Shanghai Junshi Biosciences : VOLUNTARY ANNOUNCEMENT - JS007 INJECTION RECEIVED THE ACCEPTANCE NOTICE FOR THE INVESTIGATIONAL NEW DRUG APPLICATION

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.

SHANGHAI JUNSHI BIOSCIENCES CO., LTD.*

上海君實生物醫藥科技股份有限公司

(a joint stock company incorporated in the People's Republic of China with limited liability)

(Stock code: 1877)

VOLUNTARY ANNOUNCEMENT -

JS007 INJECTION RECEIVED THE ACCEPTANCE NOTICE FOR

THE INVESTIGATIONAL NEW DRUG APPLICATION

This announcement is made by Shanghai Junshi Biosciences Co., Ltd.* (上海君實生物醫藥科技 股份有限公司) (the "Company") on a voluntary basis. Reference is also made to the overseas

regulatory announcement of the Company dated 7 April 2021.

The board (the "Board") of directors (the "Directors") of the Company is pleased to announce that, the Company has received the Acceptance Notice 《( 受理通知書》) issued by the National Medical Products Administration (the "NMPA"). The investigational new drug application for the JS007 injection (project code: "JS007") has been accepted. Relevant information is as follows:

ABOUT JS007

Drug name: JS007 injection

Application matter: Registration of Domestic Production of Pharmaceutical Product

Acceptance No.: CXSL2100110

Applicant: Shanghai Junshi Biosciences Co., Ltd.* (上海君實生物醫藥科技股份有限公司)

Review conclusion: Accepted upon review according to the requirements of Article 32 of the Administrative License Law of the People's Republic of China.

JS007 is a recombinant humanized anti-CTLA-4 monoclonal antibody injection developed independently by the Company that is mainly used for the treatment of advanced cancer. Cytotoxic

1. lymphocyte-associatedantigen-4(CTLA-4) is an important receptor for T cell surface modulates immune response. JS007 is able to bind to CTLA-4 specifically and block the interaction between CTLA-4 and its ligand B7 (CD80 or CD86) effectively, thereby activates T-lymphocyte and inhibits the growth of tumor. Currently, ipilimumab, a marketed drug with the same target overseas, as the first immunity checkpoint inhibitor, has been proved to have significant tumor suppressor effect in multiple tumor types including melanoma, lymphoma, renal cell cancer, urothelial carcinoma, ovarian cancer and non-small cell lung carcinoma, and has been approved for the treatment of advanced melanoma. According to the data of pre-clinical studies, compared with ipilimumab with the same target but different sequence, JS007 shows similar level of safety but better efficacy.

1

RISK WARNING

Due to the high-tech,high-risk and high-value-added characteristics of pharmaceutical products, there are substantial risks and uncertainties in the process of drug research, development and commercialization. These many stages make it susceptible to uncertainties and therefore, investors are advised to make cautious decisions and pay careful attention to investment risks. The Company will actively pursue the above research and development projects and fulfill its information disclosure obligations in a timely manner for subsequent progress in strict accordance with relevant regulations.

By order of the Board

Shanghai Junshi Biosciences Co., Ltd.*

Mr. Xiong Jun

Chairman

Shanghai, the PRC, 7 April 2021

As at the date of this announcement, the board of directors of the Company comprises Mr. Xiong Jun, Dr. Li Ning, Dr. Feng Hui, Mr. Zhang Zhuobing and Dr. Yao Sheng as executive Directors; Dr. Wu Hai, Mr. Tang Yi, Mr. Li Cong, Mr. Yi Qingqing and Mr. Lin Lijun as non-executive Directors; and Dr. Chen Lieping, Mr. Qian Zhi, Mr. Zhang Chun, Dr. Jiang Hualiang and Dr. Roy Steven Herbst as independent non-executive Directors.

• For identification purpose only

2