957 Salts Too Many To "At Once Envisage"; Mylan's Attacks On Patentability Peter Out

• Published date: 12 October 2022
• Subject Matter: Intellectual Property, Patent
• Law Firm: Finnegan, Henderson, Farabow, Garrett & Dunner, LLP
• Author: Ms Jill MacAlpine, Stacy Lewis and Thomas Irving

Holding:

In Mylan Pharms. Inc. v. Merck Sharp & Dohme Corp., No. 21-2121 (Fed. Cir. Sept. 29, 2022), the Court of Appeals for the Federal Circuit ("the Federal Circuit") affirmed the Final Written Decision of the Patent Trial and Appeal Board ("the Board") upholding the claims of U.S. Patent No. 7,326,708 ("the '708 patent") challenged in IPR2020-00040.

Background:

The '708 patent describes sitagliptin dihydrogenphosphate ("sitagliptin DHP 1:1 salt") or a hydrate thereof, a dipeptidyl peptidase-IV ("DP-IV") inhibitor which can be used for treating non-insulin-dependent (i.e., Type 2) diabetes. Claim 1 of the '708 patent reads:

1. A dihydrogenphosphate salt of a 4-oxo-4-[3-(trifluoromethyl)-5,6-dihydro[1,2,4]tria-zolo[4,3-a]pyrazin-7(8H)-yl]-1-(2,4,5-tri-fluorophenyl)butan-2-amine of Formula I:

or a hydrate thereof.

Dependent claim 2 recites the (R)-configuration of the sitagliptin DHP 1:1 salt, dependent claim 3 recites the (S)-configuration of the sitagliptin DHP 1:1 salt, and dependent claim 4 recites a crystalline monohydrate form of the (R)-configuration of the sitagliptin DHP 1:1 salt. Id. at *3.

Mylan challenged several claims of the '708 patent, including claims 1-3, as anticipated by WO 2003/004498 ("the '498 publication"), which is owned by Merck and is the equivalent of U.S. Patent 6,699,871 (collectively "Edmonson"). Id. Edmondson discloses a genus of DP-IV inhibitors and 33 species, one of which is sitagliptin. Id. Edmondson also discloses that pharmaceutically acceptable salts can be formed using one of eight "[p]articularly preferred" acids, and names phosphoric acid as a particularly preferred acid. Id. Finally, Edmonson discloses that the salts may exist in crystalline forms, including as hydrates. Id. at *3-4.

Mylan also argued that several claims of the '708 patent, including claims 1-4, would have been obvious over Edmondson and two additional publications, Brittain and Bastin. Id. at *4.

Board:

According to the Board, Mylan did not show that the claims of the '708 patent were anticipated because there was "no express disclosure of all of the limitations of the 1:1 sitagliptin DHP salt in Edmondson," and Mylan could not fill in the gaps by arguing that one of ordinary skill in the art would "at once envisage" what is missing. Id. at *5. Inherent anticipation was ruled out because the evidence "showed that 1:1 sitagliptin DHP does not form every time sitagliptin and DHP were reacted." Id.

With respect to obviousness, the Board concluded that Merck was able to antedate Edmonson with respect to the subject matter of certain claims, including claims 1 and 2, drawn to sitagliptin DHP 1:1 salt or a hydrate thereof and to the (R)-configuration of the sitagliptin DHP 1:1 salt or hydrate thereof, respectively. Specifically, the Board determine that Merck had reduced to practice at least as much, and in fact more, of the claimed subject matter than was shown in Edmondson. Id. By...