Five-year PFS results show advantage for niraparib maintenance in patients with advanced ovarian cancer, with no OS benefit

At the ESMO Congress 2024 (Barcelona, 13–17 September), final overall survival (OS) data after a median follow-up of approximately 6 years revealed no benefit of niraparib maintenance over placebo for patients newly diagnosed with advanced ovarian cancer at high risk of recurrence in the phase III PRIMA/ENGOT-OV26/GOG-3012 study (LBA29). The median OS was 46.6 months with niraparib and 48.8 months with placebo (hazard ratio [HR] 1.01) in the overall population, and 71.9 months with niraparib and 69.8 months with placebo (HR 0.95) in patients with homologous-recombination-deficient (HRd) tumours.  

Previously, PRIMA had met its primary endpoint, demonstrating significantly prolonged progression-free survival (PFS) for first-line niraparib maintenance versus placebo in patients with advanced ovarian cancer who responded to first-line platinum-based chemotherapy, regardless of whether they had HRd tumours (N Engl J Med. 2019;381:2391–2402).

Ad-hoc analysis results presented at the Congress show that 5-year PFS in the overall population was 22% for niraparib and 12% for placebo. For patients with HRd tumours alive at 5 years, there was a striking difference in PFS results, with patients in the niraparib arm twice as likely to be progression free than patients in the placebo arm (35% versus 16%, respectively). In the HRd patient population, the median time to first subsequent therapy was prolonged in the niraparib arm compared with the placebo arm (26.9 months versus 13.9 months, respectively; HR 0.55). Niraparib also prolonged the median time to first subsequent therapy in the overall population compared with placebo (17.0 months versus 12.0 months, respectively; HR 0.74). No new safety signals were reported.