Shanghai Junshi Biosciences : VOLUNTARY ANNOUNCEMENT - TORIPALIMAB HAS BEEN INCLUDED IN DRUG LIST OF THE PROCEDURE FOR BREAKTHROUGH THERAPY DESIGNATION

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.*

ɪऎёྼ͛يᔼᖹ߅Ҧٰ΅Ϟࠢʮ̡

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

(Stock code: 1877)

VOLUNTARY ANNOUNCEMENT -

TORIPALIMAB HAS BEEN INCLUDED IN DRUG LIST OF

THE PROCEDURE FOR BREAKTHROUGH THERAPY DESIGNATION

This announcement is made by Shanghai Junshi Biosciences Co., Ltd.* (ɪऎёྼ͛يᔼᖹ߅Ҧ ٰ΅Ϟࠢʮ̡) (the "Company") on a voluntary basis. Reference is also made to the overseas regulatory announcement of the Company dated 24 March 2021.

The board (the "Board") of directors (the "Directors") of the Company is pleased to announce that the Company's product, the recombinant humanized anti-PD-1 monoclonal antibody for injection (generic name: toripalimab, trade name: TUOYI®, product code: JS001) has been recently included in the Drug List of the Procedure for Breakthrough Therapy Designation for the first-line treatment of advanced mucosal melanoma by the National Medical Products Administration (the "NMPA"). Relevant information is as follows:

ABOUT TORIPALIMAB

Drug name: Recombinant humanized anti-PD-1 monoclonal antibody for injection Classification of drug: Biological product

Class of registration: 1

Acceptance No.: CXSL1400138

Proposed indications (or efficacies): First-line treatment of advanced mucosal melanoma

Reason and basis: Upon review, the application is in compliance with relevant requirements under the Administration Measures for Drug Registration and the Announcement of NMPA on the Three Documents Including the Procedures on Evaluation of Drugs for Breakthrough Therapy (Trial) (No. 82[2020]), and it is agreed to include toripalimab in the drug list of the procedure for breakthrough therapy.

Toripalimab was the first domestic anti-PD-1 monoclonal antibody approved for marketing in China. More than thirty company-sponsored clinical studies covering more than fifteen indications have been conducted globally, including in China and the United States. On 17 December 2018, toripalimab obtained a conditional approval from the NMPA for the second-line treatment of unresectable or metastatic melanoma. Toripalimab was included in the 2019 and 2020 Guidelines of Chinese Society of Clinical Oncology (CSCO) for the Diagnosis and Treatment of Melanoma.

In December 2020, toripalimab injection was successfully included in the updated National Reimbursement Drug List. In February 2021, the supplemental new drug application ("NDA") for toripalimab for the treatment of patients with recurrent or metastatic nasopharyngeal carcinoma after failure of at least two lines of prior systemic therapy has been granted conditional approval by the NMPA.

The supplemental NDA of toripalimab for the second-line treatment of metastatic urothelial carcinoma was accepted by the NMPA in May 2020 and received priority review designations from the NMPA in July 2020. In September 2020, toripalimab was granted Breakthrough Therapy Designation by the US Food and Drug Administration ("FDA") for the treatment of recurrent/ metastatic nasopharyngeal carcinoma. In February 2021, the supplemental NDA application of toripalimab in combination with chemotherapy for the first-line treatment of patients with advanced, recurrent or metastatic nasopharyngeal carcinoma was accepted by the NMPA. As at the date of this announcement, toripalimab has been granted 1 Breakthrough, 1 Fast Track and 3 Orphan Drug Designations ("ODD") by the FDA for the treatment of mucosal melanoma, nasopharyngeal carcinoma, and soft tissue sarcoma.

ABOUT THE COMBINATION CLINICAL TRIAL

The clinical trial of toripalimab in combination with axitinib for the first-line treatment of patients with mucosal melanoma ("Combination Clinical Trial") is an international, multi-center, randomized, open-label Phase III study designed to evaluate the efficacy and safety of toripalimab in combination with axitinib versus pembrolizumab (trade name: KEYTRUDA®) as a first-line treatment for patients with unresectable, locally advanced or metastatic mucosal melanoma. The

Combination Clinical Trial intends to enroll 220 patients who will be randomized at a 1:1 ratio into two study arms. The primary endpoint of the Combination Clinical Trial is progression-free survival (PFS). The secondary endpoints include objective response rate (ORR), overall survival (OS), duration of response (DOR), safety and tolerance.

In March 2020, toripalimab in combination with axitinib for the treatment of mucosal melanoma was granted the ODD by the FDA. In January 2021, toripalimab for the first-line treatment of mucosal melanoma has been granted the Fast Track Designation by the FDA.

Mucosal melanoma is a subtype of melanoma, which is less responsive to traditional chemotherapy, with low response rate for single-drug immunotherapy. Toripalimab is the world's first PD-1 inhibitor applied in anti-PD-1 monoclonal antibody in combination with VEGFR inhibitor for the treatment of mucosal melanoma. The results of the study on toripalimab in combination with axitinib for the treatment of advanced mucosal melanoma (NCT03086174) were published in the Journal of Clinical Oncology in August 2019. The study showed that the combination of toripalimab with axitinib in the first-line setting achieved an ORR of 48.3% and a disease control rate (DCR) of 86.2% for advanced mucosal melanoma with a manageable safety profile. The median progression-free survival (mPFS) was 7.5 months.

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 described research and development project 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, PRC, 24 March 2021

As at the date of this announcement, the Board 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