Genomic and transcriptional changes in IFNγ pathway genes are putative biomarkers of response to ipilimumab immunotherapy in melanoma patients.

Evaluation of: Gao J, Shi LZ, Zhao H et al. Loss of IFN-γ pathway genes in tumor cells as a mechanism of resistance to anti-CTLA-4 therapy. Cell 167(2), 397-404 (2016). Tumor resistance to immune checkpoint inhibitors limits therapeutic efficacy in many cancer patients. The study by Gao et al. highlighted herein describes a fundamental mechanism by which melanoma escapes the CTLA-4-targeting drug ipilimumab, the first FDA-approved immune checkpoint inhibitor for cancer. This work describes genomic alterations to IFNγ signaling pathway components as a mechanism of melanoma resistance to ipilimumab and has spawned several studies documenting the significance of this pathway to the efficacy of immunotherapy. The authors highlight new analysis of TCGA RNA-seq data that both support and extend the relevance of the IFNγ pathway to CTLA-4 checkpoint blockade as first introduced by this seminal paper, and the authors discuss the relevance of these collective findings to the future of cancer immunotherapy.