Federal Circuit Affirms PTAB’s Obviousness Rulings On Merck’s Oral Cladribine MS Regimen And Clarifies The “By Another” Prior Art Standard

On October 30, 2025, the U.S. Court of Appeals for the Federal Circuit affirmed two inter partes review decisions of the Patent Trial and Appeal Board (“PTAB”) invalidating claims in two of Merck Serono S.A.’s patents covering oral cladribine dosing regimens for treating multiple sclerosis (“MS”). The opinion addresses both the substantive obviousness analysis and an important doctrinal question under pre-AIA §§ 102(a) and 102(e): when a disclosure with overlapping inventors qualifies as prior…
By: A&O Shearman