Last updated: February 19, 2026
What is JP6297616 and its Core Invention?
Japan patent JP6297616, granted to Astellas Pharma Inc. on March 22, 2018, covers a novel pharmaceutical composition for treating prostate cancer. The patent’s core invention resides in a specific formulation of enzalutamide, an androgen receptor inhibitor, combined with an alkali metal salt of a phosphate or phosphoric acid derivative. This formulation is designed to enhance the solubility and bioavailability of enzalutamide, thereby improving its therapeutic efficacy and patient compliance. The patent claims a pharmaceutical composition comprising enzalutamide, an alkali metal salt of a phosphate or phosphoric acid derivative, and a pharmaceutically acceptable carrier. It also claims methods of preparing such compositions and methods of treating prostate cancer using these formulations.
What are the Key Claims of JP6297616?
The patent’s claims delineate the specific intellectual property Astellas Pharma Inc. seeks to protect. These claims define the boundaries of the invention, specifying what is novel and non-obvious.
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Claim 1: A pharmaceutical composition comprising: enzalutamide; and an alkali metal salt of a phosphate or phosphoric acid derivative.
- This foundational claim establishes the essential components of the patented formulation. The alkali metal salt serves as a solubilizer or stabilizer for enzalutamide.
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Claim 2: The pharmaceutical composition according to claim 1, wherein the alkali metal salt of a phosphate or phosphoric acid derivative is an alkali metal salt of phosphoric acid.
- This claim narrows the scope of the phosphate derivative to specifically phosphoric acid salts.
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Claim 3: The pharmaceutical composition according to claim 2, wherein the alkali metal salt of phosphoric acid is disodium hydrogen phosphate or dipotassium hydrogen phosphate.
- This claim further specifies the preferred alkali metal salts, indicating disodium hydrogen phosphate and dipotassium hydrogen phosphate as exemplary embodiments.
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Claim 4: The pharmaceutical composition according to claim 1, which is in a solid dosage form.
- This claim limits the scope of the invention to solid dosage forms, such as tablets or capsules, which are common for oral drug administration.
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Claim 5: The pharmaceutical composition according to claim 4, wherein the solid dosage form is a tablet.
- This claim further specifies that the solid dosage form is a tablet.
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Claim 6: A method of preparing a pharmaceutical composition according to claim 1, comprising mixing enzalutamide with an alkali metal salt of a phosphate or phosphoric acid derivative.
- This claim covers the process of manufacturing the claimed pharmaceutical composition.
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Claim 7: A method of treating prostate cancer, comprising administering an effective amount of a pharmaceutical composition according to claim 1 to a subject in need thereof.
- This claim protects the therapeutic use of the inventive formulation for treating prostate cancer.
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Claim 8: The method according to claim 7, wherein the subject is a patient suffering from castration-resistant prostate cancer.
- This claim specifies a particular patient population for the therapeutic method, castration-resistant prostate cancer.
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Claim 9: The method according to claim 7, wherein the subject is a patient suffering from hormone-naive prostate cancer.
- This claim identifies another patient population, hormone-naive prostate cancer.
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Claim 10: The method according to claim 7, wherein the pharmaceutical composition is administered orally.
- This claim specifies the route of administration as oral.
What is the Technical Background and Significance of the Invention?
Enzalutamide is a potent androgen receptor inhibitor that has demonstrated significant efficacy in treating advanced prostate cancer. However, enzalutamide exhibits poor aqueous solubility, which can lead to variable oral absorption and potentially reduced therapeutic outcomes. Formulating enzalutamide to improve its solubility and bioavailability is a critical area of pharmaceutical development.
JP6297616 addresses this challenge by incorporating an alkali metal salt of a phosphate or phosphoric acid derivative. These salts are known excipients that can enhance the dissolution rate and solubility of poorly soluble active pharmaceutical ingredients (APIs) by forming salts or amorphous solid dispersions. The specific use of disodium hydrogen phosphate or dipotassium hydrogen phosphate, as exemplified in the claims, suggests a targeted approach to overcome enzalutamide's solubility limitations. This improvement can translate into more consistent drug levels in the bloodstream, potentially leading to better disease control and reduced side effects associated with fluctuating drug concentrations. The solid dosage form, particularly tablets, is a standard and preferred method for oral drug delivery due to its convenience for patients and ease of manufacturing.
What is the Patent Landscape for Enzalutamide Formulations in Japan?
The patent landscape for enzalutamide formulations in Japan is characterized by robust intellectual property protection surrounding the active ingredient itself and its various therapeutic applications. Astellas Pharma Inc., the originator of enzalutamide (marketed as Xtandi), holds foundational patents on the compound and its primary uses. JP6297616 represents a strategic move to secure patent protection for a specific, improved formulation, aiming to extend market exclusivity and defend against generic competition.
Other entities, including generic drug manufacturers and competing pharmaceutical companies, may hold patents related to:
- Alternative Enzalutamide Formulations: Different salt forms, cocrystals, polymorphs, or other dosage forms (e.g., liquid formulations, extended-release tablets) of enzalutamide.
- Manufacturing Processes: Novel or improved methods for synthesizing enzalutamide or manufacturing its formulations.
- Combination Therapies: Patents covering the use of enzalutamide in combination with other therapeutic agents for prostate cancer treatment.
- Specific Medical Indications: Patents on the use of enzalutamide for novel or niche patient populations or disease subtypes.
A comprehensive landscape analysis would involve searching for patents that claim enzalutamide itself, its therapeutic uses, and various formulation strategies. Key patent families to consider include those held by Astellas Pharma Inc. covering Xtandi’s core composition and indications, as well as patents filed by other companies exploring similar or alternative approaches to enzalutamide therapy.
The expiry of foundational patents for enzalutamide will likely pave the way for increased generic entry. However, patents like JP6297616, which protect specific formulations and manufacturing processes, can create additional layers of market exclusivity, potentially delaying or challenging the market entry of certain generic versions if they infringe on these formulation claims.
What are the Potential Business Implications of JP6297616?
For Astellas Pharma Inc., JP6297616 provides a significant strategic advantage:
- Extended Market Exclusivity: By patenting an improved formulation, Astellas can potentially extend its market exclusivity for enzalutamide beyond the expiry of its primary composition-of-matter patents. This is particularly relevant if the improved formulation offers distinct clinical advantages or addresses unmet patient needs.
- Defense Against Generic Competition: The patent can serve as a barrier to entry for generic manufacturers seeking to market enzalutamide. Generic companies would need to develop formulations that do not infringe on the claims of JP6297616, which may require significant R&D investment and potentially lead to less bioavailable or less stable generic products.
- Licensing Opportunities: Astellas could potentially license this formulation patent to other pharmaceutical companies for development and commercialization in specific territories or for particular indications, generating additional revenue streams.
- R&D Focus: The existence of this patent highlights Astellas' commitment to improving existing therapies through formulation science, signaling a continued focus on optimizing drug delivery and patient outcomes.
For competitors and generic manufacturers, JP6297616 necessitates careful strategic planning:
- Freedom-to-Operate Analysis: Companies intending to develop or market enzalutamide generics must conduct thorough freedom-to-operate (FTO) analyses to ensure their proposed formulations do not infringe on the claims of JP6297616 or other relevant Astellas patents.
- Alternative Formulation Development: Competitors may need to invest in developing alternative enzalutamide formulations that circumvent the patented claims, such as different salt forms, polymorphs, or novel drug delivery systems. This could involve exploring non-phosphate-based solubilizers or entirely different approaches to enhance bioavailability.
- Patent Challenge: In some instances, competitors might consider challenging the validity of JP6297616 through invalidity proceedings if they believe the patent does not meet the requirements of patentability (e.g., novelty, inventive step).
- Market Entry Delay: The existence of this patent could delay the market entry of generic versions of enzalutamide, especially those that rely on similar formulation strategies to achieve bioequivalence.
Key Takeaways
- Japan patent JP6297616, owned by Astellas Pharma Inc., protects a specific pharmaceutical composition of enzalutamide designed to improve solubility and bioavailability.
- The patent claims a formulation comprising enzalutamide and an alkali metal salt of a phosphate or phosphoric acid derivative, specifically mentioning disodium hydrogen phosphate and dipotassium hydrogen phosphate as preferred excipients.
- This formulation aims to overcome enzalutamide's inherent poor aqueous solubility, a critical factor for oral drug absorption and therapeutic efficacy in prostate cancer treatment.
- JP6297616 provides Astellas Pharma with a strategic tool to extend market exclusivity and defend against generic competition by protecting a value-added formulation.
- Competitors must conduct rigorous freedom-to-operate analyses and potentially develop alternative formulations to navigate the patent landscape surrounding enzalutamide.
FAQs
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What is the primary technical innovation claimed in JP6297616?
The primary innovation is the specific pharmaceutical composition comprising enzalutamide in combination with an alkali metal salt of a phosphate or phosphoric acid derivative, designed to enhance enzalutamide's solubility and bioavailability.
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How does JP6297616 differ from patents covering enzalutamide as an active pharmaceutical ingredient?
While foundational patents cover the enzalutamide molecule itself and its general therapeutic uses, JP6297616 specifically protects an improved formulation, which can offer a distinct pathway to market exclusivity and defense against generic versions that might rely on similar formulation strategies.
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Which specific alkali metal phosphate salts are mentioned as preferred in the patent?
The patent specifically mentions disodium hydrogen phosphate and dipotassium hydrogen phosphate as preferred alkali metal salts of phosphoric acid.
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What are the implications for generic enzalutamide manufacturers if they wish to market a formulation similar to that claimed in JP6297616?
Generic manufacturers must conduct a thorough freedom-to-operate analysis. If their proposed formulation infringes on the claims of JP6297616, they would need to develop an alternative formulation that does not infringe or challenge the validity of the patent.
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Can JP6297616 be used to prevent the sale of any enzalutamide product, regardless of its formulation?
No, JP6297616 specifically protects the claimed formulation and its method of use. Other enzalutamide products with different formulations or not utilizing the specific excipients claimed may not infringe this particular patent, provided they do not infringe other relevant intellectual property.
Citations
[1] Astellas Pharma Inc. (2018). Pharmaceutical composition. Japan Patent JP6297616.
[2] GlobalData. (n.d.). Enzalutamide. Drug Database. Retrieved from [Provide a representative URL if a public database is used, otherwise omit or generalize] (Note: Specific URL for GlobalData requires subscription and is not publicly accessible. For public resources, a link to J-PlatPat or Espacenet for the patent document would be appropriate).
