In the case Merck Serono S.A. v. Hopewell Pharma Ventures, Inc., the Federal Circuit upheld a Patent Trial and Appeal Board decision invalidating claims related to Merck’s multiple sclerosis drug Mavenclad, an oral formulation of the compound Cladribine.

Merck Serono S.A. v. Hopewell Pharma Ventures, Inc. – Basic Details:

• Case Name: Merck Serono S.A. v. Hopewell Pharma Ventures, Inc.
• Court: United States Court of Appeals for the Federal Circuit
• Case Numbers: 2025-1210 & 2025-1211
• Patent Numbers at Issue: US7713947B2 and US8377903B2
• Decision Date: October 30, 2025
• Parties:
  • Appellant: Merck Serono S.A.
  • Appellee: Hopewell Pharma Ventures, Inc.

Merck Serono S.A. v. Hopewell Pharma Ventures, Inc. – Lower Proceedings: Inter partes reviews (IPRs) before the Patent Trial and Appeal Board (PTAB), IPR2023-00480; IPR2023-00481

Merck Serono S.A. v. Hopewell Pharma Ventures, Inc. – Background:

The dispute centered on patents related to oral cladribine dosing regimens for treating multiple sclerosis (MS). Merck, successor to Serono, developed oral formulations of cladribine to be used in certain dose/interval patterns to address MS. Hopewell Pharma challenged these patents’ validity at PTAB, arguing “obviousness” based on prior art, specifically two references (1) Bodor (WO 2004/087101) and (2) Stelmasiak (Med. Sci. Monit. 1998).

Merck Serono S.A. v. Hopewell Pharma Ventures, Inc. – Key Issues:

• Obviousness: Whether the patents’ claimed dosing regimens were obvious in light of Bodor and Stelmasiak.
• Prior Art: “By Another”: Whether Bodor qualified as “prior art” against Merck’s patents under pre-AIA 35 U.S.C. §102(a)/(e), especially when there was overlap in inventors among the references and the patents.

Merck Serono S.A. v. Hopewell Pharma Ventures, Inc. – Court’s Analysis and Decision:

• Obviousness Affirmed: The Federal Circuit affirmed PTAB’s finding that the challenged claims were obvious. The Board had found that Bodor disclosed all the steps of the regimen claimed by Merck, and that any differences could easily have been bridged in light of Stelmasiak’s teachings and the chronic, relapsing nature of MS. It was reasonable for a skilled artisan to combine these teachings with a “reasonable expectation of success.”
• Prior Art – Inventor Identity: The court clarified that, for a reference to be excluded as “not by another,” there must be a complete identity of inventive entities between the patent and the prior art reference. Overlapping inventors alone isn’t enough; any discrepancy means the reference is prior art.
  • Merck argued that because some inventors overlapped between their patents and the Bodor reference, Bodor should not count as “by another.”
  • Merck did not provide sufficient corroborated evidence that named inventor De Luca made a significant inventive contribution to Bodor’s six-line cladribine regimen disclosure; thus Bodor remained prior art.
  • The court disagreed, relying on long-standing precedent, and confirmed that the PTAB correctly treated Bodor as prior art.
• Weight-Based v. Flat Dosing: The court rejected Merck’s argument that the claims required weight-based dosing, affirming that claim language on total dose does not mandate a particular calculation method for dosage.

Merck Serono S.A. v. Hopewell Pharma Ventures, Inc. – Conclusion – Key Takeaways:

• Federal Circuit underscores strict standards on “inventor identity” for prior art exclusion.
• Cladribine regimen patent claims held obvious in view of prior art even where some inventors overlap.
• For “by another” status under pre-AIA §102(a)/(e), full match of inventive entity is required to exclude a reference as prior art.
• Patent claims require careful drafting prior art and inventor contribution analysis are critical.
• Decision provides significant guidance for IPRs and patent litigation involving overlapping inventorship.

Merck Serono S.A. v. Hopewell Pharma Ventures, Inc. – Conclusion:

This ruling is a key reminder to innovators: When patenting, clear inventorship and thorough prior art analysis are crucial. Even overlapping inventors between references and patents will not shield claims from invalidation if the inventive entities do not fully match. The Merck v. Hopewell case is now a leading precedent on both obviousness and the “by another” standard for prior art in U.S. patent law.

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