IP Law Daily, PATENT—Fed. Cir.: Obviousness affirmed in multiple sclerosis treatment dispute, (Oct 31, 2025)

By Kevin M. Finson, J.D.

Claims for the use of oral cladribine to treat multiple sclerosis were obvious because a disputed prior art reference was properly considered as it did not have completely identical inventorship.

A pharmaceutical company failed to show any error in a PTAB determination which found its claims unpatentable as obvious, the U.S. Court of Appeals for the Federal Circuit has held. The parties had disputed the propriety of considering a prior art reference which partially shared inventorship with the patents at issue (Merck Serono, S.A. v. TWi Pharmaceuticals, Inc., Nos. 25-1463, 25-1464, (Fed. Cir. Oct. 30, 2025)).

Merck Serono, S.A. (Merck) was the owner of U.S. Patents Nos. 7,713,947 (the ’947 patent) and 8,377,903 (the ’903 patent), both of which related to the use of oral cladribine to treat multiple sclerosis. TWi Pharmaceuticals, Inc. (TWi) petitioned for inter partes review of several claims of each patent on the ground of obviousness. The Patent Trial and Appeal Board (PTAB) instituted review and found the challenged claims unpatentable as obvious. Merck appealed.

The Federal Circuit noted that this case is a companion case to Merck Serono S.A. v. Hopewell Pharma Ventures, Inc. (No. 25-1210, -1211). The court’s contemporaneous precedential decision in that case–holding that U.S. Patent No. 7,888,328 (Bodor) qualified as prior art as to the ’947 and ’903 patents–applied to this case.

Prior Art. The Board had found all of the challenged claims unpatentable as obvious Bodor, a patent for oral cladribine filed by people who had worked with Merck’s business partner on the development of oral cladribine treatment for multiple sclerosis prior to Merck’s own patent applications. The parties disputed whether this qualified as prior art “by another.” The court found that the Board had properly applied its longstanding precedent that any difference in the named inventors rendered the prior art reference “by another” for obviousness purposes.

Obviousness. Merck argued that even if Bodor was to be considered prior art, the board’s determination that the combination of Bodor and the other relevant prior art reference rendered the claimed invention obvious. The court found that substantial evidence in the form of expert declarations supported the board’s findings that a person of ordinary skill in the art would have combined the two references and would have understood that combination, and that the combination would have suggested using Bodor’s initial treatment dosage as a reasonable starting point. The declarations also supported the finding that ordinary artisans would be able to optimize the dosage for both retreatment and initiation.

The Fedral Circuit affirmed the decision of the Board.

The case is Nos. 25-1463, 25-1464

Judge: Linn, R.

Attorneys: Mark Christopher Fleming (Wilmer Cutler Pickering Hale and Dorr LLP) for Merck Serono S.A. Philip D. Segrest, Jr. (Husch Blackwell LLP) for TWI Pharmaceuticals, Inc.

Companies: Merck Serono S.A.; TWI Pharmaceuticals, Inc.

Cases: Patent FedCirNews USPTO