Dr. Kastelein previously served as Synthekine’s Head of Therapeutic Discovery since the company’s formation in 2019 until 2023, upon his retirement. He is a long-time collaborator of Synthekine founder, Christopher Garcia, Ph.D. Prior to Synthekine, he led a team at Merck that was responsible for building the company’s discovery portfolio of cancer immunotherapies. He joined Merck when it merged with his prior company, DNAX Research Institute. While there, his research interests in the area of cytokine structural biology led him and his teams to the discovery and functional characterization of many novel cytokines, including IL-23, IL-27, TSLP and IL-33. Discovery of these novel cytokines has led to fundamental insights into functioning of the human immune system in disease, and it has yielded major human disease targets such as IL-23 in psoriasis and Crohn’s disease, as well as TSLP in asthma and atopic dermatitis. Dr. Kastelein holds a Ph.D. in biochemistry from Leiden University, the Netherlands, and he completed his postdoctoral work at Genentech in South San Francisco.