SinoMab BioScience Limited — Regulatory Filings 2021

Jul 23, 2021

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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 COMPLETION OF SN1011 PHASE I LAST SUBJECT LAST VISIT IN CHINA

Reference is made to the announcements of SinoMab BioScience Limited (中國抗體製藥有限 公司) (the “ Company ”, together with its subsidiaries, the “ Group ”) on 14 November 2019, 29 January 2020, 29 June 2020, 1 September 2020, 15 January 2021 and 24 June 2021 in relation to the latest research and development progress of one of the Group’s key products, SN1011.

The board of directors (the “ Board ”) of the Company is pleased to announce that SN1011 has completed last subject last visit on 23 July 2021 in a Phase I dose-escalation study in China, in which 71 healthy subjects were enrolled. The highest dosage was ascended to 800 mg, and none of the subjects reported serious adverse event (SAE). This product showed well tolerability and safety. Clinical study report is expected to be released by the end of third quarter of this year. This Phase I clinical trial is to evaluate safety, tolerability, pharmacokinetics, pharmacodynamics and recommended Phase II dose of SN1011 in the treatment for autoimmune disease.

Following the approval of Investigational New Drug (IND) application for pemphigus vulgaris (“ PV ”) and systemic lupus erythematous (“ SLE ”) indication of SN1011, the Company is initiating the Phase II clinical study targeting on PV in China. The Company also plans to initiate Phase II clinical study targeting on SLE in the near future.

SN1011 is the Company’s third generation, covalent reversible BTK inhibitor designed for higher selectivity, superior efficacy and improved safety for the long-term treatment of SLE, PV, multiple sclerosis, rheumatoid arthritis, and other immunological diseases. SN1011 differentiates from existing BTK inhibitors currently available in the market, such as Ibrutinib, in terms of mechanism of action, affinity, selectivity and safety.

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

Hong Kong, 23 July 2021

As at the date of this announcement, the executive director of the Company is Dr. Shui On LEUNG, the non-executive directors of the Company are Dr. Haigang CHEN, Mr. Xun DONG, Mr. Senlin LIU, Ms. Wenyi LIU, Mr. Huiyuan MA and Mr. Jing QIANG, and the independent non-executive directors of the Company are Mr. George William Hunter CAUTHERLEY, Mr. Ping Cho Terence HON, Dr. Chi Ming LEE and Mr. Dylan Carlo TINKER.