NRAS and neoplasm: On the other hand, the apparent lower efficacy of immunotherapy in patients with KRAS/NRAS mutated tumours treated with anti-PD-1 monotherapy in the KEYNOTE -177 and CheckMate-142 studies, contrasted with a preserved benefit of combined immunotherapy in CheckMate-142, deserved further study as the subgroups were too small for a valid conclusion (19–21, 23).