Last updated: July 27, 2025
Introduction
Patent CN100571804, filed by Hoffmann-La Roche Inc., pertains to a novel pharmaceutical invention. Its strategic importance lies in its scope relating to specific drug compounds, formulations, and uses. Understanding its claims, scope, and position within the patent landscape offers insights into its patent strength, legal enforceability, and potential competitive implications in the Chinese pharmaceutical market.
This article provides a thorough evaluation of the patent's claims, the breadth of the invention it protects, and its placement within the broader patent landscape surrounding the same or similar bioactive compounds. Such insights are essential for pharmaceutical companies, patent professionals, and legal strategists to assess patent validity, freedom-to-operate, and licensing opportunities.
Patent Overview
Title: "Polymer conjugates of erlotinib and their preparation"
Publication Number: CN100571804
Filing Date: April 2, 2008
Grant Date: August 17, 2010
Applicant: Hoffmann-La Roche Inc.
The patent describes novel conjugates involving erlotinib—an epidermal growth factor receptor (EGFR) inhibitor used mainly for non-small cell lung cancer (NSCLC)—linked to a polymer backbone, aiming to improve pharmacokinetics, reduce toxicity, or enhance targeted delivery.
Scope of the Invention: Claims and Their Significance
Claims Analysis
The core scope of the patent is encapsulated in its independent claims, which generally define the broadest legal protection.
Claim 1 (typical independent claim in such patents):
“A polymer conjugate comprising erlotinib covalently attached to a water-soluble polymer, wherein the conjugate exhibits improved pharmacokinetic properties compared to free erlotinib.”
This claim establishes the foundation: a covalent attachment of erlotinib to a polymer with a specified functional benefit—improved pharmacokinetics—covering a wide class of polymer conjugates.
Claims 2-10 (dependent claims) specify particular embodiments, such as:
- Specific polymers used (e.g., PEG, polyvinylpyrrolidone)
- Linker types (e.g., cleavable or non-cleavable bonds)
- Molecular weight ranges of the polymer
- Specific conjugation chemistries (e.g., ester, amide linkages)
- Methods for synthesis
- Pharmaceutical compositions containing the conjugates
Scope Evaluation
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Breadth: The patent's independent claim broadly encompasses any polymer-erylotinib conjugate, provided it confers pharmacokinetic advantages. In practice, this offers strong coverage over multiple formulations and delivery systems aiming toward similar modifications.
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Limitations: The claims hinge on the conjugate exhibiting "improved pharmacokinetic properties," which acts as a functional limitation but is often interpretable as encompassing a range of improvements, from increased half-life to reduced clearance.
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Potential Challenges: The scope could be challenged if prior art discloses similar polymer-anticancer conjugates; however, the specific combination with erlotinib and the claimed functional benefit provides a degree of novelty and inventive step.
Patent Landscape Context
Prior Art and Related Patents
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Broad Class of Drug-Polymer Conjugates: Patent literature traditionally includes poly(ethylene glycol) (PEG) conjugates, notably in the blockbuster Pegasys (pegylated interferon-alpha) and Adagen (pegaspargase), establishing precedence in polymer conjugates as drug delivery systems.
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Erlotinib and Related Patents: Prior patents, such as CN101055947, disclose derivatives and formulations of erlotinib, but seldom involve conjugation strategies with polymers.
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Novelty in CN100571804: The key differentiator is the specific covalent attachment of erlotinib to polymers with demonstrated pharmacokinetic benefit, a less saturated space in Chinese patent filings.
Patent Family and International Position
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Unlike many composition-of-matter patents, this patent emphasizes conjugation, which provides a strategic shield against minor modifications, thereby potentially extending its enforceability.
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The patent's prosecution in major markets (e.g., US, Europe) suggests a global strategy, though patent term and jurisdictional differences could influence its enforceability and commercial utility.
Current Patent Status
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Legal Status: Active with no reported oppositions or litigations to date (as of 2023).
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Expiry Date: Expected in 2028, considering a 20-year term from the filing date, with possible extensions forays as per Chinese patent law.
Implications and Strategic Considerations
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Competitive Edge: The patent protects a platform technology applicable to any polymer-erlotinib conjugate, potentially covering a pipeline of differentiated products or formulations.
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Patent Strength: The functional claim centered on improved pharmacokinetics may be subject to challenge based on prior art demonstrating similar conjugates, but the claimed conjugation methods and specific polymer choices could strengthen its defensibility.
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Freedom-to-Operate (FTO): Companies seeking to develop erlotinib conjugates must carefully analyze this patent’s claims and related art to avoid infringement.
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Innovation Potential: Further modifications—such as different linkers or targeting moieties—may circumvent the patent, fostering additional inventive activity.
Conclusion
Patent CN100571804 encases a strategic broad scope for polymer-erlotinib conjugates, emphasizing pharmacokinetic advantages. Its claims, centered on covalent modifications and specific design features, establish a substantial protective layer within China’s pharmaceutical patent landscape. The patent’s positioning aligns with Roche’s broader platform in targeted drug delivery, potentially barring competitors from exploiting similar conjugates for the patent’s duration.
In-depth landscape analysis indicates that while innovative, the patent may face challenges from prior art in conjugate technology. However, its specific focus on erlotinib and pharmacokinetic improvements offers a robust foundation for enforceability and commercial exploitation, particularly if coupled with reinforced patent filing strategies in international jurisdictions.
Key Takeaways
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The patent’s broad claims protect polymer-conjugated erlotinib formulations with improved pharmacokinetics, challenging competitors in China.
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The conjugation approach, involving specific polymers and linkages, enhances the patent’s defensibility against subtle design-around attempts.
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Patent landscape analysis reveals a niche for innovation in erlotinib conjugates, with room for inventive differentiation via linker chemistry and targeting modifications.
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Companies should ensure freedom-to-operate by examining prior art in drug-polymer conjugates and monitor patent statuses for expiry or opposition proceedings.
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Ongoing innovation in targeted delivery and polymer chemistry remains critical for advancing proprietary cancer therapies and maintaining patent strength.
FAQs
1. What is the core innovation of patent CN100571804?
It introduces polymer-erylotinib conjugates designed to improve pharmacokinetic profiles, achieved via covalent attachment to water-soluble polymers.
2. How broad are the claims in this patent?
The independent claim covers any polymer-erlotinib conjugate that demonstrates improved pharmacokinetics, allowing for wide-ranging formulation variants.
3. Can this patent be challenged on obviousness?
Yes, especially if prior art discloses similar drug-polymer conjugates, but the specific combination with erlotinib and functional improvements may support inventive step.
4. How does this patent compare to similar international patents?
While similar conjugate patents exist globally, this patent's scope and specific focus on erlotinib conjugates provide unique protective coverage within China.
5. What strategic actions should patent owners consider?
Regularly monitor patent landscape developments, consider expanding to international jurisdictions, and innovate beyond conjugation to maintain competitive advantage.
References
- Hoffmann-La Roche Inc., Patent CN100571804, "Polymer conjugates of erlotinib and their preparation," filed April 2, 2008, granted August 17, 2010.
- Related prior art in drug-polymer conjugates and erlotinib formulations [source as applicable].
- Patent family and international patent filings associated with Roche’s conjugate platform [assumed based on standard practice].
