Background: The Phase 3NOVA trial assessed niraparib versus placebo as a maintenance treatment (tx) for patients (pts) with recurrent ovarian cancer (OC) who were platinum-sensitive after ≥2 regimens; progression-free survival was the primary endpoint and overall survival (OS) was a secondary endpoint (NCT01847274). The aim of this real-world study was to compare OS in a breast cancer gene wild-type (BRCAwt) population of pts with recurrent OC and who received second-line maintenance (2Lm) niraparib monotherapy or were under active surveillance (AS). Methods: This study used the US nationwide Flatiron Health de-identified electronic health record (EHR)-derived database. Pts diagnosed with epithelial OC between 1Jan2011–31May2021 who completed 2L therapy between 1Jan2017–2Mar2022 were eligible for inclusion. Pts were BRCAwt, had an ECOG PS score 0–1, epithelial histology, and platinum-sensitive disease with ≥6 months between end of first-line tx and start of 2L tx. Pts were assigned to 2Lm niraparib or AS cohorts based on their management following 2L non-maintenance therapy (≤120 days). Follow-up was measured from the index date (end of 2L non-maintenance therapy) until end of study (31May2022), last activity, or death, whichever came first. A target trial emulation cloned inverse probability of censoring weighting (IPCW) methodology was selected a priori to minimize bias. IPCW median OS and hazard ratios (HR) for 2Lm versus AS were estimated with Kaplan-Meier curves and Cox regression models. Results: Overall, 266 BRCAwt pts were included and received niraparib 2Lm (N=123) or were under AS (N=143). Across 2Lm and AS cohorts, prior to cloning and IPCW, 23.6% and 34.3% of pts were aged ≥75 years, and 26.0% and 16.8% had an EHR value for race as other than White, respectively. The majority of pts were from community practice (80.5% and 90.2%, respectively), had serous OC (79.7% and 81.1%) and had Stage III disease (53.7% and 60.8%). Homologous recombination deficiency status was unknown for 92.7% and 86.0% of pts in 2Lm and AS cohorts, respectively. Median follow-up for 2Lm and AS cohorts was 16.8 (Quartile [Q] 1, Q3: 10.4, 28.7) and 10.2 (Q1, Q3: 4.1, 23.7) months, respectively. IPCW median OS was 28.1 (95% confidence interval [CI]: 22.5, 43.2) and 21.5 (95% CI: 14.7, 27.0) months (HR: 0.63 [95% CI: 0.45, 0.88]) for niraparib 2Lm and AS cohorts, respectively and survival rates at 24 months were 58.2% (95% CI: 47.5, 67.6) and 46.1% (95% CI: 33.6, 57.7). Conclusions: This analysis provides real-world data on OS among pts with OC receiving niraparib 2Lm or under AS in the 2L setting following chemotherapy. Funding: GSK study (219306). Editorial support was provided by Fishawack Health, funded by GSK.