Future investigations for a better understanding of immunotherapy response should include imaging, clinical and biological features, e.g. patient BMI or baseline plasma levels for PD-1 and PD-L1 which were previously reported to be associated with time-to-treatment-failure in a recent study involving Merkel cell carcinoma patients treated with avelumab (anti-PD-L1) (110). This evidence concerns the gene CD274 and Merkel cell skin cancer.