Activating Wnt, Inhibiting VEGF: SZN-8141 Cleared to Enter a Diabetic Macular Edema Trial

Diabetic macular edema damages central vision, and treatment research is seeking new ways to improve retinal vascular function alongside inhibiting abnormal vascular signaling. Surrozen’s SZN-8141 combines two actions in a single antibody. It has now cleared the regulatory hurdle for entering human trials, setting the stage to test whether this concept can translate into tangible benefits for patients.

Surrozen announced on October 2 that the U.S. Food and Drug Administration (FDA) had cleared the investigational new drug application (IND) for SZN-8141, allowing the company to advance clinical development in diabetic macular edema. The company expects to dose the first patient in the Phase 1b/2a trial, named DUET, in the fourth quarter of 2026. This development allows the trial to begin; it is neither marketing approval nor confirmation of efficacy.

SZN-8141 is administered by intravitreal injection and activates Wnt signaling through the Frizzled 4 (FZD4) receptor while also antagonizing vascular endothelial growth factor (VEGF). Anti-VEGF therapies are already an important treatment for these retinal diseases; the addition of Wnt activity is intended to further improve vascular health. The company said preclinical models had shown regeneration of normal retinal blood vessels and suppression of abnormal blood vessel growth, but these results do not yet establish that the same effects will occur in humans.

DUET will first address questions of safety and dosing. According to the company’s announcement and reporting by ophthalmology publication Retinal Physician, Phase 1b uses an open-label design and includes both treatment-naive and previously treated patients to evaluate escalating single doses. After one injection, patients will be followed for approximately three months to assess tolerability, how the drug behaves in the body, immune responses, vision, and retinal imaging.

The subsequent Phase 2a is expected to enroll approximately 60 treatment-naive patients and compare two doses of SZN-8141 with faricimab in a randomized, double-blind design. The plan calls for one injection per month for a total of three injections, followed by four months of follow-up to explore whether the effects persist. This design may provide early indications of how the drug compares with an existing therapy, but the trial’s size and follow-up period remain limited and are not yet sufficient to establish a long-term advantage.

The regulatory progress also affects development funding. According to the company’s announcement, IND clearance satisfied a milestone condition for the second tranche closing of its March 2025 private placement; BioTuesdays also reported this connection. The company expects the closing to occur on or around October 20, 2026, raising approximately $95.1 million in gross proceeds for SZN-8141, another drug candidate, SZN-8143, and operations. However, the closing remains subject to other applicable conditions, and the amount has not yet been reduced by related expenses.

Surrozen expects initial DUET data in the second half of 2027. The key questions then will be whether this dual-function antibody can improve both retinal structure and vision with acceptable safety, and how long those effects last. Until the first patient is dosed and clinical results are released, the dual Wnt and VEGF pathway strategy remains a therapeutic hypothesis awaiting human evidence.