Yet in melanoma and lung cancer—the two cancers where cancer evolution during immunotherapy is studied best—genetic alterations in IFNγ signaling pathways were relatively uncommon [60,63,64,65] and some of the mutations (such as in STAT1) occurred in both responders and non-responders [60,81,82], indicating that loss of INFγ responsiveness does not necessarily favor tumor progression. This evidence concerns the gene STAT1 and cancer.