KUBOTA

July 8, 2025

Patent News

Research and Study on the Establishment of a Mechanism to Incorporate the Opinions of Experts on Pharmaceutical Patents in the Japanese Patent Linkage System

The Ministry of Health, Labour and Welfare (hereinafter referred to as “MHLW”) has adopted a patent linkage system under which, when reviewing applications for manufacturing and marketing approval (“MA”) of generic drugs and biosimilars (hereinafter referred to as “generic drugs, etc.”), it reviews whether there is any infringement of patents covering originator drugs and leading biopharmaceuticals (hereinafter referred to as “originator drugs, etc.”) and determines whether MA should be granted or denied. To improve the operation of this patent linkage system, a research team was established, and on June 30, 2025, a report on the survey and research was published. This report summarizes the results of the survey and consideration regarding the following three points: (1) the scope of patents considered in the MA review of generic drugs, etc., (2) the criteria for reviewing the existence of patent infringements and determining the MA of generic drugs, etc., and (3) proposals for mechanisms to incorporate the opinions of experts in pharmaceutical patents into the system. Going forward, based on this report, discussions are expected to proceed regarding the introduction of a system for soliciting opinions from experts to improve the patent linkage system.

Background
From the perspective of ensuring a stable supply of pharmaceuticals, the MHLW checks whether there is any infringement of patents covering originator drugs, etc., including substance patents for active ingredients and use patents related to indications, dosage and administration, when reviewing applications for MA of generic drugs, etc., and then decides whether to approve them.
This version of Japanese patent linkage worked if the infringement of a patent was straightforward but because the MHLW did not have any people who were trained for judging patent infringement, it was sometimes difficult for the MHLW to come to a conclusion.
This became more complicated after the Oxaliplatin® case (Intellectual Property High Court (“IP High Court”), Special Division, January 20, 2017, Case number: 2016 (Ne)10046), where the IP High Court, Special Division ruled that the scope of extended patent rights covers those generic drugs, etc. that are “substantially similar” to the original drugs, etc. and the MHLW had to judge what was “substantially similar”.
Under these circumstances, on July 25, 2024, the Pharmaceutical and Medical Devices System Council of the Health and Medical Sciences Council of Japan approved the following draft guidelines for improving the operation of the patent linkage system in the approval review of generic drugs, etc., as proposed by the Pharmaceutical Affairs and Food Safety Bureau of the MHLW.

Establish a research group to investigate and analyze the following items (1) to (3).
(1) The definition and scope of “substance patents” and “use patents” of originator products considered in the MA review of generic drugs (particularly biosimilar drugs).
(2) Procedures for confirming the absence of patent infringement and criteria for determining the approval or rejection of generic drugs.
(3) Mechanisms to incorporate the opinions of experts in pharmaceutical patents
Based on the results of the research, advance discussions on the introduction of a system for soliciting opinions from experts* to improve the patent linkage system.

Summary of the Report

1 Types of patents considered in the MA review of generic drugs, etc., and definitions and scope of “substance patents” and “use patents” for original drugs, etc.

Patents other than substance patents and use patents related to the active ingredients of drugs (e.g., manufacturing method patents) will not be subject to patent linkage, as in the past.
Substance patents subject to patent linkage are those that seek to identify the active ingredient of a pharmaceutical product itself by specifying the chemical formula, etc., as the inventive subject matter, and where it is clear from the description at the end of the claims that the subject matter is a substance.
The term “substance patent” here does not include patents that specify only “salts,” “crystals,” or “hydrates” as the inventive subject matter, nor does it include claims relating to compounds defined by a manufacturing method (product-by-process claims).
A use patent subject to patent linkage is a patent that has a pharmaceutical use as its inventive feature, which is specified in the claims, and where the patent claims clearly indicate that the invention is for pharmaceutical use through the use of terms such as “therapeutic agent,” “therapeutic composition,” or “therapeutic drug” at the end of the claims.
Second medical use inventions, patent for an invention for medical use for a specific disease with specified dosage and administration, such as administration time, administration procedure, dosage, administration site, etc., (dosage and administration patents), patents that subdivide target patients and treatment regimens and include in the claims wording that is not found in the package inserts of the original drugs regarding indication, dosage, and administration (one of treatment method patent) and also Swiss-type claims are also considered as a type of use patent.
Patents for biopharmaceuticals that should be subject to patent linkage are the same as above. Substance patents are patents that include claims covering, for example, amino acid sequences or nucleic acids themselves, while use patents are patents that include claims covering the diseases, etc., to which such substances are applied.

2 Evaluation criteria for patent infringement risks by experts

Experts should evaluate patent infringement risks from the perspective of “how likely it is that a court would grant an injunction against the manufacture and sale of a generic drug in the event of a patent infringement lawsuit after the approval and start of manufacturing and sales of a generic drug for which an MA application has been filed.”
In principle, experts should not evaluate patent infringement risks based on equivalent infringement or indirect infringement.
In principle, the composition and use of Generic drugs, etc. for which MA has been applied shall be determined by referring to the package inserts of the original drugs.
If all of the elements in the patent claims are met by the Generic drugs, etc. for which MA has been applied, it is generally interpreted as falling within the technical scope of the patented invention, and the risk of patent infringement is evaluated as high. However, if there are elements that are different from the Generic drugs, etc. for which MA has been applied in the patent claims, it is generally interpreted as not falling within the technical scope of the patented invention, and the risk of patent infringement is evaluated as low.
When the patent for the original drugs, etc. is a substance patent, the risk of patent infringement shall be evaluated primarily based on whether Generic drugs, etc. for which MA has been applied falls within the technical scope of the patent invention of the original drugs, etc.
When the sole issue is whether the Generic drugs, etc. for which MA has been applied falls within the technical scope of a patent, and a determination procedure was filed before the Patent Office, any result of such determination submitted by the applicant for the MA of the generic drugs, etc. or the manufacturer of the original drugs, etc. shall be referenced.
When the patent for the original drugs, etc. is a use patent, in addition to the comparison of the patent claims to the Generic drugs, etc. described above, the likelihood of the Generic drugs, etc. for which MA has been applied being used for the purpose of the patent invention of the original drugs, etc. is also examined. If such likelihood is high, the risk of infringement of the patent is evaluated as high.

3 Guidelines for the Operation of the Expert System in Patent Linkage (Draft)

An expert system will be introduced to reflect the opinions of experts on pharmaceutical patents in the patent linkage system.
To ensure the effectiveness of the expert system, the Drug Patent Information Report Form, which has been submitted on a voluntary basis, must be submitted within a specified period.
Experts will receive publicly available information such as patent bulletins from the MHLW and materials provided by the relevant companies with their consent, receive an overview of the case, and after deliberation (by a panel of three or five members), shall jointly prepare an opinion paper on patent infringement risks and submit it to the MHLW.
The opinion should be a neutral, expert opinion provided by the expert to the MHLW and has no legal binding force.
The MHLW will review the content of the opinion submitted by the experts, evaluate the existence or absence of patent infringement from the perspective of ensuring the stable supply of pharmaceuticals, and make the final decision on the approval or rejection of generic drugs, etc.
The MHLW will select candidates for experts from among individuals who meet the selection criteria, including academics, lawyers, and patent attorneys, and publish a list of their names and affiliations on the MHLW website.
When the MHLW deems it necessary to seek opinions from experts on pharmaceutical patents during the MA review of generic drugs, etc., it will select individuals from the list of expert candidates who meet the appointment criteria and confirm that they do not have any special conflicts of interest that could raise doubts about the fairness of the review, and appoint them as experts for the relevant case and entrust them with the relevant duties.
When the MHLW decides to seek opinions from experts regarding the presence or absence of patent infringements between originator drugs, etc. and generic drugs, etc., it shall notify the applicant for MA of the generic drugs, etc. and the originator company of such decision.
Upon receiving such notification, the applicant for MA of the generic drugs, etc., and the originator company shall identify the documents, including written opinions on the existence or non-existence of patent infringement, relevant case law and academic opinions, and expert opinions or expert reports from external experts, that they consent to be shared with the experts by the MHLW, and notify the MHLW thereof.
After publicly announcing the final decision on the MA of the generic drugs, etc., the MHLW shall promptly disclose the opinion submitted by the experts to the applicant for MA of the generic drugs, etc., and the originator company of the product under review who requests disclosure of the opinion. However, the following information shall be deemed confidential and the relevant portions shall be redacted:

Discussion
It is unclear whether the scope of patents considered in the MA review of generic drugs, etc., will be the same as that indicated in this report in future improvements to the patent linkage system. This report states that Swiss-type claims (e.g., “Use of compound Y for the manufacture of drug X”) are also considered as a type of use patent. However, regarding Swiss-type claims, a research collaborator of this report also note that “the Japan Patent Office and others interpret them as ‘methods for using substance Y for the manufacture of therapeutic X,’ i.e., as (simple) method inventions”, there is doubt as to whether courts will interpret Swiss type claims as use patents for drugs under Japanese patent law, which stipulates that the effect of a (simple) method invention extends only to the act of implementing that method and not necessarily to the final product.

Written by: Ms. Emiko Yano (Patent Attorney)