Results of Phase 3 EMBRACA trial in patients with germline (inherited) BRCA1/2-positive (gBRCA+) locally advanced and/or metastatic breast cancer (MBC) demonstrated superior progression-free survival (PFS) in patients treated with talazoparib, compared to patients who received physician’s choice standard of care chemotherapy. Median PFS was 8.6 months (95% CI: 7.2, 9.3) for patients treated with talazoparib and 5.6 months (95% CI: 4.2, 6.7) for those treated with chemotherapy [HR: 0.54 (95% CI: 0.41, 0.71), p<0.0001]. This represents a 46% reduction in the risk of disease progression. In addition, the proportion of patients achieving a complete or partial response (objective response rate) in the talazoparib group was more than twice that of the control arm (62.6% for talazoparib vs. 27.2% for chemotherapy [OR: 4.99 (95% CI: 2.9-8.8), p<0.0001]). Talazoparib is an investigational, oral, dual-mechanism poly ADP ribose polymerase (PARP) inhibitor that is taken once daily. EMBRACA is a global Phase 3, open-label, randomized, parallel, 2-arm trial of talazoparib versus protocol-specific physician’s choice of standard single-agent chemotherapy (PCT [capecitabine, eribulin, gemcitabine or vinorelbine]) in gBRCA+ patients who may have received up to three prior cytotoxic chemotherapy regimens for locally advanced and/or metastatic breast cancer. Patients enrolled had a diagnosis of TNBC or HR+/HER2-negative breast cancer. The trial randomized (2:1) 431 patients to receive talazoparib (1.0 mg) once daily or PCT. The results of the EMBRACA trial also showed that the PFS benefit with talazoparib was consistent across prespecified subgroups, including hormone receptor (HR) status (triple negative [TNBC] or hormone receptor-positive [HR+]), BRCA mutation (1 or 2), prior chemotherapy (whether patients had none or up to three chemotherapies before talazoparib), and history of central nervous system (CNS) metastases. There also was a statistically significant delay in the time to clinically meaningful deterioration in global health status/quality of life with talazoparib versus chemotherapy (HR 0.38 [95% CI 0.26-0.55], p<0.0001), as measured by the EORTC QLQ-C30, a cancer-specific, patient-reported quality of life questionnaire. Adverse events (AEs) observed with talazoparib were consistent with findings from previous trials. The most common AEs observed with talazoparib (any grade in at least 15% of patients) were anemia (52.8%), fatigue (50.3%), nausea (48.6%), neutropenia (34.6%), headache (32.5%), thrombocytopenia (26.9%), alopecia (25.2%), vomiting (24.8%), diarrhea (22%), constipation (22%), decreased appetite (21.3%), back pain (21%) and dyspnea (17.5%). The incidence of serious AEs was 31.8% in the talazoparib arm and 29.4% in the chemotherapy arm. Discontinuations due to AEs occurred in 7.7% of patients in the talazoparib arm and 9.5% of patients in the chemotherapy arm. In addition to EMBRACA, talazoparib demonstrated promising activity in patients with gBRCA+ MBC in the Phase 2 ABRAZO trial. Patients in ABRAZO had either been previously treated with platinum-based chemotherapy or were heavily pretreated with at least three prior lines of non-platinum-based chemotherapy.

 

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