Long-Term Efficacy and Safety of CT-P42 in Patients with Diabetic Macular Edema: 52-Week Results from a Phase 3 Randomized Clinical Trial

Introduction: A 24-week phase 3 analysis previously demonstrated equivalent efficacy and comparable tolerability between candidate biosimilar CT-P42 and reference aflibercept in participants with diabetic macular edema. Here, we report long-term outcomes through week 52. Methods: This was a randomized, double-masked, active-controlled, phase 3 international trial, conducted at 83 study centers across Czech Republic, Estonia, Germany, Hungary, India, Latvia, Lithuania, Poland, Republic of Korea, Russia, Slovakia, Spain, and Ukraine. Adults (aged ≥ 18 years) diagnosed with type 1 or 2 diabetes mellitus, with diabetic macular edema involving the center of the macula, were randomized (1:1) to receive CT-P42 or reference aflibercept (2 mg in 0.05 mL) by intravitreal injection every 4 weeks (five doses), then every 8 weeks (four doses), over a 52-week study period. Study data were collected from July 2021 to April 2023. Efficacy, safety, and immunogenicity of CT-P42 compared with reference aflibercept were evaluated until week 52. Results: Overall, 306 participants (CT-P42, 153; reference aflibercept, 153) completed the study through week 52. The primary efficacy endpoint of mean change from baseline in best corrected visual acuity through week 8 was reported previously. Improvements in best corrected visual acuity were maintained throughout and were similar between CT-P42 and reference aflibercept, with mean (standard deviation) change from baseline at week 52 of 12.1 (8.9) versus 11.1 (9.9) letters, respectively. Changes from baseline in central subfield thickness and other secondary efficacy endpoints as well as safety endpoints, including treatment-emergent adverse events and immunogenicity, were comparable between groups through week 52. Conclusions: Results through week 52 support the therapeutic equivalence between CT-P42 and reference aflibercept by demonstrating comparable long-term efficacy, safety, and immunogenicity. Trial Registration: ClinicalTrials.gov identifier: NCT04739306.