How to smoothly obtain a pharmaceutical patent in China? | Linda Liu & Partners

[author: Barbara Bai]

As a major pharmaceutical consumer market, China’s position in pharmaceutical patents has been appreciated. Patents such as medical use, drug crystal form and others have received more attention as they play an important role in pursuing the patent protection of the original drug.

However, applicants for these patents may encounter many difficulties in the process of obtaining compensation from CNIPA, while their counterpart applications are smoothly granted in other jurisdictions.

The reasons for the above situation may be related to special provisions on pharmaceutical patents in the Chinese patent system and special examination standards for certain fields. In the following, a brief introduction will be given on the particulars of the invention for medical use, the invention of the crystal form of the drug, and additional experimental data in Chinese practice.

For inventions for medical use, the CNIPA currently only accepts Swiss-type claims, for example, drafted as “use of a compound in the preparation of a medicament for the treatment of cancer”. Disease treatment methods are not eligible in China. This means that the characteristics set out in the Swiss-type claim and related to the method of treatment, such as the characteristics of administration, will be considered irrelevant for the preparation of a medicament and will have no limiting effect on the claims. .

These regulations are quite different from those of the USPTO and the EPO. The therapeutic method is patentable subject matter in the United States. The claim that “the compound or pharmaceutical for use in the treatment of cancer” is allowable in the EPO. This means that treatment-related features, such as dosage features, can substantially define the claims, and improvements based on them can be the basis for being patentable.

Due to the above differences, claims drafted in a manner authorized by the United States or Europe must be changed to Swiss-type claims when entering China. Please note that, if the improvement of the invention lies in the delivery of drugs, it may be more difficult for the same invention to be granted in China.

For the invention of a crystal form of medicine, according to our practice, the CNIPA examination shows two characteristics: the first is that the examiners like to infer that the specific crystal form claimed is not new on the basis of a prior art which only discloses the preparation of solid compound; the other is that examiners may have a relatively high standard for inventiveness, which is primarily reflected in the fact that CNIPA often asserts that it is a conventional choice in the art to prepare a crystalline form from ‘an organic compound, the crystallization method is the routine work, and the higher stability or higher purity of the crystal form compared with an amorphous form belongs to an expected technical effect.

In order to overcome the rejection of inferred non-novelty, in addition to the general novelty argument, the most direct and effective means is to provide an X-RPD spectrum to demonstrate that the claimed crystal form is different from the state of the art.

The aforementioned high standard for judging inventiveness may lead to the need for more data that can prove the unpredictability of the crystal shape effect in order for the application to be granted in China. Such data includes: data characterizing physical stability, chemical stability, solubility, hygroscopicity, bioavailability, etc. Among them, experimental data related to drug efficacy, for example bioavailability data, can be more convincing to argue inventiveness.

Moreover, for drug-related patent applications, technical effects usually play a key role in arguing inventiveness in China. It may be necessary, in some cases, to provide additional experimental data to prove the effect of the invention. The acceptability of the data often has a big impact on the results of the examination.

the Patent Examination Guidelines stipulate that the technical effect proven by the additional experimental data must be obtained by the person skilled in the art from the content disclosed in the patent application.

The latest revision of the Guidelines for Patent Examination Implemented January 15, 2021 provides two sample reviews for the review of additional experimental data for drug patent applications.

Example 1:

Compound A is claimed in the claims, and the description describes the hypotensive effect of compound A and the experimental method for measuring the hypotensive activity, but does not describe the experimental result. The applicant has completed the data on the hypotensive effect of Compound A. According to the description of the original application, the hypotensive effect of Compound A has been disclosed, and the technical effect to be proved by the additional experimental data can be obtained at from the content disclosed in the application documents.

Example 2:

The description of the experimental results in the description is that the IC50 of the example compounds against tumor cells is in the range of 10-100 nM. In order to prove the inventiveness, the applicant supplemented the comparative experimental data, showing that the IC50 of compound A was 15 nM, whereas the IC50 of the compound of the reference document is 87 nM. For those skilled in the art, according to the records of the original application documents, Compound A and its anti-tumor effect have been disclosed, and the technical effect to be proved by the additional experimental data can be obtained from the contents disclosed in the patent application documents.

It can be seen that, compared to previous guidelines, this revision provides a scenario in which additional experimental data can be accepted, and the change in the acceptance of additional experimental data is positive.

According to the provisions of the guidelines, it can be confirmed that if there is a original description of the technical effect in the application is an important basis for judging whether the additional experimental data could be taken into account by the examiner. A relatively clear standard is that additional experimental data cannot be used to prove the technical effect which cannot be known by the person skilled in the art after reading the original application documents.

Moreover, even if the additional experimental data is taken into consideration, the question of whether the proven effect may constitute an unexpected technical effect must be specifically considered depending on the circumstances of the case.

Understanding the relevant regulations and review standards for pharmaceutical applications in China is of great value in reducing the risk in the prosecution or invalidation proceeding. In order to reduce the risk in the follow-up procedure, it is suggested to describe the technical effect and experimental data as much as possible when writing an application, although a general description can also provide a basis for submitting data. additional experiments in the future.

For inventions in crystalline drug form, proving that the invention can produce unpredictable technical effects plays a key role in obtaining clearance. For inventions for medical use, only Swiss-type claims are allowed in China and grant features are not considered by examiners. Applicants should therefore pay attention to this special Chinese practice at the drafting stage if they wish to obtain patents in China. In addition, the correlation between the pharmaceutical product and its technical effects should be highlighted as much as possible.