When determining whether the replacement between two groups in a pharmaceutical compound is common knowledge in the art, bioisosterism may generally be considered. However, for non-classical bioisosteres, whether a person skilled in the art will make specific group replacement generally need to be supported by prior arts that can prove the drug structure activity relationship, and the application of the concept “bioisostere” shall not be expanded arbitrarily.
Two American Companies are the applicants of an invention patent application of pyridine-based inhibitors transduced by Hedgehog signal (the disputed patent application), which was rejected by the CNIPA on October 8, 2016. The two American Companies were dissatisfied and initiated legal proceedings with the first-instance court, requesting to revoke the challenged decision of rejection and order the CNIPA to make a decision anew.
The first-instance court rejected the claims of the two American Companies, leading to their subsequent appeal. The Supreme People’s Court made the second-instance judgment on December 14, 2023, revoking the first-instance judgment and the challenged decision, and the court ordered the CNIPA to make an examination decision anew for the disputed patent application of the two American Companies.
First, the effective judgment determined that the technical teaching shall be decided based on the technical problems solved by the invention. If Fomula I in Reference 8 is used as the basis for technical teaching in the prior art, those skilled in the art should recognize that Formula I can achieve technical effects equivalent to those of Formula II. However, while the challenged decision explicitly chose the subordinate Formula II in Reference 8 as the closest prior art, there is no evidence proving that those skilled in the art can confirm the effect of the superior Formula I is equivalent to that of Formula II. On the contrary, Evidence 7 submitted by the two American companies in the first instance can prove that in Reference 8, the compound with benzopyrimidinone structure (Compound 4) has a better effect than the compound without benzopyrimidinone structure (Compound 9). On the basis that Reference 8 has disclosed embodiments with benzopyrimidinone structure and partial active data, those skilled in the art do not have the motivation to seek for enlightenment in the more general Formula I. The ability of those skilled in the art to confirm Hedgehog signaling inhibitory activity contained in the compound in the present application after reading the description does not necessarily mean that Reference 8 taught the equivalent effect of benzopyrimidinone and Benzene ring or heterocyclic ring. Therefore, the challenged decision determining that Fomula I in Reference 8 provided technical teaching is not tenable.
In addition, for those skilled in the art, when investigating whether the replacement between two groups in a pharmaceutical compound is common knowledge in the art, Bioisosterism is most commonly used. Bioisosterism means that atoms or groups with similar three-dimensional structures and electronic arrangements can retain similar or metabolically antagonistic biological effects when replaced with each other in their drug molecular structures.
Meanwhile, medicinal research progress also detected some atoms and groups conflicting with the classic Bioisosterism can still have the equivalent effect after being swapped in the pharmaceutical molecular design procedure. Bioisosterism is an experience conclusion. Due to the relevance of the swap of non-classical bioisostere to the prior art research progress in the drug structure-activity relationship in the field, whether the concept of Bioisosterism can be applied to designing drug molecular for a specific class of drugs requires prior art evidence supporting the drug structure-activity relationships associated with that class of drug, and the application scope of bioisostere cannot be arbitrarily expanded. It’s common knowledge to those skilled in the art that Benzene ring and benzopyrimidinone ring are non-classical bioisostere, and the evidence in the case did not prove the swap of Benzene ring and benzopyrimidinone ring in molecular design of anti-cancer drugs are bioisostere; therefore, the challenged decision determining that the prior art provides teaching to replace benzopyrimidinone ring with Benzene ring lacks basis.
(2021) Zui Gao Fa Zhi Xing Zhong No. 846
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