On June 2, 2006, Beijing No. 1 Intermediate People's Court (hereinafter referred to as "No. 1 Court") made a first instance decision concerning the disputed void declaration of the State Intellectual Property Office (SIPO) Patent Reexamination Board for patent No. ZL 94192386.X (hereinafter referred to as the "Patent"), revoking the Board's examination decision, and requiring the Board to render a new examination decision concerning the patent. This means that the patentee Pfizer had prevailed in the first instance case.

The Board decided that the patent specification was not set forth in a manner sufficiently clear and complete, failing to conform to Article 26.3 of the Patent Law of the P.R. China; and therefore, the patent should be revoked. Since the No. 1 Court held that it was wrong for the Board to decide that the patent was inconsistent with Article 26.3 of the Patent Law, it reversed the Board's decision.

The author thinks that the reason for the material discrepancy between the views held by the No. 1 Court and the Board lies in the different interpretation of the standard set forth in Article 26.3 of the Patent Law in the field of medical technology requiring the patent " to be set forth in a manner sufficiently clear and complete".

1. Content of the Patent

The patent specification involves several medical compounds which consist of a certain general formula (hereinafter referred to as the "Formula 1") or pharmaceutically acceptable salts or medicinal compounds containing such salts. There are large quantities of such materials and they may be divided into 5 levels of preference based on the difference of substituents in Formula 1:
       Level 1 - compound of Formula 1
       Level 2 -preferred set of compounds of Formula 1
       Level 3 - more preferred set of compounds of Formula 1
       Level 4 - specially preferred set of compounds of Formula 1
       Level 5 -specially preferred 9 kinds of compounds of Formula 1. One of these 9 compounds is sildenafil.

In the authorizing text of this patent, there is only one claim involving sildenafil, one of the Level 5 compounds. The range of the claim is as follows: the use of sildenafil or its pharmaceutically acceptable salts or the medical compounds containing one of them in making medicine for healing or preventing erectile dysfunction in male animals (including human beings).

The specification presents data regarding invitro selective inhibition activity of one of the Level 1 and Level 4 compounds,describes the toxicity test of Level 1 and Level 4 compounds, records the effect obtained by the volunteers who have taken one of the Level 4 compounds, prescribes the preferred method of taking Level 1 compounds, but does not mention the exact names of the specific compounds used in the test which produced the aforesaid data.

2. Viewpoint of the Patent Reexamination Board

The Board held that: as concerns the invention of the second medical usage of known compounds, if a person skilled in the relevant art, combined the technical content recorded in the specification with technology presently available, that person would still need to do creative work to ensure the known compounds have the aforesaid second medical usage, and therefore, the specification was not set forth in a manner sufficiently clear and complete.

The specification of the patent records the data regarding the invitro selective inhibition activity of one of the Level 1 and Level 4 compounds but does not record any specific data regarding the nine kinds of specific compounds contained in Level 5 compounds. Furthermore, there is only one point in the specification which is related to the effect of healing or preventing male penile erection dysfunction, i.e. "up to now, the research performed on patients has proven that: a kind of specially preferred compound may induce penile erection in males who have erectile dysfunction". This expression only demonstrates that the compound involved is one of the Level 4 compounds but cannot determine exactly which Level 4 compound it is.

As the test data recorded in the specification is limited, and the healing effect lacks adequate connection with Level 5 compounds (including sildenafil), it is necessary to do creative work to select from Level 4 compounds and confirm that sildenafil has a curative effect. A person skilled in the relevant art still needs to do creative work to ensure that sildenafil may "induce penile erection in males who have erectile dysfunction".

Therefore, the technical program in the claim of the patent specification is not set forth "in a manner sufficiently clear".

3. Viewpoint of the No. 1 Court 

No. 1 Court held that: this patent specification specifies the compounds range from Level 1 to Level 5 according to their gradual development and a person skilled in the relevant art may naturally understand that defining the so- called preferred level shall be closely related to the realization of the inventions’ purpose and that the standard shall be consistent. In other words, the healing effect of Level 5 compounds shall be the best.

The patent specification records an invitro test of a kind of specially preferred compound. Meanwhile, the specification also records the result of the in vivo clinical test, i.e. a kind of special compound inducing penile erection in males who have erectile dysfunction. Although there are more than 100 kinds of such compounds, the specification does not specify which kind of compound has the aforesaid effect. But generally, the data of specific compounds or the test result given in the specification come from compounds which provide better results. Therefore it can be concluded that the preferred Level 4 compounds have in vitro and in vivo activities.

Level 5 compounds are the most preferred compounds given in the specification. The structures of nine kinds of these compounds are quite similar and their pharmacological activities should also be similar. Therefore, it is reasonable for a person skilled in the relevant art to confirm that the compound in the patent claims is one of these nine compounds, and that it has the same healing effect as described in the specification of the patent. Such a conclusion entails no further creative work.
Therefore, it is wrong for the Board to think that the specification is not set forth in a manner sufficiently clear.

4. Author's Viewpoint

1) The test result did not necessarily come about due to the compounds having a better effect.

The No. 1 Court points out that in general cases, the data of the specific compounds or the test results given in the specification occur as result of the compounds having a better effect. The author thinks that this view is questionable.

The term general cases does not necessarily mean specific cases. In the field of medicine and bio-chemical technology, if one technical solution contains several compounds (or combinations), the specific data or test results given in the specification by the applicant do not necessarily arise from the compounds (or combination) having a better effect, especially not from the one having the best effect. This is because the applicants have different purposes and strategies in applying for a patent. In many cases the applicants avoid mentioning the compounds or combinations on purpose in order to keep the technical know-how secret or to evade the risk of disclosing core technology completely. Therefore, it is questionable to conclude that the data of specific compounds or the test results given in the specification occur as a result of the compounds having a better effect or even the best effect. 

In the patent specification, there is no illustration regarding which compound produces the test data or test result. Even when it concludes that the data of the specific compounds or the test results given in the specification come about from the compounds having a better effect, it is impossible to conclude that it is produced by sildenafil. Furthermore, there is no definition as to what "better effect" means in the specification. People may have different understandings. For instance, all the preferred compounds may be regarded as better. Compounds from Level 2 to Level 5 may be regarded as those "having a better effect". The quantity of those compounds having a "better effect" is very large, and there are more than 100 kinds of compounds in Level 4.

Therefore, under the premise that the specification does not specify which compounds produce the aforesaid result, it is impossible for a person skilled in the relevant art to completely, and positively conclude that 100% of the said data or test results must be attributed to the usage of sildenafil; that is, it is impossible to conclude that the sildenafil has the specific healing effect as described in the specification. 

2) Compounds with similar structures do not necessarily have similar pharmacological activities

The No. 1 Court points out that the structures of the nine kinds of Level 5 compounds are similar, so their pharmacological activities should be similar. The author thinks it is a rather arbitrary conclusion.

As we all know, the bioactivities of medicines are related with the functional groups of molecules. The introduction of different functional groups in some basic structures may change their activities or in vivo absorption and transition. That is to say, a compound of general formula usually contains many specific compounds, which have similar structures, but their pharmacological activities may be quite different; sometimes the replacement of a residue may even result in the total loss of its effectiveness. Such examples are quite normal in the medicinal field. For instance, the replacement of the contraposition nitryl of chloramphenicol with other residues (p-nitro group of chloramphenicl is substituted with other groups (for example, cyano, hydroxy, amido, halo, pheno, or heterocyclic group)) may produce a set of compounds whose structures are quite similar with that of chloramphenicol, but their healing effects decrease materially, and some may even lose their effectiveness completely.

The greatest difficulty with the discovery of new medicines lies in the uncertainty of the corresponding relationship between the structure and its activities. The selection of a new medicine, like looking for a needle in a haystack, requires testing various compounds with similar structures one by one. It is evident that with this patent, it is impossible for a person skilled in the relevant art to ensure that sildenafil, chosen from so many compounds with similar structures, has the healing effect as described in the specification without requiring any creative work. Therefore, the presumption is based on inadequate evidence.

3) The invention for the second medical usage of specific compounds must contain certain data demonstrating its effects

Under Article 26.3 of the Patent Law, as concerns patent applications for an invention involving the second medical usage of unknown compounds, the description shall set forth the invention in a manner sufficiently clear and complete, including not only the method of making such compounds, but also the effective amount for usage, the usage method and the specification. Further, it should include specific data explaining the results of laboratory tests, animal tests and clinical tests to prove that certain compounds have specific healing effects for the second invention. 

The patent specification contains no express illustration for which compounds have been used for the test, nor clarify whether these several tests have used the same compounds. It is well-known that different compounds have different toxicity and invitro and in vivo activities. Therefore, it is difficult for people to believe that both the toxicity and in vitro and in vivo activities indicated in the specification may necessarily appear on the compounds of sildenafil at the same time. Furthermore, even the toxicity and invitro and in vivo activities as well as the healing effect indicated in the specification may satisfy the requirement that certain Level 4 compounds have been set forth in a manner sufficiently clear and complete. Even if there is no evidence to ascertain that the compound is sildenafil, it is still difficult for a person skilled in the relevant art to be certain about whether sildenafil will attain this invention's effect of "healing or preventing erectile dysfunction in male animals (including human beings)". Meanwhile, it is difficult for a person to believe that sildenafil may be used with the same dosage, indication and prescription as mentioned in the specification.

5. Follow-up proceedings

Although the No. 1 Court revoked the null and void decision made by the Board and demanded that the Board make another review decision, the destiny of the patent is still a mystery.

The "Third Parties" to this case have appealed to the Beijing High People's Court ("the High Court") within the appeals period. The High Court may maintain or revoke the first instance ruling. 

Even the High Court's affirmation of the first instance decision does not mean that the validity of the patent will be maintained. In the decision declaring the patent null and void, the Board did not judge whether the patent was consistent with relevant Article 22.3 and Article 26.4 of the Patent Law, so it is possible that the Board will declare the patent void again under these grounds in a subsequent examination.

As sildenafil belongs in the series of inhibitors of phosphodiesterase type 5)(PDE-5), its numerator structure was publicized at a Singapore academic conference in 1990, and the fact that the series of inhibitors of phosphodiesterase type 5 have a healing effect for erectile dysfunction is well-known in the fields of biology and medicine. Furthermore, the specification of the patent does not provide any specific useage method for sildenafil. Therefore, when the Board reexamines whether the patent boasts sufficient creativity and whether the claim is supported by the specification, all these other issues may make it difficult for the patent to pass the examination process.

The ruling of the No. 1 Court does not mean that this is the end of this patent dispute. There will be other developments in the future. This may be seen from the large team of patent agents (lawyers) hired by the "Third Parties" in the first instance hearing of this case. Let's wait and see for the ultimate outcome.

What is worth mentioning is that many people mistakenly regard this patent as the "Viagra patent". The active element of Viagra is citrate salt contained in sildnafil, but the claim of this patent involves sildenafil, salts of sildenafil, and the medicinal compounds containing sildnafil or its salts. That is to say, the active element of Viagra is only one of these materials, and as a medical product, "Viagra" contains other materials such as excipient. Furthermore, this patent is for patent usage, and it does not mean that the patent can only be used to make "Viagra" as it covers more than the use of "Viagra". The making of " Viagra" is only one specific scheme for this patent.  

It was not easy for Pfizer to develop "Viagra", so it seems unfair that Pfizer would not have a monopoly position in this medicinal market after making a tremendous investment in "Viagra". However the occurence of such a situation is probably due to the substantial defect in the patent application's specification. This example provides a good lesson for people. Good products and technology cannot lead to the manifestation of legal rights and interests without the guarantee and protection of high quality patent application documents. (This article is finished on August 8, 2006.)

About the Author
    Xie Shunxing is Chairman of CN-KnowHow Intellectual Property Agent Limited, one of the experts of the State Intellectual Property Strategy Experts Group, vice director of the Intellectual Property Commission for All-China Patent Agents Association (ACPAA), and expert of the Industry Commission of  Beijing  Intellectual Property Working Meeting Office. Mr. Xie graduated from Chinese Peking Union Medical College where he majored in the Biochemical Pharmacology specialty. He once worked in SIPO for ten years as a patent examiner and vice director, and also worked as a senior consultant in a domestic Bio-chem group and was assistant president in a foreign medicine making group. He was in charge of many null and void patent litigation cases and delivered speeches in various national and local seminars (such as in Zhongguancun and Peking University). He also acted as a sponsor for some software projects concerning government and enterprise intellectual property rights. Mr. Xie also hosted many intellectual property projects for the government and various enterprises.

                                                                                      (Translated by Luo Duoqun)