Objective: To evaluate the impact of age on the efficacy and safety of niraparib first-line maintenance therapy in patients with newly diagnosed advanced ovarian cancer with a complete/partial response to first-line platinum-based chemotherapy., Methods: Post hoc analysis of the phase 3 PRIMA/ENGOT-OV26/GOG-3012 study (NCT02655016). Patients in the intent-to-treat population were categorized according to age at baseline (<65 years vs ≥65 years), and progression-free survival (PFS), safety, and health-related quality of life (HRQOL) were evaluated for each age subgroup (clinical cutoff date, May 17, 2019). Safety findings were also evaluated according to a fixed starting dose (FSD) or an individualized starting dose (ISD)., Results: Of 733 randomized patients, 289 (39.4%) were ≥65 years (190 niraparib, 99 placebo) at baseline. Median PFS (niraparib vs placebo) and hazard ratios (95% CI) were similar in patients aged <65 years (13.9 vs 8.2 months; HR, 0.61 [0.47-0.81]) and ≥65 years (13.7 vs 8.1 months; HR, 0.53 [0.39-0.74]). The incidences of any-grade and grade ≥3 treatment-emergent adverse events (TEAEs) were similar across age subgroups; in the niraparib arm, TEAEs leading to dose discontinuation occurred in 7.8% of patients <65 years and 18.4% of patients ≥65 years. ISD use lowered the incidence of grade ≥3 thrombocytopenia events in niraparib-treated patients compared with the FSD (<65 years: 42.8% vs 18.0%; ≥65 years 57.0% vs 26.1%). HRQOL was comparable across age subgroups., Conclusion: Niraparib efficacy, safety, and HRQOL were generally comparable across age subgroups, although patients ≥65 years had a higher rate of discontinuations due to TEAEs. ISD use reduced grade ≥3 thrombocytopenia events regardless of age., Competing Interests: Declaration of competing interest Dr. Valabrega reports consulting fees from GSK; honoraria from AstraZeneca, Eisai, GSK, and MSD; travel support from AstraZeneca and PharmaMar; and participation in advisory boards for AstraZeneca, Eisai, GSK, and MSD. Dr. Pothuri reports institutional grant support from AstraZeneca, Celsion, Clovis Oncology, Eisai, Genentech/Roche, GSK, I-Mab, Immunogen, Incyte, Karyopharm, Merck, Mersana, Onconova, SeaGen, Sutro, and Toray; consulting fees from AstraZeneca, GOG Foundation, GSK, Merck, and Seagen; support for attending meetings from GOG Partners; and advisory board fees from Arquer Diagnostics, Atossa, Deciphera, Eisai, Elevar Therapeutics, GOG Foundation, I-Mab, Immunogen, Lily, Merck, Mersana, Natera, Onconova, Regeneron, Sutro Biopharma, Tesaro/GSK, Toray, and VBL Therapeutics. Dr. Oaknin reports institutional grants from AbbVie Deutschland, Advaxis, Aeterna Zentaris, Amgen, Aprea Therapeutics AB, BMS, Clovis Oncology, Eisai, F. Hoffmann–La Roche, Immunogen, MSD de España SA, Millennium Pharmaceuticals, PharmaMar SA, Regeneron Pharmaceuticals, and Tesaro; consulting fees from Agenus, AstraZeneca, Clovis Oncology, Corcept Therapeutics, Deciphera Pharmaceuticals, Eisai, Exelixis, EMD Serono, F. Hoffmann–La Roche, Genmab, GSK, ImmunoGen, Iteos, MSD de España SA, Mersana Therapeutics, Novocure, OncXerna Therapeutics, PharmaMar, Regeneron, Shattuck Labs, Seagen, and Sutro Biopharma; honoraria from Asociación Colombiada de Ginecológos Oncólogos, AstraZeneca, ESO, GSK, Medscape, NSGO, Peerview, and Peervoice; individual travel support from AstraZeneca, PharmaMar, and Roche; and advisory board participation for Agenus, AstraZeneca, Clovis Oncology, Corcept Therapeutics, Deciphera Pharmaceuticals, Eisai, Exelixis, EMD Serono, F. Hoffmann–La Roche, Genmab, GSK, ImmunoGen, Iteos, MSD de España SA, Mersana Therapeutics, Novocure, OncXerna Therapeutics, PharmaMar, Regeneron, Seagen, Shattuck Labs, and Sutro Biopharma. Dr. Graybill reports consulting and speaker fees from GSK. Dr. Sánchez reports consulting fees from AstraZeneca, GSK, and MSD; honoraria from AstraZeneca, GSK, and MSD; and travel support from AstraZeneca, GSK, and MSD. Dr. McCormick reports personal fees for advisory boards for Clovis, GSK, ImmunoGen, and Merck. Dr. Baurain reports consulting fees from AstraZeneca, BMS, GSK, Immunocore, Merck, MSD, Novartis, Pfizer, Pierre-Fabre, Regeneron, Sanofi, and Sun Pharma. Dr. Tinker reports honoraria from AstraZeneca, Eisai, GSK, and Merck and travel support from GSK. Dr. Denys reports an institutional research grant from Gilead; consulting fees from Gilead and GSK; honoraria from Amgen, AstraZeneca, Daiichi Sankyo, Eli Lilly, Gilead, GSK, Leo Pharma, MSD, and Roche; travel support from AstraZeneca, Gilead, GSK, MSD, Pfizer, PharmaMar, Roche, and Teva; and participation on advisory boards for AstraZeneca, Eli Lilly, Gilead, GSK, Menarini, MSD, and Pfizer. Dr. O'Cearbhaill reports institutional research support from NIH/NCI Cancer Center Support Grant (P30 CA008748) and support grants from AstraZeneca/Merck, Atara Biotherapeutics/Bayer, Genentech, Genmab, GSK, Gynecologic Oncology Group Foundation, Juno Therapeutics, Kite/Gilead, Ludwig Institute for Cancer Research, Regeneron, Sellas Life Sciences, StemcentRx, Syndax, TapImmune, and TCR2 Therapeutics; participating in advisory boards with Bayer, Carina Biotech, Fresenius Kabi, Immunogen, Regeneron, R-Pharm, Seattle Genetics, and Tesaro/GSK; personal fees from GOG Foundation; travel fees from Hitech Health; and service as a noncompensated steering committee member for the DUO-O (olaparib) and PRIMA and Moonstone (niraparib) studies. Dr. Hietanen reports consulting fees from AstraZeneca, Eisai, GSK, and MSD and honoraria from AstraZeneca and GSK. Dr. Moore reports institutional grants from Angle Plc and Fujirebio Diagnostics and personal fees from Fujirebio Diagnostics. Dr. Knudsen has nothing to disclose. Dr. de La Motte Rouge reports receiving consulting fees from AstraZeneca, Clovis Oncology, Eisai, Gilead, GSK, MSD, Novartis, Pfizer, and Sanofi; receiving honoraria from AstraZeneca, GSK, MSD, NetCancer, and Pfizer; and travel support from Gilead, MSD, and Pfizer. Dr. Heitz reports honoraria from AstraZeneca, GSK, Roche, and Tesaro and consulting fees from AstraZeneca, GSK, Roche, and Tesaro. Dr. Levy has nothing to disclose. Dr. Monk reports consulting fees from Agenus, Akeso Biopharma, Amgen, Aravive, Bayer, Elevar, EMD Merck, Genmab/Seagen, GOG Foundation, Gradalis, ImmunoGen, Iovance, Karyopharm, MacroGenics, Mersana, Myriad, Novartis, Novocure, Pfizer, Puma, Regeneron, Sorrento, US Oncology Research, and VBL and speakers' bureau honoraria from AstraZeneca, Clovis, Eisai, Merck, Roche/Genentech, and Tesaro/GSK. Dr. González-Martín reports for different educational or advisory-related activities from Alkermes, Amgen, AstraZeneca, Clovis, Genmab, GSK, Hedera Dx, Immunogen, Illumina, Mersana, MSD, Novartis, Novocure, Oncoinvent, PharmaMar, Roche, Seagen, Sotio, Sutro, Takeda, and Tubulis. Ms. York is a current employee of GSK. Dr. Gupta is a former employee of GSK and Mersana Therapeutics and is currently an employee of Cullinan Oncology., (Copyright © 2024 The Authors. Published by Elsevier Inc. All rights reserved.)