Nanjing Leads Biolabs Co., Ltd. ("Leads Biolabs" or the "Company," Stock Code: 9887.HK) announced that the first patient has been dosed in an open-label, multicenter Phase Ib/II clinical trial evaluating opamtistomig (LBL-024), a PD-L1/4-1BB bispecific antibody, in combination therapy for metastatic colorectal cancer (mCRC). This milestone marks a further expansion of the Company’s strategy to address immunologically cold tumors, building on the clinical development of opamtistomig in extrapulmonary neuroendocrine carcinoma (EP-NEC), biliary tract cancer (BTC), hepatocellular carcinoma (HCC), and platinum-resistant ovarian cancer (PROC).

In mCRC, patients with microsatellite stable (MSS) and proficient mismatch repair (pMMR) status account for approximately 95% of cases. Due to insufficient T-cell infiltration in the tumor microenvironment, this patient population responds poorly to conventional immune checkpoint inhibitors, and standard treatment remains centered on chemotherapy combined with targeted therapy, leaving a significant need for new treatment strategies. Opamtistomig conditionally activates 4-1BB, reactivating and substantially expanding T cells while relieving PD-1/PD-L1 immunosuppression. This dual mechanism is expected to help address the immunotherapy gap for this patient population and has the potential to deliver durable, long-tail survival benefit.

The Phase Ib/II clinical trial is led by Academician Xu Ruihua of Sun Yat-sen University Cancer Center and will be conducted concurrently across multiple hospitals nationwide, with the aim of evaluating the efficacy and safety of opamtistomig in combination therapy in patients with mCRC. A translational medicine study of opamtistomig in MSS colorectal cancer has been selected for poster presentation at the 2026 European Society for Medical Oncology (ESMO) Congress. Opamtistomig has also shown a trend of markedly prolonged survival benefits compared with historical data across several representative immunologically cold tumor types, including EP-NEC, BTC, HCC, and PROC, supporting further development of opamtistomig in mCRC.

Executive Commentary
Dr. Charles Cai, Chief Medical Officer of Leads Biolabs, stated: “Colorectal cancer, particularly MSS/pMMR disease, remains a major challenge for immunotherapy. Opamtistomig combines PD-L1 blockade with conditional 4-1BB activation, a differentiated approach designed to enhance antitumor immunity in immunologically cold tumors. We are encouraged by our translational research in MSS colorectal cancer and the clinical findings emerging across multiple cold tumor types. The enrollment of the first patient in this trial represents an important step in extending our strategy to mCRC. We look forward to further evaluating opamtistomig’s potential to address the unmet medical needs of these patients.”