Innovation in Sight: How Mosaic and Catalyst are Redefining Treatment for Dry AMD

At Mosaic Biosciences, we describe ourselves as “drug hunters” and “problem solvers.” We thrive on taking complex therapeutic challenges and applying our protein engineering expertise to turn concepts into viable preclinical candidates. One of our most rewarding collaborations has been our work with Catalyst Biosciences to tackle Geographic Atrophy (GA), an advanced form of dry Age-related Macular Degeneration (dAMD).

GA is a devastating condition and a leading cause of irreversible blindness. For years, the complement system—specifically the C3 protein—has been identified as a key driver of the disease, yet finding an effective way to inhibit it while maintaining patient convenience has remained a significant hurdle.

Engineering a Better Protease

Our mission was to develop a long-acting therapeutic that could provide powerful C3 inhibition with fewer injections. To achieve this, we focused on PEG CB-2782, a novel protease engineered to catalytically eliminate C3.

The challenge with ocular therapies is often the “half-life problem”—drugs are cleared from the eye too quickly, requiring frequent, burdensome injections for the patient. By leveraging Mosaic’s specialized protein engineering and purification platforms, we modified the protease with a 40 kDa PEG (PEGylation). This precision modification was a game-changer: it successfully increased the drug’s ocular half-life by 55% without compromising its potent enzymatic activity.

Results That Speak for Themselves

The data from our preclinical studies in rabbit and non-human primate models confirmed the potential of this approach. We observed a staggering 99% elimination of C3 in the vitreous humor for at least 28 days.

What does this mean for the future of patient care? Based on these results, we estimate that PEG-CB 2782 could potentially be administered just three or four times a year. This “best-in-class” profile offers a dual benefit: high efficacy in halting disease progression and a significantly reduced treatment burden for patients.

Your Research Team in Action

This project exemplifies why we do what we do. By working as an integrated extension of the Catalyst team, we were able to combine our technical rigor in protein discovery with their vision for a next-generation AMD therapy.

We are proud of the role Mosaic played in advancing PEG CB-2782, and we look forward to continuing to solve the toughest problems in protein and antibody discovery for our partners.