AQX-1125, small molecule SHIP1 activator inhibits bleomycin-induced pulmonary fibrosis

Background and Purpose: The phosphatase SHIP1 negatively regulates the PI3K pathway, and its predominant expression within cells of the haematopoietic compartment makes SHIP1 activation a novel strategy to limit inflammatory signalling generated through PI3K. AQX-1125 is the only clinical-stage, orally administered, SHIP1 activator. Here, we demonstrate the prophylactic and therapeutic effects of AQX-1125, in a mouse model of bleomycin-induced lung fibrosis. Experimental Approach: For prophylactic evaluation, AQX-1125 (3, 10 or 30 mg·kg⁻¹·d⁻¹, p.o.) or dexamethasone (1 mg·kg⁻¹·d⁻¹, i.p.) were given to CD-1 mice starting 3 days before intratracheal administration of bleomycin (0.1 IU per mouse) and continued daily for 7 or 21 days. Therapeutic potentials of AQX-1125 (3, 10 or 30 mg·kg⁻¹·d⁻¹, p.o.) or pirfenidone (90 mg·kg⁻¹·d⁻¹, p.o.) were assessed by initiating treatment 13 days after bleomycin instillation and continuing until day 28. Key Results: Given prophylactically, AQX-1125 (10 and 30 mg·kg⁻¹) reduced histopathological changes in lungs, 7 and 21 days following bleomycin-induced injury. At the same doses, AQX-1125 reduced the number of total leukocytes, neutrophil activity, TGF-β immunoreactivity and soluble collagen in lungs. Administered therapeutically, AQX-1125 (10 and 30 mg·kg⁻¹) improved lung histopathology, cellular infiltration and reduced lung collagen content. At 30 mg·kg⁻¹, the effects of AQX-1125 were similar to those of pirfenidone (90 mg·kg⁻¹) with corresponding improvements in disease severity. Conclusions and Implications: AQX-1125 prevented bleomycin-induced lung injury during the inflammatory and fibrotic phases. AQX-1125, given therapeutically, modified disease progression and improved survival, as effectively as pirfenidone.