AstraZeneca’s and MSD’s Lynparza is being given a priority review by US regulators as a potential treatment for breast cancer, marking the first time a PARP inhibitor has been filed for an indication outside of ovarian cancer.

The US Food and Drug Administration is assessing use of the drug in patients with germline BRCA-mutated (gBRCAm), HER2-negative metastatic breast cancer who have been previously treated with chemotherapy in the neoadjuvant, adjuvant, or metastatic settings.

The submission is based on data from the Phase III OlympiAD trial, which showed that patients with HER2-negative germline BRCA1 or BRCA2-mutated breast cancer treated with Lynparza (olaparib) had a 42-percent reduced risk of disease worsening or death compared to those who received chemotherapy.

Also, the objective response rate (ORR) was more than doubled, with 59.9 percent of patients in the Lynparza arm showing response to treatment, compared to 28.8 percent of patients treated with chemotherapy, while no new safety signals were identified.

In the US the drug is already cleared as monotherapy for patients with deleterious or suspected deleterious germline BRCA-mutated advanced ovarian cancer who have been treated with three or more prior lines of chemotherapy, and also as maintenance therapy for recurrent, epithelial ovarian, fallopian tube or primary peritoneal adult cancer who are in response to platinum-based chemotherapy, regardless of BRCA status.

In the EU, it is approved as maintenance treatment for adults with platinum-sensitive relapsed BRCA-mutated (germline and/or somatic) high grade serous epithelial ovarian, fallopian tube or primary peritoneal cancer who are in response (complete or partial) to platinum-based chemotherapy.

A decision by the FDA is expected during the first quarter of next year.