Multiomic profiling of checkpoint inhibitor-treated melanoma: Identifying predictors of response and resistance, and markers of biological discordance

This study concurrently examined the genome, transcriptome, methylome and immune cell infiltrates in baseline tumors from advanced cutaneous melanoma patients treated with anti-PD-1 +/- anti-CTLA-4 immune checkpoint immunotherapy. Illumina MethylationEPIC BeadChip array analysis of 43 melanoma tumors was carried out as part of the study. Higher PSMB8 methylation (and therefore lower PSMB8 expression) was associated with poor response to immunotherapy. There were higher amounts of CD8+ T cells, as estimated by methylCIBERSORT, in the tumor microenvironment of good responders. Although we observed a significant correlation between PD-L1 expression and methylation of the cg197224470 CpG site, there was no significant difference between PD-L1 methylation in good and poor responders. Illumina Infinium MethylationEPIC BeadChip array analysis of 43 melanoma tumours. Samples were collected prior to immune checkpoint immunotherapy