JAK1 and cancer: However, the high CNA burden and frequently triploid genomes in the immune deficient subtype is consistent with data from other cancer types showing that tumour aneuploidy is associated with a poor response to immune checkpoint inhibition.63, 64, 65 Of particular relevance, JAK1 and JAK2 were identified as frequent targets of chromosomal losses and concurrent downregulated expression in the immune deficient MPNSTs.