September 1, 2021

Patent News

The Tokyo District Court denied patent infringement of the generic drug of Remitch® OD Tablets 2.5 μg.

Toray Co., Ltd. ("Plaintiff"), which owns Japanese Patent No. 3531170 ("Patent"), filed a patent infringement action for seeking injunction and damages against Sawai Pharmaceutical Co., Ltd. and Fuso Pharmaceutical Industries, Ltd. (collectively, "Defendants"), by claiming that the Defendants’ generic drugs (“Defendants' Generic Drugs) infringe the Patent. The Tokyo District Court dismissed the Plaintiff's request, by saying that neither literal infringement nor infringement under the doctrine of equivalents (“DoE”) is not established (Tokyo District Court Judgement, 30 March 2021 (Case numbers: 2018(wa)38504 and 2018(wa)38508).

Summary of the case

The Plaintiff is the owner of the Patent and manufactures and sells antipruritic drugs under the trade name of "Remitch OD Tablets 2.5 μg".

The filing date of the Patent is November 21, 1997, and the title of the invention is "antipruritic drug". The Plaintiff filed an application for the registration of extension of the duration of the Patent on June 29, 2017, but the Japan Patent Office (“JPO”) did not approve the extension, so the Plaintiff filed an action to revoke the JPO’s decision (“Revocation Action”). The Revocation Action was still pending when the oral hearing of the patent infringement action ended.

The Defendants obtained approvals for manufacturing and marketing of the Defendants' Generic Drugs on 15 February 2018 that is 20 years after the filing date of the Patent. The Defendants’ Generic Drugs have been manufactured and sold since 15 June 2018 when the Defendants’ Generic Drugs were listed in the National Insurance drug price list.

The chronological order is summarized below.

21 November 1997: The Patent application was flied

29 June 2017: The application for the registration of extension of the duration of the Patent was filed

(20 years have passed from the application date)

15 February 2018: Defendants obtained approvals for manufacturing and marketing of Defendants’ Generic Drugs

15 June 2018: Defendants started manufacturing and selling Defendants’ Generic Drugs

30 March 2020: The JPO denied the application for the registration of extension of the duration of the Patent

(The Plaintiff filed the Revocation Action)

Patent and Defendants’ Generic Drugs

Claim 1 (“Invention”) of the Patent is divided into the elements as follows (the general formula is omitted).

A. Antipruritic drug comprising,

B. the active ingredient which is an opioid κ receptor-operated compound (“Compound”) represented by the general formula (I).

Defendant's formulation
a. Antipruritic drug containing,
b. nalfurafine hydrochloride

The nalfurafine hydrochloride (Element b) contained in the Defendants' Generic Drugs does not fall under the Compound (Element B), but the nalfurafine (free form) falls under the Compound (Element B).

Both the Plaintiff's Drug and the Defendants' Generic Drugs contain nalfurafine hydrochloride in the tablet, and when administered to humans, nalfurafine (free form) is released from nalfurafine hydrochloride and absorbed by the living body to exert an antipruritic effect.

The parties disputed over which one of the nalfurafine hydrochloride and the nalfurafine (free form) should be seen as the "active ingredient" of the Invention.

Judgment
The Tokyo District Court denied the Plaintiff’s request by ruling the decisions in the following two issues.

Issue 1: Does the Defendants' Generic Drugs use nalfurafine (free form) that is the Compound as the "active ingredient"?

Issue 2: Are the Defendants' Generic Drugs equivalent to the constitution of the Invention?

(1) Issue 1 (Literal Infringement)

The Tokyo District Court held that a person skilled in the art would have understood that the term, "active ingredient" in Element B, means a drug substance that is composed as a pharmaceutical product by adding an additive, based on descriptions of publications relating to pharmaceutical products. On the other hand, since the Defendants' Generic Drugs use nalfurafine hydrochloride as the drug substance, the Tokyo District Court judged that the "active ingredient" corresponding to Element B in the Defendants' Generic Drugs is not nalfurafine (free form), but nalfurafine hydrochloride which is acid addition salt, therefore, the Defendants' Generic Drugs do not satisfy Element B.

The Plaintiff argued that the "active ingredient" of Element B means a portion that is absorbed into the body and has a pharmacological action (i.e., nalfurafine (free form)), and submitted evidence supporting its argument. The Tokyo District Court denied the Plaintiff's argument by saying that the evidence submitted by the Plaintiff was not related to the pharmaceutical product, and even if it was related to the pharmaceutical product, it cannot be said to be related to the composition of the pharmaceutical product.

(2) Issue 2 (Infringement under the DoE)
As stated above, the Tokyo District Court held that the Defendants’ Generic Drugs differ from the Invention as while the Invention contains nalfurafine (free form) as an active ingredient, the Defendants’ Generic Drugs contain nalfurafine hydrochloride as an active ingredient. Then, the Tokyo District Court considered whether infringement under the DoE is established for the Defendants' Generic Drugs.

If no literal infringement is found because elements of the accused product are different from the elements of the patented invention, patentees can claim infringement under the doctrine of equivalents only where all five conditions are met, as the Supreme Court previously ruled. Regarding the fifth condition, the Tokyo District Court followed the following requirement that was indicated by the Supreme Court in the Maxacalcitol case.

"In the case where at the time of filing a patent application, while the applicant could easily conceive a configuration in the accused product that is different from the claim of the patent, the applicant did not include such a different configuration in the claim, if it can be said that, objectively and externally, the applicant has indicated that the configuration relating to the product is not included in the claim while recognizing that it substitutes for the configuration described in the claim, the accused product is deemed to be consciously excluded from the scope of claim"(Supreme Court Judgement on 24 March 2017( 2016 (received) No. 1242 No.)

In addition to the Compound (nalfurafine (free form)), the original specification of the Patent explicitly disclosed an acid addition salt containing a hydrochloride of the Compound. Therefore, the Tokyo District Court found that (i) while the Plaintiff who is the applicant could easily conceive a composition containing the pharmacologically acceptable acid addition salt of the Compound as an active ingredient at the time of filing the application, the Plaintiff did not include such configuration in the claim, (ii) moreover, it can be said that, objectively and externally, the Plaintiff has indicated that nalfurafine hydrochloride replaces the configuration containing nalfurafine (free form) as an active ingredient, and the Tokyo District Court held that Defendants' Generic Drugs containing nalfurafine hydrochloride as the active ingredient is consciously excluded from the claim of the Patent, and the infringement under the DoE is not established.

Comments
Regarding the Patent, on 25 March 2021 that was just before this judgment was rendered, the IP High Court cancelled the JPO’s decision of refusal for application for extension of duration registration in the Revocation Action (Case number: 2020 (Gyo-ke) 10063).

The Plaintiff filed an application for extension of the duration registration based on the approval of a drug containing nalfurafine hydrochloride as an active ingredient. The JPO denied the extended registration since the Invention does not include the drug containing nalfurafine hydrochloride as an active ingredient. On the other hand, the IP High Court ruled that it should not be formally judged from the descriptions of "active ingredient" stated in the approval certificate when deciding to extend the duration, and found that the active ingredient of the drug subject to the approval is both nalfurafine (free) and nalfurafine hydrochloride and cancelled the JPO’s decision.

In interpreting the "active ingredient," the IP High Court examined publications relating to pharmaceutical products, publications relating to pharmaceutical products containing nalfurafine hydrochloride, publications on handling of active ingredients in pharmaceutical administration, and expert opinions, and found that a person skilled in the field of pharmaceuticals may consider not only the additive salt contained in a pharmaceutical product but also its free form as an "active ingredient", paying attention to the desired efficacy and action of the pharmaceutical product, unlike the Tokyo District Court. The publications cited in the Tokyo District Court's judgment and the IP High Court's judgment were different, but we assume that the same evidence was submitted in the proceedings filed in parallel. The Plaintiff has appealed against the Tokyo District Court’s judgement. Although the situations of extension of the duration registration and patent infringement lawsuit are different, the interpretation of the same term, "active ingredient", was divided between the Tokyo District Court and the IP High Court. It is interesting to see how the IP High Court, which is the appeal court of this judgement of the patent infringement case, decides.
In the Maxacalcitol case, the “cis” form of vitamin D structure was claimed and the “trans” form of vitamin D structure was not disclosed in the patent specification, therefore, the court judged that the infringement under the DoE was found in the manufacturing method using the “trans” form of the vitamin D structure. On the other hand, in the instant case, since hydrochloride was disclosed in the specification of the Patent in addition to the free form, the Court judged that the fifth requirement under the DoE was not satisfied.
At the time of filing the application of the Patent, the antipruritic drug containing a pharmacologically acceptable salt as an active ingredient was described in the claims and the specification but, the antipruritic agent containing a pharmacologically acceptable salt as an active ingredient was removed from the scope of claims by the amendment made in response to the notice of reasons for refusal. Based on such prosecution history, the JPO determined that the antipruritic drug containing a pharmacologically acceptable salt as an active ingredient was considered to have been excluded from the scope of claims. In this regard, the Plaintiff argued in the Revocation Action, that the amendment was made for practical and technical reasons in order to deal with the violation of the enablement requirement and the breach of the clarity requirement, and the amendment did not mean to exclude the antipruritic drug containing a pharmacologically acceptable salt as an active ingredient. In the Revocation Action, the IP High Court found that the active ingredient of the drug subject to the drug approval was both nalfurafine (free form) and nalfurafine hydrochloride regarding the "active ingredient" in the "Plaintiff’s product". However, the IP High Court did not judge on the interpretation of the "active ingredient" in the "Invention" and did not judge whether the antipruritic drug containing the acid addition salt as the active ingredient was intentionally excluded. The Tokyo District Court in the instant case made the above-mentioned judgment based on the description of the examples stated in the specification without mentioning the prosecution history and purpose of the amendment.

In the Maxacalcitol case, the Supreme Court ruled that “such as the case where it is stated in the specification that the configuration described in the claim can be replaced with the configuration related to the accused product regarding the part that is different from the accused product in the configuration described in the claim, when it can be said that the applicant indicated that, objectively and externally, the configuration related to the accused product was not described in the claim while recognizing that it would replace the configuration described in the claim, since a third party who receives the disclosure of the specification would also understand that the accused product is excluded from the scope of claim based on such an indication, it can be said that the applicant has taken an action that is understood to have approved that the accused product does not fall into the technical scope of the patented invention." The above underlined example can apply to the instant case as it is.

Written by: Ms. Kiyoko Nakaoka (Attorney at Law and Patent Attorney)