SinoMab BioScience Limited — Regulatory Filings 2020

Jun 22, 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.

==> picture [29 x 43] intentionally omitted <==

==> picture [29 x 43] intentionally omitted <==

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

Reference is made to the announcements dated 7 April 2020 and 8 June 2020 of SinoMab BioScience Limited (the “ Company ”). The board (the “ Board ”) of directors (the “ Directors ”) of the Company hereby wishes to provide an update on the progress of the clinical trial of the Company’s flagship product, SM03.

With regards to SM03’s Phase III clinical trial in China, the Company has been carrying out clinical trial studies (“ Phase III Study ”), for the purpose of evaluation of the clinical efficacy and long term safety of SM03 in active rheumatoid arthritis patients with a multi-center randomized, double blind, placebo-controlled, parallel group study. The Board is pleased to announce that as of 19 June 2020, 290 eligible patients were randomized into the clinical trial and phase III clinical trial interim analysis was completed.

The objective of the phase III clinical trial interim analysis is to have an assessment of safety and tolerability profile of patients against existing SM03 safety information as a protection of the subjects recruited into the Phase III Study (the “ Phase III Clinical Trial Interim Analysis ”). The Phase III Clinical Trial Interim Analysis was conducted by the Independent Data Management Committee (“ iDMC ”) and the members of which are senior level experts in relevant medical community. By reviewing in unblinded manner the adverse events data collected as thus far in the Phase III Study, members of the iDMC can judge and determine if there is new or unexpected safety signal. The clinical data of the Phase III Study, however, has been maintained in blinded manner to the investigators and the Company as sponsor. According to the Phase III Clinical Trial Interim Analysis:

• as of 19 June 2020, a total of 290 patients were randomized into the study;

• among such 290 patients, 244 cases (84%) have completed the 24-week primary end-point visit and 132 cases (46%) have completed the 52-week extended period study;

• less than 12% of patients dropped out before the 52-week endpoint of the study, reflecting a satisfactory adherence to the study treatment in the study;

• judged against the Development Safety Update Report which was submitted to the Center for Drug Evaluation under the National Medical Products Administration of the People’s Republic of China, no new unexpected safety problem has been observed;

1

• as at the date of this announcement, there is no case of coronavirus disease (COVID-19) infection in all the subjects despite the outbreak of COVID-19; and

• a satisfactory safety and tolerability profile, which is generally in line with what had been observed in phase II study, has been shown in the patients recruited. iDMC therefore makes its recommendation to continue the present study based on the assessment of Phase III Clinical Trial Interim Analysis.

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 SinoMab BioScience Limited Dr. Shui On LEUNG Executive Director, Chairman and Chief Executive Director

Hong Kong, 22 June 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 Ms. Wenyi LIU, Dr. Haigang CHEN, Mr. Senlin LIU, Mr. Huiyuan MA and Mr. Xun DONG, and the independent non-executive Directors are Mr. Dylan Carlo TINKER, Mr. Michael James Connolly HOGAN, Mr. Ping Cho Terence HON and Mr. George William Hunter CAUTHERLEY.

2