Recently, an invention patent was granted, with a patent No. ZL202110172158.7 and issue No. CN113046327B, named “Pangolin Coronavirus xCoV and Application thereof and Application of Medicine in Resisting Coronavirus Infection”. As this patent relates to the use of drugs for the treatment of coronavirus infection, it has received a lot of attention. The author also studied the drafting of the application documents, the procedure of substantive examination thereof and some divisional applications of this patent, with the hope of gaining further insights.

In this case, the multiple independent claims in the original published application documents focus on the subject matter as follows:

1) a pangolin coronavirus xCoV;

2) the applications of the pangolin coronavirus xCoV: i) for screening and evaluation of active drugs against SARS-COV-2 virus; ii) for screening and evaluation of vaccines against SARS-COV-2 virus, and the preparation of attenuated or inactivated vaccines against SARSCOV-2 virus;

3) the use of any one, two or three of the following compounds for the preparation of drugs for the treatment of coronavirus infectious diseases: cepharanthine (stephanotis), silamectin, mefloquine hydrochloride, and mefloquine;

4) a drug screening model for screening and/or evaluating anti-coronavirus active drugs;

5) a method for screening and/or evaluating anti-coronavirus active drugs, and the like. [i]

During the substantive examination, the applicant deleted claims that were considered to have lack of unity in the first Office Action when responding, and then the application was granted a patent on May 10, 2022. The parent application for which the patent was granted only retained one claim, that is, application of cepharanthine for the preparation of a drug for the treatment of infectious diseases caused by SARS-COV-2 virus. [ii]

In this paper, the author intends to analyze the drafting of the parent application documents, the response to the office action, and the layout of the divisional applications, so as to provide some suggestions for patent applicants on how to consider the layout of drug patent applications.

As is well known, the third paragraph of Article 42 of the Fourth Revised Patent Law stipulates that[iii], in order to compensate for the time taken up by the review and approval for the marketing of new drugs, the patent administration department under the State Council shall, at the request of the patent holder, give compensation for the duration of the patent right for the invention patents related to new drugs that have been approved for marketing in China. The period of compensation shall not exceed five years, and the total effective patent term shall not exceed fourteen years after the approval of the new drug for marketing.

While, according to the provisions of Rule 85(4) newly added in the proposal for the amendments to the Implementing Regulations of the Patent Law (Draft for Comment) [iv], for the product patents of the chemical drugs, biological products, and new traditional Chinese medicines, the patents of the preparation methods or the patents of pharmaceutical use that have been approved for marketing in China and meet the conditions for compensation for drug patent term, compensation for drug patent term may be given. The patents related to new drugs mentioned in the preceding paragraph refer to the patents related to the active ingredients of new drugs that are first approved for marketing by the national medical products administration (NMPA) under the State Council. The patents of the new traditional Chinese medicines include the patents related to innovative traditional Chinese medicine drugs and the patents related to improved new traditional Chinese medicines with increased functional indications. Accordingly, Rule 85(7) newly added in the proposal for the amendments to the Implementing Regulations of the Patent Law (Draft for Comment) [v], stipulates that where a patentee requests compensation for the term of a drug patent, he/she/it shall, within 3 months from the date of approval of the application for marketing authorization for the drug, submit a request for compensation for the term of the drug patent to the patent administration department under the State Council, together with relevant supporting documents, and the drug and its patent shall meet the following conditions at the time of submitting the request: (1) where multiple patents exist for a drug, the patentee can only request compensation for the term of the drug patent for one of the patents; (2) where a patent involves multiple drugs at the same time, an application for compensation for the term of the drug patent can only be submitted for one drug; (3) the patent has not been compensated for the term of the drug patent; and (4) the remaining term of protection of the patent for which compensation for the term of the drug patent is requested shall not be less than 6 months.

As can be seen from the above provisions, the layout of patent applications involving drugs will bring completely different effects on the compensation of the subsequent drug patent protection period. Hereinafter, the parent application and its divisional applications will be used as a specific case to illustrate how to consider the layout of patent applications involving pharmaceuticals/drugs.

During the substantive examination of the parent application, the applicant also filed three divisional applications on April 11, 2022, with application numbers of 202210375336.0 [vi] (Pangolin Coronavirus xCoV and the Application thereof, published on August 16, 2022, with publication No. CN114908061A), 202210377234.2[vii] (Application of Mefloquine Hydrochloride or Mefloquine in the Preparation of Medicine for Treating Coronavirus Infectious Diseases, published on August 16, 2022, with publication No. CN114908062A), and 202210386551.0[viii] (Application of Silamectin in the Preparation of Medicine for Treating Coronavirus Infectious Diseases, Published on June 24, 2022, with publication No. CN114908061A).

The granted parent application and the three divisional applications thereof protect the following drug-related subject matters (the individual subject matters of patent applications here have been slightly re-drafted by the author, but the substantive contents of the protected subject matters have not been changed), for example “the use of cepharanthine for the preparation of a drug for the treatment of infectious diseases caused by SARS-COV-2 virus”, “the application of the pangolin coronavirus xCoV for the preparation of attenuated or inactivated vaccines against SARSCOV-2 virus”, “the use of mefloquine hydrochloride, and mefloquine for the preparation of drugs for the treatment of coronavirus (SARSCOV-2 virus) infectious diseases”, and “the use of silamectin for the preparation of drugs for the treatment of coronavirus (SARSCOV-2 virus) infectious diseases”.

In accordance with the provisions of Rule 85(4) and 85(7) newly added in the proposal for the amendments to the Implementation Regulations of the Patent Law (Draft for Comment), it is presumed that the above three divisional applications can be granted under the current subject matters in future, and the four known compounds can all be authorized and obtained approval of the drug registration of the National Medical Products Administration of China (NMPA), and then this granted parent application together with the three divisional applications would make it possible that the three of four known compounds, cepharanthine, mefloquine hydrochloride or mefloquine, silamectin, and a newly discovered and deposited virus by International Depository Authority, the panolin coronavirus xCoV, may obtain the compensations for the terms of the corresponding drug patents granted, provided that the periods of the approval of the corresponding drugs meet the provisions of period of time for the term compensation of the drug patent since the following subject matters would be protected by the granted patents, respectively: drugs for the treatment of infectious diseases caused by the SARS-COV-2 virus, or vaccines against the SARS-COV-2 virus.

The author would like to emphasize that in this case the patentee/patent applicant fully understood and took advantage of the provisions and requirements of the Patent Law and the Implementation Regulations thereof for the extension of the drug patent term by filing multiple divisional applications in a timely manner. It makes it possible that different known compounds or new virus deposited for possible drugs/vaccines against SARS-COV-2 virus are expected to obtain the compensations for the terms of multiple drug patents after the subsequent patent applications are granted and the corresponding compounds/virus deposited are approved by the NMPA for drug registration as drugs/vaccine with patent protection indications.

The above content summarizes how this case makes it possible to obtain compensation for the terms of drug patents that protect multiple drug uses or vaccine by the appropriate layout of granted patents and the filed divisional applications.

In addition, while studying the parent application, the author also found that the parent application only used pangolin coronavirus xCoV as an alternative model for screening the anti-SARS-COV-2 drug, but did not use SARS-COV-2 for drug experiments, and did not supplement corresponding experiments during the substantive examination. However, only in the response to the office action, the applicant stated the state of the prior art before the application was filed and why pangolin coronavirus xCoV was used as an alternative model for screening the anti-SARS-COV-2 drug, and specifically explained that the use of highly homologous viruses for screening the antiviral drug is a routine technical means in this field. At the same time, the applicant also stated that by using this virus model, it was proven that the three drug monomers cepharanthine, silamectin and mefloquine hydrochloride had obvious inhibitory effects on the inhibition experiments of virus infected cells, and the subsequent articles published by other research teams also proved that the three drug monomers cepharanthine, silamectin and mefloquine hydrochloride also had inhibitory effects on virus infected cells.[ix] Thus, the parent application was granted as a patent.

The author believes that the applicant/patentee can comply with the relevant provisions on supplementary experimental data in the revised Guidelines for Patent Examination[x], which came into effect on January 15, 2021, and supplement experimental data for the purpose of demonstrating, for example, sufficient disclosure and/or inventiveness. The author believes that the choice of using a virus with close homology as an alternative model for drug screening is still different from the tests by using the real coronavirus SARS-COV-2, and the experimental data obtained by the tests performed by using the real coronavirus SARS-COV-2 will be cogent to those skilled in the art, and in particular, to the subsequent clinical trials and the approval of the clinical drug registration for marketing review and approval are more convincing. In addition, those skilled in the field well know that the verification of experimental data is crucial for applications involving biological experiments.

Based on the above, using this specific patent and the divisional applications thereof as an example, the following factors for drafting drug-related patent applications should be considered by patent applicants: i) what measures can be taken in the drafting of patent application and during the substantive examination so that it may be fully realized that the granted patent involving the drug can be compensated for the term of the drug patent caused by the drug registration and approval; and ii) the experimental designs and the disclosure of the experimental data of the drug patent applications to meet the requirements of sufficient disclosure, substantial support for the claims and/or inventiveness. The above content includes only a few superficial opinions of the author, if anything is incorrect, please feel free to point out any errors and give guidance.

[i] The publication documents of CN113046327A of patent No. 202110172158.7;

[ii] The issued documents of CN113046327B of patent No. 202110172158.7;

[iii] The third paragraph of Article 42 of the Fourth Revised Patent Law;

[iv] The Rule 85(4) newly added in the proposal for the amendments of the Implementing Regulations of the Patent Law (Draft for Comment);

[v] The Rule 85(7) newly added in the proposal for the amendments of the Implementing Regulations of the Patent Law (Draft for Comment);

[vi] The publication documents of CN114908061A of patent application No. 202210375336.0;

[vii] The publication documents of CN114908062A of patent application No. 202210377234.2;

[viii] The publication documents of CN114657149 of patent application No. 202210386551.0;

[ix] The substantive documents of patent No. 202110172158.7;

[x] Notice of the State Intellectual Property Office on Revising the Guidelines for Patent Examination (No.391).