Talazoparib (Tala) in patients (pts) with colorectal cancer (CRC) with BRCA1/2 mutations (mut): Results from the Targeted Agent and Profiling Utilization Registry (TAPUR) study.

Abstract

106 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 CRC 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 or partial response or stable disease of at least 16 weeks (wks) duration (SD16+) per RECIST v 1.1. Simon 2-stage design tested the null DC rate of 15% vs. 35% (power = 0.85; α = 0.10). If ≥2 of 10 pts in stage 1 have DC, 18 more pts are enrolled; otherwise, the cohort is closed. If ≥7 of 28 pts have DC, the null DC rate is rejected. Secondary endpoints were objective response (OR), progression-free survival (PFS), overall survival (OS), and safety. Results: 10 pts with advanced CRC and BRCA1 mut (n=3), BRCA2 mut (n=5), or both (n=2) were enrolled from February 2020 to June 2021. Germline or somatic status was not reported in 7 of 10 pts, 2 pts had somatic BRCA2 muts and 1 pt had a germline BRCA2 mut. 2 pts had left sided tumors, 2 had right sided, 3 had rectal tumors, and 3 pts had tumors that were site undetermined. All pts were evaluable for efficacy and toxicity. Table summarizes pt demographics and outcomes. No pts experienced DC, median PFS was 8 wks (95% CI, 6 to 8) and median OS was 24 wks (95% CI, 7 to 43). Co-alterations were observed in the following genes: KRAS (3 pts) and BRAF (2 pts). 2 pts had 3 separate grade 3 adverse events of anemia or fatigue at least possibly related to Tala. Conclusions: Monotherapy Tala did not demonstrate sufficient clinical activity in pts with advanced CRC with BRCA1/2 mut. Other tx should be considered for these pts, including tx offered in clinical trials. Clinical trial information: NCT02693535 . [Table: see text]