SD-900

SD-900 is an investigational small-molecule Janus kinase (JAK) inhibitor that was initially developed by Auspex Pharmaceuticals as part of a portfolio of deuterated kinase inhibitors. Public information is limited and indicates that SD-900 was positioned as a next-generation JAK inhibitor, conceptually related to agents such as tofacitinib, for potential treatment of inflammatory and autoimmune diseases, but without disclosed target selectivity, clinical data, or specific indications. Available regulatory correspondence suggests the compound did not advance beyond early preclinical or very early development, and there is no evidence of active clinical trials or marketing authorization.