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GSK PARP Inhibitor Trial Meets Primary Endpoint as Ovarian Cancer Maintenance Therapy

NEW YORK – GlaxoSmithKline announced that the Phase III PRIMA trial, which is investigating niraparib (Zejula) as a maintenance treatment in advanced ovarian cancer patients who have received and responded to platinum chemotherapy, met its primary endpoint.

In the study, more than 600 women receiving GSK's PARP inhibitor niraparib experienced statistically significant improvements in progression-free survival compared to those on placebo, regardless of their biomarker status. The safety of the drug was in line with what has been seen in other studies. GSK, which garnered niraparib through its acquisition of Tesaro earlier this year, will present detailed data from PRIMA at an upcoming scientific meeting.

In the study, patients were tested for somatic or germline mutations in BRCA1 and BRCA2 genes, or for their homologous recombination deficiency status. Testing was performed by Myriad Genetics. 

Niraparib is currently approved in the US as a maintenance treatment for recurrent epithelial ovarian, fallopian tube, or primary peritoneal cancer after patients' tumors have shrunk with platinum-based chemotherapy. Although in the pivotal NOVA study, which led to the approval of this niraparib indication, also evaluated responses based on BRCA mutation and HRD status, patients benefitted from niraparib regardless of their biomarker status. As such, the US Food and Drug Administration approved Myriad's BRACAnalysis CDx as a complementary diagnostic, and not a companion diagnostic. 

Earlier this year Myriad also announced it had begun premarket approval submissions for its myChoice HRD test for patients with ovarian, fallopian tube, or peritoneal cancers in the fourth line or later settings, based on the results of the QUADRA study. 

Approximately 300,000 women are diagnosed with ovarian cancer each year around the world, but only 15 percent of patients are eligible for PARP inhibitors, according to GSK CSO Hal Barron. He noted in a statement that based on the findings more women with ovarian cancer will have access to niraparib.