United States Patent 7,326,708: A Detailed Analysis of Scope, Claims, and Patent Landscape
Introduction
The United States Patent 7,326,708, owned by Merck Sharp & Dohme Corp., is a pivotal patent in the pharmaceutical industry, particularly in the treatment of diabetes. This patent covers the dihydrogen phosphate salt of sitagliptin, a key component in Merck's JANUVIA and JANUMET medications. Here, we delve into the scope, claims, and the patent landscape surrounding this invention.
Background of the Patent
The patent in question, U.S. Patent 7,326,708, describes sitagliptin dihydrogenphosphate (sitagliptin DHP), a dihydrogenphosphate salt of sitagliptin. Sitagliptin is an inhibitor of the dipeptidyl peptidase-IV (DP-IV) enzyme, which is crucial in the treatment and prevention of diseases such as type 2 diabetes[1][2][5].
Claims of the Patent
The patent includes several claims that define the scope of the invention. Here are some key claims:
Claims 1-3, 17, 19, and 21-23
These claims pertain to the composition and preparation of sitagliptin DHP. Specifically, they cover the 1:1 stoichiometry of sitagliptin DHP, which is a critical aspect of the patent. Mylan Pharmaceuticals Inc. challenged these claims, arguing they were anticipated or obvious based on prior art, but these challenges were rejected by the Patent Trial and Appeal Board (PTAB) and later affirmed by the U.S. Court of Appeals for the Federal Circuit[1][2][4].
Claim 3
This claim specifies the (S)-configuration of sitagliptin DHP. Mylan argued that this claim would have been obvious in view of prior art, but the Board found that Mylan failed to demonstrate that skilled artisans would have been motivated to combine the elements or have a reasonable expectation of success[1][4].
Claim 4
This claim pertains to the crystalline monohydrate form of (R)-sitagliptin. Similar to Claim 3, Mylan's obviousness arguments were rejected due to insufficient evidence that skilled artisans would have combined the elements or had a reasonable expectation of success[1][4].
Anticipation and Obviousness Challenges
Mylan Pharmaceuticals Inc. challenged the validity of the patent through an inter partes review before the PTAB. Mylan argued that the claims were anticipated by International Patent Publication WO 2003/004498 (the “’498 publication”) and the equivalent U.S. Patent 6,699,871 (the “’871 patent”), collectively referred to as “Edmondson.” However, the Board determined that Merck had reduced to practice the subject matter of the claims before the Edmondson publication, thereby antedating it[1][2][4].
Antedation
Merck successfully demonstrated that it had conceived and reduced to practice the invention before the effective date of the Edmondson reference. This antedation was crucial in overcoming the § 102(a) barrier, as it showed that Merck's invention predated the prior art cited by Mylan[1][4].
Obviousness
The Board also rejected Mylan's obviousness arguments. For claims 1-2, 17, 19, and 21-23, the Board found that Merck's reduction to practice before the Edmondson publication eliminated it as a reference. For claims 3 and 4, Mylan failed to show that skilled artisans would have been motivated to combine the elements or have a reasonable expectation of success[1][4].
Patent Landscape and Litigation
The patent landscape surrounding U.S. Patent 7,326,708 is complex and has been the subject of significant litigation.
Inter Partes Review
Mylan's challenges to the patent were initially heard in an inter partes review before the PTAB. The PTAB ruled in favor of Merck, finding all challenged claims valid. Mylan appealed this decision to the U.S. Court of Appeals for the Federal Circuit, which affirmed the PTAB's decision[2][4].
District Court Rulings
In addition to the inter partes review, Viatris (formerly Mylan) also challenged the patent in the U.S. District Court for the Northern District of West Virginia. The District Court ruled in favor of Merck, upholding the validity of the patent[2][5].
Patent Scope and Quality
The scope of the patent claims is a critical aspect of patent quality. Research has shown that narrower claims at publication are associated with a higher probability of grant and a shorter examination process than broader claims. The examination process tends to narrow the scope of patent claims in terms of both claim length and claim count[3].
Metrics for Patent Scope
Studies have proposed metrics such as independent claim length and independent claim count to measure patent scope. These metrics have explanatory power for several correlates of patent scope, including patent maintenance payments, forward citations, and the breadth of patent classes[3].
Impact on the Pharmaceutical Industry
The validity of U.S. Patent 7,326,708 has significant implications for the pharmaceutical industry, particularly for generic drug manufacturers. Viatris is seeking FDA approval to market generic versions of JANUVIA and JANUMET, but the patent's validity until November 24, 2026 (with pediatric exclusivity extending to May 24, 2027), protects Merck's market position[2][5].
Key Takeaways
- Patent Validity: The U.S. Court of Appeals for the Federal Circuit affirmed the validity of all challenged claims of U.S. Patent 7,326,708.
- Antedation: Merck successfully antedated the prior art cited by Mylan, demonstrating conception and reduction to practice before the effective date of the reference.
- Obviousness: Mylan's obviousness arguments were rejected due to insufficient evidence that skilled artisans would have combined the elements or had a reasonable expectation of success.
- Patent Scope: The patent's claims are narrowly defined, which is consistent with higher patent quality and a more efficient examination process.
- Industry Impact: The patent's validity protects Merck's market position for JANUVIA and JANUMET until the patent's expiration.
FAQs
What is the main subject matter of U.S. Patent 7,326,708?
The main subject matter of U.S. Patent 7,326,708 is the dihydrogen phosphate salt of sitagliptin, an inhibitor of the dipeptidyl peptidase-IV enzyme used in the treatment of type 2 diabetes.
Who challenged the validity of U.S. Patent 7,326,708?
Mylan Pharmaceuticals Inc. (now part of Viatris) challenged the validity of the patent through an inter partes review and in the U.S. District Court.
What was the outcome of the inter partes review and the appeal?
The PTAB ruled in favor of Merck, finding all challenged claims valid. The U.S. Court of Appeals for the Federal Circuit affirmed this decision.
How does the patent's validity impact the pharmaceutical industry?
The patent's validity protects Merck's market position for JANUVIA and JANUMET until the patent's expiration, preventing generic versions from entering the market during this period.
What metrics are used to measure patent scope?
Metrics such as independent claim length and independent claim count are used to measure patent scope, which have explanatory power for several correlates of patent scope.
Sources
- Mylan Pharmaceuticals Inc. v. Merck Sharp & Dohme Corp., No. 21-2121, U.S. Court of Appeals for the Federal Circuit, September 29, 2022.
- U.S. Court of Appeals for the Federal Circuit Rules in Favor of Merck in Sitagliptin Dihydrogen-phosphate Patent Lawsuit, Merck News, September 29, 2022.
- Patent Claims and Patent Scope, Hoover Institution, August 18, 2024.
- United States Court of Appeals - Merck Response Brief, MoloLamken LLP, July 19, 2020.
- U.S. District Court Rules In Favor of Merck in Sitagliptin Phosphate Patent Lawsuit, Merck News, September 22, 2022.
