Talazoparib (Tala) in patients (pts) with solid tumors with BRCA1/2 mutation (mut): Results from the Targeted Agent and Profiling Utilization Registry (TAPUR) study.

3115 Background: TAPUR is a phase II basket study evaluating antitumor activity of commercially available targeted agents in pts with advanced cancers with specific genomic alterations. Results in a cohort of pts with solid tumors with BRCA1/2 mut treated with Tala are reported. Methods: Eligible pts had measurable disease, ECOG performance status (PS) 0-2, adequate organ function, and no standard treatment (tx) options. Genomic testing was performed in CLIA-certified, CAP-accredited site selected labs. Pts received 1 mg of Tala orally daily until disease progression. Primary endpoint was disease control (DC) per investigator defined as complete (CR) or partial (PR) response or stable disease (SD) of at least 16+ weeks (wks) duration (SD16+) per RECIST v1.1. The hypothesized null DC rate of 15% was evaluated by a 1-sided exact binomial test (alpha 0.10; 82% power). Secondary endpoints were progression-free survival (PFS), overall survival (OS), duration of response (DOR) and SD, and safety. DOR is defined as time from pt’s first documented objective response (OR) to progressive disease (PD). Duration of SD is defined as time from tx start to PD. Results: 28 pts with 16 solid tumors (6/28 pts had lung cancer) with BRCA1 (n=9) , BRCA2 (n=16) , or BRCA1/2 (n=3) mut were enrolled from Dec 2019 to Sept 2021. All pts were included in efficacy analyses. Demographics and outcomes are shown. 1 CR, 9 PR and 6 SD16+ were observed for a DC rate of 57% (1-sided 90% CI: 43% to 100%) and an OR rate of 36% (95% CI: 19% to 56%); the null hypothesis of a 15% DC rate was rejected (p<0.001). 11/16 pts with OR or SD16+ had a BRCA2 mut, 4 had BRCA1 mut, and 1 had both. The pt with a CR (duration of 93 wks) had non-melanoma skin cancer, with BRCA2 and ATM muts, and was microsatellite instability high with 41 muts per megabase. Pts with PR had various solid tumors; 6/9 pts had BRCA2 mut, 2 had BRCA1 mut , 1 had both. Of pts with DC, 11 had tumor types for which PARP inhibitors are not yet FDA approved. Median duration of PR was 20 wks (range, 11-80). 10/16 pts with DC had a co-alteration in the 24 homologous recombination-related genes examined, mainly ATM (3) or ARID1A (2). 13 pts had ≥1 grade 3 tx-related adverse or serious adverse events including: anemia, AST or bilirubin increase, hyponatremia, nausea, vomiting, neutrophil, platelet, or white blood cell decrease. Conclusions: Tala demonstrated antitumor activity in heavily pretreated pts with advanced solid tumors with BRCA1/2 mut. Additional study is warranted to confirm the efficacy of Tala in non-breast, non-ovarian cancer pts with BRCA1/2 mut. Clinical trial information: NCT02693535 . [Table: see text]