Understanding the Scope and Claims of United States Patent 5,532,372
United States Patent 5,532,372, owned by Sumitomo Dainippon Pharma Co., is a significant patent in the pharmaceutical industry, particularly concerning the compound lurasidone, which is the active ingredient in the drug LATUDA®. Here is a detailed analysis of the patent's scope, claims, and the surrounding patent landscape.
Background of the Patent
The patent, titled "Imide derivatives, and their production and use," was granted for novel imide compounds and their acid addition salts, which are useful as therapeutic agents. The patent is crucial for understanding the protection and application of lurasidone and its enantiomers[2].
Claim Construction and Scope
Claim 14: The Central Dispute
Claim 14 of the patent has been at the center of several legal disputes. This claim recites a structural drawing of the (–)-enantiomer of lurasidone. The Federal Circuit has provided clear guidance on the construction of this claim.
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Plain Claim Language: The Federal Circuit held that the plain claim language covers, at a minimum, the (–)-enantiomer depicted in the structural drawing. This interpretation was based on the understanding that a person of ordinary skill in the art would recognize the claim's structural formula as specifically depicting the (–)-enantiomer[2][3].
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Inclusion of Enantiomers and Mixtures: The court also determined that the claim could cover the (+)-enantiomer and mixtures of the two enantiomers, although it did not explicitly opine on this broader scope. The key point is that nothing in the claim or specification limited the claim to only a racemic mixture or disclaimed the (–)-enantiomer[2].
Ordinary and Customary Meaning
The construction of claim terms is guided by the principle of giving them their "ordinary and customary meaning" as understood by a person of ordinary skill in the art at the time of invention. This approach is consistent with the Federal Circuit's precedents, such as in Phillips v. AWH Corp. and Vitronics Corp. v. Conceptronic, Inc.[1].
Intrinsic and Extrinsic Evidence
The court relies on intrinsic evidence (the patent specification and prosecution history) and extrinsic evidence (external expert testimony, dictionaries, etc.) to determine claim scope. However, intrinsic evidence is given more weight, and extrinsic evidence is reviewed for clear error when made by a district court[1].
Legal Precedents and Rulings
Federal Circuit Rulings
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In the case of Sumitomo Dainippon Pharma Co. v. Emcure Pharma Ltd., the Federal Circuit affirmed the district court's construction of Claim 14, rejecting the argument that the claim should be limited to only a racemic mixture. The court emphasized that the specification did not disclaim or disparage the (–)-enantiomer[1][2].
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This ruling aligns with other Federal Circuit decisions, such as SciMed Life Systems, Inc. v. Advanced Cardiovascular Systems, Inc., which highlighted the importance of express disclaimers or restrictions in the specification to limit claim scope[1].
Patent Landscape and Infringement
Infringement and ANDA Filers
The construction of Claim 14 was critical in determining infringement by ANDA (Abbreviated New Drug Application) filers. Since the branded and proposed ANDA drug products included the (–)-enantiomer, the court's construction was dispositive as to infringement. Appellants stipulated to infringement and the entry of permanent injunctions following the district court's claim construction order[1][2].
Inter Partes Review (IPR)
In a separate context, U.S. Patent No. 5,532,372 was cited as prior art in an IPR proceeding involving another Sumitomo Dainippon Pharma patent (U.S. Patent No. 8,273,827). The Patent Trial and Appeal Board held all claims of the '827 patent unpatentable for obviousness over the '372 patent, among other references[4].
Importance of Claim Scope
Balancing Breadth and Specificity
The importance of getting the claim scope right is underscored by the challenges faced in this patent. While broader claims offer broader protection, they are more difficult to get granted and easier to invalidate. Claims must be anchored to the embodiments disclosed in the specification to avoid invalidation grounds such as the abstract idea exception and failure to meet the written description requirement[3].
Risk of Overly Broad Claims
Overly broad claims can lead to invalidation, as seen in various court decisions. The abstract idea exception and failure to meet the written description requirement are common grounds for invalidating such claims. Therefore, patent applicants must carefully balance the breadth of their claims with the specificity required to ensure validity[3].
Key Takeaways
- Claim Construction: The Federal Circuit's construction of Claim 14 emphasizes the importance of plain claim language and the absence of disclaimers or restrictions in the specification.
- Infringement: The correct construction of claims is crucial for determining infringement, especially in pharmaceutical patents.
- Patent Landscape: The '372 patent has been significant in both infringement disputes and IPR proceedings.
- Claim Scope: Balancing the breadth and specificity of claims is essential to ensure the validity and enforceability of a patent.
Frequently Asked Questions (FAQs)
1. What is the main compound covered by U.S. Patent 5,532,372?
The main compound covered is lurasidone, specifically the (–)-enantiomer, which is the active ingredient in the drug LATUDA®.
2. How did the Federal Circuit construe Claim 14 of the patent?
The Federal Circuit construed Claim 14 to cover, at a minimum, the (–)-enantiomer depicted in the structural drawing, without limiting it to only a racemic mixture.
3. Why is the correct construction of claims important in patent law?
The correct construction of claims is crucial for determining infringement and ensuring the validity and enforceability of a patent.
4. What are the risks of having overly broad claims in a patent application?
Overly broad claims can lead to invalidation due to grounds such as the abstract idea exception and failure to meet the written description requirement.
5. How does the '372 patent relate to other legal proceedings, such as IPR?
The '372 patent has been cited as prior art in IPR proceedings, such as the one involving U.S. Patent No. 8,273,827, where it contributed to the unpatentability of all claims for obviousness.
Cited Sources:
- SUMITOMO DAINIPPON PHARMA CO. v. EMCURE PHARM. LTD., U.S. Court of Appeals for the Federal Circuit, April 12, 2018.
- Federal Circuit Provides Guidance for Stereochemistry Claim, Mintz, April 25, 2018.
- The Importance of Getting the Claim Scope Right in a US Patent Application, Rimon Law, October 4, 2021.
- Sumitomo Pharma Co. v. Vidal, U.S. Court of Appeals for the Federal Circuit, April 5, 2024.
