Phase 3 trial confirms efficacy of tarcocimab in diabetic retinopathy | ASRS 2026

Zenkuda (tarcocimab) resulted in improvement in diabetic retinopathy in a second phase 3 trial. The GLOW2 trial met both primary and secondary endpoints, including in patients who were taking GLP-1 agonists for their diabetes.

“About half of patients were on GLP-1 agonists, which is a still relatively new class of medications for retina clinical trials, because most DME [diabetic macular edema] and DR trials in the past have either excluded patients on GLP-1 agonists, but this trial allowed all comers,” investigator Charles C. Wykoff, M.D., Ph.D., FASRS, director of research at Retina Consultants of Texas and the Greater Houston Retina Research Foundation, said in an interview ahead of the American Society of Retina Specialists Annual Scientific Meeting, which is being held in Montreal between July 15 and July 18.

Approximately 9.7 million people in the United States have diabetic retinopathy, a progressive disease that occurs when damaged blood vessels leak blood and fluid into the retina. Diabetic retinopathy can progress quickly into vision-threatening complications.

Developed by Kodiak Sciences, Zenkuda is an anti-vascular endothelial growth factor (VEGF) intravitreal biologic built on Kodiak’s antibody biopolymer conjugate (ABC) platform.

GLOW2 is a confirmatory phase 3 study designed to replicate and extend the findings of the positive pivotal GLOW1 study. The GLOW2 trial was a phase 3 study of tarcocimab in 255 patients with diabetic retinopathy. This formulation is 80% biopolymer-conjugated and 20% free antibody, a change from the fully conjugated version used in GLOW1.

Patients were randomized equally to tarcocimab 5 mg or sham. Each patient received five injections through week 48 (baseline, weeks 4, 8, 20, and 44), including a six-month interval between the final two doses. The trial allowed patients on GLP-1 agonists (about half the population), unlike many previous DME/DR trials.

At one year, 63% of tarcocimab-treated patients improved two or more steps on the Diabetic Retinopathy Severity Scale (DRSS), versus about 3% with sham, meeting the primary endpoint. DRSS is a scale that is used to measure progression and severity of eye disease in patients with diabetes. In this video, Wykoff discusses the full results of the GLOW2 study.