Talazoparib (BMN 673) is a novel and orally active poly(ADP-ribose) polymerase (PARP) 1 and 2 inhibitor. Talazoparib (BMN 673) inhibits PARP1 and PARP2 enzyme activity with Ki = 1.2 and 0.87 nM, respectively. In a cell-based assay, Talazoparib (BMN 673) inhibits PARP-mediated PARylation with an EC50 of 2.51 nM. It also inhibits the proliferation of cancer cells carrying mutant BRCA1/2, such as MX-1 (EC50 = 0.3 nM) and Capan-1 (EC50 = 5 nM). [1] Talazoparib (BMN 673) demonstrates remarkable antitumor efficacy in a BRCA1 mutant MX-1 breast cancer xenograft model. [1]

Talazoparib (BMN 673) is currently being studied in a Phase III clinical trial in breast cancer patients with BRCA mutation. [2]