Updated project metadata. Immunotherapy and targeted therapy dramatically changed the treatment of metastatic melanoma. Yet, many patients do not respond to these treatments and improve the understanding of response and resistance is an urgent need. Thus, we utilized mass spectrometry-based proteomic analysis of 185 metastatic melanoma samples. Metastases from different sites demonstrate differences in cellular processes such as immune, metabolism, translation and proliferation. Complementary epidemiology analysis uncovers prognosis variance between different metastases locations after treated with anti-PD1. Examination of lung melanoma metastases reveals clinical and molecular heterogeneity that mainly reflected in immune-related processes. Analysis of BRAF mutation status and prior treatments with MAPK inhibitors also indicate differences in immune and metabolic processes and suggest a molecular basis for the combination of immunotherapy and targeted therapy. These results shed new light into biology and therapeutic resistant mechanisms and the pathogenesis of metastatic melanoma.