Evaluation of treatment response to niraparib in patients with platinum-sensitive recurrent ovarian cancer and measurable lesions at baseline: a sub-analysis of the phase III NORA trial

Abstract

<h3>Objectives:</h3> This sub-analysis investigated treatment response to niraparib maintenance therapy in patients with platinum-sensitive recurrent ovarian cancer (PSROC) included in the NORA trial who had measurable lesions after finishing chemotherapy and before initiating niraparib. <h3>Methods:</h3> In the double-blind, phase III NORA trial, 265 adult (≥18 years) Chinese women with PSROC were randomised 2:1 to receive oral niraparib (n=177; 300 mg/day, patients with bodyweight <77 kg or platelet count <150×10³/µL received 200 mg/day) or matched placebo (n=88)(NCT03705156). The primary endpoint was progression-free survival (PFS). This sub-analysis assessed treatment outcomes among patients with measurable lesions after finishing chemotherapy and before initiating niraparib maintenance therapy. Baseline disease assessment (before niraparib initiation) and subsequent tumour response was assessed using the Response Evaluation Criteria in Solid Tumors (RECIST) v1.1 by blinded independent central review (BICR). In patients with measurable lesions at baseline, the objective response rate (ORR) was evaluated. Odds ratios (OR) were adjusted for response to previous platinum-based chemotherapy and time to disease progression following the penultimate platinum-based chemotherapy, and were calculated using logistic regression. Adverse events (AEs) were graded using the Common Terminology Criteria for Adverse Events (CTCAE) v4.03. <h3>Results:</h3> Of the 265 patients included in the NORA study, 64 (24.2%) had measurable lesions at baseline (niraparib, n=43; placebo, n=21), 21.9% (14/64) of whom had received secondary cytoreductive surgery before the last round of chemotherapy. Among patients with measurable lesions, those who received niraparib achieved a higher ORR compared with those receiving placebo (32.6 vs 14.3%; OR=2.7, 95% CI, 0.67-11.18), and niraparib also led to a higher ORR regardless of germline <i>BRCA</i> mutation status (g<i>BRCA</i> mutation: 50.0 vs 28.6%, non-g<i>BRCA</i> mutation: 25.8 vs 7.1%) (Table). Niraparib was well tolerated by patients in this sub-analysis, with a safety profile in-line with previous reports. <h3>Conclusions:</h3> Among patients included in the NORA study with measurable lesions at baseline, niraparib maintenance therapy induced additional antitumour activity versus placebo, with a higher ORR regardless of germline <i>BRCA</i> mutation status, and was well tolerated. The high rates of tumour response observed for niraparib-treated patients in the NORA study further support the role of niraparib as maintenance treatment for patients with PSROC and measurable lesions after chemotherapy.