Relevance of MIA and S100 serum tumor markers to monitor BRAF inhibitor therapy in metastatic melanoma patients.

BRAF V600 mutation has been reported in more than 50% of melanoma cases and its presence predicts clinical activity of BRAF inhibitors (iBRAF). We evaluated the role of MIA, S100 and LDH to monitor iBRAF efficiency in advanced melanoma patients presenting BRAF V600 mutations. This was a prospective study of melanoma patients harboring the BRAF V600 mutation and treated with iBRAF within a clinical trial (dabrafenib) or as part of an expanded access program (vemurafenib). MIA, S100 and LDH were analyzed in serum at baseline, and every 4-6 weeks during treatment. Eighteen patients with melanoma stages IIIc-IV were enrolled with 88.8% of response rate to iBRAF. Baseline concentrations of all the tumor markers correlated with tumor burden. MIA and S100 concentrations decreased significantly one month after the beginning of treatment and, upon progression, their concentrations increased significantly above the minimum levels previously achieved. MIA levels lower than 9 μg/L one month after the beginning of treatment and S100 concentrations lower than 0.1 μg/L at the moment of best response were associated with improved progression-free survival. In conclusion, MIA and S100 are useful to monitor response in melanoma patients treated with iBRAF.