LEADS BIOLABS-B - VOLUNTARY ANNOUNCEMENT -

COMPLETION OF FULL PATIENT ENROLLMENT IN PHASE II STUDY OF LBL-024 (OPAMTISTOMIG, PD-L1/4-1BB BISPECIFIC ANTIBODY) FOR BILIARY TRACT CANCER

with its subsidiaries, the "Group") on a voluntary basis to inform shareholders and potential investors of the Company about the latest business development of the Company.

The Company is pleased to announce that the Phase II clinical study evaluating Opamtistomig

(LBL-024, a PD-L1/4-1BB bispecific antibody) for the treatment of first-line advanced biliary tract cancer (BTC) has completed enrollment of all 70 patients. In April 2026, the study successfully entered the expansion phase based on the favorable safety profile and efficacy data that exceeded expectations. All patient enrollment was completed rapidly, fully demonstrating the efficient clinical advancement and continuously validated significant efficacy of LBL-024.

Although PD-(L)1 immunotherapy in combination with chemotherapy has become one of the first-line standard treatments for advanced BTC in recent years, clinical benefit remains very limited. Existing standard-of-care regimens represented by pembrolizumab plus chemotherapy and durvalumab plus chemotherapy have an objective response rate (ORR) of less than 30% and a median overall survival (OS) of only approximately 12–13 months, indicating that clinical needs are far from being met. The potential of Opamtistomig as an IO 2.0 pan-tumor

cornerstone therapy has been continuously validated across three dimensions: broad-spectrum anti-tumor activity, long-term survival benefit trends, and a safety profile comparable to PD-(L)1 monoclonal antibodies. Existing data show that, following extrapulmonary neuroendocrine carcinoma (EP-NEC) and small cell lung cancer (SCLC), Opamtistomig has once again demonstrated highly competitive efficacy in BTC, a typical immune-cold tumor, with the potential to elevate the efficacy of immunotherapy in BTC to new heights. Given that

the predominant pathological type of BTC is adenocarcinoma, combined with the positive data previously observed in squamous cell carcinoma subtypes of major cancer types such as non-small cell lung cancer (NSCLC), Opamtistomig has shown clear efficacy in both adenocarcinoma and squamous cell carcinoma types, with its broad-spectrum anti-cancer potential being continuously validated.

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The study is led by Academician Zhou Jian (周儉) of Zhongshan Hospital, Fudan University

(復旦大學附屬中山醫院) and is being conducted across multiple hospitals in China. Safety run-in data showed that LBL-024 in combination with chemotherapy demonstrated a favorable overall safety profile and good tolerability, with no new safety signals identified. Preliminary efficacy assessments showed an encouraging tumor shrinkage trend. Specific data will be

presented at the European Society for Medical Oncology (ESMO) Annual Meeting to be held in Madrid, Spain from October 23 to 27, 2026.

ABOUT BTC

BTC mainly includes gallbladder cancer and intrahepatic and extrahepatic cholangiocarcinoma, with approximately 419,100 new cases recorded globally in 2024. The vast majority of BTC cases are adenocarcinomas, which are highly aggressive. Most patients are diagnosed at an advanced stage, resulting in a poor prognosis, with a five-year survival rate of less

than 5%. Currently, the global incidence of BTC is on an upward trend, with the highest prevalence observed in Asian countries. Although PD-1/PD-L1 inhibitors in combination with chemotherapy have been approved as first-line treatment for advanced BTC, the overall survival benefit remains limited, with median overall survival improving from approximately

11.5 months to 12.8 months, and the objective response rate (ORR) remaining below 30%, indicating a significant unmet medical need.

ABOUT LBL-024 (OPAMTISTOMIG)

LBL-024 is a bispecific antibody simultaneously targeting PD-L1 and 4-1BB, and is a pan tumor IO 2.0 cornerstone therapy with potential survival benefit. Leveraging our self developed X-body™ platform with full intellectual property rights, LBL-024 achieves conditional activation of 4-1BB, relieving PD-1/PD-L1 immunosuppression while enhancing

4-1BB regulated T-cell activation, achieving a synergistic effect in eliminating tumors. LBL024 demonstrates a safety profile comparable to PD-1/PD-L1 inhibitors and greater potential for broad-spectrum cancer treatment, and has demonstrated first-in-class (FIC) or best-in class (BIC) potential in non-small cell lung cancer (NSCLC), small cell lung cancer (SCLC),

extrapulmonary neuroendocrine carcinoma (EP-NEC) and biliary tract cancer (BTC).

As the first molecule targeting the co-stimulatory receptor 4-1BB to have reached the pivotal single-arm registrational clinical stage globally, LBL-024 has the potential to become the first

drug approved for treating EP-NEC. LBL-024 has initiated clinical studies across 13 solid tumor indications in China, including one pivotal registrational clinical study and eight proof of-concept studies, covering EP-NEC, NSCLC, SCLC, BTC, ovarian cancer (OC), esophageal squamous cell carcinoma (ESCC), hepatocellular carcinoma (HCC), gastric cancer (GC), triple-negative breast cancer (TNBC) and melanoma, among other areas with high unmet

medical needs.

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4-1BB, as an agonist, can reactivate apoptotic T cells and induce substantial proliferation,

making it suitable for treating "cold tumors" that are resistant or unresponsive to PD-1/PD-L1 therapies. LBL-024 received the Breakthrough Therapy Designation (BTD) from CDE of the NMPA in October 2024, as well as the Orphan Drug Designation in treating neuroendocrine carcinoma (NEC) from the FDA in November 2024. In January 2026, LBL-024 received

Fast Track Designation (FTD) from the FDA for the treatment of EP-NEC and Orphan Drug Designation from the European Union.

Cautionary Statement required by Rule 18A.05 of the Rules Governing the Listing of Securities on The Stock Exchange of Hong Kong Limited: The Company cannot guarantee

that it will be able to develop, or ultimately market, LBL-024 successfully. Shareholders and potential investors of the Company are advised to exercise due care when dealing in the shares of the Company.

By order of the Board Nanjing Leads Biolabs Co., Ltd. 南京維立志博生物科技股份有限公司 Dr. KANG XIAOQIANG

Chairman, Executive Director and Chief Executive Officer

Nanjing, PRC, July 30, 2026