Phase II Trial of Talazoparib in BRCA1/2 Wild-type HER2-negative Breast Cancer and Other Solid Tumors

Talazoparib (BMN 673) is a novel, dual-mechanism PARP inhibitor that potently inhibits the PARP enzyme and effectively traps PARP on DNA. Talazoparib has shown promising single-agent anti-tumor efficacy in several BRCA1/2 mutation-associated advanced cancers. The efficacy of PARP inhibition in BRCA1/2 wild-type TNBC with homologous recombination (HR) defects and in breast tumors with mutations in other non-BRCA1/2 HR pathway genes is currently unknown. This phase 2 trial explores the activity of single agent talazoparib in BRCA1/2 wild-type BC patients using an optimal Simon two-stage design. Eligible subjects will be assigned to one of two parallel cohorts: 1) Cohort A: Subjects (n=29) with advanced TNBC with underlying HR defects as assessed by the HRD assay and, 2) Cohort B: Subjects (n=29) with advanced HER2-negative BC with a somatic or germline mutation in a non-BRCA1/2 HR pathway gene. Gene mutations of interest are: PTEN, PALB2, CHEK2, ATM, NBN, BARD1, BRIP1, RAD50, RAD51C, RAD51D, MRE11, ATR, Fanconi anemia complementation group of genes (FANCA, FANCC, FANCD2, FANCE, FANCF, FANCG, FANCL).