incb-018424 and Autoimmune-Diseases

The Janus kinases (JAKs) are a family of intracellular tyrosine kinases that play an essential role in the signaling of numerous cytokines that have been implicated in the pathogenesis of inflammatory diseases. As a consequence, the JAKs have received significant attention in recent years from the pharmaceutical and biotechnology industries as therapeutic targets. Here, we provide a review of the JAK pathways, the structure, function, and activation of the JAK enzymes followed by a detailed look at the JAK inhibitors currently in the clinic or approved for these indications. Finally, a perspective is provided on what the past decade of research with JAK inhibitors for inflammatory indications has taught along with thoughts on what the future may hold in terms of addressing the opportunities and challenges that remain.

Topics: Animals; Anti-Inflammatory Agents; Antirheumatic Agents; Autoimmune Diseases; Clinical Trials as Topic; Cytokines; Humans; Inflammation; Inflammatory Bowel Diseases; Janus Kinases; Piperidines; Protein Conformation; Protein Kinase Inhibitors; Pyrimidines; Pyrroles; Signal Transduction

Janus kinases (JAKs) are intracellular tyrosine kinases that mediate the signaling of numerous cytokines and growth factors involved in the regulation of immunity, inflammation, and hematopoiesis. As JAK1 pairs with JAK2, JAK3, and TYK2, a JAK1-selective inhibitor would be expected to inhibit many cytokines involved in inflammation and immune function while avoiding inhibition of the JAK2 homodimer regulating erythropoietin and thrombopoietin signaling. Our efforts began with tofacitinib, an oral JAK inhibitor approved for the treatment of rheumatoid arthritis. Through modification of the 3-aminopiperidine linker in tofacitinib, we discovered highly selective JAK1 inhibitors with nanomolar potency in a human whole blood assay. Improvements in JAK1 potency and selectivity were achieved via structural modifications suggested by X-ray crystallographic analysis. After demonstrating efficacy in a rat adjuvant-induced arthritis (rAIA) model, PF-04965842 (25) was nominated as a clinical candidate for the treatment of JAK1-mediated autoimmune diseases.

Topics: Animals; Arthritis, Experimental; Autoimmune Diseases; Cyclobutanes; Dogs; Drug Evaluation, Preclinical; Humans; Inhibitory Concentration 50; Janus Kinase 1; Janus Kinase 2; Models, Molecular; Protein Conformation; Protein Kinase Inhibitors; Pyrimidines; Pyrroles; Rats; Substrate Specificity; Sulfonamides; Tissue Distribution