2 supernatants were harvested and used to infect the amphotropic packaging cell line PA317 (Miller et al., Mol.
Cell Biol. 6 ( 1986) 2895) for 16 hrs in the presence of 8 pg/ml polybrene.
Infected PA317 cells were selected in DMEM (Gibco, Grand Island, New York}, supplemented with 10 % FCS (Hyclone, Logan, UT) and containing 0.8 mglml 6418 (Gibco), and then used to generate helper-free virus-containing supernatants with titers ranging from 104 : 105 CFUImI. All vectors contained a gene neon gene coding for neomycinphosphotransferase that confers in vitro resistance to the neomycin analogue 6418.
Instead of psi2 and PA317, also packaging cell lines of higher safety standard can be used (e.g. E86 and AM 12 (Markowitz et al., 1988 (3~); Markowitz et al., (24); WO 89/07150 (9)).
Infection of antigen-specific CTLs Viral infection was carried out by exposure of stimulated CTLs (according to Example 1) to a cell-free viral stock for 6 hrs in the presence of polybrene (8 pg/ml). 48 hrs after infection PBLs were selected in RPMI1640, supplemented with 2 mmol/1 L-glutamine, 1 % non-essential amino acids, 1 % Na pyruvate, % human serum (HS), and 100 U/ml r-hu-IL2 (complete medium) containing 0.4 mglml 6418. Cell density was maintained constant (5 x 105 cells/ml) during two weeks of G 148 selection. Reri~oviral transducted human T-lymphocytes were _I.,_ 2190281 also cloned in Cerasxki plates at different cell concentrations (I x 103 eells/well) in complete medium containing 0.4 mg/ntl Gdl8 in the presence of irradiated Imman CTLs as Iccder cells.
In order to imlnavc tlic rctruviral infculiun cl7icicncy, Imunm C'I Ls were co-cultivated with virus-producing cells fur 48 to 72 pus in complete medium. Co-cultivation was also cauried out in transwell plates (Costar, Cambridge, M1A) to prevent cell-to-cell contact. 3 x 105 producer cells were seeded in the duster plate wells oC6-well dishes and incubated at 37°C overnight. 5 x IUS
stimulated CTLs were added into tl~e transwells and grown for 48 to 72 Itrs in the presence of 8 ltg/ml polybrene.
IZetroviral transduced cells were analyzed by l7ow cylometty for receptor expression and expanded for further analyses.
Example 3 (;ase Report A 29 year-old wonum with grade G lymphoma, in second remission alter I year of treatment wish conventional chemotherapy, received a 'I'-cell depleted bone tnatrow transplantation From leer Ii LA-identical and MLC-compatible brother.
The pretransplant conditioning was perfonned accordingly with Kernan et al.
with modifications, and included TBI (1320 cGy in 11 fractions over four days), Cyclofoslanude (6U mg/Kg/die in each of two successive days), VI'16 ( 375 mg/nul/die in each uh two successive days), and rabbit Antithymocyte Globulin (5 mg/Kg/die in each of four successive days) administered over four days pretransplant. T-cell depletion was performed by soybean pectin agglutination and G-resetting (/?). In order to preveun graft rejection (/3J, the patient received prednisouc (I mg/kg/day) Cor the first 6U days post-transplantation (!?~. I~lic patient was discharged from tlic hospital on the day d0 post-transplant, with a documented engrafUnent, in good conditions.

Between day 55 and 60, the patient developed a right laterocervical mass, accompanied by high fever, sharp fall in peripheral blood counts, and increase of AST, ALT, LDH and alkaline phosphatase (see results). An ecotomographic analysis of the neck mass showed multiple packed lymphonodes of about 2 cm each. At a chest CT-scan numerous smaller right paratracheal adenopathies were observed. A laterocervical lymphonode biopsy was performed and confirmed the presence of a diffuse large cell lymphoma, associated with areas of necrosis.
The in situ hybridization for EBV showed the presence of EBV RNA in the nuclei of the neoplastic cells. A myeloaspirate and a bone marrow biopsy showed a myelodisplastic pattern and an overt infiltration of the bone marrow by lymphoid paratrabecolar nodules. On this basis, the diagnosis of EBV-induced secondary lymphoproliferation was made. The possibility of an adoptive immunotherapy by the administration of donor lymphocytes that could control this severe complication by providing to the patient donor immunity against EB V was considered (10).
A clinical protocol for utilization of gene-modified donor lymphocytes in the contest of allogeneic transplantation was approved by the Ethical Committee of Istituto Scientifico San Raffaele in accordance with the guidelines of the National (Italian) Committee for Biosafety on May 15, 1993 . Accordingly, Witn this protocol, donor lymphocytes are transduced in vitro by a retroviral vector for transfer and expression of two genes: 1 - a modified (non-functional) form of the low affinity receptor for the nerve growth factor gene (OLNGFR), for in vitro selection of transduced cells and for in vivo follow-up of the infused donor lymphocytes; 2 - the thymidine-kinase gene that confers to the transduced PBL
in vivo sensitivity to the drug ganciclovir (l5), for in vivo modulation of donor-anti tumor response, and for in vivo specific elimination of cells potentially responsible for GVHD.
After diagnosis, the patient's informed consent was obtained, and she received 2 x 106lKg CD3+ lymphocytes obtained from her donor brother, in two subseduent infusions. The detailed description of the clinical impact of infusion of donor lymphocytes is reported in the Results section. In a brief summary, the patient cleared the clinical signs of EBV lymphoma in two weeks from the first infusion of donor lymphocytes. Due to the development of grade II G she received gancyc~ovir treatment that resulted in complete elimination of marked PBLs from the peripheral blood, was discharged from the hospital on day 116 from BMT, with no signs of EBV lymphoproliferation, GvHD, nor underlying disease. The frequency of anti-EBV lymphocytes in hex blood was in the range of 1/3000. This compares to normal individuals, including her transplant donor who has a frequency of 1/1100.
Clinical impact of the infusion of donor lymphocytes In the two weeks following the administration of vector-transduced donor cells, all clinical symptoms associated with EBV-induced B-cell proliferation regressed, with full hematopoietic recovery. During this time, marked donor cells increased progressively in the patient peripheral blood up to 13.4 % of total mononuclear cells, as detected by FRCS analysis of LNGFR-expressing cells. As indicated in Figure 3, at the time of regression of clinical symptoms, a sharp increase in PBL counts was observed. Circulating tl-ansduced donor lymphocytes were almost exclusively CD3+/CD8+ lymphocytes (> 90 % of total mononuclear cells from day +10 to day +15), with high proliferation index. More than 1/10 cells recognized EBV-infected autologous B-cells in vitro.
Immunomodulation of donor vs host alloreactivity in vector-transduced lymphocytes Approximately four weeks after infusion of gene-modified lymphocytes, the patient progressively developed signs of acute GVHD, with increasing liver function enzymes, and a positive skin biopsy. The i.v. administration of two doses of 10 mglkg of the drug ganciclovir resulted in reduction of marked lymphocytes to 3.1 %, with disappearance of clinical signs of skin GVHD and reduction of over 50 % of all altered liver function enzymes. This patient was discharged six weeks after treatment with no apparent signs of disease.

~' ° W 0 95/31208 ~ 1 O J

_ 17_ Methods In situ hybridization for EBV genome: In situ hybridization for the detection of EBV was performed using deoxyribo-oligonucleotides of 30-mers complementary to the two nuclear EBER RNAs encoded by Epstein-Barr Virus (Dako, Glostrup, Denmark) (l6).
Analysis of the chimerism in the patient BM, PBLS, and the EBV-lymphoma infiltrated lytnphonode was performed by PCR polymorphism of ApoB, ApoC, and YNZ22 (17).
Gene transfer into peripheral blood lymphocytes is accomplished in accordance with Example 1 and Reference (!8).
Determination of antigen-specific lymphocytes precursors frequencies: The frequency of EBV-specific T-cells and allospecific T-cells was performed by limiting dilution as described in (!9) with minor modifications. Briefly, PBMC
were co-cultured in limiting numbers in round-bottom microtiter plates with 2 x 104 irradiated (5000 rods) autologous EBV-transformed B-cells, or 4 x 104 irradiated (3000 rods) allogenic PBMC as stimulators, and 103 irradiated (3000 rods) autologous PBMC as feeders in 200111 of supplemented RPMI 1640 (Gibco, containing 5 % autologous serum). 24 con<:entrations were set-up for each responder dilution. 20 units of hr-IL-2 were added on day 6. A chromium release assay was performed on days 8 and 12 using autologous EBV-B cells or allogeneic PBMC as targets. The proliferation assay was pe~fo~med, after identical culture conditions, on day 8 by an incorporation of 3H-thymidine (Amershan) for 6 hrs. Precursor frequency was calculated by Poisson distribution relationship between the responding cell number and log of the percentage of non-responding cultures as described (20, 2!).
Cell surface phenotyping: Cell surface expression of LNGFR was monitored by flow cytometry utilizing the murine anti-human LNGFR monoclonal antibody 20.4 (ATCC) with an indirect fluorescence labelling method (!8). Cell surface phenotype of T-lymphocytic lines and clones was determined by flow cytometry W095/31208 j ~ (~ ~ ) ~ ~ PC1'/EP94/01573 _18_ using PE-conjugated anti-human-CD4 (T4), CD8 (T8), CDS, B4, CDZSR, Leu7, CD34 monoclonal antibodies (MoAb) (Coulter Immunologry, Hialeah. FL).
Briefly, 5 x 105 cells were stained with 100 ml of diluted antibodies at 4°C for 30 min., washed twice in medium without FCS and resuspended in 0.5 ml of PBS
for FACS analysis or in 100 ml of diluted FITC-conjugated secondary antibody.
Double-staining analysis was performed by sequential incubation of FITC- and PE-conjugated antibodies.

Claims (9)

CLAIMS:

1. Method for the production of antigen-specific cytotoxic T-cells (CTLs) characterized by i) activating proliferation of CTLs in a T-cell-containing cell preparation by incubation of said preparation with an antigen;
ii) selectively transferring a vector into the proliferating CTLs, said vector containing a marker gene by means of which marked and non-marked cells can be separated; and iii)separating the transfected antigen-specific CTLs on the basis of said marker gene.

2. The method according to claim 1, characterized by using a retrovirus as said vector.

3. The method according to claim 1 or 2, characterized by using, as the marker gene, the low affinity nerve growth factor (NGF) receptor.

4. The method according to claims 1 to 3, characterized in that the vector contains in addition a suicide gene.

5. The method according to claim 4, characterized by using, as a suicide gene, the thymidine kinase (TK) gene of Herpes Simplex Virus (HSV).

6. The method according to claims 1 to 5, characterized by using, as said antigen, inactivated viruses or parts thereof, isolated antigens or antigen-presenting cells.

7. The method according to claim 6, characterized by using, as viruses, Cytomegalovirus (CMV), Hepatitis B Virus (HBV), Epstein-Barr virus (EBV), Human Immunodeficiency Virus (HIV), Herpes Simplex Virus (HSV) and Hepatitis C
Virus (HCV).

8. The method according to claims 1 to 7, characterized by cultivating the activated Cytotoxic T-cells (CTLs) in the presence of Interleukin-2 (IL-2) for a time period of 2 to 30 days, infecting the cells with said vector, cultivating the cells in the presence of IL-2 for another period of 2 to 4 days, and selecting CTLs on the basis of said marker gene.

9. The method according to claim 8, wherein CD8+ CTLs are selected.