Kathryn S. Kayali

Kathryn S. Kayali is a patent litigation attorney at Williams & Connolly LLP, focusing her practice predominantly on the pharmaceutical sector, including disputes involving both small-molecule and biologic drugs. Her experience spans all stages of litigation, from initial complaint through trial.

Kayali primarily represents patent holders. Her notable work includes representing Regeneron Pharmaceuticals, Inc. as plaintiff in disputes concerning its blockbuster anti-VEGF therapy EYLEA® (aflibercept). Specifically, she was involved in Regeneron Pharmaceuticals, Inc. v. Celltrion, Inc., a 38-patent biosimilar dispute which was dismissed without prejudice, preserving Regeneron's ability to reassert claims. She also represented Regeneron in Regeneron Pharmaceuticals, Inc. v. Sandoz Inc., another EYLEA® biosimilar case that reached a settlement. Her firm's involvement in related Federal Circuit appeals in EYLEA® patent litigation against other biosimilar defendants further highlights her experience in this area.

Kayali also has experience with Patent Trial and Appeal Board (PTAB) proceedings, having appeared pro hac vice in inter partes review (IPR) matters, including BioNTech SE and Pfizer Inc. v. ModernaTX, Inc.

She joined Williams & Connolly in 2016 after clerking for Judge Richard G. Taranto of the U.S. Court of Appeals for the Federal Circuit. Kayali earned her J.D. from Harvard Law School in 2014, an M.S. in Molecular and Cell Biology from the University of Texas at Dallas in 2011, and a B.A. cum laude in Molecular, Cellular, and Developmental Biology from Yale University in 2009. She is admitted to practice in the District of Columbia and Massachusetts, and before the U.S. Court of Appeals for the Federal Circuit.