Dr Williams on Frontline Niraparib Maintenance Therapy in Ovarian Cancer

Heather R. Williams, MD, assistant professor, Department of Obstetrics and Gynecology – Division of Gynecologic Oncology, University of Arkansas for Medical Sciences, discusses findings from the phase 3 PRIMA trial (NCT02655016) in patients with ovarian cancer.

PRIMA evaluated the efficacy and safety of the PARP inhibitor niraparib (Zejula) vs placebo as maintenance therapy in patients with newly diagnosed advanced ovarian cancer who had responded to first-line platinum-based chemotherapy. In total, 373 of 733 patients who were randomly assigned in this trial had homologous repair–deficient (HRD) tumors; 223 patients had BRCA-mutated tumors and 150 had BRCA wild-type tumors.

In this trial, treatment with niraparib led to a survival benefit compared with placebo across all prespecified subgroups, Williams says. In the entire population, the median progression-free survival (PFS) was 13.8 months and 8.2 months with niraparib and placebo, respectively (HR, 0.62; 95% CI, 0.50-0.76; P < .001). The median PFS in the HRD subgroup was 21.9 months with niraparib and 10.4 months with placebo (HR, 0.43; 95% CI, 0.31-0.59; P < .001).

Additionally, the interim overall survival (OS) analysis showed estimated 24-month OS rates of 84% and 77% in the niraparib and placebo arms, respectively, in the overall population (HR, 0.70; 95% CI, 0.44-1.11). In the HRD subgroup, the estimated 24-month OS rate was 91% with niraparib vs 85% with placebo. Although the estimated OS benefit with niraparib was modest in this subgroup, this agent still provided a benefit in the HRD population, which has limited treatment options, Williams notes.

Based on these findings, frontline niraparib maintenance therapy was approved by the FDA in 2020 for patients with advanced ovarian cancer who have responded to platinum-based chemotherapy.

Subsequently, at a median follow-up of 3.5 years, the median investigator-assessed PFS in the overall population was 13.8 months with niraparib vs 8.2 months with placebo (HR, 0.66; 95% CI, 0.56-0.79). Furthermore, the median investigator-assessed PFS in the HRD subgroup was 24.5 months with niraparib vs 11.2 months with placebo (HR, 0.52; 95% CI, 0.40-0.68).