On Apr. 11, 2024, Federal Circuit affirmed District court’s determination regarding obviousness, effective approval date of ANDA and motion to modify the final judgement.

 

Salix Pharmaceuticals contested a final judgment from the District of Delaware, which invalidated several of its patents (US 8,309,569; 10,765,667; 7,612,199; 7,902,206) as obvious. The patents in question pertained to the treatment of various conditions using rifaximin, a widely used antibiotic. Salix’s appeal focused on the invalidation of specific patent claims related to the treatment of irritable bowel syndrome with diarrhea (IBS-D) and rifaximin’s polymorph patents. Norwich Pharmaceuticals, on the other hand, cross-appealed against the infringement ruling concerning certain patents (US 8,624,573; 9,421,195; 10,335,397) and sought modification of the judgment. The court’s order instructed the FDA not to approve Norwich’s ANDA until the expiration of the relevant patents.

 

The case primarily revolved around whether the dosage and treatment methods outlined in Salix’s patents were obvious based on prior art, including clinical trial protocols and scientific literature. The court found that Norwich’s challenge to the validity of the patents was valid and affirmed the district court’s decision. Federal Circuit affirmed the district court’s decision, agreeing that the combination of the Protocol and Pimentel provided sufficient evidence to support a finding of obviousness. Despite Salix’s arguments challenging the dosage and prior art interpretation, the court concluded that a skilled artisan would have had a reasonable expectation of success in administering the claimed dosage of rifaximin for the treatment of IBS-D.

Federal Circuit also affirmed the District court’s decision regarding polymorph patent. The polymorph patents focused on rifaximin form β, claiming specific characteristics of the compound. Norwich challenged these claims’ validity, citing prior art, particularly the Cannata patent, which disclosed rifaximin’s crystalline form and preparation protocols. The district court concluded that a skilled artisan would have had good reason to characterize rifaximin obtained through Cannata’s protocols, leading to the identification of rifaximin form β and rendering the polymorph claims obvious.

 

Court next addressed Norwich’s arguments concerning the interpretation of the 35 U.S.C. § 271(e)(4)(A) statute, which relates to the approval of generic drugs. The court concludes that the statute requires delaying the approval of specific infringing uses of the drug, not all uses of the drug including non-infringing ones. Court said that the statutory scheme makes clear that it is not the potential use of Norwich’s rifaximin for HE that constitutes the relevant infringement here, nor is it the unpatented drug compound itself, but rather it is the submission of the ANDA that included an infringing use. That the ANDA further recited a non-patent-protected indication does not negate the infringement resulting from the ANDA’s submission. The order thus appropriately delayed the effective final approval date of “this infringing ANDA” submission. Norwich sought to modify the final judgment to allow for prompt approval of an amended ANDA that removed the infringing use. The court affirms the district court’s denial of this motion, stating that consideration of the amended ANDA would be inequitable and inappropriate. The court noted that “[i]t is not a simple matter to determine whether an ANDA applicant has successfully carved out language from a label to turn infringement into non-infringement” and that what Norwich sought in its Rule 60(b) motion “would essentially be a second litigation” following final judgment.

 

In a dissenting legal opinion regarding US 8,309,569 and 10,765,667 (the “IBS-D patents”), the circuit judge, Cunningham dissented from the majority’s opinion, which found the asserted claims of the patents to be obvious. The dissent argues that the district court’s finding of obviousness was based on errors in the reasonable expectation of success analysis. Specifically, it criticizes the reliance on evidence such as the RFIB 2001 Press Release, which did not adequately support a reasonable expectation of success for the claimed dosage. Furthermore, it questions the majority’s reliance on a sentence from Pimentel 2006, stating that it does not sufficiently support the claimed dosage.