Biologics Patent Dispute between Amgen and Sanofi in Japan

A Darts-ip user, Japanese Patent Attorney Ms. Yasuko Tanaka from S-Cube Corporation, introduces a recent remarkable Japanese patent decision in pharma sector.

Biologics Patent Dispute between Amgen and Sanofi in Japan

darts-030-276-G-ja: Tokyo District Court Case 平成29(ワ)16468 on Jan. 17, 2019


Amgen (Plaintiff) owns two patents both titled “Antigen binding proteins to protein convertase subtilisin kexin type 9 (PCSK9)” (JP5705288 and JP5906333).
Sanofi (Defendant) imports and sells an anti-PCSK9 antibody drug Praluent® that includes a monoclonal antibody “alirocumab” binding to PCSK9 and reduce blood LDL cholesterol by inhibiting the binding of PCSK9 and LDL receptor. Plaintiff who also markets an anti-PCSK9 antibody drug Repatha® (evolocumab) sued Defendant for injunction and disposal of their drug in the Tokyo District Court (TDC).

Claimed inventions at issue:

The following is outline of the claimed inventions at issue.

JP 5705288
1A: An isolated monoclonal antibody,
1B: which is capable of neutralizing binding of PCSK9 to LDLR,
1C: wherein the antibody competes with 21B12 antibody

JP 5906333 (Div. of JP5705288)
1A: An isolated monoclonal antibody,
1B: which is capable of neutralizing binding of PCSK9 to LDLR,
1C: wherein the antibody competes with 31H4 antibody

The claims are defined functionally not with any sequences and could cover a huge number of antibodies, however, in the specification, only 20-30 antibody sequences binding to the same antigen and X-ray crystallography of two antibodies were disclosed and Amgen antibody evolocumab sequence was not disclosed. However, screening methods to produce or screen antibodies bound to the antigen were disclosed in detail.

Statute on Support Requirement and Enablement:

In Japan, support requirement is stipulated in Patent Act. Art 36(6)1 and enablement is in Patent Act. Art 36(4)1 (see below) and post priority date evidence is not allowable.

Patent Act. Art 36(6)1: Support requirement
A claimed invention shall be disclosed in the description to prevent a patent from being granted for an invention which is not disclosed to the public

Patent Act. Art 36(4)1: Enablement
The statement shall be clear and sufficient in such a manner as to enable any person ordinarily skilled in the art to which the invention pertains to work the invention

Arguments and Ruling:

Sanofi argued that the claim should be limitedly constructed to antibodies obtained by substituting one or a few amino acids of the antibodies described in the specification (the range enabled by the description ), and the claims were invalid for lack of support requirement, enablement and inventive step.
The court ruled that the claims were NOT limitedly constructed since a skilled artisan would understand that they may obtain antibodies which competing with 21B12 and 31H4 and neutralizing the binding of PCSK9 and LDLR, including those not described in the specification, by the screening methods in the specification, then Sanofi antibody alirocumab fell within the scope of the claim. Also, the court found the claims met the support and enablement requirement as well as inventive step. For the inventive step, the court decided that the prior art did not disclose a PCSK9-LDLR neutralizing antibody, and thus a specific 21B12/31H4 reference antibody could have been easily obtained based on the prior art disclosure.


This is a remarkable and would be a leading case in biologics patent dispute, especially in a claim construction and ruling of written description requirements such as support requirement and enablement, and inventive step of functionally defined antibody claim. As for the written description requirements, description of screening methods in the specification would be a key factor. In other words, if how to make claimed antibodies are fully disclosed with detailed producing or screening methods, a functionally defined antibody claim may meet written description requirements. And, this case will be one of the criteria how/what to describe those methods to satisfy the written description requirements.

The case was appealed to the IP high court of Japan. However, the high court has already ruled that the Amgen patents were satisfied with support requirement and enablement and had inventive step, so the claims were valid in the decisions of the Rescission of Trial Decision of Invalidation for the same JP patents in December 2018 (darts-889-833-F-ja, darts-889-834-F-ja). Therefore, the high court could overturn the district court decision on the claim construction, but they will affirm it at least as for the validity (support requirement, enablement and inventive step). We should keep eye on future developments in the high court.

We should also pay attention to the battles between the same parties on the corresponding US patents (US 8,829,165 and 8,859,741; Amgen Inc. v. Sanofi (Fed. Cir. 2017), e.g. darts-249-330-E-en-2). On the validity, Amgen claims were found invalid at first, then found NOT invalid on Feb. 25, 2019 by a jury in the District of Delaware after the Supreme court denied Amgen certiorari, and the battles are still on going.

It looks patent disputes are moving to biologics area after saturation of low molecular drug markets. As recent further developments in Japan, the following cases should be reviewed.

darts-309-355-G-ja: Novelty and inventive step on new use of known biologics
darts-989-413-E-ja:Scope of functionally defined claims

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