Adjuvant immunotherapy of resected, intermediate-thickness, node-negative melanoma with an allogeneic tumor vaccine: impact of HLA class I antigen expression on outcome.

PURPOSE: An association between expression of > or = two of five HLA class I antigens (HLA-A2, HLA-A28, HLA-B44, HLA-B45, and HLA-C3; collectively called M5) and response to an allogeneic melanoma vaccine (Melacine; Corixa Corporation, Seattle, WA) has been described in stage IV melanoma. This study investigated whether class I antigen expression impacted relapse-free survival (RFS) after adjuvant therapy with this vaccine. PATIENTS AND METHODS: We performed class I (HLA-A, HLA-B, and HLA-C) serotyping on patients enrolled onto Southwest Oncology Group Trial 9035, a randomized, observation-controlled, phase III trial of adjuvant Melacine. All patients had clinically node-negative cutaneous melanoma (1.5 to 4.0 mm). Interactions between treatment and class I antigen expression were tested. Analyses involved all serotyped patients and were adjusted for tumor thickness, method of nodal staging, sex, ulceration, and primary tumor site. RESULTS: HLA typing was performed on 553 (80%) of the 689 enrolled patients (294 vaccinated and 259 observed). Expression of > or = two M5 antigens was associated with a superior vaccine treatment effect. Among patients who matched > or = two of the M5, the 97 vaccine-treated patients had improved RFS compared with the 78 observation patients (5-year relapse-free survival, 83% v 59%; P =.0002). The major components of this effect were contributed by HLA-A2 and HLA-C3. Among those who were HLA-A2-positive and/or HLA-C3-positive, the 5-year RFS for vaccinated patients was 77%, compared with 64% for observation (P =.004). There was no impact of HLA-A2 and/or HLA-C3 expression among observation patients. CONCLUSION: This prospective analysis indicates a highly significant benefit of adjuvant therapy with Melacine among patients expressing > or = two of the M5 class I antigens, validating a prior observation in stage IV disease. HLA-A2 and HLA-C3 contributed most to this effect. Processed melanoma peptides found in Melacine may be presented by HLA-A2 and HLA-C3 and play a role in preventing relapse in vaccinated patients.

Adjuvant immunotherapy of resected, intermediate-thickness, node-negative melanoma with an allogeneic tumor vaccine: overall results of a randomized trial of the Southwest Oncology Group.

PURPOSE: Patients with clinically negative nodes constitute over 85% of new melanoma cases. There is no adjuvant therapy for intermediate-thickness, node-negative melanoma patients. PATIENTS AND METHODS: The Southwest Oncology Group conducted a randomized phase III trial of an allogeneic melanoma vaccine for 2 years versus observation in patients with intermediate-thickness (1.5 to 4.0 mm or Clark's level IV if thickness unknown), clinically or pathologically node-negative melanoma (T3N0M0). RESULTS: Six hundred eighty-nine patients were accrued over 4.5 years; 89 patients (13%) were ineligible. Surgical node staging was performed in 24%, the remainder were clinical N0. Thirteen eligible patients refused assigned treatment: seven on the observation arm and six on the vaccine arm. Most vaccine patients experienced mild to moderate local toxicity, but 26 (9%) experienced grade 3 toxicity. After a median follow-up of 5.6 years, there were 107 events (tumor recurrences or deaths) among the 300 eligible patients randomized to vaccine compared with 114 among the 300 eligible patients randomized to observation (hazard ratio, 0.92; Cox-adjusted P(2) = 0.51). There was no difference in vaccine efficacy among patients with tumors < or = 3 mm or > 3 mm. CONCLUSION: This represents one of the largest randomized, controlled trials of adjuvant vaccine therapy in human cancer reported to date. Compliance with randomization was excellent, with only 2% refusing assigned therapy. There is no evidence of improved disease-free survival among patients randomized to receive vaccine, although the power to detect a small but clinically significant difference was low. Future investigations of adjuvant vaccine approaches for patients with intermediate-thickness melanoma should involve larger numbers of patients and ideally should include sentinel node biopsy staging.

Adjuvant vaccine immunotherapy of resected, clinically node-negative melanoma: long-term outcome and impact of HLA class I antigen expression on overall survival.

Associations between HLA class I antigen expression and the efficacy of a melanoma vaccine (Melacine; Corixa Corp.) were initially described in stage IV melanoma. Similar associations were observed in S9035, a phase III adjuvant trial evaluating Melacine for 2 years compared with observation in patients with stage II melanoma. This report provides long-term results. The effects of treatment on relapse-free survival (RFS) and overall survival (OS) were evaluated, and prespecified analyses investigated associations between treatment and HLA expression. Multivariable analyses were adjusted for tumor thickness, ulceration and site, method of nodal staging, and sex. P = 0.01 was considered statistically significant in subset analyses to account for multiple comparisons. For the entire study population of 689 patients, there were no significant differences in RFS or OS by treatment arm. HLA serotyping was performed on 553 (80%) patients (vaccine, 294; observation, 259). Among the subpopulation with HLA-A2 and/or HLA-Cw3 serotype, vaccine arm patients (n = 178) had marginally improved RFS (adjusted P = 0.02) and significantly improved OS compared with observation arm patients (n = 145), with 10-year OS of 75% and 63%, respectively [hazard ratio (HR), 0.62; 99% confidence interval (CI), 0.37-1.02; P = 0.01]. There was no impact of HLA-A2 and/or HLA-Cw3 expression on observation arm patients. An analysis of mature data from S9035 indicates a significant OS benefit from adjuvant vaccine therapy for patients with HLA-A2- and/or HLA-Cw3-expressing melanoma. The possibility of interactions between HLA type and outcome should be considered in future immunotherapy trials. Further investigations of melanoma-associated antigens present in Melacine and presented by HLA-A2 and HLA-Cw3 may be warranted.