We have now shown that MHC Class I downregulation occurred in 31% of PROG tumors, regardless of whether resistance was innate or acquired, with downregulation of MHC class I associated with TGFß activity, SNAI1 upregulation, cancer-associated fibroblast signatures and the MITFlow/AXLhigh melanoma phenotype. This evidence concerns the gene SNAI1 and melanoma.