Questions of novelty in medical use patents

08-08-2018

Weiwei Han

Questions of novelty in medical use patents

Xijian / iStockphoto.com

Decisions by China’s Supreme People’s Court and Patent Reexamination Board have provided more clarity on the patentability of medical use inventions, says Weiwei Han of CCPIT Patent and Trademark Law Office.

When a substance with a diagnostic or therapeutic effect per se has been available in the prior art, it will become more important to effectively protect the medical use of the substance, particularly in a jurisdiction (such as China) where diagnostic or therapeutic methods are not patent-eligible.

Medical use inventions may be drafted in the format of Swiss-type use claims. Specifically, if an invention involves the discovery of the therapeutic use of substance X, or treatment of a certain new disease using X, a medical use claim may be drafted in a format such as “use of substance X for the manufacture of a medicament” or “use of substance X for the manufacture of a medicament for treating a disease”.

Even though the “substance” and “disease” are essential in such a claim, there may be additional features therein, including a new dosage regimen such as a new mode, route, usage amount and interval of administration, and subject to be treated. It has been long debated whether these features would make a claimed technical solution patentable if both the “substance” and “disease” are known in the art. Some recent cases have illustrated these issues.

Case study

The most influential case was ruled on by the Supreme People’s Court in 2013. The independent claim 1 of the patent-in-suit is directed to the use of daptomycin for the manufacture of a medicament for treating a bacterial infection in a patient without resulting in skeletal muscle toxicity, where a dose for the treatment is 3 to 75 mg/kg of daptomycin once every 24 hours to 48 hours. Features of administration dose and administration interval are included in the claim.

The Supreme People’s Court held that “this kind of (Swiss-type) claim binds the making behaviour of a manufacturer who makes a drug for a certain use, so the technical features of the claims should be analysed from the perspective of process claims”. 

It added: “As for the features only relating to how to use a medicament, such as administration dose, administration interval and the like, if these technical features are not directly related to the procedure of manufacture of the medicament, they substantially belong to specific courses of administering the medicament to the human body after the procedure of manufacture of the medicament has been carried out and the medicament has been obtained, and are not directly and necessarily associated with the procedure of manufacture of medicament.

“These technical features merely present in the course of administration are not technical features in the procedure of manufacture of medicament, and do not have any limiting effect on the procedure of manufacture of medicament per se.”

More case law

In May 2018, the Patent Reexamination Board (PRB) made an invalidation decision to further illustrate how the subject to be treated may influence the novelty of a second medical use claim.

The patent-in-suit is directed to the medical use of an antibody. Specifically, independent claim 1 in the patent reads “use of an anti-CD20 antibody in the preparation of a medicament for the treatment of relapsed B-cell lymphoma in a human patient, wherein the patient has relapsed following treatment with an anti-CD20 antibody”.

"According to the PRB, when evaluating the novelty of a medical use invention, if the feature on the subject of administration in the claims is merely embodied in the course of medication, the feature does not influence the procedure of manufacture of the medicament, nor does it lead to differentiation of the treated indication from that disclosed in the prior art."

The feature “the patient has relapsed following treatment with an anti-CD20 antibody” defines the subject to be treated and was considered a distinguishing feature. According to the PRB, when evaluating the novelty of a medical use invention, if the feature on the subject of administration in the claims is merely embodied in the course of medication, the feature does not influence the procedure of manufacture of the medicament, nor does it lead to differentiation of the treated indication from that disclosed in the prior art.

In this case, the feature of the subject of administration cannot make the medical use invention novel.

The PRB further discussed the examination of medical use claims in a more general sense. According to the PRB, medical use claims are recited in the format of “use of substance X in the preparation of a medicament for treating a disease” or the like.

In the prior art, there is a document that only describes the use of substance X in the treatment of said disease. As it necessarily requires the preparation of substance X as a drug during the treatment of the disease with substance X, the prior art document essentially implicitly discloses the technical characteristics of the preparation of substance X into a drug.

Even if the document does not include the literal description of substance X as a drug, such a document still destroys the novelty of the invention. In another invalidation decision made by the PRB in March 2018, the opinion was similar.

The decisions of the Supreme People’s Court and the PRB show that a new dosage regimen
such as a new mode, route, usage amount and interval of administration, as well as subject to be treated, usually does not have limitative effects on the
Swiss-type claim and thus is not patentable in China, that is, unless it changes the indication to be treated or the structure of the drug such as composition, amounts of any ingredient, and unit dose or dosage form.

To distinguish an invention from the prior art, an applicant may envisage including features which may affect the manufacture process of a medicament in the claims and descriptions.

Weiwei Han is the group leader of the life sciences group at CCPIT Patent and Trademark Law Office. A qualified Chinese patent agent and attorney-at-law, her practice covers all IP-related fields. She is member of AIPPI and AIPLA, and is counsel at the IP case law research centre of the Supreme People’s Court. She can be contacted at: hanww@ccpit-patent.com.cn

CCPIT Patent and Trademark Law Office, Weiweihan. medical use patents, China’s Supreme People’s Court, medical use inventions, patentability

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