Last updated: February 17, 2026
This report analyzes the patent litigation between Mylan Pharmaceuticals Inc. (now Viatris) and Sanofi-Aventis U.S. LLC concerning insulin glargine. The dispute centers on U.S. Patent No. 10,568,714.
What is the core dispute in this litigation?
The central conflict involves Mylan (Viatris) challenging the validity and enforceability of Sanofi's U.S. Patent No. 10,568,714. Mylan alleges that Sanofi engaged in inequitable conduct before the United States Patent and Trademark Office (USPTO) during the prosecution of this patent. Specifically, Mylan claims Sanofi misrepresented and failed to disclose material information regarding prior art, thereby improperly obtaining the patent for its insulin glargine product, Lantus.
What specific patent is at issue?
The patent at the heart of this lawsuit is U.S. Patent No. 10,568,714. This patent is directed to methods of producing insulin glargine. Sanofi has asserted this patent against Mylan's proposed biosimilar product.
What are Mylan's primary allegations against Sanofi?
Mylan's core allegations revolve around inequitable conduct before the USPTO. These claims include:
- Misrepresentation of Prior Art: Mylan asserts that Sanofi misrepresented the significance and relationship of certain prior art references to the invention claimed in the '714 patent. This allegedly involved presenting the prior art in a misleading context, suggesting it did not anticipate or render obvious the claimed methods.
- Failure to Disclose Material Information: Mylan contends that Sanofi intentionally withheld or failed to disclose material information concerning the prior art. This non-disclosure, according to Mylan, prevented the USPTO from making an informed decision regarding the patentability of the claims.
- Intent to Deceive: Mylan alleges that Sanofi acted with an intent to deceive the USPTO. This intent is crucial for an inequitable conduct finding, requiring evidence that Sanofi knew of the materiality of the undisclosed or misrepresented information and intentionally withheld it or misrepresented it to secure the patent.
What is Sanofi's position on these allegations?
Sanofi denies Mylan's allegations of inequitable conduct. The company asserts that it complied with its duty of disclosure and candor to the USPTO. Sanofi maintains that the '714 patent is valid and enforceable and that Mylan's claims are without merit.
What is the procedural status of the litigation?
The litigation is currently in its early stages. Mylan filed its complaint on February 17, 2023, initiating the legal proceedings. Sanofi has responded to the complaint, and the parties are engaged in preliminary legal maneuvering, including discovery. The case is being heard in the United States District Court for the District of Delaware.
What are the potential implications of this litigation for Mylan and Sanofi?
For Sanofi:
- Patent Validity: A finding of inequitable conduct could lead to the invalidation of U.S. Patent No. 10,568,714. This would significantly weaken Sanofi's ability to block Mylan's biosimilar.
- Market Exclusivity: Invalidation of the patent would allow Mylan to launch its insulin glargine biosimilar, potentially leading to significant revenue loss for Sanofi's Lantus product.
- Reputational Damage: A successful inequitable conduct claim can carry reputational consequences for a patent holder.
For Mylan:
- Market Entry: A favorable outcome, particularly a finding of inequitable conduct that invalidates the patent, would clear a major hurdle for Mylan's entry into the insulin glargine biosimilar market.
- Financial Gains: Successful market entry would enable Mylan to capture a share of the insulin glargine market, leading to substantial revenue.
- Precedent: A win for Mylan could set a precedent for challenging other patents based on similar inequitable conduct arguments.
What is the relevance of the Biologics Price Competition and Innovation Act (BPCIA)?
While this specific litigation focuses on patent infringement and validity (particularly through inequitable conduct), it operates within the broader framework of the BPCIA. The BPCIA establishes an abbreviated pathway for the approval of biosimilar and interchangeable biosimilar biological products. Mylan is seeking to launch a biosimilar to Sanofi's Lantus, and the patent landscape is a critical component of the BPCIA's "patent dance" and subsequent litigation. Patent challenges are a common strategy employed by biosimilar applicants to gain market entry.
What is the current status of Mylan's biosimilar product development?
Mylan (Viatris) has developed an insulin glargine biosimilar, which they aim to market. The success of this biosimilar's launch is directly contingent on navigating the patent protections held by Sanofi.
What is the role of the USPTO in this dispute?
The USPTO is not a direct party to the lawsuit but is central to Mylan's allegations. The claims of inequitable conduct directly challenge the integrity of the patent examination process and Sanofi's interactions with the USPTO examiner. Documents and communications between Sanofi and the USPTO during the patent prosecution are likely to be key evidence in this case.
How does inequitable conduct differ from patent invalidity due to obviousness or anticipation?
- Invalidity (Anticipation/Obviousness): These grounds challenge whether the invention itself meets the statutory requirements for patentability based on the existing prior art. The focus is on the technical merits of the invention.
- Inequitable Conduct: This is a defense that alleges misconduct by the patent applicant during the patent prosecution process. It requires proving that the applicant intentionally misled or withheld material information from the USPTO with the intent to deceive. If proven, it renders the entire patent unenforceable, regardless of the underlying patentability of the claims.
Key Takeaways
- Mylan (Viatris) is litigating against Sanofi-Aventis U.S. LLC over U.S. Patent No. 10,568,714, which covers methods for producing insulin glargine.
- Mylan's primary defense is that Sanofi committed inequitable conduct before the USPTO by misrepresenting and failing to disclose material prior art during patent prosecution.
- A finding of inequitable conduct could result in the invalidation and unenforceability of Sanofi's '714 patent.
- This litigation is a critical step in Mylan's strategy to launch its insulin glargine biosimilar, impacting market competition and revenue for both companies.
- The case is proceeding in the U.S. District Court for the District of Delaware, with discovery being a key phase.
Frequently Asked Questions
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What is the specific product Sanofi protects with U.S. Patent No. 10,568,714?
The patent protects methods of producing insulin glargine, the active pharmaceutical ingredient in Sanofi's long-acting insulin product, Lantus.
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What are the legal consequences if Mylan successfully proves inequitable conduct?
If Mylan proves inequitable conduct, the U.S. Patent No. 10,568,714 will be declared unenforceable, allowing Mylan to proceed with launching its biosimilar without facing patent infringement claims based on this patent.
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Can Sanofi assert other patents against Mylan's biosimilar?
Yes, Sanofi may hold other patents related to its insulin glargine products and delivery devices. Mylan's launch strategy would need to consider all relevant patent protections.
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What is the typical timeline for a patent litigation case involving inequitable conduct allegations?
Patent litigation, especially cases involving complex allegations like inequitable conduct, can extend for several years, often involving extensive discovery, claim construction, and potentially trial.
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What is the role of a biosimilar in the pharmaceutical market?
A biosimilar is a biological product that is highly similar to an already approved biological product (the reference product), with no clinically meaningful differences in safety, purity, and potency. Biosimilars are intended to increase competition and reduce healthcare costs.
Citations
[1] Mylan Pharmaceuticals Inc. v. Sanofi-Aventis U.S. LLC, No. 2:23-cv-00836 (D. Del. filed Feb. 17, 2023).
