OMI Urges Appeals Court to Allow Antitrust Challenge to Amgen’s Extension of Enbrel Monopoly — Open Markets Institute
Open Markets Institute filed an amicus brief in CareFirst v. Amgen, urging the U.S. Court of Appeals for the Fourth Circuit to let an antitrust case proceed. The suit challenges Amgen’s alleged use of acquired pending patent rights to extend Enbrel’s monopoly until 2029, blocking biosimilar entry. A district court rejected Amgen’s dismissal bid in Sept 2025.
How this was made
The 30-second read
Why it matters
The brief argues that acquiring pending patent rights to extend a biologic monopoly can constitute exclusionary conduct under Section 2 of the Sherman Act, and asks the Fourth Circuit to affirm the district court’s refusal to dismiss.
Market read
This is litigation-process news that can affect perceived legal risk around Enbrel’s competitive timeline, but it is not a new ruling or settlement.
What to watch
The article does not provide new court rulings, damages estimates, or changes to Enbrel exclusivity; market reaction may be muted unless the appeals court issues a substantive decision.
Background
The Open Markets Institute filed an amicus brief supporting plaintiffs in CareFirst v. Amgen, an antitrust challenge tied to Amgen’s Enbrel patent strategy.
Ticker impact
Open Markets urges the Fourth Circuit to let CareFirst v. Amgen proceed, challenging Amgen’s use of acquired Enbrel patent rights to block biosimilar entry until 2029.
Near-term: modest risk-off bias for AMGN on litigation headline risk; medium-term: depends on case survival and any subsequent rulings affecting exclusivity or enforcement posture.
The article is an amicus filing, not a court decision, but it targets the viability of the lawsuit and directly concerns Amgen’s Enbrel patent-based exclusion narrative.
Market effects
Highlights potential antitrust scrutiny of patent acquisition and pending-application transfers in pharma, which could affect perceived litigation risk across large biologics players.
US appellate process in the Fourth Circuit keeps focus on US antitrust enforcement for branded biologics.
Could influence global biosimilar competitive dynamics by shaping how patent strategies are treated under antitrust law.
Counterpoint
An amicus brief is not binding; the appeals court may still dismiss or narrow the case, limiting any incremental impact on Amgen’s Enbrel economics.
Key entities
- companyAmgen
Defendant in CareFirst v. Amgen, accused of using acquired Enbrel patent rights to delay biosimilar competition until 2029.
- plaintiffCareFirst
Plaintiffs challenging Amgen’s alleged monopolization tactics related to Enbrel patent rights.
- organizationOpen Markets Institute
Filed the amicus brief urging the appeals court to allow the antitrust lawsuit to proceed.
- courtFourth Circuit
Appellate court being asked to affirm the district court’s denial of Amgen’s motion to dismiss.
