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Federal Circuit Upholds Enbrel® Patents and Blocks Biosimilar

Earlier this month, in Immunex Corp. v. Sandoz Inc., the Federal Circuit upheld two patents covering Enbrel’s active protein and a process used to manufacture the drug, effectively blocking Sandoz’s Enbrel® biosimilar Erelzi from the U.S. market until 2029 and providing a major victory for Amgen.[1]  Enbrel is the brand name for the molecule etanercept, which is used to treat rheumatoid arthritis and several other inflammatory conditions.  A blockbuster drug, last year Enbrel generated over $5.2 billion in sales for Amgen, representing 22% of the company’s revenue.

In February 2016, patent owner Hoffman-La Roche (“Roche”), exclusive licensee Immunex Corp., and exclusive sublicensee Amgen initiated a patent infringement suit under the BPCIA against Sandoz on the grounds that Erelzi infringed two patents covering Enbrel’s active ingredient and a method for manufacturing it.  After Sandoz stipulated to infringement, the validity of the patents went to trial in September 2018 before Judge Cecchi in the U.S. District Court for the District of New Jersey.  In August 2019, Judge Cecchi issued a detailed opinion upholding the patents’ validity and, in October 2019, Judge Cecchi entered final judgment for the plaintiffs.  Sandoz appealed, arguing, as it had before the district court, that the patents-in-suit were invalid for (1) obviousness-type double patenting (“ODP”); (2) failure to meet the written description requirement; and (3) obviousness.[2]

The Federal Circuit affirmed in a 2-1 decision written by Judge O’Malley, with Judge Reyna dissenting.  First, the court addressed the issue of ODP, which is a judicially created doctrine aimed at preventing claims in separate patents that claim obvious variants of the same subject matter where granting both exclusive rights would effectively extend the patent exclusivity period.[3]  The doctrine has two purposes: “(1) to prevent timewise extension of the right to exclude; and (2) to prevent multiple infringement suits by different assignees.”[4]

The first step in the ODP analysis is to determine if the patents are subject to common ownership.  Sandoz argued that common ownership should be determined by applying the “all substantial rights” test, under which an agreement that conveys “all substantial rights” in a patent is tantamount to an assignment of ownership.  The Federal Circuit agreed that the “all substantial rights” test was informative in determining common ownership for purposes of ODP but found, contrary to Sandoz, that the agreement at issue did not transfer all substantial rights from assignee Roche to exclusive licensee Immunex.  Rather, Roche still had substantial rights under the licensing agreement because it had retained a secondary right to sue that is exclusive once triggered and a right to veto assignments of interest.  These retained rights were sufficient to establish that the patents were not commonly owned and ODP had not occurred.[5]

Second, the Federal Circuit upheld the district court’s ruling that the priority application for the patents-in-suit disclosed two aspects of the invention, specifically a DNA sequence and a fusion protein, thereby satisfying the written description requirement.[6]

Third, the Federal Circuit rejected Sandoz’s obviousness argument.  Sandoz had argued that the district court erred by focusing on therapeutic effects when analyzing motivation to combine the prior art because the claims at issue were not directed at therapeutic treatment.  The Federal Circuit disagreed, reasoning that (1) treating inflammatory diseases was a stated objective of the claimed invention; (2) the arguments at trial were focused on therapeutic effects; and (3) at least two of the asserted claims were directed to pharmaceutical compositions.[7]  Additionally, the Federal Circuit rejected Sandoz’s argument that the district court’s analysis of objective indicia of non-obviousness was legally erroneous.[8]

Judge Reyna dissented, criticizing the majority’s ODP analysis as allowing for “gamesmanship in prosecution which could result in unjustified extension of patent rights.”[9]  Judge Reyna argued that Roche’s rights in the patent agreement were merely “illusory” and not substantial, because Immunex had the right to demand the patents from Roche in exchange for a mere $50,000, and because Immunex could nullify Roche’s right to sue by issuing a royalty-free sublicense to the alleged infringer.[10]  Judge Reyna also argued that although the majority did not reach this issue, the patents-in-suit were patentably indistinct from a previously issued Immunex patent, and therefore invalid for ODP.[11]

Immunex provides a clear victory for Amgen in its battle against biosimilars of Enbrel, as well as an interesting illustration of how the Federal Circuit plans to approach ODP analyses in future cases.


[1] No. 2020-1037 (Fed. Cir. July 1, 2020).

[2] Id. at 2-5, 8.

[3] Id. at 9.

[4] Id.

[5] Id. at 11-21.

[6] Id. at 22-26.

[7] Id. at 26-29.

[8] Id. at 29-30.

[9] Id. at PDF page 33 (Reyna, J., dissenting).

[10] Id. at PDF pages 34-36 (Reyna, J., dissenting).

[11] Id. at PDF pages 38-39 (Reyna, J., dissenting).

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