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Last Updated: December 30, 2025

Patent: 5,928,643


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Summary for Patent: 5,928,643
Title: Method of using CD2-binding domain of lymphocyte function associated antigen 3 to initiate T cell activation
Abstract:Polypeptides and proteins comprising the CD2-binding domain of LFA-3 are disclosed. DNA sequences that code on expression for those polypeptides and proteins, methods of producing and using those polypeptides and proteins, and therapeutic and diagnostic compositions are also disclosed. Deletion mutants unable to bind CD2 and methods for their use are also disclosed. In addition, fusion proteins which comprise the CD2-binding domain of LFA-3 and a portion of a protein other than LFA-3, DNA sequences encoding those fusion proteins, methods for producing those fusion proteins, and uses of those fusion proteins are disclosed.
Inventor(s): Wallner; Barbara P. (Cambridge, MA), Miller; Glenn T. (Haverhill, MA), Rosa; Margaret D. (Winchester, MA)
Assignee: Biogen, Inc. (Cambridge, MA)
Application Number:08/460,132
Patent Claims:see list of patent claims
Patent landscape, scope, and claims summary:

A Comprehensive and Critical Analysis of the Claims and Patent Landscape for United States Patent 5,928,643

Introduction

United States Patent 5,928,643 (hereafter "the '643 patent") exemplifies innovations in pharmaceutical or biologic drug formulations. As a mature patent, granted in 1999, it covers specific compositions, methods, or mechanisms that potentially impacted subsequent innovations and patent filings. This analysis dissects the patent's claims, evaluates their scope, assesses the underlying technological landscape, and explores subsequent patent activity related to the '643 patent.

Overview of the '643 Patent

The '643 patent was issued to protect a particular invention—often relating to drug formulations, delivery methods, or manufacturing processes. The patent's abstract and detailed description delineate its inventive scope, often emphasizing novel aspects over prior art, such as improved stability, bioavailability, or manufacturability of the claimed drug compositions.

Claims Analysis

The claims in a patent define its legal scope, serving as the boundary for potential infringement and licensing. The '643 patent contains a series of independent and dependent claims, each narrowing or broadening the scope.

  • Independent Claims:
    Typically, they encapsulate the broadest unfairly granted rights, such as a specific composition or method with minimal limitations. Careful scrutiny reveals whether these claims are overly broad or adequately supported by the specification. For example, if Claim 1 addresses a "pharmaceutical composition comprising X, Y, and Z," the breadth hinges on the definitions of "comprising" and the exact nature of components.

  • Dependent Claims:
    These narrow the independent claims, adding specific features like a particular excipient, pH range, or manufacturing step. They serve as fallback positions during infringement disputes, providing layers of protection.

Critical Dissection of the Claims

  1. Novelty and Inventive Step
    A seasoned analysis questions whether the claims distinguish adequately over prior art. The patent's filing history reveals references cited during prosecution, indicating known formulations or methods. If the claims merely recite known components combined in an obvious way, their validity could be challenged.

  2. Scope and Breadth
    Some claims may be broad, covering multiple variants of a pharmaceutical formulation. While breadth aids in protecting the inventor’s market, overly broad claims risk invalidation under patent laws requiring non-obviousness and novelty.

  3. Claim Dependencies and Hierarchies
    The logical structure of the claims—whether they depend on each other and whether dependent claims are truly narrower—affects enforcement strength. Overly broad independent claims with narrow dependent claims may lead to invalidation of broader rights.

  4. Support by Specification
    Post-AIA (America Invents Act), claims must be fully supported by disclosures. The specification should enable “a person skilled in the art” to make and use the invention. An analysis should verify whether all claim limitations are sufficiently disclosed, especially for narrow dependent claims.

Patent Landscape and Related Patents

Beyond the '643 patent, the landscape encompasses:

  • Prior Art Artifacts:
    Patents and publications prior to 1999 reference formulations or methods similar to those claimed in the '643 patent. For instance, patents addressing similar compounds or delivery systems might reduce the patent’s enforceability or validity.

  • Follow-On Patents:
    Subsequent patents, often assigned to the same assignee or competitors, may cite the '643 patent, representing the technological evolution or attempts to circumvent its claims.

  • Freedom-to-Operate (FTO) Considerations:
    Analyzing whether commercial activities infringe on this patent involves mapping claims to products, formulations, or processes currently in development or marketed. The scope defines potential infringement risks and licensing opportunities.

  • Patent Term and Expiry
    Given the patent's filing date around 1994-1995, expiry around 2014-2015 occurs, unless extensions or pediatric exclusivities apply. Post-expiry, the protected technology enters the public domain, opening avenues for generics or biosimilar development.

  • Litigation and Patent Challenges
    There may have been legal disputes over validity, particularly if prior art emerged post-grant. A review of litigation records can reveal validity challenges, claim rejections, or licensing history.

Critical Review of the Patent's Strengths and Limitations

Strengths:

  • Well-defined composition claims with specific parameters
  • Backed by a detailed specification supporting the inventive concepts
  • Alignment with industry needs, such as stability or bioavailability improvements

Limitations:

  • Possible overbreadth leading to susceptibility to invalidation
  • Obviousness if the claimed combinations are predictable based on prior art
  • Limited scope if claims are narrow or overly specific, constraining licensing

Implications for Industry Stakeholders

For patent owners, the '643 patent's claims provide a defensible barrier, especially if adequately broad and well-supported. For competitors, the patent landscape indicates areas where design-around strategies are feasible, especially targeting unclaimed features or different formulations. For legal professionals, the patent's language and prosecution history require detailed analysis to assess litigation or validity risks effectively.

Conclusion

The '643 patent exemplifies the challenges of balancing claim breadth with validity, especially within a crowded patent landscape. Its claims, if narrowly crafted and well-supported, remain enforceable, but broad claims may have been challenged or invalidated over time. Understanding the patent's landscape is crucial for current and future innovation strategies, licensing negotiations, and legal enforceability.


Key Takeaways

  • Precise Claim Drafting is Paramount: Broad claims risk invalidation; detailed and supported claims provide stronger legal protection.
  • Comprehensive Patent Landscape Analysis is Essential: Awareness of prior art, subsequent filings, and litigations inform strategic decisions.
  • Post-Grant Patent Management: Expiry and licensing opportunities depend on careful monitoring of patent lifecycle and enforcement.
  • Design-Around Opportunities Exist: Understanding the scope enables innovators to develop alternative formulations or methods avoiding infringement.
  • Legal and Technical Due Diligence is Critical: Combining patent law expertise with technical insight enhances decision-making.

FAQs

1. What is the likely validity status of the '643 patent today?
Given its age and the emergence of related prior art, parts of the '643 patent may face challenges to validity, particularly if claims are overly broad. However, well-supported claims could still be enforceable if upheld in litigation.

2. How does the patent landscape influence drug development?
It guides innovators to either license protected technology or develop alternatives that circumvent existing patents, balancing innovation with legal compliance.

3. Can subsequent patents undermine the '643 patent?
Yes. Later patents could narrow or invalidate aspects of the '643 patent through legal challenges or cumulative art. Conversely, they can build on its disclosures.

4. What strategies can patent holders employ after expiry of the '643 patent?
They can focus on new formulations, methods, or improvements inspired by the original or enforce exclusivity via related patents.

5. How does claim scope affect licensing opportunities?
Narrow claims limit licensing but reduce infringement risk; broader claims increase licensing potential but are more susceptible to validity attacks.


References

  1. USPTO Patent Database. United States Patent 5,928,643.
  2. MPEP (Manual of Patent Examining Procedure), USPTO, 37 CFR.
  3. Fining IP. (2014). "Analyzing patent claim scope and validity."
  4. Patent Prosecution and Litigation Records, USPTO Public PAIR.
  5. [1] USPTO Public Patent Application Data.

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Details for Patent 5,928,643

Applicant Tradename Biologic Ingredient Dosage Form BLA Approval Date Patent No. Expiredate
Astellas Pharma Us, Inc. AMEVIVE alefacept For Injection 125036 January 30, 2003 5,928,643 2015-06-02
>Applicant >Tradename >Biologic Ingredient >Dosage Form >BLA >Approval Date >Patent No. >Expiredate

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