For pharmaceutical compound inventions, a common rejection arising during patent prosecution in China is lack of support. The examiners often arrive at their conclusion by saying that the generic terms in the claims cover too many compounds, and a person skilled in the art has reasonable doubts that not all the claimed compounds can achieve the technical effects of the invention.

When facing the problem of rejection based on lack of support, the burden of proof lies with the applicants to show that the claims are supported by the description. It is common practice in Europe and the US to provide post-filing supplementary data to prove that the claimed compounds achieve the intended effects. However, the Guidelines for Patent Examination in China have made it clear that the post-filing supplementary data will be ignored from consideration, if it is used as evidence to show the support of the compounds.

It looks as though the easiest way to overcome a rejection based on lack of support is to narrow down the generic terms in the claims on the basis of the description. Although applicants are entitled to get claims that can be obtained or summarized from the contents sufficiently disclosed in the specifications, in practice, it may be very difficult to obtain such claims without incurring new matter, if the specifications are not drafted in line with the practice in China. In the end, the applicants could merely obtain the claims directed to the specific compounds in the specifications.

For a discussion of the new matter criteria in China, see Amy Feng's article "Take Local Practice into Account" (Managing IP Life Science Industry Focus, June 2008). As mentioned in Feng's article, under current practice in China, a new matter issue is rendered by a new combination of 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.

In an application for compound inventions, claim one was directed to a compound of general formula, in which the radical R1 is an alkyl, whereas radicals R2 and R3 are selected from C6-8 aryl or C1-6 alkoxy. During the prosecution, the examiner rejected the compound in claim one because of lack of support in the description, for the reason that the generic term "alkyl" in R1 of claim one covers too many compounds, while the description merely illustrates the compounds in which alkyl is methyl or ethyl. The examiner required the applicant to limit alkyl on the basis of the disclosure of the description.

In the specification of this case, neither the definition of alkyl is provided in the specification, nor any recitation of alkyl as methyl or ethyl is given in the general description part of the specification. The definition of alkyl as methyl or ethyl can only be found in the specific compounds.

The applicant amended the word "alkyl" in R1 of claim one to "methyl" or "ethyl" with the intention of overcoming the rejection based on lack of support. The examiner, however, raised a new matter rejection against the amended claim one. The rationale of the examiner is that the groups methyl and ethyl are recited in the description with respect to the specific compounds in which R2 and R3 are specific groups, whereas the groups methyl and ethyl are not recited with respect to the compounds in which R2 and R3 have the definitions in claim one. The examiner thus concluded that the amended claim one was a new combination, because the relationship between methyl and ethyl for R1 and C6-8 aryl or C1-6 alkoxy for R2 and R3 is not mentioned in the original specification. The applicant finally narrowed down claim one merely to the specific compounds.