Molecular mechanisms of resistance to anti-programmed cell death 1 (PD-1) therapy in melanoma

intermediate-risk (n=104) and high-risk (n=25) phenotype groups based on a created index of the risk factors; eye colour, hair colour, ability to tan, and freckles.The endpoint were distant metastasis free survival and overall survival from stage IV disease.Results: Neither sun exposure groups nor phenotype groups showed any significant differences in distant metastasis free survival.Numerically, but non-significantly, longer overall survival was observed for patients with high compared to low sun exposure (median survival 2.8 vs. 1.6 years respectively, p = 0.20, log-rank test), and for patients with high-risk and intermediate-risk compared to low-risk phenotypes (median survival 1.9 vs. 2.0 vs. 1.0 years, respectively p = 0.18, log-rank test).When adjusted for sun exposure, stage, age and gender, intermediate-risk and high-risk phenotype (borderline significant) were associated with a decreased risk of death compared to low-risk phenotype (HR 0.348, p = 0.014 and HR 0.352, p = 0.050 respectively, Cox regression).There was also a borderline significantly decreased risk of death for patients with high sun exposure when adjusted for phenotype (HR 0.407, p = 0.050, Cox regression). Conclusions:The preliminary results of this study indicate an impact on the prognosis in metastatic MM by pigmentation phenotype and sun exposure.We intend to perform the analysis in an expanded study population.