Impact of niraparib on reducing the platelet count in patients with ovarian cancer

Niraparib (NIRA) is a poly(ADP-ribose) polymerase inhibitor used as maintenance therapy for ovarian carcinomas. Thrombocytopenia is a common adverse event associated with NIRA. This study aimed to evaluate the frequency of NIRA-induced thrombocytopenia and the associated risk factors in clinical practice. Data from 30 patients who received NIRA as a first-line or recurrent treatment at our institution were retrospectively analyzed to assess reductions in platelet count (PLT). The median participant age was 59 (range: 39–75) years, and the median weight was 50 (range: 36–80) kg. NIRA was initiated at a median of 4 (range: 3–8) weeks after the last chemotherapy dose. The prevalence of grade ≥3 thrombocytopenia was 23.3 %, dose interruptions occurred in 53.3 % and dose reductions occurred in 40 %. The median follow-up time was 20 (range: 2–166) months after resumption. Due to thrombocytopenia, one patient discontinued treatment 2 weeks after administration (nadir PLT: 1 × 10 9 /L), and 2 others discontinued treatment after resumption. For the non-interruption and interruption groups, the median nadir PLTs were 194 (91–318) and 57 (1–89) × 10 9 /L (p < 0.001), respectively, the median baseline PLTs were 215 vs. 120 × 10 9 /L (p < 0.001), respectively, and the nadir PLTs during prior chemotherapy were 175 vs. 73 × 10 9 /L (p = 0.007), respectively. Lower baseline PLTs were significantly associated with an increased risk of thrombocytopenia (OR 0.793, 95 % CI 0.654–0.964; p = 0.019). Our real-world data reaffirmed that thrombocytopenia is a significant adverse event that affects the continuation of NIRA and requires careful monitoring. Adjusting the start time to ensure an adequate baseline PLT may help mitigate this risk, but larger-scale studies are needed to validate these findings.