Development of a Scalable Process for an IL-17A Inhibitor LY3509754: Part III. Assembly of Drug Substance, Salt Formation, and Impurity Control

A 5-step cGMP sequence for the preparation of an IL-17A inhibitor 1 was optimized and scaled up to deliver a total of 66 kg of the final drug substance 1 to support clinical and product development studies. Salt formation and polymorph screening identified a suitable polymorph of the hemiedisylate salt that provided desirable physical properties. Key impurities in the final drug substance were identified, and control strategies were developed and executed to control them to acceptable levels in the production batches.