[author: Barbara Bai]

As a large pharmaceutical consumer market, China's position in the pharmaceutical patents has been valued. Patents such as medical use, drug crystalline form and the like have been paid more attention as they play a great role in continuing the patent protection of the original drug.

However, applicants for such patents may face many difficulties in the process of getting allowance with the CNIPA, while their counterpart applications are smoothly getting granted in other jurisdictions.

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

For medical use inventions, the CNIPA currently only accepts Swiss-type claims, for example, drafting as “use of a compound in the preparation of a drug for treating cancer”. Treatment methods for diseases are ineligible subject matter in China. This means that characteristics recited in Swiss-type claim and related to treating method, such as administration features, will be considered irrelevant to the preparation of a drug and have no limiting effect on the claims.

Such regulations are quite different from those in USPTO and EPO. Therapeutic method is a patentable subject matter in the United States. The claim reciting that “the compound or the pharmaceutical for use in treating cancer” is allowable in EPO. This means that features related to the treatment, such as dosing features can substantially define the claims, and improvements based thereon can be the support for being patentable.

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

For the invention of crystalline form of drug, according to our practice, the examination of CNIPA shows two characteristics: one is that the examiners like to infer that the specific crystalline form claimed is not novel based on a prior art that only discloses the preparation of solid compound; the other is that the examiners may hold a relatively high standard for the inventiveness, which is mainly 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 crystalline 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 argument for novelty, the more direct and effective way is to provide a X-RPD spectra to demonstrate that the claimed crystalline form is different from the prior art.

The above said high standard for judging inventiveness may lead to the need for more data that can prove the unpredictability of crystalline form’s effect in order to have the application granted in China. Such data include: data characterizing physical stability, chemical stability, solubility, hygroscopicity, bioavailability, and the like. Among them, experimental data related to drug efficacy, e.g., bioavailability data, may be more convincing for arguing inventiveness.

In addition, for drug-related patent applications, technical effects generally play a key role in arguing the inventiveness in China. It may be necessary, in some cases, to provide supplementary experimental data to prove the effect of the invention. Whether the data is acceptable often has an important impact on the examination results.

The Guidelines for Patent Examination stipulate that the technical effect proved by the supplementary experimental data should be obtained by the skilled in the art from the content disclosed in the patent application.

The latest revision of the Guidelines for Patent Examination implemented on January 15, 2021 provides two examination examples for the examination of supplementary 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 supplemented 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 supplementary experimental data can be obtained from the contents disclosed in the application documents.

Example 2:

The description of the experimental results in the specification is that the IC50 of the compounds of the examples to tumor cells are in the range of 10 to 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, while 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 supplementary experimental data can be obtained from the contents disclosed in the patent application documents.

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

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

Additionally, even if the supplementary experimental data is taken into consideration, whether the proven effect can constitute an unexpected technical effect needs to be specifically examined based on the circumstances of the case.

Understanding relevant regulations and examination standards for pharmaceutical application in China is of great value in reducing the risk in the prosecution or invalidation procedure. 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 drafting an application, even if a general description can also provide some basis for submitting supplementary experimental data in the future.

For drug crystalline form inventions, proving that the invention can achieve unpredictable technical effects plays a key role in obtaining allowance. For medicinal use invention, only Swiss-type claim is allowable in China and delivery characteristics are not considered by the examiners, so applicants should pay attention to this special Chinese practice at the drafting stage if they wish to obtain patents in China. In addition, the correlation between pharmaceutical product and its technical effects should be highlighted as much as possible.