NEW YORK – The US Food and Drug Administration expanded the approval of niraparib (GlaxoSmithKline's Zejula) as a fourth- or later-line treatment option for advanced ovarian, fallopian tube, or primary peritoneal cancer patients who have homologous recombination deficiency.
The agency simultaneously approved Myriad Genetics' myChoice CDx as a companion diagnostic for determining patients' HRD status. Myriad highlighted in a statement that its test is the only FDA-approved companion diagnostic on the market for identifying patients who are HRD-positive and are likely to benefit from niraparib. The test determines HRD positive status by analyzing for mutations and large rearrangements in BRCA1 and BRCA2 genes, and by gauging three biomarkers: loss of heterozygosity, telomeric allelic imbalance, and large-scale state transitions.
The FDA made its decision based on results from the Phase II, single arm QUADRA study, which enrolled women who received three or more treatments for advanced ovarian cancer, including women with BRCA1/2 mutations with platinum-sensitive, resistant, and refractory disease, and those who were HRD-positive with platinum-sensitive disease.
The study overall showed a 24 percent objective response rate and a median duration of response of 8.3 months. In patients harboring BRCA mutations, the objective response rate was 39 percent in those with platinum sensitive disease, 29 percent in platinum-resistant disease, and 19 percent in platinum-refractory disease. In patients without BRCA mutations, but with a genomic instability score of 42 or greater as determined by MyChoice CDx and platinum sensitive disease, the objective response rate was 20 percent.