Functional Limitation, Claim Construction, and Obviousness: Bayer v. Mylan
| September 24, 2025
BAYER PHARMA AKTIENGESELLSCHAFT, v. MYLAN PHARMACEUTICALS INC., TEVA PHARMACEUTICALS USA, INC., INVAGEN PHARMACEUTICALS INC.
Date of Decision: September 23, 2025
Before: MOORE, Chief Judge, CUNNINGHAM, Circuit Judge, and SCARSI, District Judge.
Summary
The Federal Circuit affirmed in part, vacated in part, and remanded the Patent Trial and Appeal Board’s decision invalidating claims of Bayer Pharma AG’s patent. The court upheld the invalidation of claims 1-4 but vacated and remanded with respect to claims 5-8.
Background
Bayer owns the ’310 patent (U.S. Patent No. 10,828,310), which claims methods for reducing the risk of cardiovascular events in patients with coronary artery disease (CAD) and/or peripheral artery disease (PAD) through administration of rivaroxaban and aspirin.
Independent claim 1 recites administration of rivaroxaban and aspirin in clinically proven amounts. Independent claim 5 recites once-daily administration of a first product comprising rivaroxaban and aspirin and a second product comprising rivaroxaban. Claims 1 and 5 are listed below with emphasis added:
1. A method of reducing the risk of myocardial infarction, stroke or cardiovascular death in a human patient with coronary artery disease and/or peripheral artery disease, comprising administering to the human patient rivaroxaban and aspirin in amounts that are clinically proven effective in reducing the risk of myocardial infarction, stroke or cardiovascular death in a human patient with coronary artery disease and/or peripheral arterial dis-ease, wherein rivaroxaban is administered in an amount of 2.5 mg twice daily and aspirin is administered in an amount of 75-100 mg daily.
5. A method of reducing the risk of myocardial infarction, stroke or cardiovascular death in a human patient with coronary artery disease and/or peripheral artery disease, the method comprising administering to the human patient rivaroxaban and aspirin in amounts that are clinically proven effective in reducing the risk of myocardial infarction, stroke or cardiovascular death in a human patient with coronary artery disease and/or peripheral arterial disease, wherein the method comprises once daily administration of a first product comprising rivaroxaban and aspirin and a second product comprising rivaroxaban, and further wherein the first product comprises 2.5 mg rivaroxaban and 75-100 mg aspirin and the second product comprises 2.5 mg rivaroxaban.
Mylan, Teva, and InvaGen filed substantively identical IPR petitions, arguing that a 2016 journal article by Foley (summarizing a trial which includes its dosing regimen of 2.5 mg rivaroxaban twice daily and 100 mg aspirin once daily without disclosing the trial results) and a 2014 journal article by Plosker (disclosing a dosing regimen of 2.5 mg rivaroxaban twice daily, co-administered with 75-100 mg aspirin) anticipated or rendered the claims obvious. The Board agreed and held all challenged claims unpatentable. Bayer appealed.
Discussion
The Federal Circuit addressed four disputes.
The first dispute is related to the phrase “clinically proven effective.” The Board had treated it as non-limiting or inherently anticipated. Bayer argued that the phrase should operate as a substantive limitation on the claims. According to Bayer, the language required that the claimed dosages of rivaroxaban and aspirin be supported by actual clinical trial evidence of efficacy, which in turn distinguished the claims from prior art references such as Foley. Bayer emphasized that Foley disclosed dosing regimens but did not provide trial results demonstrating that the regimens were effective and therefore could not anticipate or render the claimed methods obvious.
The Federal Circuit rejected this position, explaining that it did not decide whether the phrase “clinically proven effective” was a limiting element in claims 1-8. Even assuming it was limiting, the court reasoned that the phrase would not affect patentability because it merely described a characteristic of the treatment regimen rather than altering the steps of the claimed method. The court emphasized that the claims already specify the exact dosages of rivaroxaban and aspirin to be administered, and those dosages remain unchanged regardless of whether clinical trials later demonstrate efficacy. Accordingly, the limitation was deemed functionally unrelated to the claimed method and insufficient to distinguish the claims from the prior art.
The second dispute concerned the proper construction of the phrase “first product comprising rivaroxaban and aspirin” in claim 5. The Board had construed this language broadly to encompass circumstances where rivaroxaban and aspirin were provided in separate dosage forms and administered together, not limited to a single dosage form, and, if administered separately, the dosage forms could be administered simultaneously or sequentially.
The Federal Circuit disagreed with that interpretation. Relying on both the plain language of the claim and the description in the specification, the court concluded that “a first product comprising rivaroxaban and aspirin” required a single dosage form containing both ingredients. The court emphasized that the specification describes that “combination therapy may be administered using separate dosage forms for rivaroxaban and aspirin, or using a combination dosage form containing both rivaroxaban and aspirin.” The court agreed with Bayer that “first product comprising rivaroxaban and aspirin” corresponds to the latter, which narrows the term.
Therefore, the Federal Circuit remanded for further consideration so that the Board’s analysis of the obviousness arguments would be under the correct construction of the “first product” term.
The third dispute concerned whether the Board adequately explained a skilled artisan’s motivation to combine the prior art references with a reasonable expectation of success. The Federal Circuit agreed with the Board’s decision and found it supported by substantial evidence. The court noted that the Board identified both an overlap in the disclosed dosage ranges and the established practice of administering aspirin within that range. The court further found that Foley and Plosker described similar motivations for combining rivaroxaban with aspirin in patients with cardiovascular risk, which supported the Board’s conclusion that a skilled artisan would have had reason to combine the references with a reasonable expectation of success. Accordingly, the Federal Circuit affirmed the Board’s determination of obviousness as to dependent claims 3-4 and 6-7.
The fourth dispute concerned Bayer’s argument that its own clinical trial provided clinical proof of efficacy was an unexpected result. The Federal Circuit rejected this position, holding that there was no nexus between the asserted unexpected property and the claimed invention. The court explained that the asserted results were tied only to the “clinically proven effective” limitation, which it had already deemed functionally unrelated to the actual treatment method. Without that nexus, the secondary consideration of unexpected results could not support nonobviousness.
Takeaways
- Claim language that merely recites a property or result, without further defining the claimed steps or structure, may be deemed functionally unrelated and insufficient to establish distinction over the prior art.
- Secondary considerations require a demonstrated nexus between the evidence presented and the claimed invention as construed.
