Addressing allegations of patent infringement by a generic version of Fentora®, the U.S. Court of Appeals for the Federal Circuit reversed in part and affirmed in part the district court’s ruling for generic manufacturer, finding that New Drug Application (NDA) holder’s patents were not invalid for lack of enablement, but also finding that the Abbreviated New Drug Application (ANDA) product did not infringe those patents. Cephalon, Inc. v. Watson Pharma., Inc., Case No. 11-1325 (Fed. Cir., Feb. 14, 2013) (Wallach, J.)

The appeal grew out of Watson’s filing of an ANDA for a generic version of Fentora, a drug for the treatment of cancer pain. The U.S. Food and Drug Administration’s (FDA’s) Orange Book listed three patents as covering Fentora. After Watson made a certification under Paragraph IV of the Hatch-Waxman Act that its generic version would not infringe any patent covering Fentora and/or that any patent covering Fentora was invalid, Cephalon, the NDA holder, sued. After a bench trial, the district court found that the asserted patents were not infringed and were invalid for lack of enablement. Cephalon appealed.

On appeal, the Federal Circuit reversed the finding on lack of enablement. The Court found that the district court’s determination that Watson had made a prima facie case that Cephalon had failed to rebut was the wrong standard, and that the burden of proof by clear and convincing evidence was Watson’s alone. The panel then found that Watson’s expert had not shown by clear and convincing evidence that undue experimentation would be necessary to practice the invention.

The Federal Circuit noted that Watson’s expert had failed to apply the undue experimentation factors from In re Wands, which, while not dispositive, is a factor to be considered in judging his testimony. The Court also found that the expert’s statements that use of the patents would be “difficult” and “complicated” was insufficient to meet clear and convincing evidence standard. There was no evidence of record that testing would involve an unreasonable length of time, or that testing would not involve repetition of known or commonly used techniques.

However, the Federal Circuit upheld the district court’s finding of non-infringement either literally or under the doctrine of equivalents. The parties did not dispute the district court’s construction that the patent required that an effervescent agent be activated by human saliva. Cephalon’s experts performed tests on Watson’s ANDA product in water only, and the district court found that there was no record evidence regarding the properties of human saliva and how the ANDA product would react. The Federal Circuit found that the district court had not committed clear error, based on testimony from Watson’s expert that testing in water could not be translated to human saliva. The Court’s ruling thus cleared the way for Watson’s generic product to be approved by the FDA and marketed to the public.