Teagan J. Gregory

Teagan J. Gregory is a patent litigation attorney with a primary focus on complex civil litigation, particularly in intellectual property and licensing disputes. Based at Williams & Connolly LLP, he specializes in biotechnology and pharmaceuticals, with extensive experience in proceedings under the Biologics Price Competition and Innovation Act (BPCIA) and the Hatch-Waxman Act. His practice also encompasses patent cases across medical and mechanical devices.

Gregory consistently represents innovator pharmaceutical companies, primarily on the plaintiff side, in high-stakes patent infringement disputes against generic and biosimilar manufacturers. His significant roles as counsel and lead counsel for Regeneron Pharmaceuticals, Inc. in its "Eylea" (aflibercept) biosimilar litigation against Mylan Pharmaceuticals Inc., Celltrion, Inc., and Sandoz Inc. highlight this focus.

Notable cases include Regeneron Pharmaceuticals, Inc. v. Mylan Pharmaceuticals Inc. et al., where Regeneron secured a permanent injunction in June 2024, which was subsequently vacated following a settlement in April 2025 that allowed Mylan's biosimilar to launch in the second half of 2026. He also represented Regeneron in its disputes against Celltrion, Inc. and Sandoz Inc., both of which resolved through settlements in October 2025 and September 2025, respectively, permitting biosimilar launches in late 2026. These cases frequently involved appeals to the Federal Circuit, affirming preliminary injunctions.

Gregory also possesses experience in Patent Trial and Appeal Board (PTAB) proceedings, having supported patent owners in inter partes reviews (IPRs), including multiple IPRs involving JSR Corporation and Cytiva Bioprocess R&D AB. He is a partner at Williams & Connolly LLP, having joined the firm in 2013 and being elected to partnership effective January 1, 2022. He is admitted to the bars of Delaware and the District of Columbia. Gregory earned his J.D., magna cum laude, from the University of Michigan Law School in 2012 and his B.A., magna cum laude, from the University of Delaware in 2009, and clerked for Judge Gregory M. Sleet in the U.S. District Court for the District of Delaware.