Abstract 4017: Anti-tumor activity of a BRAF inhibitor and IFNα combination in BRAF mutant melanoma

Abstract

Abstract Background. BRAFV600E mediated-MAPK pathway activation is associated in melanoma cells with IFNAR1 down-regulation. IFNAR1 regulates melanoma cell sensitivity to IFNα, a cytokine currently used for the adjuvant treatment of melanoma patients. These findings in conjunction with limited therapeutic efficacy of BRAF-I prompted us to examine whether the efficacy of IFNα therapy of melanoma harboring BRAFV600E can be increased by its combination with BRAF-I. Methods. BRAF/NRAS genotype, ERK activation, IFNAR1 and HLA class I antigen expression were tested in 60 primary melanoma tumors of treatment naïve patients. The effect of BRAF-I on IFNAR1 expression was assessed in 3 melanoma cell lines and in 4 tumor biopsies of BRAFV600E metastatic melanomas. The anti-proliferative, pro-apoptotic and immunomodulatory activity of BRAF-I and IFNα combination was tested both in vitro and in vivo utilizing 3 melanoma cell lines, HLA class I antigen-MA derived peptide complex-specific T cells and immunodeficient mice (5 mice /group for mice survival and 10 mice/group for inhibition of tumor growth). All statistical tests were two-sided. Differences were considered statistically significant when the P value was <0.05. Results. IFNAR1 level was statistically significantly (P<0.001) lower in BRAFV600E primary melanoma tumors than in BRAF wild type tumors. IFNAR1 down-regulation was reversed by BRAF-I treatment in the 3 melanoma cell lines (P≤0.02) and in 3 out of 4 tumor biopsies from metastatic melanoma patients. IFNAR1 level in the melanoma tumors analyzed was increased as early as 10-14 days following the beginning of the treatment. These changes were associated with i) an increased susceptibility in vitro of melanoma cells to the anti-proliferative (P≤0.04), pro-apoptotic (P≤0.009) and immunomodulatory activity, including induction of HLA class I antigen APM component (P≤0.02) and MA expression as well as recognition by cognate T cells (P<0.001), of BRAF-I and IFNα combination, and ii) an increased mice survival (P<0.001) and inhibition of tumor growth of melanoma cells (P<0.001) in vivo by BRAF-I and IFNα combination. Conclusions. The results of this study provide a strong rationale for the novel clinical trials implemented in BRAFV600E melanoma patients with BRAF-I and IFNα combination Citation Format: Francesco Sabbatino, Yangyang Wang, Giosuè Scognamiglio, Elvira Favoino, Steven A. Feldman, Vincenzo Villani, Keith T. Flaherty, Sjoerd Nota, Diana Giannarelli, Ester Simeone, Anna M. Anniciello, Giuseppe Palmieri, Stefano Pepe, Gerardo Botti, Paolo A. Ascierto, Cristina R. Ferrone, Soldano Ferrone. Anti-tumor activity of a BRAF inhibitor and IFNα combination in BRAF mutant melanoma. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 4017.