Tolerability of the niraparib individualized starting dose in the PRIMA/ENGOT-OV26/GOG-3012 trial of niraparib...

To explore safety and tolerability parameters for the niraparib individualized starting dose (ISD) in patients with newly diagnosed advanced ovarian cancer that responded to platinum-based chemotherapy who participated in the phase 3 PRIMA/ENGOT-OV26/GOG-3012 trial (NCT02655016).

The PRIMA protocol was amended so newly enrolled patients received an ISD based on baseline body weight/platelet count. In this ad hoc analysis, the timing, duration, and resolution of the first occurrence of common any-grade hematologic (thrombocytopenia, anemia, neutropenia) and nonhematologic (nausea, asthenia/fatigue, constipation, insomnia, hypertension) treatment-emergent adverse events (TEAEs) were evaluated by treatment arm in the ISD safety population (data cutoff, November 17, 2021; median follow-up, 3.5 years).

Of 733 randomized patients, 255 were enrolled after the ISD protocol amendment and received ≥ 1 dose of study treatment (niraparib, 169; placebo, 86). In the niraparib arm, median times to first events were 22.0-35.0 days for hematologic TEAEs and 7.0-56.0 days for nonhematologic TEAEs. First events resolved in ≥ 89.8% of patients for hematologic TEAEs; for nonhematologic TEAEs, resolution rates ranged from 55.3% (insomnia) to 86.0% (nausea). Median durations of first hematologic TEAEs were ≤ 16.0 days, but for first nonhematologic TEAEs ranged from 18.0 days (nausea) to 134.0 days (insomnia).

The niraparib ISD was generally well tolerated and TEAEs were manageable. Common hematologic and nonhematologic TEAEs occurred early and first events of hematologic TEAEs had a short duration (≈ 2 weeks) and a high resolution rate. These findings support close monitoring immediately following niraparib initiation and may help inform patient expectations for niraparib safety.