On April 29, the U.S. Food and Drug Administration (FDA) approved niraparib (Zejula) 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.
Efficacy was investigated in PRIMA, a double-blind, placebo-controlled trial in which 733 patients were randomly assigned to receive niraparib or a matched placebo. Patients were in a complete or partial response to first-line platinum-based chemotherapy.
The main efficacy outcome measure—progression-free survival—was first tested in the homologous recombination–deficient study population, then in the overall population, and was determined by blinded independent central review per Response Evaluation Criteria in Solid Tumors, version 1.1. Tumor samples were tested for homologous recombination deficiency status; homologous recombination deficiency was defined by either presence of tumor breast cancer susceptibility gene (BRCA) mutation or genomic instability score ≥ 42. An FDA-approved companion diagnostic is not required to initiate treatment with niraparib for this indication.
The trial demonstrated a statistically significant improvement in progression-free survival for patients treated with niraparib compared with placebo in the homologous recombination–deficient and overall populations. Median progression-free survival in the homologous recombination–deficient population was 21.9 months for patients receiving niraparib compared with 10.4 months for those receiving placebo (hazard ratio [HR] = 0.43, 95% confidence interval [CI] = 0.31–0.59, P < .0001). Median progression-free survival in the overall population was 13.8 months for patients receiving niraparib compared with 8.2 months for those receiving placebo (HR = 0.62, 95% CI = 0.50–0.76, P < .0001).
The most common adverse reactions in ≥ 10% of all patients receiving niraparib in the PRIMA trial were thrombocytopenia, anemia, nausea, fatigue, neutropenia, constipation, musculoskeletal pain, leukopenia, headache, insomnia, vomiting, dyspnea, decreased appetite, dizziness, cough, hypertension, AST/ALT elevation, and acute kidney injury.
The recommended niraparib dose for first-line maintenance treatment of advanced ovarian cancer is based on body weight or platelet count. For patients weighing less than 170 lb or with a platelet count of less than 150,000/μL, the recommended dose is 200 mg taken orally once daily. For patients weighing 170 lb or more and who have a platelet count greater than or equal to 150,000/μL, the recommended dose is 300 mg taken orally once daily.