Background: Multipeptide vaccines for melanoma may cause inflammatory adverse events (IAE). We hypothesize that IAE are associated with a higher rate of immune response (IR) to vaccination and improved clinical outcomes.
Methods: Adult patients with resected, high-risk (stage IIB to IV) melanoma were vaccinated with a combination of 12 class I major histocompatibility complex (MHC)-restricted melanoma epitopes, and IAE were recorded. A separate category for hypopigmentation (vitiligo) was also assessed. CD8(+) T cell IR was assessed by direct interferon gamma ELISpot analysis. Overall survival and disease-free survival were analyzed by Cox proportional hazard modeling.
Results: Out of 332 patients, 57 developed IAE, the majority of which were dermatologic (minimum Common Terminology Criteria for Adverse Events [CTCAE] grade 3). Most nondermatologic IAE were CTCAE grade 1 and 2. Vitiligo developed in 23 patients (7 %). A total of 174 patients (53 %) developed a CD8(+) response. Presence of IAE was significantly associated with development of IR (70 vs. 49 %, p = 0.005) and with disease-free survival (hazard ratio 0.54, p = 0.043). There were no significant associations relating vitiligo or IR alone with clinical outcomes.
Conclusions: IAE are associated with a higher rate of CD8(+) T cell response after vaccination therapy for high-risk melanoma. Our findings suggest either that antitumor activity induced by class I MHC-restricted peptide vaccines may depend on immunologic effects beyond simple expansion of CD8(+) T cells or that the intrinsic inflammatory response of patients contributes to clinical outcome in melanoma.