Prometheus Labs, Inc. v. Roxane Labs., Inc.

Addressing obviousness issues, the U. S. Court of Appeals for the Federal Circuit affirmed the district court’s invalidity conclusion, agreeing that the elements present in the prior art—including earlier disclosed genus claims—would have given a person of ordinary skill a reasonable expectation of successfully treating a subset of patients. Prometheus Labs, Inc. v. Roxane Labs., Inc., Case Nos. 14-1634, -1635 (Fed. Cir., Nov. 10, 2015) (Dyk, J.).

In 2009, Roxane filed an Abbreviated New Drug Application (ANDA) seeking approval to sell a generic version of the branded pharmaceutical Lotronex. Lotronex is a Prometheus product used to treat various irritable bowel syndrome (IBS) symptoms. Prometheus responded by filing a district court action against Roxane.

IBS is a condition with multiple forms, each form diagnosed based on a patient’s symptoms. For example, IBS-D refers to diarrhea-predominant symptoms, IBS-C refers to constipation-predominant symptoms, and IBS-M refers to mixed symptoms. The asserted patent’s claims are directed to treatment of female IBS patients with IBS-D who have experienced diarrhea-predominant symptoms for at least six months and who have moderate pain. The asserted patent followed an earlier Prometheus patent (the “prior art patent”), now expired, that also covered treating IBS symptoms with alosetron but did not distinguish between the various forms of the condition.

Following a bench trial, the district court found all of the asserted claims obvious. According to the district court, the prior art patent taught treatment of IBS with alosetron in a manner virtually identical to the asserted claims, and the results of the asserted claims were not unexpected in view of research findings that the drug would have increased efficacy for female IBS-D patients exhibiting symptoms for more than six months. The district court also concluded that the remaining evidence relating to secondary considerations of non-obviousness was insufficient to overcome the showing of insubstantial differences between the claimed inventions and the prior art. Prometheus appealed.

On appeal, the Federal Circuit affirmed the conclusion of obviousness under § 103, finding that the district court’s opinion was supported by specific evidence showing that the limitations of the asserted claims (i.e., IBS-D symptoms or female patients with symptoms for more than six months) were either known in the medical literature or common practice.

Prometheus also argued that secondary considerations of non-obviousness in the form of commercial success, unexpected results and long-felt need overcame the teachings of the prior art. The Federal Circuit disagreed, noting that Prometheus did not submit evidence demonstrating a nexus between the commercial success of the branded drug and the asserted patent. Instead, the drug’s commercial success could be attributed to other variables such as the drug compound disclosed in the prior art patent, marketing campaigns and pricing of the product to stimulate sales. The Federal Circuit confirmed that while the burden of proof to demonstrate obviousness always rests with the party challenging validity, once a prima facie case of invalidity has been introduced through appropriate evidence, the patentee is well advised to introduce rebuttal evidence. In other words, here, Roxane had the burden of proof but Prometheus had the burden of production for secondary considerations such as commercial success.

Practice Note: The opinion discusses circumstances where a narrow species claim can be non-obvious and patent-eligible despite an earlier disclosure of a genus, noting in dicta that the genus-species distinction “may have particular relevance in the field of personalized medicine.” The decision seems to offer important guidance as to when claims directed to a particular subset of patients may be patent eligible, noting that directing a specific treatment to patients with a particular gene may reflect a new and useful invention even if the treatment method was generally known in the prior art.