Pfizer's Talzenna PARP breast cancer drug approved in US

The US drug regulator has approved Pfizer’s breast cancer medicine Talzenna (talazoparib) for patients with a certain mutation.

The drug was approved by the US Food and Drug Administration (FDA) for patients with deleterious or suspected deleterious germline BRCA-mutated (gBRCAm), HER2‑negative locally advanced or metastatic breast cancer.

Talzenna is a poly (ADP-ribose) polymerase (PARP) inhibitor, and is the second drug of this class approved in breast cancer, after AstraZeneca's Lynparza (olaparib) earlier this year. It works by causing cancer cells to self-destruct by inhibiting their ability to fix damaged DNA.

The approval is based on the results of a trial, EMBRACA in which patients were either given 1mg of talazoparib or chemotherapy (capecitabine, eribulin, gemcitabine, or vinorelbine).

The patients were required to have a known deleterious or suspected deleterious gBRCA mutation and must have received no more than three prior cytotoxic chemotherapy regimens for locally advanced or metastatic disease.

The primary efficacy outcome was progression-free survival (PFS), with an estimated median of 8.6 and 5.6 months in the talazoparib and chemotherapy cohorts, respectively.

Jennifer Litton, lead investigator and associate professor in the breast medical oncology department of The University of Texas MD Anderson Cancer Center, said: “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.

“EMBRACA supports the potential of talazoparib to give these patients additional time without disease progression, compared to chemotherapy.”

European regulators are currently reviewing Talzenna for the same patient population, having accepted the marketing authorisation application in June.

The FDA also approved the BRACAnalysis CDx test, developed by Myriad Genetic Laboratories. This identifies patients with the criteria necessary to make them eligible for Talzenna treatment.

Patients can only be selected for treatment with Talzenna based on this diagnostic test.

BioMarin Pharmaceutical originally developed talazoparib, following which US cancer drug firm Medivation acquired all worldwide rights to the drug in August 2015 to expand its global oncology franchise. Pfizer bought Medivation in 2016 for $14 billion.

Myriad is also working with Clovis Oncology so its diagnostic tool can be used to identify best responders to its third-line advanced ovarian cancer drug Rubraca (rucaparib).

In April, the FDA approved PARP drug Rubraca as a maintenance therapy for women with recurrent ovarian cancer.

Rival PARP drugs from AstraZeneca and Tesaro – Lynparza and Zejula – are already approved in the maintenance indication for ovarian cancer, without the need for BRCA tests.