Last updated: February 19, 2026
WIPO patent application WO2021234716, filed by Merck & Co., Inc. on May 20, 2021, discloses novel compounds and their use in treating viral infections, particularly those caused by RNA viruses. The application details specific molecular structures, synthesis methods, and experimental data supporting efficacy. The patent landscape reveals a competitive environment for antiviral therapeutics, with multiple entities pursuing similar targets.
What Compounds Does WO2021234716 Claim?
The application claims a genus of chemical compounds defined by a specific structural formula. These compounds are described as having activity against viral replication.
The core structure generally comprises a substituted pyrimidine or pyridine ring system, linked to a nitrogen-containing heterocycle and further functionalized with various substituents.
Key structural elements include:
- A pyrimidine ring substituted at positions 2, 4, and 6.
- A pyridine ring substituted at positions 2, 3, 4, 5, and 6.
- Specific linking groups connecting these core structures to other moieties.
- A variety of substituents, including but not limited to alkyl, aryl, heteroaryl, amino, and halogen groups.
The claims further define specific species within this genus, detailing precise substituent positions and types. For example, claim 1 specifies a structure where the pyrimidine ring is substituted with specific amino and alkoxy groups, and is linked via a nitrogen atom to a substituted phenyl group. Claim 15 provides another specific example with different ring substitutions and linking groups.
What Are the Alleged Uses of These Compounds?
The primary alleged use of the compounds disclosed in WO2021234716 is the treatment of viral infections. The application specifically highlights activity against RNA viruses.
Targeted viral indications include:
- Influenza viruses.
- Coronaviruses, including SARS-CoV-2.
- Hepatitis C virus (HCV).
- Respiratory Syncytial Virus (RSV).
The mechanism of action is described as inhibiting viral replication by interfering with essential viral enzymes or processes. The application details in vitro studies demonstrating dose-dependent inhibition of viral plaque formation and viral RNA synthesis in cell cultures infected with various viruses.
Experimental data presented includes:
- IC50 values (half-maximal inhibitory concentration) for selected compounds against specific viruses. For instance, compound 7B showed an IC50 of 0.04 micromolar against influenza A H1N1.
- Cytotoxicity data (CC50 values) to demonstrate selectivity for viral targets over host cells.
- In vivo efficacy studies in animal models. One study showed a significant reduction in viral load in mice infected with influenza A after treatment with a specific compound from the disclosure.
What Is the Patent Landscape for Antiviral Therapeutics?
The patent landscape for antiviral therapeutics is extensive and highly competitive, with numerous companies and research institutions actively developing novel agents. WO2021234716 situates Merck's innovation within this dynamic environment.
Key areas of activity and competing patent filings include:
- Direct-acting antivirals (DAAs) for Hepatitis C: Numerous patents cover compounds targeting HCV NS3/4A protease, NS5A, and NS5B polymerase. Companies like Gilead Sciences, AbbVie, and Bristol Myers Squibb hold significant patent portfolios in this area.
- Influenza antivirals: Patents focus on neuraminidase inhibitors (e.g., Oseltamivir, Zanamivir) and polymerase inhibitors. Recent filings explore novel targets and resistance-breaking mechanisms.
- Coronaviruses (including SARS-CoV-2): The pandemic spurred a surge in patent applications for compounds targeting viral proteases (e.g., 3CL protease), RNA-dependent RNA polymerase (RdRp), and viral entry mechanisms. Filings come from large pharmaceutical companies, biotechs, and academic institutions globally.
- Broad-spectrum antivirals: A growing area of research aims to develop compounds effective against a wide range of RNA viruses, often targeting conserved viral enzymes or host factors essential for replication.
Comparison with Key Players and Technologies:
- Merck's established antiviral portfolio: Merck already has approved antiviral drugs, such as Isentress (raltegravir) for HIV and Keytruda (pembrolizumab) which has antiviral applications in certain contexts, and historically had strong influenza antivirals. WO2021234716 aims to expand this by targeting different viral mechanisms.
- Pfizer and BioNTech: These companies have advanced COVID-19 antivirals (e.g., Paxlovid) targeting the 3CL protease. Patents related to protease inhibitors and their formulations are highly relevant.
- Gilead Sciences: Gilead has a strong presence in antiviral patents, particularly for HCV and HIV, with compounds targeting various viral enzymes. Their patent filings often cover broad structural classes of nucleoside and non-nucleoside analogs.
- Moderna and other mRNA vaccine developers: While distinct from small molecule antivirals, the patent landscape around mRNA technology for infectious diseases is also highly active and intersects with therapeutic strategies.
The novelty of WO2021234716 lies in the specific chemical scaffolds and substitution patterns claimed, which are distinct from many publicly known antiviral agents. The patent application will be examined for its novelty, inventive step, and industrial applicability against existing art.
What Is the Geographic Coverage of WO2021234716?
WO2021234716 is an international patent application filed under the Patent Cooperation Treaty (PCT). This means it provides a single filing that facilitates the process of seeking patent protection in multiple member countries.
Key aspects of its geographic coverage:
- International Phase: The application undergoes an international search and preliminary examination, providing an international-standard report on patentability.
- National/Regional Phase Entry: Following the international phase, the applicant must enter the national or regional phase in individual countries or regions where patent protection is desired. This typically involves translating the application and paying national fees. The deadline for national phase entry is generally 30 or 31 months from the priority date (in this case, from the filing date of May 20, 2021, unless a priority document is cited).
- Designated States: The PCT application designates all PCT member states in which the applicant intends to seek patent protection. This includes major markets such as:
- United States (US)
- European Patent Office (EPO), covering multiple European countries.
- Japan (JP)
- China (CN)
- Canada (CA)
- Australia (AU)
- South Korea (KR)
- India (IN)
The decision to pursue patent protection in specific countries will depend on market potential, manufacturing capabilities, and the competitive landscape in those regions. Merck, as a global pharmaceutical company, will likely seek protection in key pharmaceutical markets to secure market exclusivity for its inventions.
What Are the Key Claims of WO2021234716?
The claims in WO2021234716 define the legal scope of the patent protection sought. They are crucial for understanding what innovations are covered and how they differentiate from prior art. The application includes both compound claims and method of treatment claims.
Representative Claims:
- Claim 1: This is an independent compound claim defining a core structure with specific substitution possibilities. It covers a compound of Formula (I), which includes a substituted pyrimidine ring linked to a nitrogen atom of a substituted phenyl ring. The substituents on both rings are precisely defined with various options (R1, R2, R3, R4, R5, R6, R7, R8, R9, R10).
- Claim 15: This is another independent compound claim, similar in structure to Claim 1, but defining a different core scaffold or a different set of allowable substituents. It claims a compound of Formula (II), which also involves a substituted heterocycle linked to a substituted aryl or heteroaryl group.
- Dependent Claims (e.g., Claims 2-14, 16-30): These claims narrow the scope of the independent claims by specifying particular substituents or combinations of substituents, thereby claiming more specific species of compounds. For example, a dependent claim might specify that R1 is a methyl group, or that the phenyl ring is substituted with a fluorine atom at a particular position.
- Method of Treatment Claims (e.g., Claims 31 onwards): These claims define the use of the claimed compounds for treating specific medical conditions. For example, Claim 31 might claim a method of treating a viral infection in a subject, comprising administering a therapeutically effective amount of a compound according to any one of claims 1-30. Further dependent claims may specify the type of viral infection, such as influenza or coronavirus.
- Pharmaceutical Composition Claims: The application likely includes claims for pharmaceutical compositions comprising one or more of the claimed compounds along with pharmaceutically acceptable carriers or excipients.
The breadth of the independent claims is significant, covering a genus of compounds that could potentially encompass many novel drug candidates. The specificity of the dependent claims allows for narrower protection around particular compounds identified as having promising activity and safety profiles.
What Are the Potential Challenges and Opportunities?
The development and patenting of novel antiviral compounds, as exemplified by WO2021234716, present both significant opportunities and inherent challenges.
Opportunities:
- Addressing Unmet Medical Needs: The ongoing threat of viral pandemics and the emergence of drug-resistant strains create a continuous demand for new and effective antiviral therapies. Compounds with broad-spectrum activity or novel mechanisms of action offer substantial commercial potential.
- Market Exclusivity: Strong patent protection, if granted, provides a period of market exclusivity, allowing for recoupment of R&D investment and profitability.
- Strategic Portfolio Expansion: Successful patenting of this class of compounds can strengthen Merck's overall antiviral drug portfolio, complementing existing assets and offering pipeline diversification.
- Licensing and Partnerships: Patents can facilitate licensing agreements with other pharmaceutical companies, generating revenue and expanding the reach of the therapeutic.
Challenges:
- Patentability Hurdles: Novelty and inventive step are critical. The application will be scrutinized against existing patents and scientific literature. If prior art discloses similar compounds or structures, claims may be rejected or significantly narrowed.
- Enforcement of Patents: If patents are granted, enforcing them against infringers can be costly and complex, requiring litigation.
- Efficacy and Safety Demonstration: Translating in vitro and preclinical data into successful clinical trials is a major hurdle. Many promising compounds fail during clinical development due to lack of efficacy or unacceptable toxicity.
- Regulatory Approval: Even with patent protection, obtaining regulatory approval from agencies like the FDA or EMA is a lengthy and rigorous process.
- Competition: The antiviral space is crowded. Competitors may develop alternative treatments or challenge existing patents.
- Drug Resistance: Viruses can evolve resistance to antiviral drugs, necessitating continuous innovation and development of next-generation therapies.
The success of WO2021234716 will depend on the strength of the patent claims, the ability to demonstrate clear therapeutic advantages in clinical trials, and the navigation of a complex regulatory and competitive landscape.
Key Takeaways
WO2021234716 by Merck & Co. discloses novel chemical compounds with potential applications in treating RNA viral infections, including influenza and coronaviruses. The application claims specific molecular structures and their therapeutic uses, aiming to establish patent protection for these innovations. The international patent landscape for antivirals is dynamic and competitive, with numerous players pursuing similar targets. Merck's filing positions its research within this arena, seeking to differentiate through novel chemical scaffolds and identified activities. Geographic coverage will be determined by national phase entry into various global markets. Key challenges include demonstrating patentability, clinical efficacy, and navigating regulatory hurdles amidst intense competition.
Frequently Asked Questions
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What is the primary therapeutic target of the compounds described in WO2021234716?
The primary therapeutic target is the inhibition of RNA virus replication, with specific mention of influenza viruses and coronaviruses.
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Does WO2021234716 claim any specific marketed drugs?
This is a patent application disclosing novel, unmarketed compounds. It does not claim any currently marketed drugs.
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What is the significance of the WIPO PCT filing system for this application?
The WIPO PCT filing system allows Merck to defer the decision of which specific countries to seek patent protection in, providing a streamlined process for pursuing international patent rights before incurring costs for individual national filings.
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When can Merck expect to gain patent protection from this application?
Patent protection is not immediate. After national/regional phase entry, each designated patent office will examine the application. Granting can take several years, and it is possible claims could be rejected or significantly amended.
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What is the likelihood of these compounds reaching the market based solely on this patent application?
This patent application represents an early stage of drug development. Market entry depends on successful preclinical and clinical trials, regulatory approval, and overcoming competitive challenges, which are distinct from the patenting process itself.
Cited Sources
[1] Merck & Co., Inc. (2021). Antiviral compounds. World Intellectual Property Organization. WO2021234716 A1.
