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SHANGHAI JUNSHI BIOSCIENCES CO., LTD.*

Shanghai Junshi Biomedical Technology Co., Ltd. (a joint stock limited company incorporated in the People's Republic of China) (Stock code: 1877)

Overseas regulatory announcement

This announcement is made in accordance with Rule 13.10B of the Rules Governing the Listing of Securities on The Stock Exchange of Hong Kong Limited.

This is to set forth the "Shanghai Junshi Biomedical Technology Co., Ltd. voluntarily discloses information about toripalimab first-line treatment of HER2 expression

Announcement that the marketing application for new indications of urothelial cancer was approved" is for reference only.

By order of the board of directors Shanghai Junshi Biomedical Technology Co., Ltd. Mr. Xiong Jun

Chairman

China, Shanghai, May 21, 2026

As of the date of this announcement, the Company’s Board of Directors includes Executive Directors Mr. Xiong Jun, Dr. Li Ning, Dr. Zou Jianjun,

Mr. Li Cong, Mr. Zhang Zhuobing, Dr. Yao Sheng, Dr. Wang Gang and Dr. Li Xin; Non-executive Director Tang Yixian students; and independent non-executive directors Mr. Zhang Chun, Dr. Feng Xiaoyuan, Mr. Li Zhongxian, Ms. Lu Kun and Yang Jin Ph.D.

*For identification purposes only

Securities code: 688180 Securities abbreviation: Junshi Biotechnology Announcement number: Lin 2026-029

Shanghai Haijunjunshi Biomedical Pharmaceutical Technology Co., Ltd.

Voluntary Disclosures Regarding Expressions Regarding the Treatment of First-Line Treatment with Triterygium, Prilimumab HER2 Announcement on the approval of the marketing application for new indications for urothelial carcinoma of the urinary tract

The board of directors and all directors of the company guarantee that the contents of this announcement do not contain any false records or misleading statements.

or major omissions, and shall bear legal responsibility for the authenticity, accuracy and completeness of its content in accordance with the law.

Recently, Shanghai Junshi Biomedical Technology Co., Ltd. (hereinafter referred to as the "Company") received a national

The "Drug Registration Certificate" approved and issued by the Food and Drug Administration, Toripalimab (trade name: Tuoyi®,

Product code: JS001) Antibody conjugate independently developed by United Rongchang Biopharmaceutical (Yantai) Co., Ltd.

combination drug vedicitumab for HER2 expression (HER2 expression is defined as HER2 immunohistochemistry New indication application for patients with locally advanced or metastatic urothelial carcinoma (test result 1+, 2+ or 3+)

Please get approval. This is the 13th indication for toripalimab injection approved in mainland China. due to

The commercialization of drugs after they are approved for marketing is easily affected by some uncertain factors, so please invest

Investors should make prudent decisions and pay attention to preventing investment risks. The relevant information is now announced as follows:

11. Basic information on pharmaceuticals and drugs Drug name: Toripalimab injection

Application matters: Drug registration (domestic production)

Acceptance number: CXSS2500079, CXSS2500080

Certificate number: 2026S01727, 2026S01728

Marketing authorization holder: Shanghai Junshi Biomedical Technology Co., Ltd. Approval conclusion: According to the "Drug Administration Law of the People's Republic of China" and relevant regulations, after review, this product

Complying with the relevant requirements for drug registration, new indications were approved, specifically: this product combined with vedesitomab

For patients with locally advanced or metastatic urothelial carcinoma with HER2 expression, defined as HER2

Immunohistochemistry results were 1+, 2+, or 3+.

22. Other related situations of pharmaceuticals and drugs Urothelial carcinoma is one of the ten most common malignant tumors in the world, and the incidence and mortality rates in China are increasing year by year.

Uptrend. According to the latest data from the National Cancer Center, the number of new cases of urothelial cancer in China in 2022 is 9.29

10,000 cases and more than 40,000 deaths, seriously threatening the lives and health of patients and leaving huge unmet clinical needs.

Ask.

In 2021, toripalimab injection was approved for the second-line and above treatment of advanced urothelial cancer. It is the first immunotherapy drug approved in China for non-selective population indications for advanced urothelial cancer.

The approval of this new indication is mainly based on the RC48-C016 study (NCT05302284), which

It is a multi-center, randomized, open, active drug-controlled phase III clinical study, designed to compare toripal monotherapy

Anti-combination vedesitomab versus gemcitabine combined with cisplatin/carboplatin in patients who have not received prior systemic anti-tumor therapy

HER2 (human epithelial growth factor receptor-2) expression (defined as HER2IHC1+, 2+, or 3+) localized Efficacy and safety in patients with advanced or metastatic urothelial carcinoma. The study was funded by Peking University Cancer Hospital

Professor Guo Jun and Professor Zhou Aiping from the Cancer Hospital of the Chinese Academy of Medical Sciences serve as the principal investigators, conducting research in 74 hospitals across the country.

clinical center.

In October 2025, the research results of RC48-C016 were published in The New England Journal of Medicine (TheNew England Journal of Medicine).

England Journal of Medicine, NEJM), and simultaneously at the 2025 European Society for Medical Oncology (ESMO) Oral presentation at the Annual Meeting President’s Forum (Abstract Number: #LBA7). The results showed that the primary endpoint of the study was no

Progression survival (hereinafter referred to as "PFS", based on independent imaging assessment) and overall survival (hereinafter referred to as "OS")

Achieved "double endpoint positive results". Compared with traditional chemotherapy, toripalimab combined with vedesitomab

First-line treatment of HER2-expressing advanced urothelial carcinoma doubled median PFS (13.1 months vs. 6.5 months,

Hazard ratio HR=0.36, 95%CI: 0.28-0.46; p<0.0001), the median OS was significantly prolonged (31.5 Months vs. 16.9 months, HR=0.54, 95%CI: 0.41-0.73; p<0.0001), objective response rate (ORR)

Significantly improved (76.1% vs. 50.2%), and the median duration of efficacy was extended several times (14.6 months vs. 5.6 months

month). The safety of the combination treatment group was significantly improved compared with traditional chemotherapy.

Toripalimab injection is the first domestically produced monoclonal antibody drug targeting PD-1 approved for marketing in China.

Once won the "China Patent Gold Award", the highest award in the national patent field, it has been awarded worldwide (including China, the United States). (China, Europe, Southeast Asia and other places), more than 40 clinical trials initiated by the company covering more than 15 indications have been carried out.

bed research. Ongoing or completed pivotal registrational clinical studies evaluating tripril across multiple tumor types

Safety and efficacy of monoclonal antibodies. As of the disclosure date of this announcement, 13 indications of toripalimab have been approved in China.

Approved domestically. In December 2020, toripalimab injection passed the national medical insurance negotiation for the first time.

12 approved indications have been included in the national medical insurance directory, and it is the only indication in the national medical insurance directory for kidney cancer,

Anti-PD-1 monoclonal antibody for the treatment of negative breast cancer and melanoma. Toripalimab for advanced nasopharyngeal cancer and food

Three indications for the treatment of ductal squamous cell carcinoma have been approved in Hong Kong, China.

In terms of international layout, as of the disclosure date of this announcement, toripalimab is currently available in the United States, the European Union,

It has been approved for marketing in more than 40 countries and regions including India, the United Kingdom, Australia and Singapore, and is sold globally It is subject to marketing review in many countries and regions.

33. Risk reminders

Because pharmaceutical products are high-tech, high-risk, and high-value-added, and the drugs have been approved for marketing

The subsequent commercialization is also susceptible to some uncertain factors. Investors are advised to make cautious decisions and pay attention.

Be careful to prevent investment risks. The company will actively promote the above projects and promptly monitor the subsequent progress of the projects in strict accordance with relevant regulations.

Perform information disclosure obligations. Relevant company information shall be disclosed in the company's designated media, "China Securities Journal" and "Shanghai Securities".

The announcements published in "Newspaper", "Securities Times" and the website of Shanghai Stock Exchange shall prevail.

Announcement is hereby made.

Shanghai Junshi Biomedical Technology Co., Ltd.

board of directors

May 22, 2026