High-affinity omalizumab variants with optimized disruptive potency prevent anaphylaxis in vivo

BACKGROUND: Omalizumab, a therapeutic mAb targeting IgE, is approved for the treatment of multiple allergic indications. However, its moderate affinity for IgE necessitates frequent high-dose administrations, limiting its therapeutic use and efficacy. Attempts to develop next-generation anti-IgE antibodies with improved affinity, such as ligelizumab or HAE1, have yielded alternatives that are either less safe or not demonstrably superior. OBJECTIVE: We sought to generate optimized omalizumab variants featuring 2 specific molecular enhancements: increased IgE binding affinity while preserving epitope specificity to enhance target neutralization and improved potency to actively dissociate prebound IgE from its high-affinity receptor FcεRI. METHODS: Using a targeted yeast display selection strategy applied to mutated omalizumab libraries, we identified the anti-IgE clone C03 and engineered 2 flexible variants, C03-H1L2 and C03-H2L2. RESULTS: The C03 antibodies demonstrated approximately 10-fold higher IgE binding affinity compared with omalizumab, resulting in superior inhibition of IgE binding to FcεRI. Furthermore, C03-H1L2 and C03-H2L2 exhibited enhanced potency in displacing FcεRI-bound IgE from humanized mouse mast cells and human basophils without triggering spontaneous cell activation. In a systemic anaphylaxis mouse model, single-dose administration of the flexible C03 variants, in contrast to omalizumab, desensitized allergic effector cells within 36 hours, fully preventing antigen-induced anaphylaxis. CONCLUSIONS: These findings underscore the importance of engineering next-generation anti-IgE therapies with higher affinity and disruptive potency to optimize current treatment approaches.