Leonard Schleifer

Leonard S. Schleifer, M.D., Ph.D. is an American physician, neuroscientist, and biotechnology executive who co-founded Regeneron Pharmaceuticals, Inc. in 1988 and has served continuously as its president and chief executive officer.

A licensed neurologist certified by the American Board of Psychiatry and Neurology, Schleifer earned a B.A. from Cornell University and both an M.D. and a Ph.D. in pharmacology from the University of Virginia before transitioning from academic neurology at Weill Cornell Medical College to entrepreneurship. Under his leadership, Regeneron advanced genetic engineering and monoclonal antibody technologies to yield multiple FDA-approved therapies, including the vascular endothelial growth factor inhibitor Eylea for wet age-related macular degeneration and the interleukin-4 receptor antagonist Dupixent for severe atopic dermatitis and asthma, both achieving blockbuster status with annual sales exceeding $1 billion.

Leonard Schleifer was born in 1953 in Queens, New York, to Florence and Charles Baker Schleifer. His father, a sweater manufacturer who had attended Cornell University on a scholarship during the Depression era, aspired for his son to pursue a medical career. The family was middle-class and Jewish, providing a stable environment in the borough's urban setting.

Schleifer has been married to Harriet Schleifer (née Partel), whom he first met in junior high school, since December 24, 1974. The couple has two sons, Adam and David; their younger son David was diagnosed with a rare genetic disorder known as transketolase (TKT) deficiency, which prompted the family to fund research and awareness initiatives, including a program at Yale University focused on the condition, which appears disproportionately common among Ashkenazi Jews.