To Prove Lack Of Enablement, The Challenger Must Present More Than Mere Unsubstantiated Expert Testimony That Undue Experimentation Is Required To Practice The Invention

In Cephalon, Inc. v. Watson Pharmaceuticals, Inc., No. 11-1325 (Fed. Cir. Feb. 14, 2013), the Federal Circuit reversed the district court's finding that the asserted patents were invalid for lack of enablement, and affirmed the district court's finding of noninfringement.

Cephalon, Inc. and CIMA Labs, Inc. (collectively "Cephalon") are holders of the NDA for fentanyl buccal tablets, sold under the brand name FENTORA® for the treatment of breakthrough cancer pain. U.S. Patent Nos. 6,200,604 ("the '604 patent") and 6,974,590 ("the '590 patent") (collectively "the Khankari patents") are listed in the FDA's Orange Book for FENTORA® and cover methods of administering a fentanyl tablet containing an effervescent agent and a pH adjusting substance via the mucous membrane lining or mucosa in the oral cavity.

Watson Pharmaceuticals, Inc., Watson Laboratories, Inc., and Watson Pharma, Inc. (collectively "Watson") filed an ANDA seeking approval to market a generic version of FENTORA®. In response, Cephalon sued Watson for patent infringement, first asserting the Khankari patents and later asserting an additional patent in a subsequent suit. The district court consolidated the two actions and after a bench trial concluded that Cephalon did not prove, by a preponderance of the evidence, that Watson's ANDA products infringed either of the Khankari patents. The district court also found that Watson proved, by clear and convincing evidence, that the Khankari patents were invalid for lack of enablement. Further, the district court found that Watson failed to show that the asserted patents were invalid as anticipated or obvious in view of prior art. Cephalon appealed the ruling with respect to the Khankari patents.

On appeal, the Federal Circuit first addressed whether the district court erred in ruling that Watson had carried its burden of proving, by clear and convincing evidence, that the Khankari patents were invalid for lack of enablement. The dispute arose from the district court's construction of the term "effervescent agent" in claim 1 of the Khankari patents to require "at least one compound that evolves gas by means of an effervescent reaction," and its conclusion that "effervescent agent" referred to a single compound. Slip op. at 10 (quoting Cephalon, Inc. v. Watson Pharms., Inc., 769 F. Supp. 2d 729, 744 (D. Del. 2011)). The effervescent reaction, which may play a role in increasing the rate and extent of absorption of an active drug, is most...