SinoMab BioScience Limited — Regulatory Filings 2020

Sep 28, 2020

Hong Kong Exchanges and Clearing Limited and The Stock Exchange of Hong Kong Limited take no responsibility for the contents of this announcement, make no representation as to its accuracy or completeness and expressly disclaim any liability whatsoever for any loss howsoever arising from or in reliance upon the whole or any part of the contents of this announcement.

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SinoMab BioScience Limited 中國抗體製藥有限公司

(Incorporated in Hong Kong with limited liability)

(Stock code: 3681)

VOLUNTARY ANNOUNCEMENT – UPDATE ON SM03 REGARDING ORAL PRESENTATION AT 22[ND] APLAR VIRTUAL CONGRESS

The board (the “ Board ”) of directors (the “ Directors ”) of SinoMab BioScience Limited (中國抗 體製藥有限公司) (the “ Company ”) hereby wishes to announce a recent update in relation to a recognition of the Company’s flagship product, SM03, received from the Asia-Pacific League of Associations for Rheumatology (the “ APLAR ”), which is a confederation of various rheumatology associations that represent different countries of the Asia-Pacific region striving to propagate and consolidate rheumatology endeavours in the Asia-Pacific region.

The Board is pleased to announce that on 27 August 2020, the Company was informed by the APLAR that an abstract previously submitted by the Company has been accepted for a live program oral presentation (the “ Presentation ”) at the 22[nd] APLAR Virtual Congress, which is currently scheduled to be held between 24 October and 29 October 2020. The Company submitted an abstract titled “Anti-drug antibody response against SM03, an anti-human CD22 monoclonal antibody, in Chinese rheumatoid arthritis patients”. The Presentation, which forms part of the research and development of SM03, will focus on the clinical study of SM03 against rheumatoid arthritis (“ RA ”). Subsequent to the oral presentation made at the European League Against Rheumatism 2020 Congress on 5 June 2020 (the “ First International Oral Presentation ”), the Presentation is the second international oral presentation on an abstract of the clinical study report of SM03 against RA. Please refer to the Company’s announcements dated 7 April 2020 and 8 June 2020 for further information relating to the First International Oral Presentation.

The Company’s flagship product, SM03, is a potential global first-in-target anti-CD22 monoclonal antibody for the treatment of RA and potentially for the treatment of other immunological diseases, which is currently in Phase III clinical trials in China and expected to be commercialised by the end of 2021.

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The Company may not be able to ultimately develop and market SM03 successfully. Shareholders of the Company and potential investors are advised to exercise caution when dealing in the shares of the Company.

By order of the Board of SinoMab BioScience Limited Dr. Shui On LEUNG Executive Director, Chairman and Chief Executive Officer

Hong Kong, 28 September 2020

As at the date of this announcement, the executive Directors are Dr. Shui On LEUNG and Mr. Jing QIANG, the non-executive Directors are Dr. Haigang CHEN, Mr. Xun DONG, Mr. Senlin LIU, Ms. Wenyi LIU and Mr. Huiyuan MA, and the independent non-executive Directors are Mr. George William Hunter CAUTHERLEY, Mr. Michael James Connolly HOGAN, Mr. Ping Cho Terence HON and Mr. Dylan Carlo TINKER.

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