Patenting a new second medical indication of a known pharmaceutical compound could help to prolong the lifespan of patents for the pharmaceutical compound. However, because the practice for patenting a second medical indication invention in China is quite different from other jurisdictions such as Europe, the US and Japan, the patent protection of a second medical indication invention in these jurisdictions may not be necessarily available in China.

Moreover, since the current Guidelines for Patent Examination entered into force two years ago, much stricter criteria for novelty and new matter issues make it more and more difficult to get patents for second medical indication inventions in China. It thus may be worthwhile for a patent practitioner to take Chinese patent practice in this field into consideration when drafting the specifications, in view of the importance of getting patent protection for second medical indication invention in China.

Swiss-type claims

Under Article 25 of the Chinese Patent Law, methods for the diagnosis or treatment of diseases are unpatentable subject matters. No patent right will be granted to a claim directed to a second medical indication of a known pharmaceutical compound, if it is presented in the form of a method for the treatment of diseases.

For novelty reasons, a second medical indication of a known pharmaceutical compound cannot be patented either in the form of "compound X for treating disease Y" or in the form of "a pharmaceutical composition comprising a compound X for treating disease Y". The underlying rationale is that the gist for a second medical indication lies in the finding of a new use of a known compound, which cannot render the compound itself novel. It has been a long-established practice in China that a product claim should be defined by the structural features of the product, such as its name, structural formula, and components. It is commonly held that the use feature of a product does not have any definitions on the product per se.

But the current Guidelines do provide some guidance on how to patent a second medical indication of a known pharmaceutical compound in China. According to the current Guidelines, a second medical indication of a known pharmaceutical compound could be patented in the form of Swiss-type use claim, which is presented as "use of compound X in the preparation of a medicament for the treatment of disease Y." The current Guidelines further provide that no patent right shall be granted to the claims directed to the medical use of a pharmaceutical compound if they are presented in such forms as "use of a compound for the treatment of diseases", "use of a compound for the diagnosis of diseases" and "use of a compound as a medicament".

Quite often, a second medical indication invention of a known compound has been initially presented either in the form of a method for the treatment of diseases or in the form of a compound for treating diseases, especially for those applications that have been drafted outside China. An unpatentable subject matter issue or a novelty issue will be raised if a claim is presented in these two forms. It looks like the issues may be easily overcome by simply converting the claim into the Swiss-type use claim. However, due to the amendment, some other issues may arise that will prevent the inventions from being granted if the specifications have not been drafted in line with the Chinese patent practice. Among those issues, novelty issues and new matter issues are the most difficult issues to be dealt with during the prosecution.

Novelty criteria

The previous Guidelines are silent with respect to the criteria for novelty of a medical use claim of a known compound, thus leaving some room for us to argue for the novelty of such claims. However, the current Guidelines provide clear guidance on the determination of novelty of the medical use claim of a known chemical product. Specifically, the current Guidelines say that the following factors must be considered when determining the novelty of the medical use claim of a known chemical product:

Whether the new use is substantively different from the known use. An invention that differs only in expression from the known use does not possess novelty.

Whether the new use is directly revealed by the mechanism of action or pharmacological function of the known use. A use with a mechanism of action or pharmacological function directly identical to that of the known use does not possess novelty.

Whether the new use belongs to the genus of a known use. A known use species may destroy the novelty of the genus of the use.

Whether the features involved in the use of the chemical product, such as the subjects to be administered, administration ways, administration routes, pathways, dosages and time intervals, have any definitions to the preparation process. The different features embodied only in the administration process cannot render the use novel.

It is clear that the Guidelines set a much higher standard for the novelty of the medical use of a known chemical product.

Raising the bar

It has been provided by the Chinese Patent Law that any amendments to the application may not go beyond the scope of the disclosure contained in the initial description and claims. The current Guidelines further interpret "the scope of the disclosure contained in the initial description and claims" to mean "the contents that are literally recited in the initial description and claims, and the contents that can be directly and undoubtedly determined from the initial description and claims."

In practice, it is normally difficult to establish that the amended contents can be directly and undoubtedly determined from the initial description and claims. As a result, examiners are reluctant to accept the amended contents, if the amended contents are not literally recited in the initial description and claims.

The current Guidelines add two new provisions to the amendments to the claims and description, which were not provided in the previous Guidelines.

One says that a new matter issue is rendered by a new combination if the new combination is formed from the several discrete features in the initial claims and description, if the relationship among the several discrete features is not explicitly mentioned in the initial disclosure.

The other concerns the amendments to a numerical range in a claim, which provides that "an amended numerical range is acceptable only when the two endpoints in the amended numerical range are recorded in the initial claims and/or description, and the amended numerical range is within the initial numerical range."

We offer the following case to illustrate how the novelty issue and the new matter issue bar the allowance of the second medical indication invention if the specification has not been drafted in accordance with the practice in China.

Don't generalize

This case relates to a method for the treatment of a human patient diagnosed with a disorder Y, which is characterized by the administration of the initial dosage and subsequent dosage of the compound X. After three office actions, the applicant abandoned the case.

The initial claim 1 of the case reads as:

In the two examples of the description, it was recited that the dosages of the compound X administered to the human patient were 2 mg/kg and 8 mg/kg, respectively.

In a First Office Action, the examiner rejected the claim 1 with the reason that said claim falls under the scope of methods for the treatment of diseases and is unpatentable. In response to this office action, the applicant amended the claim 1 to read as

A Second Office Action was issued, in which the examiner cited a prior art document (D1) against the novelty of the claim 1. D1 discloses use of an effective amount of the compound X in the preparation of a medicament for the treatment of a human patient diagnosed with a disorder Y. D1 does not disclose the initial dosage and the subsequent dosage of the compound X recited in the claim 1. However, the examiner alleged that the dosage features do not have any definitions relating to the use claimed by the claim 1, because the administration dosages are the features involved in the administration process, which are neither the technical features involved in the process for the preparation of the medicament, nor the use features. He thus concluded that claim 1 does not possess novelty over D1, because D1 has disclosed all the technical features of the claim 1.

In response to the Second Office Action, the applicant amended the claim 1 to read as:

A Third Office Action was issued, in which the examiner asserted that the amendment to the claim 1 renders new matter, because the feature "wherein the effective amount of the compound X is in the range of 2~8 mg/kg" is neither recited in the initial claims and description, nor can be determined directly and undoubtedly from the initial claims and description. He came to the conclusion from the following two aspects: (1) it is not allowed to generalize the numerical range for the effective amount from the administration dosages, because the effective amount and the administration dosage are two different features and an effective amount is not equal to an administration dosage; and (2) it is not allowed to generalize the range "2~8 mg/kg" from the two specific points, 2 mg/kg and 8 mg/kg, because the two points were described with respect to the specific examples.

The solution to the problem

From the above case, it is clear that it is very difficult to deal with the novelty and new matter issues brought up during the prosecution of an application relating to a second medical indication invention. We thus believe that it is reasonable to consider the Chinese patent practice in this regard when initially drafting the specifications, thereby avoiding the issues from arising at later stage. The above case seems to give us some clues for drafting specifications in this field.

First of all, the Guidelines have made it clear that the features involved in the administration process cannot make the medical use claim novel. Thus, if the inventions lie only in the features involved in the administration process, such as the finding of the new dosages, we suggest also using such phrases as "effective amount" to describe the inventions, if at all possible. We may replace the dosage features with, for example, an effective amount in a claim, if a novelty rejection is raised during prosecution.

Moreover, we suggest giving a general description of the range of the effective amount, besides the specific amounts given in the examples. The above exemplary case would have gone in a different direction, if a general description of the range of the effective amount had been given in the initial specification.

Second, the Swiss-type use claim in the form of "use of compound X in the preparation of a medicament for the treatment of disease Y" is the acceptable form to protect a second medical indication invention in China, and the features related to "compound X" (for example, its amount and structure), "medicament" (for example, its dosage form and formulations) and "disease Y" (for example, different type of diseases) are considered as the features that have definitions in the Swiss-type use claims, which will be considered in determining novelty of the use claims. We suggest drafting the specifications by defining the inventions in terms of the above-mentioned features.

Third, we suggest making the Swiss-type use language itself available in the original specifications, because a simple conversion to Swiss-type use language does not always work. We have seen that new matter rejections have been raised against some cases in which the Swiss-type use language is not included in the original specifications. We strongly recommend taking Chinese patent practice into consideration when drafting specifications relating to second medical indications of known pharmaceutical compounds.

Amy Feng

Amy Feng is a partner in the chemical and biotech practice of Liu, Shen & Associates. Feng joined Liu Shen in 1996, and now has more than 12 years of experience in the field of IP law. Her practice includes all phases of patent prosecution, re-examination, patent invalidation, and patent litigation and counselling, including infringement and validity analysis in the chemical, pharmaceutical and biotech fields. Feng has numerous degrees in all the fields relevant to her practice. She holds a Bachelor's of Science degree in chemical engineering and a Master's of Science degree in fine chemicals, both from Dalian University of Technology, China. Between 2002 and 2003, Feng studied civil and commercial law in the China University of Political Science and Law in Bejing. In 2004, she earned an LLM degree in IP law, with honours, from The John Marshall Law School in Chicago, where she studied biotech patent law-related courses. Feng is qualified and admitted to practise as both an attorney-at-law and a patent attorney. She is a member of the Chinese Bar and of the All-China Lawyers Association and the All-China Patent Agents Association.