Patenting Medical Use Inventions in China

Patenting Medical Use Inventions in China

A medical use of a product may relate to i) the use of a new drug to treat a disease (“first medical use”); ii) the use of a known drug to treat a new disease (“second medical use”); or iii) the use of a known drug to treat a known disease using a new administration method (“second medical use relied on new dosage regimen or new administration mode”). Over the past few years, a number of significant cases have affected prosecution strategies of medical use patent applications in China. In this article, we highlight some of the most important issues that should be considered when building a patent prosecution strategy for medical use inventions before China National Intellectual Property Administration (CNIPA).

Proper language for a medical use claim in China

The first issue to be noted is that, claims in the format “use of product X in the treatment of disease Y” and “use of product X as a medicament for the treatment of disease Y” are not allowed as CNIPA consider that such claims relate to a method of treatment and such methods are excluded from patentability in China. Claims in the format “Product X for use in the treatment of disease Y” is not recommended for medical use inventions, because this format of claim is deemed as a product claim instead of a use claim in China and the use recited is considered as having no limiting effect on the product. Proper claims should be in the format of a so-called “Swiss-style claims”: use of product X for the manufacture/preparation of a medicament for the treatment of disease Y.

Patenting second medical uses

A second medical use may encompass the use of a known drug to treat a new disease. It may also encompass the treatment of the same disease by a new therapeutic method, for example a new dosage regime or a new administration mode. Claims relating to such new dosing or administration features may take the following form:

“Use of product X for the manufacture/preparation of a medicament for the treatment of disease Y, wherein product X is [new feature].”

For a new dosage regime, the above claim could specify that, for example, the product is administered three times daily or administered at a dose of Z mg/kg, or administered in a specific discontinuous administration pattern. For a new mode of administration, the above claim could specify that product X is “administered topically” or “administered subcutaneously”, for example.

Novelty of a second medical use relied on new dosage regimen or new administration mode

The next important question to ask is whether the above claims relating to new dosing or administration features have novelty over prior art medical use claims. In practice, the CNIPA generally holds that a dosage regimen is closely related to doctor’s treatment behaviors, only embodied in the process of treating diseases by administration of drugs and has no direct connection with the manufacture of drugs. Accordingly, when the inventive feature in a medical use claim in the Swiss format is only a new dosage regimen or a new administration mode, it usually cannot render the claimed use novel according to the practice before the CNIPA. However, if the dosage/administration feature implies a change in procedure of manufacture of a pharmaceutical, novelty may be established.

For instance, if the technical feature regarding “administration dose” can be embodied in a form of a unit dose, it may be patentable, because unit dose is generally recognized as a technical feature in procedure of manufacture of a pharmaceutical. For example, the technical feature “unit dose is about 0.05-1.0mg” defined in a Swiss-type claim is generally recognized as having limiting effect on the claim. However, if the novel feature lies merely in dosage regimen which does not change the composition of the medicament, for example, in the circumstance where the only novel feature of a known drug to treat a known disease is administering the drug “once per day prior to sleep”, the invention will not be patentable due to lack of novelty.

Case study

According to the regulations of the Guidelines for Examination in China, distinguishing features that are merely present in the course of administration do not enable the use to possess novelty. Under some circumstances, the dosing regimen feature can be converted/redrafted into a technical feature that reflects a new structure of the medicament. The new structure of the medicament can be a new dosage form, a new unit dose, a single dosage form comprising a new amount of active ingredient, a new kit comprising several unit doses suitable for dosing regimen, a combination comprising two or several unit doses, etc. Applicant may obtain inspiration from the following cases that we handled.

Case I

Case I involves the technical feature “the pharmaceutical composition is formulated as a single dose form and the single dose form comprises Compound X in the amount of 5 mg to 250 mg”. Case I was granted during the substantive examination but challenged during an invalidation procedure on the ground that this feature adds no restriction to the scope of the claim because “5 mg to 250 mg” is a dosage feature that merely present in the course of administration.

The panel of the Re-examination Board holds that “single dose form” is a structural feature that defines the form of the pharmaceutical composition that is suitable for one-time administration to patients. It distinguishes the product from a multi-dose product comprising multiple unit doses of the same compound for multiple administrations. The feature “single dose form” is not equal to “daily dose”. The latter is related to a doctor’s treatment behavior while the former implies that the pharmaceutical composition is adapted for administration to the patient in one time and has restriction to the scope of the claim.

It is noteworthy that the term “single dose form” is different from “unit dose” and “administration dose”. For example, the Supreme People’s Court (SPC) discriminated “unit dose” from “administration dose” in a retrial ruling (Administrative Ruling (2012) ZhiXingZhongZi No.75) directed to the patent invalidation case of Cubist Pharmaceuticals, Inc. The SPC held that unit dose is an amount of drug in a single unit of drug, which depends on the drug added during the preparation of the drug. Administration dose is an amount administered to patients per dose or per day, that is, the amount of use of drug, and can be determined by the users, and belongs to the methods for using drugs. Administration dose does not have a limiting effect on the Swiss type claim unless it can be embodied in the procedure of manufacture of a pharmaceutical.

Case II

Case II involves the technical feature “a vaccine for treating …, which is formulated for being administered subcutaneously in a first dose, orally in a second dose…”. The claim was challenged during an invalidation procedure on the ground that this feature belongs to “administration characteristics” and has no limiting effect on the claim.

The panel of the Re-examination Board applies the same examination standard and holds the opinion that features merely relating to use of the medicament that will not change the structure and component of the product do not contribute to the novelty. However, if the administration features do change the composition of the product, these features shall be considered when examining the novelty.

The feature “formulated for being administered subcutaneously in a first dose, orally in a second dose” implies that the vaccine is formulated as a combinational product comprising two different forms of preparations, one for subcutaneous injection and the other for oral administration. This differs from a vaccine product where only one form of formulation is included, but with one part for subcutaneous injection and the other part for orally administration. Therefore, the feature essentially defines a new form of combinational product and contributes to novelty of the claim.

Conclusion

Under the current China Patent Law and its practice, although it is difficult to claim a medical use of a known substance for a known disease characterized by a dosing regimen/administration feature, it may be possible to get such a claim allowed, if the dosing regimen/administration feature is converted into a technical feature that reflects a new structure of the medicament or different composition of the formulation. The new structure can be a new dosage form/unit dose, a single dosage form comprising a new amount of active ingredient, a new kit comprising several unit doses suitable for dosing regimen, a combination comprising two or several unit doses, etc. These technical features can usually change the manufacturing process of the product, and therefore Chinese examiners are expected to recognize that these features have a limiting effect on medical use claims.