Patent applications on inventions for pharmaceutical use

By Wu Xiaoping and Zhang Mengqian, Wanhuida Intellectual Property

If a Chinese medical research institute applies for the patent of a US brand-name drug that might cure COVID-19, as a ‘secondary use’ invention does it constitute squatting? Just what are the requirements for pharmaceutical patentability?

On 4 February 2020, the Wuhan Institute of Virology (WIV), which is affiliated to the Chinese Academy of Sciences, announced that Remdesivir can effectively inhibit infection caused by SARS-CoV-2 in vitro, and that it had filed a patent application for invention on the pharmaceutical use of Remdesivir to treat SARS-CoV-2 infections.

Patentability of “secondary use” inventions

Remdesivir was developed and patented by US-based Gilead Sciences, yet the filing of a pharmaceutical-use patent application of Remdesivir does not constitute “squatting” under the framework of China’s Patent Law. Gilead patented the compound per se in Chinese patent No. ZL201180035776.1, which also covers the pharmaceutical use of such compound in the treatment of Paramyxoviridae virus infections, without providing antiviral activity data of Remdesivir.

Wu Xiaoping
Senior Associate
Wanhuida Intellectual Property

Gilead has a few other patent applications currently pending for examination before the China National Intellectual Property Administration (CNIPA), with one patent application, No. CN201680066796.8, disclosing the use of Remdesivir to treat infections caused by Coronaviridae viruses, including the well-known SARS and MERS.

The WIV attempts to patent the pharmaceutical use of the known compound Remdesivir to treat SARS-CoV-2 infection, an invention of a new use for a known product, which is commonly known as a “secondary use” invention and is patentable under China’s Guidelines for Patent Examination. Gilead’s above-mentioned pending application on the use of Remdesivir to treat coronavirus infection is also a “secondary use” invention per se.

Zhang Mengqian
Wanhuida Intellectual Property

The Chinese patent system follows the “first filing” principle, namely, patent right is granted to the first filer. Given that the WIV is the first filer of the secondary use invention of Remdesivir for the treatment of SARS-CoV-2 infection, the “squatting” accusation is without merit. The WIV’s immediate filing of a patent application upon discovering Remdesivir’s efficacy in treating SARS-CoV-2 infection is a justified measure aiming for the protection of its research, which may give it a legitimate footing should any intellectual property dispute arise in the future.

It therefore should not be labelled as “squatting” activity. In the meantime, an early filing does not guarantee the grant of patent right. The WIV, in order to secure a patent, will still need to overcome hurdles like proving the inventiveness of its invention by experimental data.

Post-filing of experimental data

In addition to the overall state of the prior art, the patentability of a pharmaceutical patent application hinges on the efficacy data described in the application. For a variety of reasons, the description of the experimental data in the application might not be satisfactory. Given the fact that the WIV filed its application at the very outset of its research, there is a possibility that experimental data need to be supplemented in order to substantiate relevant technical effect.

Whether post-filing of experimental data should be allowed has long been hotly debated in the pharmaceutical field, largely because this matter further affects the legal assessment over substantive parameters for the granting of a patent, like sufficiency of disclosure and inventiveness.

(1) New development in the examination of Chinese pharmaceutical patents. On 15 January 2020, the US and China signed an economic and trade agreement, where the following consensus was reached regarding the matter of supplemental data pertaining to pharmaceutical patent applications: “China shall permit pharmaceutical patent applicants to rely on supplemental data to satisfy relevant requirements for patentability, including sufficiency of disclosure and inventive step, during patent examination proceedings, patent review proceedings and judicial proceedings.”

It is therefore foreseeable that, with the execution of the Sino-US agreement, the Chinese administrative and judicial authority might relax the admissibility of supplemental data in practice.

(2) Prospects for grant of the WIV’s new-use patent. Against the new backdrop of the Sino-US agreement, if the admissibility of supplemental data is relaxed, it would be good news for stakeholders of innovator pharmaceuticals like Gilead, and new use researchers like the WIV.

At the current stage, supplemental data are allowed in practice, provided that, “the technical effect substantiated by the supplemental experimental data shall be obtained by a person skilled in the art from the contents disclosed in the patent application”.

The WIV’s new-use application has yet to be disclosed, but it can be presumed that a written description of the use has been provided in the application, to say the least. Even if the experimental data described in the application are insufficient to support the patentability of the application, pursuant to the Sino-US agreement, the WIV may “rely on supplemental data to satisfy relevant requirements for patentability” during the examination proceedings.

Still, the patentability of a patent application hinges on the overall state of the prior art. The SARS-CoV-2 is a brand new coronavirus around the globe, but whether its activity, and those of the prior coronaviruses, are mediated by the same or a similar mechanism needs to be taken into account, because it may have a bearing on the assessment over the inventiveness of the new use application.

Given the above-mentioned, the state of the prior art, in combination with the disclosure in the description of the patent and the prosecution practice at the time of the examination, are to be factored in for assessing the prospect for grant of the new-use patent.

Wu Xiaoping is a senior associate at Wanhuida Intellectual Property. She can be contacted on +86 10 6892 1000 (ext. 773) or by email at

Zhang Mengqian is an associate at Wanhuida Intellectual Property. She can be contacted on +86 10 6892 1000 (ext. 319) or by email at

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