(AMGN/CHRS) Neulasta/Udenyca: Appeals Court Agrees Amgen Surrendered Certain Salt Combinations in Obtaining Neulasta Patent; Coherus’ Udenyca Does Not Infringe

Relevant Document:
Opinion

Reorg Pharma Recap
 

• This morning in a precedential opinion, an appeals court unanimously affirmed a Delaware court’s finding that Coherus’ Udenyca biosimilar did not infringe a 2030 manufacturing patent (U.S. Patent No. 8,273,707) covering Amgen’s Neulasta biologic.
   
• The only issue analyzed in today’s decision was prosecution history estoppel, wherein a patentee is not permitted to broaden claims under the doctrine of equivalents after narrowing those claims during the patent application process. The appeals court found that “Amgen clearly and unmistakably” narrowed its claims to “particular combinations of salts” due to arguments Amgen made to the Patent and Trademark Office in order to obtain the patent.
   
• This is a rather rare instance of argument-based prosecution history estoppel being found to bar a patentee’s reliance on infringement under the doctrine of equivalents.
   
• The issue of whether Amgen had dedicated certain salt combinations to the public, which the parties had argued previously, was not addressed in today’s opinion.
   
• As a result of this decision, Coherus may continue to market its Udenyca biosimilar in the United States.

This morning in a precedential opinion, the U.S. Court of Appeals for the Federal Circuit affirmed a Delaware court’s finding that Coherus’ Udenyca biosimilar does not infringe a 2030 manufacturing patent (U.S. Patent No. 8,273,707) covering Amgen’s Neulasta (pegfilgrastim), a biologic product used for the treatment of cancer. Today’s opinion affirms the Delaware court’s finding that prosecution history estoppel prevents Amgen from arguing that the combination of salts used by Coherus in the manufacturing of Udenyca infringes the 2030 patent.

Prosecution history estoppel means that a patentee may not broaden claims by invoking the doctrine of equivalents after narrowing those claims during the patent application process. In obtaining the 2030 patent, Amgen had made certain arguments regarding a “particular combination of salts” that the Federal Circuit found narrowed the claims in a manner that excluded the combination of salts used by Coherus in production of Udenyca. In today’s opinion, the appeals court states that Amgen’s actions during the patent application process contradict its contention that Coherus infringes the 2030 patent and that the Delaware court correctly dismissed Amgen’s lawsuit.

Coherus launched Udenyca in the United States in January 2018. Udenyca is not the only pegfilgrastim biosimilar available in the United States. Mylan began marketing Fulphila, its pegfilgrastim biosimilar, in July 2018. As a result of today’s opinion, Coherus may continue marketing its Udenyca biosimilar in the United States.

Amgen may request that the entire appeals court panel review today’s decision. However, such an en banc hearing is rarely granted.

The appeals court heard argument on May 8. Reorg Pharma’s recap of that hearing can be found HERE. Below is a summary of the opinion.

Summary of Opinion

The panel consisted of Circuit Judges Jimmie Reyna, Todd Hughes and Kara Stoll. Judge Stoll wrote the opinion for the panel.

Today’s relatively brief opinion is based on Amgen’s appeal of the dismissal of a lawsuit in the Delaware court. That dismissal resulted from a magistrate judge’s finding that Amgen had surrendered part of the scope of the claims of the 2030 patent as it attempted to gain approval from the patent examiner. During the application process - and after the Patent and Trademark Office initially rejected the application based on a piece of prior art referred to as Holtz (U.S. Patent No. 5,231,178) - Amgen argued that “[n]o combination of salts is taught nor suggested in the Holtz et al. patent, nor is the particular combination of salts recited in the pending claims taught nor suggested in this reference” (emphasis in original).

As previously reported by Reorg Pharma, Judge Stoll questioned Amgen’s characterization of a “single” reference during arguments made before the panel, and today’s opinion reiterated Judge Stoll’s concerns. Though Amgen had argued in its briefing and during oral arguments that the Delaware court’s decision was based on a “single” reference to particular salts, today’s opinion notes that “Amgen emphasized ‘particular’ and referred to its particular salts three times in the span of two pages.”

While Amgen had argued that it did not distinguish Holtz based on its failure to disclose particular salt combinations - and though Amgen had also put forth arguments with regard to Holtz’s failure to disclose increased dynamic capacity or any salt combinations at all - today’s opinion notes that relevant case law “instructs that estoppel can attach to each argument” made during the patent application process. Therefore, though Amgen had set forth other arguments, its reliance on particular salt combinations nevertheless resulted in prosecution history estoppel.

Amgen had also argued that prosecution history estoppel should not apply because the final response to the patent examiner before the 2030 patent was approved did not include any argument with regard to salt combinations. However, today’s opinion noted that relevant “case law does not support this argument.” The opinion states that Amgen’s omission of arguments regarding particular salts in its final response does not mean that “Amgen’s prior statements are erased.”

Today’s opinion is a relatively rare instance where the Federal Circuit has found that a patentee is barred from relying on infringement under the doctrine of equivalents by so-called argument-based prosecution history estoppel, that is, due merely to arguments made to the patent office, as opposed to an amendment to the claims.