JAPAN Trends and Developments Contributed by: Kenji Tosaki and Takahiro Hatori, Nagashima Ohno & Tsunematsu
ing the brand-name drug under the Japanese patent linkage system could constitute unfair competition under Article 2 (1)(xxi) of the UCPA, and applicants for marketing authorisation for follow-on drugs would have no chance to obtain the court’s view on the pat ‑ ent infringement. The Tokyo District Court issued a judgment with the same ruling on 29 October 2025 concerning Nihon Generic Co., Ltd. v Bayer Yakuhin . On the other hand, according to the Tokyo District Court’s decision on 28 October 2024 in the case of Samsung Bioepis Co., Ltd. v Bayer HealthCare LLC ., the unfair competition possibility was left open. That said, this is the first instance decision, and the pos ‑ sibility could be denied by the IPHC. Two Judgments Addressing the Scope of a Patent During its Extended Term Introduction The term of a patent expires 20 years after the pat ‑ ent application filing date (Article 67 (1) of the Patent Act). However, a patent term extension (PTE) (ie, an extension of the term of a patent beyond the standard duration) may be granted when a marketing authorisa ‑ tion is required to implement the patented medicinal invention (Articles 67 (4) and 67-7 (i) of the Patent Act). When a PTE is granted, the scope of the patent dur ‑ ing the extended term is limited to the drug that was the subject of the marketing authorisation on which the PTE was based, and only for the use specified in that authorisation (Article 68-2 of the Patent Act). This means that, in order to exercise rights under a patent during its extended term, the patentee must prove that: (i) the allegedly infringing drug falls within the technical scope of the patented invention; (ii) this drug is the same as the drug that was the subject of the marketing authorisation on which the PTE was based; and (iii) the allegedly infringing drug is used for the use specified in that authorisation. On 20 January 2017, the IPHC addressed the inter ‑ pretation of Article 68-2 for the first time in a patent infringement case in Debiopharm International SA v Towa Pharmaceutical Co., Ltd . The IPHC held that the scope of the patent during the extended term covers not only a “product” (drug) specified by the “ingredi ‑ ents, quantity, dosage, administration, indication, and
usage” stipulated in the marketing authorisation but also those considered substantially identical as phar ‑ maceuticals. Even when the allegedly infringing drug differs from the configuration set out in the marketing authorisation, if such differences are merely minor or insignificant as a whole, the allegedly infringing drug is considered substantially identical to the drug sub ‑ ject to the marketing authorisation and falls within the scope of the patent during its extended term. In Debiopharm, the IPHC further identified four cate ‑ gories of drugs that may be considered “substantially identical”. Among them, the first category refers to cases in which the patented invention is characterised solely by the active ingredient of a drug, and where some inactive ingredients are added or modified using techniques that were well-known and conventional at the time of the marketing authorisation application. It should be noted that, in Debiopharm, the IPHC ulti ‑ mately held that the alleged infringing drug did not fall within the technical scope of the patented invention, without even considering the limitation under Article 68-2. Therefore, the court’s statements regarding Arti ‑ cle 68-2 in Debiopharm should still be regarded as obiter dicta. Prior to the Tokyo District Court’s judgment on 15 May 2025, there had been no judicial precedent addressing the interpretation of Article 68-2 in a case where the court determines that, or the alleged infringer admits that an allegedly infringing drug fell within the techni ‑ cal scope of a patent for which a PTE was granted. Sawai Pharmaceutical Co., Ltd. v Bristol-Myers Squibb Facts Bristol-Myers Squibb Company (“BMS”) is the pat ‑ entee of Japan Patent No 3,989,175 (“the Patent”). The filing date is 12 April 2000. Claim 9 of the Patent reads: “a compound of the following formula or a salt thereof [formula omitted].” PTEs for the Patent were granted for a period of one year, five months and 24 days based on the market ‑ ing authorisations for “Sprycel® Tablets 20mg” and “Sprycel® Tablets 50mg” (collectively, “Sprycel®
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