Antibody-hyaluronic acid conjugates for sustained treatment of neovascular ocular disease

Abstract

Purpose : Anti-VEGF therapy continues to be the gold standard to minimize the risk of vision loss due to neovascular ocular disease, including wet age-related macular degeneration (AMD) and diabetic macular edema (DME). However, current anti-VEGF biologics require frequent intravitreal (ITV) injections, and poor compliance to redosing protocols has been linked to losses in efficacy over the long-term. To solve this problem, Valitor’s multivalent protein (MVP) conjugation technology was designed to enable sustained anti-VEGF therapy after ITV injection, thereby substantially reducing the required treatment frequency. The stability of the MVPs after administration is highly dependent on the anti-VEGF biologic, and thus our goal was to engineer an antibody that can maintain the stability of an MVP in the vitreous humor.

Methods : Using phage-display screening and literature searches, we developed a library of single domain anti-VEGF antibodies (anti-VEGF VHH) with variable peptide linkers to facilitate conjugation. We synthesized MVPs comprising multiple copies (i.e. valency) the VHH antibodies conjugated to soluble, long-chain hyaluronic acid. We initially ranked the unconjugated antibodies and MVPs based on their thermal stability. We further tested top MVP performers in stability studies at ~10X the anticipated clinical ITV concentration in a vitreous mimetic buffer at 37C for up to 9 months. Periodically, we assessed stability based on changes in either VEGF binding affinity or hydrodynamic radius.

Results : Using our library, we identified several anti-VEGF VHH constructs that had high thermal stability, were compatible with our MVP conjugation platform, and were able to confer high stability following conjugation. Further, we identified specific VHH sequence characteristics and peptide linkers that enabled anti-VEGF MVPs to maintain their size and remain highly potent and soluble after more than 6 months at in situ conditions.

Conclusions : Based on our findings, we have developed a consensus sequence for in situ stability comprising key VHH and peptide linker characteristics. We then engineered a novel optimized anti-VEGF VHH that has been incorporated into our anti-VEGF product candidate (VLTR-557) that will enable long-acting treatment of wet AMD. We are currenting scaling the manufacturing of VLTR-557, and we plan to initiate IND-enabling preclinical studies in mid-2022.

This abstract was presented at the 2022 ARVO Annual Meeting, held in Denver, CO, May 1-4, 2022, and virtually.