Introduction/Background Niraparib first-line maintenance treatment was evaluated in the phase 3 PRIMA trial in patients with newly diagnosed advanced ovarian cancer that responded to platinum-based chemotherapy. In PRIMA, introduction of an individualised starting dose (ISD) based on baseline body weight/platelet count improved niraparib safety while maintaining efficacy. The ISD is the current globally approved dosing for niraparib first-line maintenance.

Methodology The PRIMA (NCT02655016) protocol was amended so newly enrolled patients received an ISD: 200 mg once daily unless baseline body weight ≥77 kg or platelet count ≥150,000/μL, in which case patients received 300 mg once daily. In this ad hoc analysis, the timing, duration, and resolution of common any-grade haematologic (thrombocytopenia, anaemia, neutropenia) and non-haematologic (nausea, asthenia/fatigue, constipation, insomnia, hypertension) treatment-emergent adverse events (TEAEs) were evaluated by treatment arm in safety population patients who received an ISD (data cutoff, 17Nov2021; median follow-up, 3.5 years).

Results Of 733 randomised patients, 255 received an ISD (niraparib, 169; placebo, 86). Median time to first onset of haematologic and non-haematologic any-grade TEAE was <3 months in the niraparib arm. In patients treated with niraparib, the median durations of the first haematologic TEAEs were ≤16 days, whereas the median durations of first non-haematologic TEAEs ranged from 18 days (nausea) to 134 days (insomnia; table 1). The percentage of patients treated with niraparib whose first event resolved was ≥90% for all haematologic TEAEs and ranged from 55% (insomnia) to 86% (nausea) for non-haematologic TEAEs. In the placebo arm, the median durations of first events of anaemia, asthenia/fatigue, and hypertension were longer than in the niraparib arm (table 1).

Conclusion In PRIMA, common haematologic and non-haematologic TEAEs occurred early during niraparib ISD treatment. First events of haematological TEAEs had a short duration (≈2 weeks) and a high rate of resolution. These findings support close monitoring immediately following niraparib initiation.

Disclosures This study (NCT02655016) was sponsored by GSK (Waltham, MA, USA). Third-party medical writing support: Medical writing and editorial assistance, funded by GSK (Waltham, MA, USA) and coordinated by Hasan Jamal, MS, of GSK, were provided by Betsy C. Taylor, PhD, CMPP, and Jennifer Robertson, PhD, CMPP, of Ashfield MedComms, an Inizio company.