Background: TAPUR is a phase II basket study evaluating anti-tumor activity of commercially available targeted agents in pts with advanced cancers with genomic alterations. Results in a cohort of NSCLC pts with CDKN2A loss or mutation treated with P are reported. Methods: Eligible pts had advanced NSCLC, no standard treatment options, measurable disease, ECOG PS 0-2 and adequate organ function. Genomic testing was performed using commercially available tests. Pts matched to P had NSCLC with CDKN2A loss or mutation and no RB mutations. A Simon two-stage design was used to test a null rate of 15% vs. 35% (power = 0.85; α = 0.10). If ≥2 of 10 pts in stage 1 have disease control (DC) (objective response (OR) or stable disease at 16 weeks (wks) (SD16+)), an additional 18 pts are enrolled. If ≥7 of 28 pts have DC, the drug is considered worthy of further study. Secondary endpoints are progression-free survival (PFS), overall survival (OS) and safety. Results: Twenty-nine pts were enrolled from January 2017 to June 2018; 1 pt was unevaluable for response but is included in safety analyses. Pts received P at 125 mg orally once daily for 21 days, followed by 7 days off. Demographics and outcomes are summarized in Table (N = 28). One PR and 6 SD16+ were observed for a DC rate of 29% (90% CI, 15% to 37%). 10 pts had at least one grade 3 or 4 AE or SAE at least possibly related to P with the most common being cytopenias. Other grade 3-4 AEs or SAEs at least possibly related to P included fatigue, anorexia, febrile neutropenia, myocardial infarction, sepsis, vomiting, and hypophosphatemia. Conclusions: Monotherapy with P demonstrated evidence of anti-tumor activity in heavily pre-treated NSCLC pts with CDKN2A loss or mutation. Additional study is warranted to confirm the efficacy of P in pts with NSCLC with CDKN2A loss or mutation. Clinical trial information: NCT02693535