Sanofi Opposes Amgen’s Petition for Rehearing En Banc in Praluent® Litigation

As we previously reported, Amgen is seeking en banc review of the Federal Circuit panel decision vacating a permanent injunction that would have otherwise prohibited the sale of Sanofi and Regeneron’s Praluent® (alirocumab) product and remanding the appeal to the district court for a new trial on the defendants’ written description and enablement defenses.  As discussed previously, Amgen asserted two primary grounds for rehearing.  First, Amgen argued that the panel improperly abrogated the Federal Circuit’s “newly characterized antigen” rule, which holds that written description of an antibody genus claim can be satisfied by describing the target antigen rather than the structure of all antibodies in the genus.  Second, Amgen argued that the panel erred in allowing defendants to rely on evidence dated after the patent’s priority date in support of their written description and enablement defenses.  Several other companies have filed an amicus brief supporting Amgen’s petition.

Sanofi has now filed its response opposing Amgen’s petition.  Sanofi made several arguments regarding each of Amgen’s two grounds for rehearing.

Newly characterized antigen test

Regarding the “newly characterized antigen” test, Sanofi first argued that the decisions that Amgen cited for establishment of the “newly characterized antigen” test discussed the test only in dicta, and the Federal Circuit has never upheld the validity of a patent based only on disclosure of a novel antigen.  Therefore, according to Sanofi, there is no conflict between the panel’s decision and other Federal Circuit decisions.  Sanofi next argued that the panel’s decision was correct because § 112 requires “a written description of the invention,” not “a description of something that is not the invention—an antigen, rather than the antibody that is the subject of the claims,” and a description of the antigen “does not tell you anything at all about the structure of the antibody.”  Finally, Sanofi argued that Amgen overstated the importance of upholding antibody genus claims to biotech companies’ ability to protect their inventions because genus claims can still be valid if the specification described enough representative species.

Relevance of post-priority date evidence

With respect to the relevance of post-priority date evidence to prove lack of written description or enablement, Sanofi again argued that Federal Circuit precedent does not support Amgen’s position.  According to Sanofi, the cases cited by Amgen for the rule that post-priority date evidence is inadmissible dealt only with particular circumstances and did not create a blanket rule, and there are other examples of cases in which the Federal Circuit allowed post-priority date evidence in different circumstances.  Sanofi next argued that the panel decision is correct because post-priority date evidence can clearly be relevant to demonstrate the breadth of a genus claim and provide examples of covered species that are not described and/or enabled.  Sanofi argued that the “most probative evidence of whether a claimed genus is supported by a representative number of species or common structural features will likely be evidence of species that fall within the scope of the claimed genus but are not described in the patent, including the accused antibody—here, Praluent, which the district court excluded.”  Finally, Sanofi again argued that Amgen overstated the impact of the panel decision on incentives for biotech innovators, and rather that allowing evidence of later-developed embodiments of a genus claim protects companies that “invest billions to discover new, life-saving medicines” from losing “those investments simply because an earlier applicant claimed an overly broad genus of antibodies by their function, when that applicant never actually performed the difficult work of discovering a representative number of species fitting in that genus.”

Stay tuned to Big Molecule Watch for further coverage of this case.

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