New PARP Inhibitor Approved for Ovarian Cancer

The U.S. Food and Drug Administration approval of niraparib means there are now three PARP inhibitors that can be used to treat women with ovarian cancer.

The U.S. Food and Drug Administration (FDA) recently announced that it had approved the molecularly targeted therapeutic niraparib (Zejula) for the maintenance treatment of adult patients with recurrent epithelial ovarian, fallopian tube, or primary peritoneal cancers that are responding to platinum-based chemotherapy.

Ovarian cancer is relatively rare. With 22,440 cases of ovarian cancer expected to be diagnosed in 2017, according to the National Cancer Institute’s Surveillance, Epidemiology, and End Results (SEER) Program, it is just the11th most commonly diagnosed cancer among women in the United States. But it is also one of the deadliest cancers for U.S. women, ranking as the fifth most common cause of cancer-related death.

Molecularly targeted therapeutics called poly ADP-ribose polymerase (PARP) inhibitors have recently emerged as a new treatment option for some patients with ovarian cancer. The first two PARP inhibitors to reach the clinic, olaparib (Lynparza) and rucaparib (Rubraca), were approved only for treating women who have advanced ovarian cancer harboring cancer-associated BRCA gene mutations.

While niraparib is the third PARP inhibitor to reach the clinic, it is the first to be approved for use in treating both BRCA mutation-positive and -negative ovarian cancers.

According to the FDA announcement, the approval of niraparib was based on results from the randomized, phase III NOVA clinical trial, which showed that among the 553 patients with epithelial ovarian, fallopian tube, or primary peritoneal cancer enrolled in the trial, the median time from starting treatment to disease progression was significantly longer among those who received niraparib than among those who received placebo.

When the data were analyzed by whether or not patients had a germline BRCA mutation, niraparib was found to improve the time to disease progression in both groups. Among germline BRCA mutation-positive patients, median progression-free survival was 15.5 months longer for those who received niraparib than those who received placebo (21.0 months versus 5.5 months). Among germline BRCA mutation-negative patients, the improvement in median progression-free survival with niraparib was 5.4 months (9.3 months versus 3.9 months).

Although the first three FDA approvals for PARP inhibitors have all been for ovarian cancer, these molecularly targeted therapeutic are being tested as potential treatments for several other types of cancer. Some of these clinical trials were discussed during the Cyclin-dependent Kinase and PARP Inhibitor Clinical Trials session at the AACR Annual Meeting 2017.

The FDA approval was rendered on March 27, 2017.