Background/Purpose: Glucocorticoids (GCs) are widely used to treat a variety of autoimmune and inflammatory diseases like rheumatoid arthritis, inflammatory bowel disease, and asthma. The anti-inflammatory properties of GCs are attributed to their ability to bind to the Glucocorticoid receptor (GR) and modulate the expression of inflammatory genes. However, systemic delivery of GCs is associated with side effects, such as osteoporosis, that restrict chronic dosing at efficacious levels. Targeted delivery of GCs to diseased tissues using antibody-glucocorticoid conjugates (GC-ADCs) offers a therapeutic alternative to overcome the adverse effects of GCs and further strengthen the efficacy of the antibody. Herein we describe a novel GC payload that exhibited great potency, and generate TNF-ADC by conjugating the compound to anti- tumor necrosis factor α (TNFα) antibody via a cleavable linker.

Methods: A serial of compounds was synthesized and tested by GR binding assay and GRE reporter assay. The compound with great potency was conjugated to anti-TNFα antibody via BrAc-Gly-Glu linker. The antibody-glucocorticoid conjugate, Adalimumab-GC, was evaluated for functional activity: (1) by GRE reporter assay in K562 cells expressing TNFα and also wild-type K562 cells that do not express TNFα; (2) by lipopolysaccharide (LPS) stimulated human monocyte cytokine release assay. Furthermore, the stability of Adalimumab-GC was tested at 37℃ for 14 days in human and mouse plasma. The surrogate TNF-ADC (anti-mouse TNFα-GC) was evaluated in mouse contact hypersensitivity (CHS) model and collagen antibody induced arthritis (CAIA) model.

Results: Compound A was shown potent GR binding affinity and cellular efficacy in GRE reporter assay. Adalimumab-GC was demonstrated TNF-dependent activity in K562-TNFα-GRE cells dissociated from the activity in K562-GRE cells. In primary immune cell assay, Adalimumab-GC inhibited the release of pro-inflammatory cytokines IL-6 and IL-1β from LPS stimulated human monocytes. After incubating Adalimumab-GC in human and mouse plasma at 37℃ for 14 days, little free payload was detected by LC/MS (< 0.5%), which indicated that the TNF-ADC was highly stable in plasma. The surrogate TNF-ADC (anti-mouse TNFα-GC) was shown to be more efficacious than the parent anti-mouse TNFα antibody in mouse CHS model and CAIA model.

Conclusion: The novel TNF-ADC specifically released GC payload in antigen-positive cells and exhibited potent efficacy in functional assays and mouse models. It is suggested that the novel GC can serve as immunology ADC payload to treat autoimmune and inflammatory diseases.

ACR Meeting Abstracts - https://acrabstracts.org/abstract/development-of-novel-glucocorticoid-as-immunology-antibody-drug-conjugate-payload-for-the-treatment-of-autoimmune-and-inflammatory-diseases/