Surrozen, Inc. has submitted an investigational new drug (IND) application to the FDA on behalf of SZN-8141, an investigational asset intended for the treatment of diabetic macular edema (DME).
First, let’s get a look at this company.
Operating out of South San Francisco, California, the biotechnology company is developing multifunctional biologics that selectively activate Wnt signaling in combination with other key disease pathways (primary: retinal disease).
As Surrozen noted, Wnt signaling “plays a central role in tissue repair and cellular renewal throughout the eye”—and has significant potential in ophthalmology.
- Click here for a rundown on the Wnt pathway.
How does this relate back to retinal disease?
Retinal blood vessels use the Wnt signaling pathway to form properly and stay sealed.
However: In inherited disease, patients born with mutations that disable Wnt signaling in the retina — the cause of familial exudative vitreoretinopathy (FEVR) and Norrie disease — develop poorly formed, leaky vessels.
And Surrozen’s approach?
The company has developed what it calls proprietary Surozen Wnt signaling activating proteins (SWAPs).
These multivalent antibodies bind the Frizzled-4 (FZD4) receptor—a protein on the cell surface that receives chemical signals—on retinal vessel cells to turn that signaling back on.
- Notably: In animal studies, the company reports this tightens the seals between cells and regrows vessels into oxygen-starved retina.
The general idea is that this approach fixes a problem not addressed by anti-vascular endothelial growth factor (VEGF): Whereas anti-VEGF quiets the signal driving leakage, Wnt activation is meant to rebuild the barrier holding fluid back.
So which diseases are these biologics targeting?
Retinal diseases such as DME, uveitic macular edema (UME), and wet age-related macular degeneration (AMD).
And its pipeline to address them?
Includes three candidates so far. But in the context of DME (and this IND submission), we’ll focus on just one: SZN-8141:
- What it is: a bifunctional antibody that combines FZD4-targeted Wnt agonism with VEGF inhibition within a single molecule
- Its purpose: to improve visual function and offer durable anatomic control in both DME and wet AMD patients
- How: by addressing vascular leakage and promoting retinal vascular integrity
See here for more on its potential.
Tell me about its clinical performance thus far.
According to Surrozen, preclinical studies have evaluated SZN-8141 compared to a Wnt agonist and anti-VEGF monotherapy in a rodent model of retinal vascular disease.
- Its performance: The antibody demonstrated “superior biological activity in reducing neovascularization and promoting retinal revascularization” versus those two aforementioned comparators.
- Moreover: A rodent model of wet AMD reportedly found that it led to “greater reductions in vascular leakage than anti-VEGF therapy.”
See here for more preclinical data, as presented during the 2025 Association for Research in Vision and Ophthalmology (ARVO) annual meeting.
Noted. Now let’s move on to this IND submission.
When reviewing an IND submission, the FDA generally looks to ensure the safety and rights of the research subjects as well as the quality of the scientific evaluation of the drug.
The review may include:
- Pharmacology and toxicology data from preclinical trials
- Proposed clinical trial protocols
- Info on manufacturing and quality control
How long does this review typically take?
Once received, the FDA has 30 days to review the application and determine if a clinical trial is safe to proceed.
- Generally: The application will go into effect 30 days after receipt (providing there is no clinical hold on it) or potentially earlier if the agency gives notice to a sponsor (the company or investigator of the trial).
Per federal rules, an IND-approved clinical trial’s start date must be at least 30 days after the FDA’s application acceptance.
And in Surrozen’s case?
The company plans to evaluate SZN-8141 in a phase 1b/2a clinical trial dubbed DUET:
- Its purpose: to assess its safety, tolerability, and early signs of biological and clinical activity among DME patients
- The timeframe: Initiation is expected to kick off by the end of 2026, with an initial data readout by the second half (H2) of 2027.
To note: No other details were disclosed on the target number of participants, trial design or setup, or the outcome measures.