44.04 Anti-tumor activity of BRAF inhibitor and IFNα combination in BRAF mutant melanoma

C. Ferrone^1,2, F. Sabbatino^1,2, Y. Wang^1,2, G. Scognamiglio³, E. Favoino^1,2, S. A. Feldman⁴, V. Villani^1,2, K. T. Flaherty⁵, S. Nota⁶, D. Giannarelli⁷, E. Simeone³, A. M. Anniciello³, G. Palmieri⁸, S. Pepe⁹, G. Botti³, P. A. Ascierto³, C. Ferrone^{1,2 1}Massachusetts General Hospital,Department Of Surgery,Boston, MA, USA ²Harvard School Of Medicine,Department Of Surgery,Brookline, MA, USA ³Istituto Nazionale Tumori Fondazione,Naples, CAMPANIA, Italy ⁴National Cancer Institute,Surgery Branch,Bethesda, MD, USA ⁵Massachusetts General Hospital,Department Of Medical Oncology,Boston, MA, USA ⁶Massachusetts General Hospital,Department Of Orthopaedic Surgery,Boston, MA, USA ⁷Regina Elena National Cancer Institute,Rome, LAZIO, Italy ⁸Institute Of Biomolecular Chemistry,Sassari, SARDINIA, Italy ⁹University Of Salerno,Baronissi, SALERNO, Italy

Introduction: BRAF^V600E 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 BRAF^V600E 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 both in melanoma cell lines and in tumor biopsies of BRAF^V600E 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 melanoma cell lines, HLA class I antigen-MA derived peptide complex-specific T cells and immunodeficient mice.

Results:IFNAR1 level was significantly (P<0.0001) lower in BRAF^V600E primary melanoma tumors than in BRAF wild type tumors. IFNAR1 down-regulation was reversed by BRAF-I treatment both in melanoma cell lines and in 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 an increased susceptibility of melanoma cells to the anti-proliferative, pro-apoptotic and immunomodulatory activity of BRAF-I and IFNα combination both in vitro and in vivo.

Conclusion:The results of this study provide a strong rationale for the novel clinical trials implemented in BRAF^V600E melanoma patients with BRAF-I and IFNα combination.