Alisertib sodium, an investigational oral oncology drug, posed some challenges toward developing a robust and scalable drying process employing an agitated filter dryer that manifested themselves during the technical transfer to a new manufacturing site. The API studied was a monohydrate that was found to readily dehydrate and agglomerate, impacting both drug product (DP) manufacture and in vitro dissolution. A scale down agitated filter dryer was designed that was used to study the drying unit operation and identify key process parameters. Through a combination of lab-and pilot plant-scale experiments, suitable drying conditions were developed that minimized agglomeration, eliminated dehydration, and produced API that behaved acceptably in downstream DP manufacture.