The regulatory agency green lit the use of MyChoice CDx as a companion diagnostic for niraparib in advanced ovarian cancer
The FDA has approved the MyChoice CDx Test as the companion diagnostic for determining whether patients with advanced ovarian cancer may be eligible to receive treatment with niraparib (Zejula).1 The test is the only companion diagnostic in the United States approved to determine eligibility for treatment with niraparib based on positive homologous recombination deficiency (HRD) status.
The approval is based on findings from the final analysis of the phase 3 PRIMA trial (NCT02655016), in which the MyChoice CDx Test was used to identify and stratify patients by HRD status.
“The FDA approval reinforces Myriad’s long-standing leadership in ovarian cancer diagnostics and underscores the clinical importance of comprehensive HRD testing,” Brian Donnelly, chief commercial officer at Myriad Genetics, stated in a news release. “By enabling precise identification of patients who may benefit from PARP inhibitors, MyChoice CDx helps ensure that treatment decisions are guided by robust genomic insights.”
Approximately half of patients with advanced ovarian cancer have HRD-positive tumors. Niraparib is indicated for the maintenance treatment of adult patients with advanced epithelial ovarian, fallopian tube, or primary peritoneal cancer who are in a complete or partial response to first-line platinum-based chemotherapy and whose cancer is associated with HRD-positive status defined by either a deleterious or suspected deleterious BRCA mutation, and/or genomic instability.2
The test can isolate HRD status using next-generation sequencing to evaluate BRCA1/2 genes, including large rearrangements, and a tumor genomic instability score that factors in loss of heterozygosity, telomeric allelic imbalance, and large-scale state transitions.1
PRIMA was a double-blind, placebo-controlled trial that randomly assigned patients (n = 733) in complete or partial response to first-line platinum-based chemotherapy 2:1 to niraparib or matched placebo.2 Patients received a starting dose of niraparib at 300 mg once daily regardless of body weight or platelet count. The study protocol was subsequently rewritten to include a starting dose of 200 mg for patients weighing less than 170 lb or with a platelet count of less than 150,000/mcL, or 300 mg for patients weighing at least 170 lb and with a platelet count of at least 150,000/mcL.
The primary end point was progression-free survival (PFS) by blinded independent central review per RECIST 1.1 criteria. Overall survival (OS) served as an additional efficacy outcome measure. Efficacy was evaluated in 373 patients with HRD-positive tumors.
The median PFS was 21.9 months (95% CI, 19.3-not evaluable [NE]) with niraparib (n = 247) vs 10.4 months (95% CI, 8.1-12.1) with placebo (n = 126; HR, 0.43; 95% CI, 0.31-0.59; P < .0001). The final analysis was performed after 185 events had occurred, at which point niraparib displayed a 5% reduction in the risk of death vs placebo, with a median OS of 71.9 months (95% CI, 55.5-NE) with niraparib vs 69.8 months (95% CI, 51.6-NE) with placebo (HR, 0.95; 95% CI, 0.71-1.29).3 Moreover, the PFS benefit was upheld, with 5-year rates of 35% in the niraparib arm vs 16% in the placebo arm.
