Chinese patent office hands down key ruling on pharma patent requirements

Terry Lu

05 Mar 2024

The Patent Re-examination Board of China’s National Intellectual Property Administration (PRB) recently issued a decision to invalidate two “orange book” patents owned by AbbVie. The ruling, which will likely to be one of the most interesting and consequential invalidity decisions issued by the Chinese patent office this year, establishes a new rule that sufficient disclosure of experimental data should be considered when reviewing the priority of a pharma patent.

Warning about the dangers of claiming priority to a document without experimental data, especially where Markush claims are concerned, the PRB’s decision relates to patent No.ZL2010800692920.6 (Decision No. 561725) and its divisional application ZL201810902092.0 (Decision No. 562232). The applications were registered in the “orange book” of the Chinese patent linkage system and cover the second-generation JAK inhibitor Upadacitinib.

The main issue of the Upadacitinib case was whether Markush claims 1-3 of ZL201810902092.0 enjoyed the earliest priority date. The petitioner Si Chuan Gowell Pharma challenged the inventiveness of the patent using one AbbVie’s early filing (WO2009/152133A1), a filing published between the priority date and the filing date of the patent, arguing it would constitute closest prior art if the priority was not established.

Yet, while the decision maintained the Markush claims 1-3 as valid as these claims successfully enjoy the earliest priority date, the board found that the specific structure of Upadacitinib was not disclosed in the priority document and corresponding claims 11-12 were declared invalid because of non-obviousness over the early filing in combination with common knowledge.

Key points of Upadacitinib case

The decision ruled that:

  • The right to claim priority, as prescribed in the Paris Convention and Article 29 of the Chinese Patent Law, is intended to give the patentee more time for preparing procedural documents when filing in different countries. It is not a grace period to complete the substantive content of the invention.
  • The patentee is not forbidden from further supplementing the invention within the priority period. However, in doing so, they will incur a risk of not enjoying priority. If the priority document provides only a general direction of research, it will not be regarded as an invention of the same subject as the later patent that has clearly confirmed one of specific technical effect.
  • Forming a new, narrower Markush claim resulting the original claim by deleting or further limiting alternative elements of some groups is permitted. But this is only so if such deletion or limitation does not produce a particular combination or highlights individual compounds or groups of compounds not specifically mentioned in the original application. Also, such amendments must be carried out within the scope of the entire Markush, and no new core compound of invention may be created. Therefore, the priority of the amended Markush claims was well-established as it shared the same subject matter as the earlier application before deletion.
  • The patentee can submit supplementary experimental data in the invalidation proceedings to prove the claimed compounds have a better effect over the prior art. But the supplementary data shall not be accepted if the technical effects or the fact to be proved by the supplementary data cannot be obtained from the disclosure of the patent document.


Takeaways from Upadacitinib case

For pharmaceutical patents, the priority documents need to sufficiently disclose experimental data relevant to the claimed compounds. Otherwise, the patent might not enjoy the priority.

For the patents in common technology fields, such as machinery, if the priority of the targeted patent is challenged, the examiner only needs to examine whether the claimed solution is recited in the priority document.

However, for pharmaceutical patents, the Chinese patent office requires the inclusion of experimental data to confirm the compound has a certain kind of pharmacological activity. Thus, two things are needed. Not only does the priority document require the same chemical structure, but it also must sufficiently disclose experimental data to prove that the invention has already completed before the priority date.

If the priority document merely alleges that the claimed chemicals can be used to treat certain disease without any experimental data, it will not be regarded as the same subject-matter as the patent behand where disclose the detailed experimental data focusing specific activities of the compounds. As a result, the later patent cannot enjoy the priority.

When claiming a priority of an individual compound, the priority document needs at least to disclose the chemical structure, manufacturing method, characterization data and activity data. When claiming a priority of a Markush claim, pharmaceutical activity data of certain number of compounds falling into the scope of the Markush claim must be included in the priority document. Although the decision did not mention how many compounds is sufficient for establishing the priority (25 compounds were disclosed within the formula Ic), the experimental data should be enough for the skilled person to confirm the Markush claim can achieve the technical effects alleged in the priority document.

The amendment of Markush claims by deleting or further limiting alternative elements of groups of Markush formula during patent prosecution or divisional process will not be detrimental to enjoying priority in the invalidation proceeding.

The decision confirmed that it is allowed to narrow a Markush claim by deleting or further limiting alternative elements of groups of Markush formula in the prosecution and divisional process. Further, the amended Markush claim can enjoy the priority of original claim in the invalidation proceeding as it is considered to have the same subject matter.

As per Daiichi Sankyo Company Limited vs. Beijing Winsunny Pharmaceutical Co., Ltd, the amendment of Markush claims in the invalidation proceedings is rigid and it is generally not allowed to delete some alternative elements of groups to narrow the scope of Markush claims. As a result, it is recommended for the patentee to file and submit a hierarchy of Markush claims with different protection scopes in the prosecution and divisional process. This strategy may let those narrowed claims have the same priority as the original claims, in addition, it may also give patentee more space to select a proper claim to deal with challenges using various prior arts in the invalidation actions.


The patentee is allowed to submit supplemental experiment data to prove the claimed solution has a better effect, but the supplemental data will be strictly reviewed by the examiner.

As per the latest Guidelines for Patent Examination, the patentee is allowed to submit supplementary experiment data to prove the inventiveness of the claims over prior arts in the invalidation proceedings. In the Upadacitinib case, the examiner carefully reviewed the supplementary data filed by the patentee in the invalidation proceedings. The review concerned not only on whether the technical effect was originally disclosed by the patent, but also on whether the supplementary data can be used to compare the effects between the closest prior art and claimed compound.

If the patentee wants to let the examiner accept the supplementary data, it may need to meet the following requirements:

  • The format of supplementary data should meet the legal format requirement for evidence. For example, if supplementary data was filed as an Affidavit of a technical expert, the hard copy of Affidavit should be notarized and legalised, and the expert should attend and testify in the oral hearing.
  • Supplementary data is preferably submitted with original experiment records, so that the examiner can check the authenticity of the data.
  • The technical effect or activity of the supplementary data needs to be disclosed in the original description. In the Upadacitinib case, the examiner only accepted the supplementary data of the inhibitor activity of JAK-3, but not the selective activity against JAK-2/JAK-1 as the original description only disclosed JAK-3 activity.
  • Supplementary data should be conducted between the claimed compound and the prior art compound having the closest chemical structure. If the supplementary data used an improper compound of the prior art document as a comparison subject, it is insufficient to prove the claimed compound has an unexpected effect and is inventive over prior arts, notwithstanding that the test results showed that the claimed compound had a better activity or effect.

The requirement for the disclosure of experimental data in priority document remains a contested and unclear issue in China. However, this case provides an important guideline to follow for pharma patent holders, especially when claiming a broad Markush claim covering compounds with various structure and medical activities. 

This article was firstly published on IAM.