Cadence Pharm. Inc. v. Exela Pharmsci Inc.

Cadence Pharmaceuticals Inc. (Cadence) (plaintiff) owned or licensed two patents used in making Cadence’s brand-name injectable acetaminophen product. The first, the ’222 patent, pertained to acetaminophen-buffering agents. The second, the ’218 patent, pertained to aqueous solutions prepared using two specialized processes. Exela Pharmsci Inc. (Exela) (defendant) developed a generic-equivalent product. Cadence sued in federal district court, charging Exela with patent infringement. Exela argued that the ’222 patent was invalid because it failed to specify the buffering agent’s chemical properties. As to the ’218 patent, Exela argued there was no infringement because Cadence and Exela used different processes to prepare their aqueous solutions. Exela also argued that the ’218 patent was invalid, because its subject matter would have been obvious to anyone skilled in the prior art. Based on examining the patents and hearing bench-trial testimony, the court concluded that: (1) the ’222 patent’s plain language generically referred to buffering agents regardless of their specific characteristics, and therefore the ’222 patent was valid as to all such agents; (2) Exela literally infringed the ’222 patent by using one specific type of buffering agent; (3) expert testimony confirmed that the solution-processing differences were insignificant, and therefore Exela’s use of those processes constituted a doctrine-of-equivalents infringement of the ’218 patent; and (4) Exela could not refute expert testimony confirming the ’218 patent’s nonobviousness, and therefore the ’218 patent was presumptively valid. The court entered judgment for Cadence. Exela appealed to the Federal Circuit, which heard the case in the immediate aftermath of the Supreme Court’s decision in Teva Pharm. USA, Inc. v. Sandoz, Inc. (Teva).