Simmiparib (2, 4 and 8 mg/kg; p.o.; qd, for 14 days) inhibits the growth of tumor in V-C8 (BRCA2-/-) and MDA-MB-436 (BRCA2-/-) xenograft mice models. Simmiparib (10 and 50 mg/kg; p.o.; qd, for 42 days) inhibits the growth of BRCA1-mutated breast cancer in xenograft mice model.