Protein display drug ANDI reduces asthmatic airway hyperreactivity

ABSTRACT/SUMMARY Causal role of FcRI-bound IgE on mast cells in IgE-mediated severe allergic asthma Since the discovery of IgE and IgE-mediated mast cell degranulation by the Ishizaka’s in 1966, the deep scientific challenge in IgE/mast cell research, is whether FcRI receptor-bound IgE, a central culprit for proinflammatory small molecules or cytokines, may be dissociated by pharmacophores. Removal of receptor bound IgE therefore eliminates en block a plethora of proinflammatory small molecules and cytokines is therefore a treatment of choice. The affinity of receptor bound IgE is around 1 nM range. Thus, the first generation Omalizumab, Xolair targeting at neutralizing and antagonizing free IgE sensitization to mast cells is discovered in the laboratories in collaboration with Tse-Wen Chang at Tanox, Inc. Asthmatic exacerbation is reduced in Xolair-treated patients; however, patients did not exhibit FEV1 improvement, despite 90% of circulating free IgE is neutralized. Xolair does not directly access to the mucosal IgE in the lung. Moreover, Xolair, which binds to regions of IgE distal to the receptor-binding C2-3, BC, DE, FG sites, is not capable of dissociating receptor bound IgE from mast cells. Removing the chief culprit upon of receptor-binding IgE is an urgent task to further reduce asthmatic exacerbation and restore FEV1. Thus, we investigate the bifunctional IgE antagonist and dissociator (ANDI) to complement the monofunctional Xolair as a second generation of IgE Therapeutics. ANDI is safe to use in that E8 VHH which accommodates receptor-binding DE/FG receptor-binding sites in camelid VHH nanobody (not a full complement of four receptor-binding IgE epitopes), does not spontaneously activate mast cells. Moreover, the long-term use of ANDI E8 or E8H can be assured by its lack of immunogenicity, highly homologous to human VH3, which is rendered further immune tolerant via the airway administrative regimen. ANDI is an innovative invention in that: (i) being a first-in-kind bifunctional IgE drug since 1966 to antagonize as well as dissociate mast cell receptor-bound pathogenic pool IgE in contrast to the first generation of Xolair; (ii) in that being the first IgE ligand-based camelid nanobody (humanized) that improves airway hyperactivity (AHR) in an animal model, and offers a promise to improve FEV1 in humans; (iii) in that using novel protein display platform to meet the challenge of improving potency and safety of the ANDI candidates; (iv) in that removing receptor-bound IgE from mast cells arrests downstream plethora of proinflammatory molecules and cytokines of mast cells, therefore improve lung function in asthmatic patients, reducing morbidity and mortality. Goal and Milestones: Taken together, Aim 1 on ANDI humanization and Aim 2 on ANDI tolerance provide foundation of studying long-term drugability of ANDI nanobody accomplish the Milestones in each respective Aim independently, as well as interactively as applied to Aim 3 humanized animal model of asthma for safety and efficacies. The three Aims contribute to the goal of a safe and efficacious innovative ANDI for its long-term use to treat SA and improve lung function of SA patients.