Merck obtains Federal Circuit affirmance of unpatentability ruling relating to antifungal drugs

Client(s) Merck & Co., Inc.

Jones Day defended Merck Sharp & Dohme Corp.'s victory before the U.S. Patent and Trademark Office Patent Trial and Appeal Board (PTAB), which held that Mayne Pharma International Pty's patent claims related to antifungal drugs were unpatentable. In its appeal to the Federal Circuit challenging the patent office's unpatentability determination, Mayne also raised challenges to the patent office's threshold determinations regarding the sufficiency of Merck's pleading of "all real parties-in-interest" pursuant to governing statutes and rules. The federal government intervened to support Merck's defense of the patent office on that point.

In a unanimous, precedential opinion, the Federal Circuit adopted Merck's arguments on both of Mayne's grounds for appeal and affirmed the PTAB's judgment of unpatentability. The victory permits Merck to continue selling its successful Noxafil^® medication without patent-infringement charges from Mayne Pharma. The decision also provides useful guidance to companies and counsel regarding "real party-in-interest" designations before the patent office.

Mayne Pharma International Pty. v. Merck Sharp & Dohme Corp., No. 18-1593 (Fed. Cir.)