Intratumoural and systemic inflammation as predictors for treatment response in BRAF-mutated melanoma patients under targeted therapies

Intratumoural as well as systemic inflammation in melanoma has thoroughly been studied in the context of patients treated with immune checkpoint inhibitors but not with BRAF/MEK inhibitors (BRAFi/MEKi). We aimed to study whether parameters of intratumoral and systemic inflammation correlate with clinical outcome in patients with BRAF-mutant metastatic melanoma treated with BRAFi/MEKi. We studied 51 CM patients with unresectable stage III or IV who had the indication for BRAFi/MEKi treatment based on confirmed BRAF mutation. Baseline systemic immune-inflammation markers such as the systemic immune-inflammation index (SII) and the expression of intratumoral inflammation markers such as COX-2 protein expression were correlated with clinical outcome measures. On multivariable analyses, lower intratumoral COX-2 expression (OR 33.9, 95% CI 3.2-356.8) and lower SII (OR 6.3, 95% CI 1.1-34.8) proved to be significant independent predictors for objective response to targeted therapy. Elevated S100B (HR 1.2, 95% CI 1.03-1.3) was a significant predictor for progressive disease. Moreover, elevated S100B (HR 1.37, 95% CI 1.14-1.65) and LDH (HR 1.002, 95% CI 1.0001-1.003) were significant independent predictors for melanoma-specific death. In conclusion, the present study indicates that low SII values and low intratumoral COX-2 protein expression are significant independent predictors for treatment response to BRAFi/MEKi.