Correlation of specific immune responses with survival in melanoma patients with distant metastases receiving polyvalent melanoma cell vaccine

Abstract

Purpose: The mechanisms that underlie the clinical efficacy of melanoma vaccines are not well understood. We hypothesized that the type and strength of the immune response generated by CancerVax (John Wayne Cancer Institute, Santa Monica, CA), a polyvalent melanoma cell vaccine (PMCV), might be correlated with its effect on overall survival (OS).

Patients and methods: Seventy-seven patients began PMCV therapy after complete surgical resection of distant metastatic melanoma. During the first two treatments, PMCV was administered with bacille Calmette-Guerin (BCG). Blood was drawn at 0, 2, 4, 8, and 12 weeks to measure serum titers of immunoglobulin G (IgG) and IgM antibodies against a tumor-associated 90-kd glycoprotein antigen (TA90) expressed on most melanoma cells, including those of PMCV. Cellular immune response to PMCV was assessed by delayed-type hypersensitivity (DTH). General immune competence was assessed by skin tests to purified protein derivative (PPD), mumps, and candida.

Results: Median follow-up time was 31.5 months. Within the first 12 weeks of PMCV immunotherapy, there was a significant increase in the anti-TA90 IgM (P=.0001) and IgG titers (P=.0001), and in the DTH response to PMCV (P=.0001). Univariate analysis showed that high anti-TA90 IgM titer and strong PMCV-DTH were associated with improved survival (P=.051 and .0173, respectively), whereas elevated anti-TA90 IgG was correlated with decreased survival (P=.0119). Multivariate analysis considering clinical variables and PMCV immune responses identified anti-TA90 IgM, anti-TA90 IgG, and PMCV-DTH as significant independent variables influencing survival following PMCV immunotherapy (P=.0342, .0105, and .0082, respectively). These responses to PMCV were not correlated with immune responses to BCG and therefore were not a manifestation of general immune competence for responses to unrelated antigens. The median survival time and 5-year survival rate were more than 76 months and 75%, respectively, if both anti-TA90 IgM and PMCV-DTH responses were strong (> or = 800 and > or = 7 mm, respectively; n=29); 32 months and 36%, respectively, if only one response was strong (n=35); and 19 months and 8%, respectively, if neither was strong (n=13) (P < .0001).

Conclusion: PMCV induces both humoral and cell-mediated immune responses to melanoma-associated tumor antigens, the type and strength of which appear to be directly related to its therapeutic efficacy.