HOPA 2019: Does Receptor Expression Affect Efficacy of Talazoparib in Advanced Breast Cancer?
Posted: Friday, April 12, 2019
A subgroup analysis of the phase III EMBRACA trial revealed that talazoparib exerts similar safety and efficacy regardless of receptor expression—either hormone receptor–positive/HER2-negative or triple-negative—in patients with advanced breast cancer and germline BRCA1/2-mutated disease. Hope S. Rugo, MD, of the University of California, San Francisco, and colleagues presented their findings at the 2019 Hematology/Oncology Pharmacy Association (HOPA) Annual Conference in Fort Worth (Poster CR007).
Talazoparib, a potent dual-mechanism PARP inhibitor that blocks PARP catalytic activity and traps PARP at sites of DNA damage, results in cell death for BRCA1/2-mutated cells. In this study, patients were assigned to receive either talazoparib at 1mg daily or standard single-agent physician’s choice of chemotherapy. Of the 431 patients enrolled in the study, 241 had hormone receptor–positive disease and 190 had triple-negative disease.
Talazoparib demonstrated significantly improved progression-free survival, overall response rate, and clinical benefit rate of more than 24 weeks compared with physician’s choice of therapy in both subgroups. The overall rate of response for talazoparib was similar for the two subgroups of patients: 61.8% for triple-negative breast cancer versus 63.2% for hormone receptor–positive patients. However, the overall rate of response was higher for talazoparib-treated patients with triple-negative disease versus physician’s choice patients (61.8% and 12.5%, respectively) than for the same treatment groups for hormone receptor–positive patients (63.2% and 37.9%, respectively).
The median duration of response was longer in patients with hormone receptor–positive disease than in those with triple-negative disease, at 6.8 and 4.3 months, respectively. Both groups included a subset of patients with a prolonged response to talazoparib of at least 12 months (28% and 17%, respectively). The safety profile in these two subgroups was comparable; the most common adverse events included anemia, nausea, and fatigue.
