Lead identification of novel and selective TYK2 inhibitors

• Biological rationale for targeting selective TYK2 inhibition is given.
• We report lead identification of potent and efficient TYK2 inhibitors.
• Analogs afford modest selectivity against other Janus Family kinases.
• We obtained crystal structures of key compounds bound to both TYK2 and JAK2.
• ADME properties of the lead compound are favorable.

A therapeutic rationale is proposed for the treatment of inflammatory diseases, such as psoriasis and inflammatory bowel diseases (IBD), by selective targeting of TYK2. Hit triage, following a high-throughput screen for TYK2 inhibitors, revealed pyridine 1 as a promising starting point for lead identification. Initial expansion of 3 separate regions of the molecule led to eventual identification of cyclopropyl amide 46, a potent lead analog with good kinase selectivity, physicochemical properties, and pharmacokinetic profile. Analysis of the binding modes of the series in TYK2 and JAK2 crystal structures revealed key interactions leading to good TYK2 potency and design options for future optimization of selectivity.

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