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Myriad Genetics Seeks Supplemental Approval of HRD Test as CDx for GSK Ovarian Cancer Drug

NEW YORK – Myriad Genetics submitted a supplemental premarket approval application with the US Food and Drug Administration for myChoice CDx to assess newly diagnosed advanced ovarian cancer patients with homologous recombination deficiency (HRD), who are likely to respond to niraparib (GlaxoSmithKline's Zejula).

Myriad made the filing for its test despite GSK's confidence that it will be able to garner approval for Zejula in newly diagnosed ovarian cancer patients who are responsive to platinum chemotherapy, regardless of their HRD status. At the JP Morgan Healthcare Conference last week, GSK CEO Emma Walmsley said, "Since Zejula demonstrated a benefit in all patients, we anticipate that doctors will be able to start patients on therapy without any need for HRD testing." She added that GSK is expecting to add this new indication to the niraparib label later this year.

In December, researchers published results from the GSK-sponsored PRIMA study in the New England Journal of Medicine, which showed that newly diagnosed advanced ovarian cancer patients had significantly longer median progression-free survival on niraparib compared to placebo (13.8 months versus 8.2 months), regardless of their biomarker status. At two years, 84 percent of niraparib-treated patients were alive versus 77 percent on placebo.

"Among patients with newly diagnosed advanced ovarian cancer who had a response to platinum-based chemotherapy, those who received niraparib had significantly longer progression-free survival than those who received placebo, regardless of the presence or absence of homologous recombination deficiency," researchers concluded in the NEJM paper.

In this same study, around 51 percent of patients had HRD as measured by Myriad's test. Among these patients, median progression-free survival for niraparib-treated patients was a lot longer than in the overall population, 21.9 months, compared to 10.4 months on placebo. Myriad's decision to file an sPMA seems to be based on this data from PRIMA.

MyChoice CDx sequences BRCA1 and BRCA2 genes, and measures three other processes involved in DNA repair: loss of heterozygosity, telomeric allelic imbalance, and large-scale state transitions. In October, the FDA approved niraparib for heavily pretreated ovarian cancer patients who are platinum sensitive and have HRD. The agency also approved myChoice CDx alongside this indication to identify those with this biomarker.