An Emulated Target Trial Case Study of Real‐World Overall Survival With Second‐Line Maintenance Niraparib Versus Active Surveillance in Patients With Recurrent Ovarian Cancer

PurposeThis retrospective real‐world study compared overall survival (OS) between patients with BRCA wild‐type (BRCAwt) recurrent epithelial ovarian cancer (OC) who received niraparib second‐line maintenance (2LM) versus active surveillance (AS) using target trial emulation, cloning, inverse probability of censoring weighting (IPCW) methodology to minimize immortal time bias.MethodsEligible patients from a United States‐based, deidentified, electronic health record–derived database were diagnosed with epithelial OC (January 1, 2011–May 31, 2021), were BRCAwt, and completed second‐line (2L) therapy (January 1, 2017–March 2, 2022). Patient data were cloned at index (2L last treatment date), assigned to niraparib 2LM and AS cohorts, and censored when treatment deviated from clone assignment. Follow‐up was measured from index to earliest of study end (May 31, 2022), last activity, or death. Median OS (mOS) and hazard ratios were estimated from stabilized IPCW Kaplan–Meier curves and Cox regression models.ResultsOverall, 199 patients received niraparib 2LM, and 707 had their care managed with AS. Key characteristics were balanced across cohorts after cloning and stabilized IPCW. Median follow‐up was 15.6‐ and 9.3‐months pre‐cloning. IPCW mOS was 24.1 months (95% CI: 20.9–29.5) and 18.4 months (95% CI: 15.1–22.8) in niraparib 2LM and AS cohorts, respectively (hazard ratio, 0.77; 95% CI: 0.66–0.89).ConclusionsThis real‐world study provides supportive evidence of an OS benefit for patients with BRCAwt recurrent OC who received 2LM niraparib monotherapy compared with those whose care was managed with AS. The analytic strategies implemented were useful in minimizing immortal time bias and measured confounding.