On Feb 01, 2019 Federal Circuit affirmed PTAB’s decision of upholding the compound patent on epileptic drug Vimpat® challenged by three generic-drug makers.
Mylan, Breckenridge and Alembic appealed from the final written decision of the PTAB in an inter partes review concluding that claims 1–13 of U.S. Reissue Patent 38,551 (“the ’551 patent”) are not unpatentable. Research Corporation Technologies, Inc. (“RCT”) owns the ’551 patent, which discloses and claims enantiomeric compounds and pharmaceutical compositions useful in the treatment of epilepsy and other central nervous system (“CNS”) disorders. Claim 1 recites the lacosamide compound generically in R configuration. Claim 8 depends from claim 1 and recites “[t]he compound according to claim 1 which is (R)-N-benzyl-2-acetamido-3- methoxypropionamide,” referred to in the patent as “BAMP” and referred to herein as lacosamide.
On Nov. 23, 2015, Argentum Pharmaceuticals LLC filed IPR against ’551 patent. In its petition, Argentum challenged claims 1–13 on eight grounds. The Board only instituted on two grounds involving three references: (1) obviousness of claims 1–9 over Kohn 1991 and Silvermanand (2) obviousness of claims 10–13 over Kohn 1991, Silverman, and U.S. Patent 5,378,729 (“the ’729 patent”). Three days after the Board instituted Argentum’s petition, Mylan, Breckenridge, and Alembic each filed their own petitions for review with concurrent motions for joinder. The Board issued its final written decision, concluding that each challenged claim had not been shown to be unpatentable. Contrary to its views in the institution decision, the Board disagreed with Petitioners. It “assumed arguendo, that an ordinary artisan would have selected compound 3l of Kohn 1991 as a lead compound” but found that converting the methoxyamino group (NH-O-CH3 ) would have been viewed as undesirable because the compounds in Kohn 1991 without a methoxyamino or nitrogen-containing moiety at the α-carbon had reduced activity.