Last updated: February 19, 2026
Patent CN105759918, filed by Shanghai Fosun Pharmaceutical (Group) Co., Ltd. on October 29, 2015, and granted on August 9, 2017, claims a novel compound and its use in treating viral infections, specifically Hepatitis C virus (HCV). The patent's core innovation lies in the chemical structure of the compound, designated as "Compound B" in the patent, and its demonstrated efficacy in inhibiting viral replication. The claims extend to pharmaceutical compositions containing Compound B and methods of treating HCV infection.
What is the core invention claimed in CN105759918?
The primary invention described in CN105759918 is a novel chemical compound, identified as Compound B. The structural formula provided in the patent defines this compound as (S)-N-(1-(4-(2-(4-chlorophenoxy)phenyl)-1H-imidazol-2-yl)ethyl)-2-methyl-2-propanesulfonamide. This compound acts as an inhibitor of the HCV NS5A protein, a critical component for viral replication and assembly.
The patent details the synthesis of Compound B through a multi-step process, outlining specific reagents, reaction conditions, and purification methods. Critical steps include the formation of the imidazole ring and the subsequent attachment of the sulfonamide moiety. Yields for key intermediates and the final product are reported, indicating the feasibility of its large-scale production.
What therapeutic applications are covered by the patent?
CN105759918 covers the use of Compound B and pharmaceutical compositions containing it for the treatment of Hepatitis C virus (HCV) infection. The patent provides in vitro and in vivo data demonstrating the compound's antiviral activity. Specifically, it details the compound's ability to inhibit the replication of various HCV genotypes, including genotypes 1, 2, 3, 4, 5, and 6.
The therapeutic method claims involve administering a therapeutically effective amount of Compound B to a subject infected with HCV. The patent suggests various pharmaceutical formulations, including tablets, capsules, injections, and oral solutions. These formulations are designed to deliver Compound B effectively and achieve sustained therapeutic levels.
What is the scope of the patent's claims?
The patent's claims are structured to provide broad protection for the core invention and its applications. Key claims include:
- Claim 1: The chemical compound (S)-N-(1-(4-(2-(4-chlorophenoxy)phenyl)-1H-imidazol-2-yl)ethyl)-2-methyl-2-propanesulfonamide. This is the independent claim defining the novel chemical entity.
- Claim 2: A pharmaceutical composition comprising Compound B and a pharmaceutically acceptable carrier. This claim extends protection to formulated drug products.
- Claim 3: A method of treating Hepatitis C virus infection comprising administering a therapeutically effective amount of Compound B to a subject in need thereof. This claim covers the use of the compound for its intended therapeutic purpose.
- Dependent Claims: The patent includes several dependent claims that further define the pharmaceutical compositions and therapeutic methods, specifying various dosage forms, routes of administration, and combinations with other antiviral agents. These claims enhance the breadth of protection by covering specific embodiments and practical applications.
The claims are drafted to encompass Compound B irrespective of its method of preparation, ensuring that any party manufacturing or using the compound for HCV treatment infringes the patent.
What are the key data supporting the invention's efficacy?
The patent presents data from various experimental studies to support the efficacy of Compound B.
In Vitro Antiviral Activity
- EC50 Values: The patent reports EC50 (half-maximal effective concentration) values for Compound B against different HCV genotypes in cell-based assays. These values represent the concentration of the compound required to inhibit viral replication by 50%.
- HCV genotype 1b: EC50 of 0.3 nM
- HCV genotype 2a: EC50 of 0.4 nM
- HCV genotype 3a: EC50 of 0.5 nM
- HCV genotype 4a: EC50 of 0.6 nM
- HCV genotype 5a: EC50 of 0.3 nM
- HCV genotype 6a: EC50 of 0.5 nM
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- Mechanism of Action: Western blot analysis and RNA replication assays confirm that Compound B inhibits the NS5A protein, a non-structural protein essential for HCV RNA replication and virion assembly. Inhibition of NS5A leads to a significant reduction in viral RNA levels and the production of infectious virions.
In Vivo Efficacy in Animal Models
- HCV Replicon System in Mice: Studies using a humanized mouse model engrafted with an HCV replicon demonstrated significant viral load reduction following oral administration of Compound B. Doses ranged from 10 mg/kg to 50 mg/kg.
- At 50 mg/kg daily for 7 days, viral RNA levels decreased by over 2 logs compared to the control group.
- Pharmacokinetic studies indicated good oral bioavailability and sustained plasma concentrations of Compound B.
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Safety and Toxicity
- Cytotoxicity Assays: In vitro cytotoxicity assays using various human cell lines (e.g., Huh7, HepG2) showed that Compound B has a low toxicity profile, with CC50 (half-maximal cytotoxic concentration) values generally above 10 µM. This indicates a favorable therapeutic window.
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- Acute Toxicity Studies: Acute toxicity studies in rats indicated no mortality at the highest tested dose of 500 mg/kg, suggesting a good safety margin.
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What is the patent landscape for Compound B and related HCV inhibitors?
The patent landscape for Hepatitis C virus (HCV) direct-acting antivirals (DAAs) is highly competitive and characterized by extensive patent filings from major pharmaceutical companies. CN105759918, originating from Fosun Pharma, is positioned within this dynamic environment.
Key competitors and their patent portfolios relevant to HCV DAAs include:
- Gilead Sciences: Holds numerous patents covering sofosbuvir (Sovaldi), ledipasvir (Harvoni), velpatasvir (Epclusa), and other NS5A inhibitors and NS5B polymerase inhibitors. Their patent strategy has been crucial in establishing market dominance.
- AbbVie: Possesses patents related to their DAA regimens, including combinations targeting various HCV proteins.
- Merck & Co.: Has a portfolio of patents covering their HCV DAAs, including inhibitors of NS3/4A protease.
- Bristol Myers Squibb: Holds patents for its HCV treatment regimens.
CN105759918's focus on a specific NS5A inhibitor, Compound B, places it in direct competition with other NS5A inhibitors already on the market or in development. The novelty of the claimed structure and its specific inhibitory profile are critical for establishing its patentability and potential market differentiation.
Freedom to Operate Considerations
Companies seeking to develop or commercialize therapies based on or similar to Compound B must conduct thorough freedom-to-operate (FTO) analyses. This involves identifying all relevant patents, including:
- Composition of Matter Patents: Such as CN105759918, which claim the novel compound itself.
- Method of Treatment Patents: Covering the use of the compound for specific indications.
- Formulation Patents: Protecting specific drug delivery systems or compositions.
- Process Patents: Covering the manufacturing method of the compound.
- Polymorph Patents: Protecting specific crystalline forms of the compound, which can have significant implications for bioavailability and stability.
The expiration dates of key patents in the HCV DAA space are also critical. Many foundational patents for earlier-generation DAAs are nearing or have already expired, opening avenues for generic competition. However, newer innovations, like Compound B, are protected by more recent patent filings.
For Fosun Pharma, CN105759918 represents a strategic asset in the highly lucrative HCV market. The patent's strength and breadth will be determined by its enforceability against potential infringers and its ability to withstand patent challenges from competitors.
What are the implications of this patent for R&D and investment?
The issuance of CN105759918 has several implications for R&D and investment in the antiviral drug sector.
For R&D
- Therapeutic Target Validation: The patent reinforces the importance of the NS5A protein as a viable drug target for HCV. Researchers can leverage this knowledge to explore modifications of Compound B or develop novel inhibitors targeting the same pathway.
- Combination Therapies: The patent's claims on methods of treatment may allow for combination therapies. This means Compound B could potentially be used in conjunction with other DAAs targeting different HCV proteins (e.g., NS3/4A protease inhibitors, NS5B polymerase inhibitors) to achieve synergistic effects and overcome resistance mechanisms. R&D efforts could focus on identifying optimal combination regimens.
- Drug Resistance Studies: Understanding the mechanism of action of Compound B is crucial for predicting and mitigating the development of drug resistance. R&D can investigate resistance pathways and develop strategies to prevent or overcome them, potentially through next-generation analogs or combination approaches.
- Preclinical and Clinical Development: Fosun Pharma will likely proceed with further preclinical toxicology studies and clinical trials to assess the safety and efficacy of Compound B in humans. Successful progression through these stages will be critical for its commercial viability.
For Investment
- Intellectual Property Protection: The patent provides Fosun Pharma with a period of market exclusivity for Compound B, protecting their R&D investment and allowing for potential revenue generation. This exclusivity is a key factor for investors evaluating the commercial potential of the drug.
- Market Opportunity: Despite a crowded market, there remains an opportunity for highly effective and well-tolerated HCV treatments, particularly for patients with difficult-to-treat genotypes or those who have failed previous therapies. Investors will assess Compound B's potential to capture market share based on its efficacy, safety profile, and dosing convenience.
- Valuation and Due Diligence: Investors will scrutinize the patent's strength, scope, and remaining term when valuing Fosun Pharma or any potential licensing/acquisition targets related to Compound B. Due diligence will involve assessing patentability, freedom to operate, and the risk of patent invalidation challenges.
- Competitive Landscape: Investors need to analyze the competitive landscape, including existing blockbuster HCV drugs and those in late-stage development. Compound B's differentiation and unique selling propositions will be critical for its commercial success and investor appeal.
The patent for Compound B represents a significant development for Fosun Pharma, potentially paving the way for a new therapeutic option in the fight against Hepatitis C. Its success will depend on rigorous clinical development, effective patent enforcement, and a competitive market strategy.
Key Takeaways
- Chinese drug patent CN105759918 protects (S)-N-(1-(4-(2-(4-chlorophenoxy)phenyl)-1H-imidazol-2-yl)ethyl)-2-methyl-2-propanesulfonamide (Compound B) and its use in treating Hepatitis C virus (HCV) infection.
- Compound B functions as an inhibitor of the HCV NS5A protein, demonstrating potent antiviral activity across multiple HCV genotypes in vitro and in vivo.
- The patent claims cover the novel chemical compound, pharmaceutical compositions containing it, and methods of treating HCV infection.
- Efficacy data include low nanomolar EC50 values against various HCV genotypes and significant viral load reduction in animal models, with a favorable safety profile observed in cytotoxicity and acute toxicity studies.
- The patent landscape for HCV direct-acting antivirals is highly competitive, requiring thorough freedom-to-operate analyses for any party involved in similar drug development.
- CN105759918 provides Fosun Pharma with market exclusivity, impacting R&D by validating NS5A as a target and informing combination therapy strategies, and influencing investment through its role in intellectual property protection and market valuation.
Frequently Asked Questions
- What is the specific mechanism of action of Compound B against HCV?
Compound B inhibits the Hepatitis C virus NS5A protein, which is essential for viral RNA replication and assembly.
- Which HCV genotypes is Compound B effective against according to the patent?
The patent indicates efficacy against HCV genotypes 1, 2, 3, 4, 5, and 6.
- What is the expiration date of patent CN105759918?
The patent was filed on October 29, 2015, and granted on August 9, 2017. Assuming a standard 20-year term from the filing date, the patent is expected to expire around October 29, 2035, in China.
- Does the patent claim any specific pharmaceutical formulations for Compound B?
Yes, the patent claims pharmaceutical compositions comprising Compound B and a pharmaceutically acceptable carrier, with suggested dosage forms including tablets, capsules, injections, and oral solutions.
- What is the current development status of Compound B?
This patent analysis is based on the granted patent filing. Further information regarding the current preclinical and clinical development status of Compound B would require access to Fosun Pharma's recent corporate disclosures and clinical trial registries, which are outside the scope of this patent document analysis.
Citations
[1] Shanghai Fosun Pharmaceutical (Group) Co., Ltd. (2017). Chinese Patent CN105759918A: A novel compound and its preparation method and application. State Intellectual Property Office of the People's Republic of China.
