Pfizer reports positive late-stage study data for PARP inhibitor talazoparib in breast cancer

Pfizer reported Friday that the experimental PARP inhibitor talazoparib demonstrated superior progression-free survival (PFS) versus physician's choice standard of care chemotherapy in certain patients with locally advanced or metastatic breast cancer. Data from the Phase III EMBRACA trial are scheduled to be presented at the San Antonio Breast Cancer Symposium (SABCS).

In the study, 431 patients with germline BRCA1/2-positive (gBRCA+) locally advanced or metastatic breast cancer who previously received as many as three prior cytotoxic treatments were randomly assigned to treatment with talazoparib once daily or physician's choice of treatment. In addition to PFS, the trial also assessed objective response rate (ORR).

Results showed that median PFS was 8.6 months for those treated with talazoparib and 5.6 months for those given chemotherapy. Pfizer noted that this represents a 46 percent reduction in the risk of disease progression. Meanwhile, the ORR in the talazoparib arm was 62.6 percent, versus 27.2 percent for the control arm, with 12 patients who received Pfizer's drug having a complete response, versus none in the other group. Additionally, talazoparib was associated with a significant delay in the time to clinically meaningful deterioration in global health status/quality of life versus chemotherapy.

FirstWord reports in this therapy area - KOL Insight Breast Cancer: Find out how KOLs expect the market to evolve, which pipeline treatments are most promising, and which clinical trials will shape treatment decisions. Learn more.

Pfizer also said that talazoparib exhibited "promising disease activity" in the Phase II ABRAZO trial of patients with gBRCA+ metastatic breast cancer. The study similarly consisted of patients who previously received platinum-based chemotherapy or three or more lines of non-platinum-based chemotherapy.

Pfizer gained talazoparib as part of its deal announced last year to acquire Medivation for around $14 billion. The company indicated that it will discuss the EMBRACA findings with global health authorities.

For related analysis, see ViewPoints: Pressure stays on PARPs as buyout options dwindle.

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