FDA Approves Pfizer’s Talzenna for Breast Cancer

Pfizer wording on side of tall building

The U.S. Food and Drug Administration (FDA) approved Pfizer’s PARP inhibitor, Talzenna (talazoparib), for patients with a germline BRCA-mutated (gBRCAm), HER2-negative breast cancer. The agency also approved Myriad Genetics diagnostic assay to identify the mutation.

The approval was built on the EMBRACA clinical trial, an open-label study that randomized 431 patients on a two-to-one ratio with gBRCAm HER2-negative locally advanced or metastatic breast cancer to receive either Talzenna or a physician’s choice of chemotherapy—capecitabine, eribulin, gemcitabine, or vinorelbine. All patients in the trial were identified as having the gBRCA mutation and had received no more than three previous chemotherapy regimens for locally advanced or metastatic disease.

Patients were also required to have had treatment with an anthracycline and/or a taxane in the neoadjuvant, adjuvant and/or metastatic treatment setting.

The primary endpoint was progression-free survival (PFS) based on a Response Evaluation Criteria in Solid Tumors (RECIST) 1.1. Those receiving talazoparib had a PFS of 8.6 months and the chemotherapy arm had a PFS of 5.6 months.

“Patients with germline BRCA-positive breast cancer are typically diagnosed at a younger age than those with non-hereditary breast cancer, and there are no therapies specifically approved for them outside of current standard of care therapies,” said Jennifer Litton, lead investigator and associate professor in the breast medical oncology department of The University of Texas MD Anderson Cancer Center, in a statement. “EMBRACA supports the potential of talazoparib to give these patients additional time without disease progression, compared to chemotherapy.”

Potential side effects include myelodysplastic syndrome/acute myeloid leukemia, myelosuppression, and embryo-fetal toxicity. The most common side effects were fatigue, anemia, nausea, neutropenia, headache, thrombocytopenia, vomiting, alopecia, diarrhea, and loss of appetite.

Talzenna is taken orally, once a day, with or without food.

PARP inhibitors (PARPi) are a fairly new class of drugs. PARP stands for poly ADP ribose polymerase, an enzyme that many cancer cells are more dependent upon than normal, healthy cells are. The enzyme is involved in repairing damaged DNA. By inhibiting it in cancer cells, they tend to die at a faster rate than the normal cells.

Pfizer picked up Talzenna when it acquired Medivation in 2016 for $14 million. It was originally developed by BioMarin Pharmaceutical. Medivation acquired worldwide rights from BioMarin to the drug in August 2015. The breast cancer caused by BRCA mutations accounts for 25 to 30 percent of hereditary breast cancers and about 5 to 10 percent of all breast cancers.

The leading PARPi is AstraZeneca’s Lynparza (olaparib). Others on the market include Tesaros Zejula (niraparib) and Clovis Oncology’s Rubraca (rucaparib).

“We congratulate Pfizer on obtaining FDA approval of Talzenna for certain patients living with metastatic breast cancer, and we are excited to expand the use of BRACAnalysis CDx as the companion diagnostic test,” said Lloyd Sanders, president of Myriad Oncology, in a statement. “We estimate there are more than 60,000 patients diagnosed with or who progress to metastatic breast cancer in the United States every year who qualify for a BRACAnalysis CDx test.”

The drug is currently being reviewed in the European Union.

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