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From the Department of Medicine, Division of Oncology, Stanford University School of Medicine, Stanford, CA.
The idiotype (Id) of the Ig expressed on the surface of non-Hodgkin's lymphoma cells is a suitable target for immunotherapy. Indeed, treatment with monoclonal anti-Id antibodies (Abs) can induce long-lasting clinical remissions. However, some of the treated patients relapse with a tumor expressing Ig with point mutations in the idio
IMMUNOTHERAPY FOR tumors depends on the existence of tumor-specific target antigens.1 The idiotype (Id) of the Ig expressed on the surface of non-Hodgkin's lymphoma (NHL) cells is a unique tumor marker. Both variable regions of heavy and light chains (VH and VL ) contribute to the Id and result from unique gene rearrangements.2,3 Apparently, malignant transformation to lymphoma occurs in a cell that has already undergone Ig gene rearrangements, since all lymphoma cells of an individual patient express a unique Id. Previous investigation from our group has shown that passive therapy with a monoclonal antibody (MoAb) binding to the Id can induce long-lasting remissions in patients with NHL.4-7 Importantly, some patients who initially responded to anti-Id MoAb eventually relapsed with a tumor that did not bind the MoAb used for the treatment.8 Molecular analysis of the relapse biopsies revealed the existence of tumor cells bearing mutations in the expressed Ig genes.9,10
One such patient (C.J.) with a follicular NHL has been well-described previously.8-10 He had achieved remission after treatment with a murine MoAb (7D11) in 1983. Within a few months, he relapsed with a lymphoma of identical histology. Relapsed tumor cells still expressed a surface Ig; however, they no longer bound the treatment MoAb 7D11. Sequence analysis of the genes coding for the variable regions of the tumor Ig proved the clonal origin of all of the tumor cells but revealed extensive point mutations. Further investigation showed that these mutations had been present in the original tumor specimen before any immunotherapy. Not all of the mutations led to amino acid changes, and not all of the changes in the protein sequence resulted in a loss of binding by the MoAb used for treatment. However, in the tumor cells leading to the relapse, a change of one or two amino acids in the second complementarity-determining region (CDR2) of the heavy chain seemed to be responsible for the loss of binding to the treatment MoAb. Thus, a particular epitope within the Id, in this case the 7D11-idio These findings suggested a change in strategy, namely the investigation of an active vaccination approach.11-14 We hypothesized that active immunization with the tumor Id would lead to a polyclonal immune response capable of recognizing mutated tumor variants. Using murine B-cell lymphoma models, our group and others have shown that Id chemically coupled to keyhole limpet hemocyanin (KLH) elicited an immune response and protected mice from a subsequent tumor challenge.15,16 Moreover, this vaccine in combination with chemotherapy was able to cure the disease in mice already bearing the lymphoma.17 Later, we demonstrated that it is possible to substitute for the carrier protein and for an adjuvant by genetically fusing granulocyte-macrophage colony-stimulating factor (GM-CSF) to the Id protein.18,19 Most recently, naked plasmid DNA encoding Id was used to vaccinate mice to elicit a protective immune response.20,21 Ongoing experiments are evaluating the use of adenovirus (Adv) encoding the Id as a vaccine in the mouse lymphoma model (Caspar C, Hakim I, Syrengelas A, Levy R, submitted).
However, the Ig of the mouse B-cell lymphoma model does not undergo somatic mutation and therefore does not allow a test of whether a polyclonal response can cover the somatic mutants that actually occur in a clinical setting. We thus returned to the mutating tumor of patient C.J. We vaccinated mice with his original Id and then tested the reactivity of the immune mouse sera with Id variants that had occurred in this patient. Several different forms of C.J. Id vaccine were evaluated: Id protein chemically coupled to KLH, Id protein fused to murine GM-CSF, naked plasmid DNA encoding Id, and AdV encoding Id. Each of these types of vaccine was able to induce antibodies that recognized all of the mutated variants contained within the C.J. tumor population.
Tumor
Tumor Proteins
Vaccines
Protein Vaccines
Naked DNA Vaccine The variable regions from the C.J. tumor (expressed in heterohybridoma 2A12) were cloned into a plasmid encoding human IgG1 and constant regions under the control of two independent cytomegalovirus (CMV) promoters.24 Plasmid DNA was purified from transfected bacterial culture with Wizard Megaprep (Promega, Madison, WI) columns. One hundred micrograms of DNA in 100 µL normal saline was split and injected intramuscularly (IM) in the hindlegs three times 1 week apart. Blood was drawn 3 weeks after the last injection.
Adv Vaccine The gene coding for the scFv (2A12) was cloned into a transfer vector, pAdXCJL1/CMV (originally from Dr Frank Graham; a gift from Drs Yifan Dai and Inder Verma, Salk Institute, La Jolla, CA).25 It was integrated in this vector into the site of the previous E1 region and expressed under the control of a CMV promoter. The circular AdV DNA pJM1726 with deleted E1 regions was used with the transfer vector to cotransfect 293 cells.27 The oversized pJM17 cannot be packaged correctly and does not produce infectious virus.28 Recombination with the transfer vector results in a DNA size suitable for packaging into an AdV envelope. The resulting AdV type 5 is replication-defective due to a deletion in early region 1 (E1). It is replicated only in 293 cells that contain the E1 genes. The virus was plaque-purified and amplified in 293 cells. The infected cells were harvested and lysed by two cycles of freezing and thawing. The virus was then purified by two cycles of cesium chloride centrifugation and dialyzed against phosphate-buffered saline (PBS), pH 7.4. The final viral titer was determined by plaque assay. Mice were immunized with a single dose of 3 × 107 plaque-forming units (pfu) IM divided between the hindlegs. Blood was drawn 3 weeks after immunization.Antibody Response The immune response of the vaccinated mice was measured by ELISA. To exclude nonspecific binding to human constant or framework regions, the sera were diluted 1:20 in 2% bovine serum albumin (BSA) in PBS and absorbed onto polyclonal human IgG covalently bound to Sepharose (Sigma, St Louis, MO) and a mixture of five unrelated class-matched monoclonal IgM proteins (different from the ones used for later testing) covalently bound to Sepharose. To remove any possible antiallotypic reactivity, the mouse sera used for specificity testing were subsequently passed over a Sepharose column containing covalently bound normal Ig from patient C.J. (isolated from banked serum by protein A chromatography).
IgG Subclasses The sera of five mice from each group were pooled and serially diluted on plates coated with anti-human IgG and Id proteins as described earlier. Bound Abs were detected with HRPO-conjugated goat Abs specific for the murine IgG subclasses (IgG1 , IgG2a , IgG2b , and IgG3 ) (Southern Biotechnology). Ab levels are expressed as relative amounts within each of the subclasses.
Molecular Rescue of Id Proteins From the Relapsed Tumor Biopsy The aim of this study was to test the hypothesis that active immunization with Id induces a polyclonal immune response that would cover mutated Id variants that did not react with the anti-Id MoAb (7D11) used for therapy. Somatic mutations within the tumor cells gave rise to 7D11-idio -negative variants that were selectively spared in the patient. Such variants led to tumor relapse after initially successful anti-Id treatment. A single 7D11-idio -negative heterohybridoma clone (1B11) was previously produced from this patient (Table 1). We knew from previous investigation10 that the 7D11 Ab reacts with the isolated heavy chain. To obtain more test proteins derived from the relapse tumor biopsy, we cloned the VH gene from the relapse tumor and produced eight additional Id proteins by transient expression in mammalian cells. None of these Id proteins reacted with the treatment MoAb 7D11 (Table 1 and Fig 2). A detailed analysis of these proteins will be presented later herein.*
Mutated Id Proteins From the Relapsed Tumor React Specifically With the Polyclonal Abs Induced by Id Vaccine Mice were immunized with four different formulations of tumor Id vaccines: Id protein coupled to KLH, scFv-muGM-CSF fusion protein, plasmid DNA coding for the Id protein, and AdV containing the gene encoding the scFv (Fig 1). Specific anti-Id Ab levels in the sera of immunized mice were measured by ELISA. To exclude nonspecific binding to human constant or framework regions and to allotypic epitopes, the immune sera were preabsorbed on irrelevant human Igs and on normal Ig obtained from the banked serum of patient C.J. In addition, three class-matched irrelevant human Igs (different from the ones used for preadsorption) and C.J. normal Ig were used as negative controls in the ELISA. All mice developed a specific anti-Id immune response after vaccination (Fig 2). These hyperimmune sera reacted specifically with all of the Id proteins, whereas reactivity was not seen with VH family-matched human Ig proteins or with C.J. normal Ig. This result was independent of the Id vaccine formulation. Most remarkably, all nine Id proteins that failed to react with the treatment MoAb 7D11 were detected by the polyclonal Abs in the sera of the individual immunized mice. Serum from a mouse immunized with an irrelevant Ig did not react with any of the tumor-derived proteins.Quantification of the Anti-Id Immune Response Reactivity of mouse sera after adsorption on irrelevant human Ig was quantified by testing with four different Id proteins of this patient: three 7D11-idio -positive (2A12, 1H1, and 2C12) and one 7D11-idio -negative (1B11). All immunized mice developed a significant and specific anti-Id immune response (Fig 3). Titers obtained by the different vaccination strategies are shown for the five individual mice, with the bar indicating the mean anti-Id titer. Serum from a mouse immunized with an irrelevant protein was used as a negative control. As an additional specificity control, the hyperimmune sera were tested against three irrelevant class-matched monoclonal human Igs. These human Igs were tested individually but are shown here as a single bar (irrelev. Ab) since they all were equally nonreactive. Sera with the highest and most consistent antibody titers were obtained from mice immunized with Id protein coupled to KLH. Injections with Id plasmid DNA resulted in slightly lower titers. The weakest humoral immune responses were obtained using either the scFv AdV construct or the scFv-muGM-CSF fusion protein. In contrast, immunization with plasmid DNA encoding Id without constant regions failed to evoke a significant anti-Id immune response (data not shown).
Isotypes The relative amount of the different murine Ig isotypes elicited by the different vaccine strategies is shown in Fig 4. A high proportion of IgG2a was seen in the groups immunized with scFv AdV and with Id DNA IM, whereas the two groups immunized with scFv-GM-CSF protein and Id-KLH protein had a stronger IgG1 immune response. Interestingly, intradermal DNA immunization induced IgG1 rather than IgG2a antibodies with overall lower titers (results not shown). No significant differences between the groups were found for IgG2b , and only minimal IgG3 could be detected (data not shown).
Sequence Analysis of the Id Proteins Previous study from our group has shown that somatic point mutations in the CDR2 of the VH gene of this patient's tumor were responsible for the loss of binding of the tumor Id to the treatment MoAb 7D11.10 In the current study, we rescued eight additional Id proteins from the relapsed tumor specimen and determined their VH gene sequences. All VH genes derived from this patient's tumor differed from each other by point mutations clustered in the CDR. Amino acid changes were most abundant in CDR2, the presumed binding site of the MoAb used in the initial treatment of the patient. All 7D11-idio -negative clones had at least one change in amino acids 51 to 61 that was not observed in the clones reactive with the treatment MoAb 7D11 (Fig 5). Interestingly, changes also occurred in the adjacent framework region 3 (FR3). This may indicate that FRs contribute to the epitope recognized by the treatment MoAb. The predicted three-dimensional structure of the VH shows that CDR2 mutational hot spots are in the immediate vicinity of FR3. The fact that none of the Id proteins derived from the relapsed tumor biopsy reacted with the treatment MoAb supports the conclusion that this antibody was extremely effective in eliminating 7D11-idio -positive cells.
Our study addresses the question of whether active immunotherapy using the Id of a lymphoma can be expected to induce an immune response capable of binding to tumor cells expressing mutated Id proteins. It is logical to assume that the polyclonal immune response contains sufficient diversity to cover all somatic mutations that would occur in a given Ig expressed by a monoclonal lymphoma. To prove that this is the case, we chose a tumor in which we had documented escape from monoclonal anti-Id therapy due to point mutations in the expressed Id variable regions. We immunized mice with a single Id sequence and analyzed the immune response against a panel of mutated Ids expressed by the patient's tumor cells. We decided to use this xenogeneic test system because murine lymphomas do not show spontaneous somatic mutations. Furthermore, the mutations we survey here actually occurred in a clinical situation, and it is relevant to ask whether they could ever be recognized by the immune system after immunization with a single Id variant. The best test of the hypothesis would have been to immunize the human subject. However, this was not possible. The limitation of a nonsyngeneic model is that xenogeneic or allogeneic epitopes in the variable regions may contribute to the generation of an anti-Id immune response or interfere with the analysis of anti-Id responses. However, the variable regions alone proved to be poorly immunogenic in our test system. Vaccination with plasmid DNA encoding Id without human constant regions failed to evoke a significant anti-Id immune response. To remove any possible antihuman and antiallotypic reactivity, we absorbed the immune sera against polyclonal human Ig and against normal Ig of patient C.J.
Submitted January 7, 1997;
accepted June 26, 1997.
The publication costs of this article were defrayed in part by page charge payment. This article must therefore be hearly marked ``advertisment'' in accordance with 18 U.S.C. section 1734 solely to indicate this fact.
1.
Grossbard M,
Press O,
Appelbaum F,
Bernstein I,
Nadler L:
Monoclonal antibody-based therapies of leukemia and lymphoma.
Blood
80:863,
1992 2. Levy R, Hatzubai A, Brown S, Maloney D, Dilley J: Immunoglobulin idiotype: A tumor-specific antigen for human B-cell lymphomas, in Rosenberg SA, Kaplan HS (eds): Malignant Lymphomas: Etiology, Immunology, Pathology, Treatment. New York, NY, Academic, 1982, p 95 3. Stevenson G, Elliot E, Stevenson F: Idiotypic determinants on the surface immunoglobulin of neoplastic lymphocytes: A therapeutic target. Fed Proc 36:2268, 1977[Medline] [Order article via Infotrieve] 4. Miller RA, Maloney DG, Warnke R, Levy R: Treatment of B-cell lymphoma with monoclonal anti-idiotype antibody. N Engl J Med 306:517, 1982[Medline] [Order article via Infotrieve]
5.
Maloney D,
Brown S,
Czerwinski D,
Liles T,
Hart S,
Miller R,
Levy R:
Monoclonal anti-idiotype antibody therapy of B-cell lymphoma: The addition of a short course of chemotherapy does not interfere with the antitumor effect nor prevent the emergence of idiotype-negative variant cells.
Blood
80:1502,
1992
6.
Brown S,
Miller R,
Horning S,
Czerwinski D,
Hart S,
McElderry R,
Basham T,
Warnke R,
Merigan T,
Levy R:
Treatment of B-cell lymphomas with anti-idiotype antibodies alone and in combination with alpha interferon.
Blood
73:651,
1989
7.
Meeker TC,
Lowder J,
Maloney DG,
Miller RA,
Thielemans K,
Warnke R,
Levy R:
A clinical trial of anti-idiotype therapy for B cell malignancy.
Blood
65:1349,
1985 8. Meeker T, Lowder J, Cleary ML, Stewart S, Warnke R, Sklar J, Levy R: Emergence of idiotype variants during treatment of B-cell lymphoma with anti-idiotype antibodies. N Engl J Med 312:1658, 1985[Abstract]
9.
Levy S,
Mendel E,
Kon S,
Avnur Z,
Levy R:
Mutational hot spots in Ig V region genes of human follicular lymphomas.
J Exp Med
168:475,
1988 10. Cleary M, Meeker T, Levy S, Lee E, Trela M, Sklar J, Levy R: Clustering of extensive somatic mutations in the variable region of an immunoglobulin heavy chain gene from a human B cell lymphoma. Cell 44:97, 1986[Medline] [Order article via Infotrieve]
11.
Sirisinha S,
Eisen H:
Autoimmune-like antibodies to the ligand-binding sites of myeloma proteins.
Proc Natl Acad Sci USA
68:3130,
1971
12.
Lynch G,
Graff R,
Sirisinha S,
Simms E,
Eisen H:
Myeloma proteins as tumor-specific transplantation antigens.
Proc Natl Acad Sci USA
69:1540,
1972
13.
Hsu F,
Caspar C,
Czerwinski D,
Kwak L,
Liles T,
Syrengelas A,
Taidi-Laskowski B,
Levy R:
Tumor-specific idiotype vaccines in the treatment of patients with B cell lymphoma 14. Kwak LW, Campbell MJ, Czerwinski DK, Hart S, Miller RA, Levy R: Induction of immune responses in patients with B-cell lymphoma against the surface-immunoglobulin idiotype expressed by their tumors. N Engl J Med 327:1209, 1992[Abstract] 15. Stevenson FK, Gordon J: Immunization with idiotypic immunoglobulin protects against development of B lymphocytic leukemia, but emerging tumor cells can evade antibody attack by modulation. J Immunol 130:970, 1983[Abstract] 16. Campbell MJ, Esserman L, Byars NE, Allison AC, Levy R: Idiotype vaccination against murine B cell lymphoma. Humoral and cellular requirements for the full expression of antitumor immunity. J Immunol 145:1029, 1990[Abstract] 17. Campbell MJ, Esserman L, Levy R: Immunotherapy of established murine B cell lymphoma. Combination of idiotype immunization and cyclophosphamide. J Immunol 141:3227, 1988[Abstract] 18. Chen TT, Tao MH, Levy R: Idiotype-cytokine fusion proteins as cancer vaccines. Relative efficacy of IL-2, IL-4, and granulocyte-macrophage colony-stimulating factor. J Immunol 153:4775, 1994[Abstract] 19. Tao MH, Levy R: Idiotype/granulocyte-macrophage colony-stimulating factor fusion protein as a vaccine for B-cell lymphoma. Nature 362:755, 1993[Medline] [Order article via Infotrieve] 20. Watanabe A, Raz E, Kohsaka H, Tighe H, Baird SM, Kipps TJ, Carson DA: Induction of antibodies to a kappa V region by gene immunization. J Immunol 151:287, 1993 21. Syrengelas A, Chen TT, Levy R: DNA immunization induces protective immunity against B-cell lymphoma. Nat Med 2:1038, 1996[Medline] [Order article via Infotrieve] 22. Felgner P, Tsai Y, Sukhu L, Wheeler C, Manthorpe M, Marashall J, Cheng S: Improved cationic lipid formulations for in vivo gene therapy. Ann NY Acad Sci 772:126, 1995[Medline] [Order article via Infotrieve] 23. Carrol W, Thielemans K, Dilley J, Levy R: Mouse x human heterohybridomas as fusion partners with human B cell tumors. J Immunol Methods 89:61, 1986[Medline] [Order article via Infotrieve]
24.
Reff ME,
Carner K,
Chambers KS,
Chinn PC,
Leonard JE,
Raab R,
Newman RA,
Hanna N,
Anderson DR:
Depletion of B cells in vivo by a chimeric mouse human monoclonal antibody to CD20.
Blood
83:435,
1994 25. Xu X, Dai Y, Heidenreich O, Nerenberg M: Adenovirus-mediated interferon-gamma transfer inhibits growth of transplanted HTLV-1 tax tumors in mice. Hum Gene Ther 7:471, 1996[Medline] [Order article via Infotrieve] 26. McGrory W, Bautista D, Graham F: A simple technique for the rescue of early region 1 mutations into infectious human adenovirus type 5. Virology 163:614, 1988[Medline] [Order article via Infotrieve]
27.
Graham F,
Smiley J:
Characteristics of a human cell line transformed by DNA from human adenovirus type 5.
J Gen Virol
36:59,
1977
28.
Bett A,
Prevec L,
Graham F:
Packaging capacity and stability of human adenovirus type 5 vectors.
J Virol
67:5911,
1993 29. Stevens T, Bossie A, Sanders V, Fernandez-Botran R, Coffman R, Mosmann T, Vitetta E: Regulation of antibody isotype secretion by subsets of antigen-specific helper T cells. Nature 334:255, 1988[Medline] [Order article via Infotrieve] 30. Irvine KR, Rao JB, Rosenberg SA, Restifo NP: Cytokine enhancement of DNA immunization leads to effective treatment of established pulmonary metastases. J Immunol 156:238, 1996[Abstract] 31. Chen P, Wang M, Bronte V, Zhai Y, Rosenberg S, Restifo N: Therapeutic antitumor response after immunization with a recombinant adenovirus encoding a model tumor-associated antigen. J Immunol 156:224, 1996[Abstract] 32. Potter K, Li Y, Capra J: Antibody production in the baculovirus expression system. Int Rev Immunol 10:103, 1993[Medline] [Order article via Infotrieve] 33. Hsu FJ, Benike C, Fagnoni F, Liles TM, Czerwinski D, Taidi B, Engleman EG, Levy R: Vaccination of patients with B-cell lymphoma using autologous antigen-pulsed dendritic cells. Nat Med 2:52, 1996[Medline] [Order article via Infotrieve] © 1997 by The American Society of Hematology.This article has been cited by other articles:
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