Taking into account evidence from clinical trials that show an effect of JAK1 inhibitors in EGFR and possible KRAS mutant tumours (NCT02155465, NCT02145637, NCT02917993, and NCT03450330) [63], this serendipitous finding might be of relevance to explain a possible mechanism of action of JAK inhibitors in cancer. This evidence concerns the gene JAK1 and cancer.