Immune cell targeting of corticosteroids transforms the treatment of severe, chronic inflammatory diseases

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Glucocorticoids (GC) are a class of drugs with overwhelming anti-inflammatory activities. However, dose limiting toxicities (DLT) caused by systemic GC exposure prevent GC from being a true panacea in the management of inflammatory disease. This Direct SBIR Phase 2 proposal requests support for a novel therapeutic that targets delivery of GC to the immune system, which will reduce DLT and allow for the long term and high dose use of GC in the treatment of inflammation. ImmuNext has established the technical merit, feasibility, proof of concept and commercial potential of this antibody-targeted, immune-specific steroid conjugate. We have achieved specific and direct targeting of GC to the immune system with INX200, an antibody-drug conjugate (ADC) of an Fc-silent, fully humanized immune-targeting mAb conjugated through a cleavable linker to budesonide. Importantly, targeting GC with INX200 results in superior potency and reduced toxicity when compared to free GC. We have shown that INX200: 1) broadly targets the immune system with minimal exposure outside the hematopoietic compartment, 2) leverages an immune-targeting mAb that itself (unconjugated) possesses no known immunologic activities and acts exclusively as a targeting agent, 3) rapidly internalizes allowing for robust and efficient uptake of the GC thereby providing superior loading of GC into immune cells, 4) is therapeutically equivalent at 1/10th the dose, and has substantially longer PD compared to free GC, 5) has minimal off target activity and reduced toxicity compared to free GC due to its specific immune system targeting, 6) is suitable for SC administration and 7) is an attractive therapeutic for the treatment of GC- dependent asthma because of the unmet GC need in this patient population. The Specific Aims of this Phase 2 application are as follows. 1) Assess the lead ADC INX200 and multiple backups for immunogenicity and stability for commercial development. 2) Define the immunologic and toxicologic GC biomarkers of INX200. These biomarkers will be measured and compared to the definitive pharmacological signatures known to be specifically altered by systemic exposure to GC. INX200-dependent modulation of cytokines and induction of steroid-specific transcripts will be assessed as immunologic and toxicity biomarkers, respectively. 3) Conduct non-GLP Tox/PK/PD studies in cynomolgus monkeys in order to confirm safety and guide the development of a subsequent IND-enabling GLP tox study. 4) Review and assess the regulatory path to IND. The data generated in aims (1)-(3), in particular non-GLP non-human primate (NHP) studies, will be reviewed to design (a) a single ascending dose Phase 1 trial in healthy volunteers, and (b) a multiple ascending dose Phase 2 trial in GC-dependent asthma patients. Based on this clinical program outline, a GLP toxicology study in NHP will be designed to support an IND. The successful targeting of GC to the immune system with the sparing of non-hematopoietic toxicities, offers a transformative advance in GC-based drugs for the treatment of severe, chronic inflammatory disease.