Talazoparib in Patients With Solid Tumors With <i>BRCA1</i>/<i>2</i> Mutation: Results From the Targeted Agent and Profiling Utilization Registry Study.

Abstract

The Targeted Agent and Profiling Utilization Registry Study is a phase II basket trial evaluating the antitumor activity of commercially available targeted agents in patients with advanced cancer and genomic alterations known to be drug targets. Results of a cohort of patients with various solid tumors with germline or somatic <i>BRCA1/2</i> mutations treated with talazoparib are reported. Eligible patients had advanced solid tumors, measurable disease (RECIST), Eastern Cooperative Oncology Group performance status 0-2, adequate organ function, and no standard treatment options. Patients with germline <i>BRCA</i>-mutated human epidermal growth factor receptor 2-negative locally advanced or metastatic breast cancer were not eligible for this study. Primary end point was disease control (DC) determined by investigator assessment of objective response (OR) or stable disease (SD) of at least 16 weeks duration (SD16+). The results were evaluated on the basis of a one-sided exact binomial test with a null DC rate of 15% versus 35% (power = 0.82; α = .10). Secondary end points were OR, progression-free survival, overall survival, duration of response, duration of SD, and safety. Twenty-eight patients (20 cancer types) with <i>BRCA1/2</i> mutations were enrolled from December 2019 to September 2021 and collapsed into a single histology pooled cohort for analysis. All patients were evaluable for efficacy. One complete response, nine partial response, and six SD16+ were observed for DC and OR rates of 57% (one-sided 90% CI, 43 to 100) and 36% (95% CI, 19 to 56), respectively. The null hypothesis of a 15% DC rate was rejected (<i>P</i> < .001). Patients with OR had the following tumor types: breast (2), nonmelanoma skin, mesothelioma, stomach, uterus, non-small cell lung cancer, ovary, hepatocellular carcinoma, and pancreas. Thirteen patients had at least one grade 3-5 adverse event (AE) or serious AE at least possibly related to talazoparib. All were consistent with the drug label except bilirubin increase and hyponatremia (both grade 3 AEs). Talazoparib demonstrated antitumor activity in patients with advanced solid tumors and <i>BRCA1/2</i> mutations, including cancer types for which poly ADP-ribose polymerase inhibitors are not yet US Food and Drug Administration-approved.