Background/aims: To evaluate efficacy, safety, pharmacokinetics (PK) and immunogenicity of SB15 versus reference aflibercept (AFL), and switching from AFL to SB15 in neovascular age-related macular degeneration (nAMD)., Design: Prospective, double-masked, randomised, phase 3 trial., Methods: Participants with nAMD were randomised 1:1 to receive SB15 (N=224 participants) or AFL (N=225). At week 32, participants either continued on SB15 (SB15/SB15, N=219) or AFL (AFL/AFL, N=108), or switched from AFL to SB15 (AFL/SB15, N=111). This manuscript reports 1-year and switching results of secondary efficacy endpoints such as changes from baseline to week 56 in best-corrected visual acuity (BCVA), central subfield thickness (CST, from internal limiting membrane (ILM) to retinal pigment epithelium), and total retinal thickness (TRT, from ILM to Bruch's membrane). Additional endpoints included safety, PK and immunogenicity., Results: Efficacy results were comparable between groups. The least squares mean (LSmean) change in BCVA from baseline to week 56 was 7.4 letters for SB15/SB15 and 7.0 letters for AFL/AFL (difference (95% CI)=0.4 (-2.5 to 3.2)). The LSmean changes from baseline to week 56 in CST and TRT were -119.2 µm and -132.4 µm for SB15/SB15 and -126.6 µm and -136.3 µm for AFL/AFL, respectively (CST: difference (95% CI)=7.4 µm (-6.11 to 20.96); TRT: difference (95% CI)=3.9 µm (-18.35 to 26.10)). Switched and non-switched participants showed similar LSmean changes in BCVA from baseline to week 56 (AFL/SB15, 7.9 letters vs AFL/AFL, 7.8 letters; difference (95% CI)=0.0 (-2.8 to 2.8)). Safety, PK and immunogenicity were comparable between groups., Conclusions: Efficacy, safety, PK and immunogenicity were comparable between SB15 and AFL and between switched and non-switched participants., Competing Interests: Competing interests: WC, IO and HJ are employed by Samsung Bioepis. Samsung Bioepis funded medical writing support and article processing charges. Additional potential conflicts of interest are listed below. SJW obtained consulting fees from Samsung Bioepis, Janssen, Novartis, Curacle, Novelty Nobility, Sometech, Rznomics and Pharmabcine, grants from Samsung Bioepis, Novelty Nobility, Novartis, Alteogen, Roche, Geneunitech, Bayer, Bio Bank Healing, and Curacle, and payments for lectures from Novartis, Bayer, and Allergan-Abbvie. He serves as equity owner of Retimark and Panolos Bioscience. SRS obtained consulting fees from Apellis, Amgen, Abbvie/Allergan, Samsung Bioepis, Biogen, Boerhinger Ingelheim, Iveric, Novartis, Roche, Bayer, Regeneron, Pfizer, Astellas, Nanoscope, Jannsen, Centervue, Optos and Heidelberg, and honoraria for lectures from Novartis, Roche, Optos, and Heidelberg. He is part of the Data Safety Monitoring/Advisory Board of Regeneron and holds leadership/fiduciary functions in ARVO and Macula Society. MB obtained honoraria for presentations by Novartis and Abbvie. He is part of the advisory board of Novartis and obtained grants for clinical trials from Iveric Bio (former Optotech), Novartis, Roche, Ophthea and Samsung Bioepis. AV obtained consulting fees and honoraria for lectures from Novartis, Roche, Pfizer, Bausch & Lomb, Zeiss, and Alcon. He also obtained support for meeting attendances by Novartis, Pfizer, Bausch & Lomb, Roche, Zeiss, Alcon, Iveric Bio, Amgen, Chengdu, Mylan, Panoptica, Formycon, Thrombogenics, Regeneron and Clearside. He is part of the Data Safety Monitoring/Advisory Board of Zeiss, Bayer, Novartis, Pfizer, and Roche. MS obtained grants from Allergan/Abbvie, Bayer and Novartis, consulting fees from Samsung Bioepis, Bayer, Novartis, Allergan/Abbvie, Roche, Alcon and Curacle, honoraria for lectures from Samsung Bioepis, Bayer, Novartis, Allergan/Abbvie, Roche, Alcon and Johnson & Johnson, and support for meeting attendances from Bayer, Allergan/Abbvie and Novartis. Min Sagong is part of the Data Safety Monitoring/Advisory board of Bayer, Novartis, and Allergan/Abbvie. JS obtained consulting fees from Abbvie and support for meeting attendances from Bayer. MV obtained consulting fees from Abbvie and Roche and support for meeting attendances from Bayer. EW obtained honoraria for lectures from Bayer, Roche, Alfa Sigma, Allergan, Zeiss and Thea, and is part of the advisory board of Allergan. SP obtained grants from Aerie, Aerpio, Allergan, Allgenesis, Apellis, Boehringer Ingelheim, Chengdu Kanghong, Clearside, EyePoint, Genentech-Roche, Ionis Pharmaceuticals, IVERIC Bio, KalVista, Kodiak Sciences, Mylan, Novartis, Oculis, Opthea, Ora, Oxurion, Regeneron, Samsung, SmileBiotek, Stealth Biotherapeutics, ThromboGenics, Xbrane Biopharma, consulting fees from AiViva, Allergan, Allgenesis, Genentech-Roche, Kala, Kodiak Sciences, Oxugenix, and RegenxBio, and support for travel expenses from EyePoint. He is part of the Data Safety Monitoring/Advisory Board of Allergan, Allgenesis Biotherapeutics, Genentech-Roche, Kodiak Sciences, and Iveric Bio and serves as equity owner and chief medical officer for Allgenesis Biotherapeutics. WC received consulting fees from Samsung Bioepis and payments for lectures from Bayer, Novartis and Chong Kun Dang., (© Author(s) (or their employer(s)) 2023. Re-use permitted under CC BY-NC. No commercial re-use. See rights and permissions. Published by BMJ.)