Since we observed in our Phase 2 clinical trial that single-agent palbociclib led to stable disease in 50% of heavily pre-treated patients with progressive NSCLC with no objective tumor responses, we recognized that combination drug therapy will be required to achieve meaningful clinical benefit to this large subgroup of CDKN2a/p16-negative NSCLC patients. Here, CDKN2A is linked to non-small cell lung carcinoma.