Leonard Schleifer was a young neurologist and assistant professor at Cornell University when he decided to leave academia and start a biotech company led by scientists. Growing up in Queens, New York, with parents who sparked his passion for science and entrepreneurship from a young age, he wasn’t interested in licensing someone else’s drug or following Wall Street’s playbook.
Instead, he wanted to build something from scratch. To raise capital, Schleifer turned to a former professor, who connected him with George Sing, a venture capitalist at Merrill Lynch Ventures.
“Once I had decided that this notion of building a company was what I wanted to do, I decided to sort of figure out how I could get my hands on some money,” Schleifer recalled. Sing stood out, with Schleifer describing him as a “guy who actually did want to build something, who respected science, who really would let us run, who respected the fact that we had really smart people we were trying to bring around.”
Over Chinese food, the two sketched out a deal on the back of a napkin—$1 million in startup funding—sealed with a handshake. That napkin marked the beginning of Regeneron, founded in 1988 and named for “regenerating neurons,” with “gene” hidden in the middle.
The early years were rocky. Regeneron’s first clinical trial, a neurotrophic factor treatment, failed in 1997, nearly derailing the company. But Schleifer and his longtime scientific partner, George Yancopoulos, regrouped, encouraged by former Merck R&D chief Roy Vagelos, who had become board chair in 1995. They focused on diseases with well-defined biology and clear clinical endpoints, paving the way for Regeneron’s first FDA approval in 2008.
Since then, Schleifer has led the company through more than a dozen FDA approvals in areas like eye disease, cancer, allergic conditions, and rare genetic disorders. Schleifer helped expand Regeneron’s reach into immuno-oncology, gene therapy, and CRISPR-based treatments. During the onslaught of the pandemic, the company developed an antibody cocktail in record time and earned use authorization.
Schleifer also oversaw major acquisitions like Decibel Therapeutics and 2seventy bio. Just this year, the company announced a $3 billion manufacturing partnership with FUJIFILM.
Throughout, he’s stayed committed to US investment, science education, and long-term research and development. Now co-chair of the board, Schleifer is one of the few founder-CEOs still leading nearly four decades later.
