Abstract

Glucocorticoid steroids (GC steroids) are broadly used as the main treatment for certain inflammatory diseases, such as rheumatoid arthritis and lupus. However, treatment is associated with often serious side effects on nearly every organ system, reflecting the broad expression of the glucocorticoid receptor (GR). Antibody steroid conjugates (steroid-ADC) could specifically deliver steroids to diseased tissue cells of interest to reduce the side effects. We have developed novel glucocorticoid  steroids for use as ADC payloads. Compared to well-known GC steroids like dexamethasone and budesonide, the novel glucocorticoid steroids showed >100 fold better potency in cell based assays. In addition, the GC steroids showed >100 fold selectivity for the GR over other nuclear hormone receptors. The novel steroids were attached to antibodies to macrophage markers using site directed conjugation and novel linker chemistries. The ADCs activated GR in reporter cell-based assays with subnanomolar potency and with 100~1000x selectivity over the isotype control ADCs. The steroid-ADCs bound to and effectively delivered payloads to THP1-differentiated macrophages and inhibited cytokine production. Our lead steroid-ADCs demonstrated favorable PK with limited targeted mediated clearance in humanized mice, and treatment of these mice prevented TNFa release from peritoneal macrophages that were challenged with LPS ex vivo. These drug linkers can be conjugated to any antibody for targeted steroid therapy of diverse inflammatory diseases.