On October 30, 2025, the U.S. Court of Appeals for the Federal Circuit affirmed two inter partes review decisions of the Patent Trial and Appeal Board (“PTAB”) invalidating claims in two of Merck Serono S.A.’s patents covering oral cladribine dosing regimens for treating multiple sclerosis (“MS”). The opinion addresses both the substantive obviousness analysis and an important doctrinal question under pre-AIA §§ 102(a) and 102(e): when a disclosure with overlapping inventors qualifies as prior art “by another.”
The case arises from consolidated appeals of PTAB’s final written decisions in IPR2023‑00480 and IPR2023‑00481, in which Hopewell Pharma Ventures challenged claims of U.S. Patent Nos. 7,713,947 and 8,377,903, both directed to a multi-phase oral cladribine regimen comprising an induction period, an extended drug-free period, and a maintenance (retreatment) period. The PTAB found the claims unpatentable as obvious over a combination of an international application published in 2004 by Bodor and Dandiker (describing an oral cladribine-cyclodextrin complex administered according to specific dosing schedules that included dosing in the first two months followed by a drug-free period) and a 1998 clinical paper by Stelmasiak (reporting a reduction in relapse rate following treatment with cladribine in cyclical courses either orally or parenterally with drug-free intervals).
Merck’s patents claim methods of treating MS via oral cladribine administered in defined sequential phases. Representative claim 36 of the ’947 patent recites an induction period lasting about 2–4 months with a total cladribine dose of about 1.7–3.5 mg/kg, followed by about 8–10 months without cladribine, followed by a 2–4 month maintenance period with a total cladribine dose of about 1.7 mg/kg, and then another drug-free interval. The ’947 patent lists four Serono scientists as inventors: Drs. De Luca, Ythier, Munafo, and Lopez-Bresnahan.
The Federal Circuit addressed the patentability of all of the challenged claims together.
Background to the Claimed Regimen
The ’947 patent arose out of a joint development effort that began in 2002 between Serono (acquired by Merck in 2006) and IVAX with the goal of formulating an oral cladribine product to treat MS. The scientists at Serono and Ivax working on the joint effort exchanged confidential information regarding the development. For example, in December 2003, Serono circulated a “Briefing Document” with a draft regimen involving repeated short daily dosing blocks separated by prolonged drug-free periods.
In March 2004, two IVAX scientists, Drs. Bodor and Dandiker, filed the Bodor international application. Bodor was published in October 2004, less than one year before the effective filing dates of the Merck patents, and it contains what the parties and the PTAB termed the “six-line disclosure,” which sets out an oral cladribine regimen specifying daily 10 mg doses for five to seven days in each of two months, followed by ten months of no treatment.
The 1998 Stelmasiak reference taught oral or subcutaneous cladribine administered in monthly five-day courses across six months, followed by additional courses at extended intervals with intervening drug-free intervals. Stelmasiak documented lymphocyte suppression and relapse reduction using the disclosed regimens.
The “By Another” Prior Art Issue
The threshold dispute addressed by the Federal Circuit was whether Bodor’s six-line disclosure qualified as prior art “by another” under pre-AIA § 102(e). Under pre-AIA § 102(e), a patent is anticipated if “the invention was described in . . . a patent granted on an application for patent by another filed in the United States before the invention by the applicant for patent.” 35 U.S.C. 102(e) (emphasis added). For the purposes of its decision, the court drew no distinction between the requirements of 102(e) and 102(a), under which, absent a statutory bar, “[o]ne’s own work is not prior art under § 102(a) even though it has been disclosed to the public in a manner or form which would otherwise fall under § 102(a).” Allergan, Inc. v. Apotex Inc., 754 F.3d 952, 968 (Fed. Cir. 2014).
Merck argued that, because at least one of the inventors named on its patents (particularly Dr. De Luca) contributed to the dosing regimen reflected in the six-line disclosure in Bodor, the reference embodied “the inventors’ own work” and should be excluded from prior art. Merck further contended that the PTAB applied a rigid, incorrect rule requiring complete identity of inventive entities to avoid “by another” status, and that the Manual of Patent Examining Procedure (MPEP) suggested a more flexible approach recognizing “at least one joint inventor’s own work.”
The Federal Circuit rejected Merck’s legal theory and affirmed the PTAB’s treatment of Bodor as prior art, clarifying that under longstanding precedent—including In re Land and its progeny—a disclosure is excluded from prior art only when it reflects the work of the same inventive entity as the later patent. Where joint inventorship is concerned, that means the relied-on portions of the earlier disclosure must reflect the collective work of the same joint inventors named on the later patent. Any incongruity—whether subtracting or adding inventors—renders the earlier disclosure “by another.”
The court also rejected Merck’s APA notice arguments based on the Manual of Patent Examination and Procedure (“MPEP”), noting that the MPEP itself includes sections that track the rule articulated in Land and the court concluded that the PTAB did not improperly shift the burden of persuasion. The court reasoned that, to the extent the MPEP describes Federal Circuit case law in a manner that conflicts with the Federal Circuit’s conclusions, the MPEP’s interpretation does not control. In addition, the court held that the PTAB permissibly required Merck to produce corroborated evidence showing that the relied-on Bodor disclosure reflected an inventive contribution from all named inventors on Merck’s challenged patents; Merck failed to do so, particularly with respect to Dr. De Luca’s specific, significant contribution to the six-line regimen. The court found no legal error in the PTAB’s application of the “rule of reason” to assess corroboration and no need to reach the PTAB’s alternative finding that Bodor’s authors were themselves joint inventors of the applied portions.
Obviousness Over Bodor and Stelmasiak
Having concluded that Bodor was prior art to Merck’s challenged patents, the Federal Circuit held that substantial evidence supported the PTAB’s obviousness determination. The PTAB found that Bodor taught the claimed induction phase and the extended cladribine-free period, and that a person of ordinary skill would have been motivated to follow Bodor’s express guidance for the regimen and, given MS’s chronic nature and cladribine’s documented effects, to implement a maintenance (retreatment) phase. Stelmasiak’s clinical study reinforced the retreatment concept, teaching cladribine re-administration after drug-free intervals in remitting-relapsing MS patients and providing efficacy evidence.
The PTAB credited expert testimony that Bodor’s specification of a finite drug-free period logically implies retreatment for a chronic disease; that practitioners would use Bodor’s initial dosing as a starting point for maintenance-phase optimization; and that dose and duration are result-effective variables that can be optimized by reference to lymphocyte suppression to balance efficacy and safety. The court rejected Merck’s contention that the claims require automatic retreatment regardless of safety or disease progression, observing that the claims do not impose such a condition, and concluded that the record established a reason to combine the references with a reasonable expectation of success, supported by Bodor’s and Stelmasiak’s efficacy data and the ability to empirically tune dosing.
Holding and Implications
The Federal Circuit affirmed the PTAB’s final written decisions, upholding the unpatentability of all challenged claims in Merck’s ’947 and ’903 patents as obvious over Bodor in view of Stelmasiak. The opinion offers two notable takeaways:
First, it clarifies and reinforces the pre-AIA “by another” doctrine in the joint inventorship context: to exclude a reference as “one’s own work,” the relied-on portions of the reference must reflect the same inventive entity as the later patent. Overlapping inventors do not suffice; identity of the inventive entity is the touchstone, and attempts to treat subset-authored disclosures as non-prior art will require strong, corroborated proof of joint inventive contribution to the specific content being relied on.
Second, it underscores the PTAB’s and Federal Circuit’s pragmatic approach to obviousness in pharmaceutical dosing regimen cases: where prior art discloses similar treatment paradigms, documented efficacy, and explicit statements that dosing can be empirically optimized, the PTAB and courts may conclude that it is within the skill of those in the art to combine the references and optimize the prior art regimens to arrive at the claimed invention.
