On November 8, 2023, Regeneron Pharmaceuticals Inc. filed a BPCIA Complaint against Celltrion Inc. in the district court for the
northern district of West Virginia, asking the Court to block Celltrion’s biosimilar product “CT-P42” – Celltrion’s proposed biosimilar of Regeneron’s drug Eylea^® (aflibercept) –
from entering the United States market. Regeneron
Pharmaceuticals Inc. v. Celltrion Inc., N.D.W.Va., No.
1:23-cv-00089. In their Complaint, Regeneron alleges that Celltrion infringes 38 patents owned by Regeneron and directed at compositions and
methods related to retinal-disease treatment.

42 U.S.C. § 262(l) outlines a framework for applicants and
reference product sponsors (“RPS”) to resolve patent
disputes and engage in the so-called “patent dance”.
Briefly, Celltrion publicly announced on June 30, 2023
that it had filed an abbreviated Biologics License Application
(“aBLA”) for CT-P42 with the FDA, followed by serving Regeneron with a copy of the aBLA on September
13, 2023 and informing Regeneron that it intended to commercially
market CT-P42 immediately upon receiving FDA approval,
which could occur as early as May 18, 2024 when Regeneron’s regulatory exclusivity for Eylea expires. On November 7, 2013 Regeneron provided Celltrion with a list of Regeneron’s patents that would be allegedly
infringed by CT-P42 and on the next day filed a Complaint seeking declaratory judgment of
patent infringement. To our knowledge, this case presents the first
BPCIA fact pattern where the RPS (i.e., Regeneron) brought suit after receiving the
biosimilar applicant’s aBLA and responsively providing a list
of patents without waiting for the “patent dance” to
proceed beyond the patent list stage.

Judge Kleeh, who is assigned to the Celltrion action, held a 10-day bench trial in
June 2023 in another BPCIA suit brought by Regeneron against Viatris Inc.’s Mylan
Pharmaceutical unit, alleging that their proposed biosimilar
for Eylea – “M710” or “Yesafili”” – infringes three of
Regeneron’s patents. Regeneron
Pharmaceuticals, Inc. v. Mylan Pharmaceuticals Inc.,
N.D.W.Va., No. 1-22-cv-00061 (filed August 2, 2022; pending). Two
of the patents asserted in the Mylan action – U.S. Pat. Nos. 10,888,601
and 11,253,572, which cover dosing – are among the 38 patents
asserted against Celltrion in the Celltrion action, and were subject to
inequitable conduct counterclaims by Mylan. A week before trial, Judge Kleeh granted
Regeneron’s request for judgment on the
pleadings and cleared both patents from Mylan’s inequitable conduct counterclaims.
Noteworthy, in August 2023, Celltrion brought a Motion to Intervene in the
Mylan action seeking to unseal or redact
certain sealed filings and noted that “At some point in the
future, Regeneron may threaten to file a patent
infringement suit against Celltrion asserting some or all of the patents
against Mylan, to delay CT-P42 from coming to market and competing with
Eylea.” Judge Kleeh ordered the unsealing
of 30 docket entries and some related exhibits.

The Celltrion Complaint can be found here. We continue to monitor both of these
pending cases.

The authors would like to thank April Breyer Menon for her contributions to
this article.

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