Mutations in the IFNγ-JAK-STAT Pathway Causing Resistance to Immune Checkpoint Inhibitors in Melanoma Increase Sensitivity to Oncolytic Virus Treatment

Clin Cancer Res. 2021 Jun 15;27(12):3432-3442. doi: 10.1158/1078-0432.CCR-20-3365. Epub 2021 Feb 16.


Purpose: Next-generation sequencing studies and CRISPR-Cas9 screens have established mutations in the IFNγ-JAK-STAT pathway as an immune checkpoint inhibitor (ICI) resistance mechanism in a subset of patients with melanoma. We hypothesized ICI resistance mutations in the IFNγ pathway would simultaneously render melanomas susceptible to oncolytic virus (OV) therapy.

Experimental design: Cytotoxicity experiments were performed with a number of OVs on a matched melanoma cell line pair generated from a baseline biopsy and a progressing lesion with complete JAK2 loss from a patient that relapsed on anti-PD-1 therapy, in melanoma lines following JAK1/2 RNA interference (RNAi) and pharmacologic inhibition and in Jak2 knockout (KO) B16-F10 mouse melanomas. Furthermore, we estimated the frequency of genetic alterations in the IFNγ-JAK-STAT pathway in human melanomas.

Results: The melanoma line from an anti-PD-1 progressing lesion was 7- and 22-fold more sensitive to the modified OVs, herpes simplex virus 1 (HSV1-dICP0) and vesicular stomatitis virus (VSV-Δ51), respectively, compared with the line from the baseline biopsy. RNAi, JAK1/2 inhibitor studies, and in vivo studies of Jak2 KOs B16-F10 melanomas revealed a significant increase in VSV-Δ51 sensitivity with JAK/STAT pathway inhibition. Our analysis of The Cancer Genome Atlas data estimated that approximately 11% of ICI-naïve cutaneous melanomas have alterations in IFNγ pathway genes that may confer OV susceptibility.

Conclusions: We provide mechanistic support for the use of OVs as a precision medicine strategy for both salvage therapy in ICI-resistant and first-line treatment in melanomas with IFNγ-JAK-STAT pathway mutations. Our study also supports JAK inhibitor-OV combination therapy for treatment-naïve melanomas without IFN signaling defects.See related commentary by Kaufman, p. 3278.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Cell Line, Tumor
  • Humans
  • Immune Checkpoint Inhibitors / pharmacology
  • Immune Checkpoint Inhibitors / therapeutic use
  • Janus Kinases / genetics
  • Janus Kinases / metabolism
  • Melanoma, Experimental* / genetics
  • Melanoma, Experimental* / therapy
  • Mice
  • Mutation
  • Oncolytic Viruses* / genetics
  • STAT Transcription Factors / genetics
  • STAT Transcription Factors / metabolism
  • Signal Transduction


  • Immune Checkpoint Inhibitors
  • STAT Transcription Factors
  • Janus Kinases