Lessons from CNIPA’s Top 2025 Cases: Post-Filing Data, Confidential Evidence, and Sufficiency of Disclosure in China
Date: 3 August 2026
【Volume 174】
The China National Intellectual Property Administration (CNIPA) issued Invalidation Decision No. 581892, upholding the validity of Pfizer’s patent relating to a crystal form of Crizotinib, entitled “Polymorphs of a C-MET/HGFR inhibitor” (Patent Application No. CN200680045883.1; hereinafter “the Disputed Patent”). This case was also selected as one of the CNIPA's representative reexamination and invalidation cases of 2025, which underscores its significance for the assessment of post-filing experimental data, evidence confidentiality, and the sufficiency of disclosure in pharmaceutical patent practice. This decision reflects the relatively open yet rigorous approach adopted in Chinese patent practice toward the use of evidence and the assessment of technical effects in the field of pharmaceutical chemistry.
Main Technical Feature of the Disputed Patent
The Disputed Patent relates to a crystal form of free base of (R)-3-[1-(2,6-Dichloro-3-fluoro-phenyl)-ethoxy]-5-(1-piperidin-4-yl-1H-pyrazol-4-yl)-pyridin-2-ylamine (hereinafter “Crizotinib”), having a powder X-ray diffraction pattern substantially identical to that shown in Fig. 1.
Key Issues and CNIPA’s Findings
During the invalidation proceedings, both parties engaged in intense arguments over the procedural evidence, the sufficiency of disclosure of the specification, and the technical effects supporting an inventive step. The decision of the CNIPA clarified the following three key principles that are expected to provide important guidance for future invalidation practice:
1. Balance between Evidence Confidentiality and the Opposing Party’s Right to Be Heard
The parties first disputed the balance between protecting confidential evidence and safeguarding the opposing party’s right to be heard. Although Pfizer submitted 110 pages of original laboratory records, it requested confidential treatment of those materials on the ground that they contained trade secrets, and was willing to disclose only selected excerpts for the opposing party’s review.
In response, the CNIPA emphasized the significance of procedural fairness, holding that the core technical information directly relevant to the grounds for invalidation should not be treated as confidential. Since confidentiality measures should not deprive the opposing party of a meaningful opportunity to examine and challenge the evidence, the CNIPA ultimately declined to recognize the evidentiary value of the incomplete submission.
2. Whether the Chemical Invention Satisfies the Sufficiency of Disclosure Requirement
Secondly, regarding the sufficiency of disclosure of the chemical invention, the invalidation petitioner questioned that the specification only provided regular analyses such as mass spectrometry (MS) and nuclear magnetic resonance (NMR), which were insufficient to characterize the absolute configuration and lacked a clear method for measuring the melting point of the crystal.
In response, the CNIPA adopted a relatively reasonable standard for assessing sufficiency of disclosure and held that an improvement invention does not need to disclose every fundamental synthetic detail in a step-by-step, textbook-like manner. As long as a person having ordinary skill in the art can implement and reproduce the invention based on the disclosure of the specification in view of the relevant technical knowledge, the requirement for sufficient disclosure is considered fulfilled.
3. Admissibility and Probative Value of Post-Filing Experimental Data in Assessment of Inventive Step
Lastly, regarding the evaluation of inventive step and admissibility of post-filing experimental data, Pfizer submitted supplementary data (Counter-evidence 22) to prove that the claimed compound has a better inhibiting activity compared to the closest prior art (Evidence 8).
The CNIPA pointed out that the closest prior art is typically identified in the course of patent examination or subsequent proceedings. Accordingly, where a patentee conducts supplementary experiments within the prescribed period of time to demonstrate the technical effects obtained by the claimed invention in comparison with the closest prior art, such post-filing experimental data constitutes a legitimate means of substantiating those technical effects. As a result, the evidentiary value of such data should not be dismissed solely because the experiments were conducted by the patentee itself. Instead, the experimental methodology and the resulting data should be evaluated on their own merits.
In the present case, the CNIPA ruled that the experimental results presented in Counter-evidence 22 could mutually corroborate one another, and the invalidation petitioner failed to propose sufficient rebuttal evidence to undermine their credibility. Accordingly, the CNIPA admitted Pfizer’s evidence and concluded that Crizotinib exhibited a better c-Met enzyme inhibition performance, thereby supporting the Disputed Patent of an inventive step.
Wisdom Analysis and Suggested Strategies
In light of the guidance provided by the CNIPA in this representative case, we propose the following three practical recommendations for patent prosecution and invalidation strategies involving pharmaceutical and chemical inventions:
1. Admissibility of Post-Filing Experimental Data and the CNIPA's Evidentiary Review
Although Chinese practice adopts an open approach to post-filing data, permitting such data to address the closest prior art identified during examination or invalidation proceedings, the evidentiary threshold has not been relaxed. Instead, the CNIPA will closely scrutinize the experimental methodology, data sources, and whether the experimental results are mutually corroborative, before determining whether any counter-evidence is capable of undermining its credibility.
2. Restrictions on Confidential Treatment of Core Technical Evidence
Core experimental evidence that is directly relevant to the determination of patent validity cannot be withheld from disclosure on the grounds of trade secret protection. Otherwise, the patentee will bear the risk that the evidence may not be accepted by the CNIPA or that its burden of proof may not be satisfied.
3. Holistic Assessment of Sufficient Disclosure for Improvement Inventions in the field of Chemistry
Regarding the assessment of sufficient disclosure, the CNIPA holds that, for improvement inventions in the field of chemistry, a holistic judgment should be made by taking into account both the prior art and the common general knowledge shared by a person having ordinary skill in the art. The specification is not required to disclose all fundamental synthesis and structure confirmation data in a step-by-step, textbook-like manner. As long as a person having ordinary skill in the art can implement the invention based on the disclosure of the specification, it would be inappropriate to impose an excessively stringent standard on the level of disclosure required.
