Attempts to Optimize Active Specific Immunotherapy for Melanoma

Abstract

During the past 5 years, we have been conducting clinical trials with a therapeutic melanoma vaccine (melanoma "theraccine"). Mechanical lysates of two melanoma cell lines chosen for their complementary characteristics were combined with the adjuvant DETOX and injected subcutaneously on weeks 1, 2, 3, 4 and 6 for one or two courses, and then monthly in patients with objective clinical responses. Of 109 patients, 22 (20%) have had objective clinical regression of tumor masses, with 5% complete responses. Ten patients have lived more than a year. Eight of the 10 are still alive, five of whom have lived more than 3 years. It was not necessary to achieve complete remissions to cause an increase in survival, and most of the long-surviving patients have one or more (stable) residual nodules. The pace of the disease process has clearly been slowed in those individuals. A rise in the level of cytotoxic T lymphocyte precursors in the blood (pCTL) has correlated with clinical response. Only one patient without such a rise in pCTL has had a response, and assays in that patient were considered unreliable. Both CD4+ and CD8+ CTL have been cloned from the blood of immunized patients. Both types of CTL killed a number of melanoma cell lines, but not other types of tumor or normal cells (lymphoblasts and melanocytes). CD8+ CTL have not been restricted to killing the autologous melanoma. MHC restriction by the HLA-A2 locus was identified. CD4+ CTL were not restricted only by Class II HLA antigens. Many CD4+ clones killed HLA Class II-negative melanomas, and we were able to block cytotoxicity of a particular clone with either anti-HLA Class I or anti-Class II MHC monoclonal antibodies, or both. An association of clinical response to the theraccine with certain HLA phenotypes, notably HLA-C3, -A2 (and the cross-reactive HLA-A28), B12 (and the related alleles (HLA-B44 and -B45) and perhaps DR4, particularly when combinations of those alleles were present, was suggested by our analysis of 70 patients. It is possible that this simply indicates the sharing of MHC antigens between the immunizing melanomas and the patient's melanoma. However, these MHC molecules may be important in their own right in presenting melanoma-associated antigens in CTL in vivo. Subtractive hybridization of mRNA from lung squamous carcinoma cells from cDNA of the M-1 melanoma cell line has yielded several DNA sequences unique to melanoma. Those are now being analyzed for possible immunogenicity, with cytotoxicity by CTL from immunized patients as the major criterion.(ABSTRACT TRUNCATED AT 400 WORDS)

MHC class‐I‐restricted auto‐tumor‐specific CD4+CD8 −T‐cell clones established from autologous mixed lymphocyte‐tumor‐cell culture (MLTC)

“…Therefore, lysis of such allogcneic targcts docs not necessarily mean non-specific interaction. This was indeed the case with the melanoma antigen detected by the auto-tumor-specific T-cell cloncs on allogeneic melanoma cell lines (Mitchell, 1991) and with the melanoma-specific antigen idcntificd by the specific CTL clones (van der Bruggen et a/., 1991). In the former the 'The clones which produced more than 10 U/ml IFNy or 50 pg/ml of TNFa during the 3 days of incubation with the autoloous tumor cells were regarded as producers.-2Six-day MLTC.-kysis of the autologous tumor cells, 5-hr Wr-release assay.…”

“…Reactivity of the auto-tumorspecific CD4+ CTL clones with the class-11-negative hepatocarcinoma cells has also been described (Shimizu et al, 1990). In a melanoma system, at least 3 of the CD4+ clones from one patient recognized the antigens on the autologous tumor cells in association with the class-I molecule (Mitchell, 1991). Class-I-restricted CD4+ clones were also encountered among the EBV-specific T cells generated from the blood of a fully reconstituted patient with severe combined immunodeficiency (H. Plotnizky, personal communication).…”

“…In this case the antigenic peptide was presented by the HLA A2/A28 allele on the different cell lines (Mitchell, 1991). The gene of one melanoma antigen has been identified.…”

“…Functional interaction between the TCR of the CD4+ CTL and the MHC class-I molecules of the autologous class-ITnegative melanoma line was demonstrated with the antigenspecific clones established by stimulation of the pre-immunized patient's blood lymphocytes with allogeneic melanoma cell lines. In this case the antigenic peptide was presented by the HLA A2/A28 allele on the different cell lines (Mitchell, 1991). The gene of one melanoma antigen has been identified.…”

Treatment of patients with progressive unresectable metastatic melanoma with a heterologous polyvalent melanoma whole cell vaccine

“…Therapeutic vaccines can be classified according to the tumour antigens used in their composition. Some use tumour peptides, either singly or in combination,9 while others use lysates of tumour cells10, 11, 12 or whole tumour cells 13, 14, 15. The former have the advantage of easy monitoring, but they promote the appearance of genetic variants that have lost the expression of the integrating peptid 16…”