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Leads Biolabs' Opamtistomig (PD-L1/4-1BB Bispecific Antibody) Enrolls First Patient in Phase Ib/II Combination Trial in Metastatic Colorectal CancerNANJING, China , Oct. 16, 2026 (GLOBE NEWSWIRE) -- Nanjing Leads Biolabs Co., Ltd. ("Leads Biolabs" or the "Company," Stock Code: 9887.HK) today 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 About Colorectal Cancer Approximately 15% to 30% of patients with CRC have metastatic disease at initial diagnosis, and 20% to 50% of patients initially diagnosed with localized disease eventually develop mCRC. Despite advances in treatment, mCRC remains associated with poor prognosis, with a five-year survival rate of only approximately 15%. Currently, immunotherapies are primarily approved for patients with microsatellite instability-high (MSI-H) or mismatch repair-deficient (dMMR) CRC. However, these patients account for only approximately 5% of mCRC cases, whereas approximately 95% of patients have microsatellite-stable (MSS) or mismatch repair-proficient (pMMR) disease, which generally exhibits limited responsiveness to conventional immunotherapy, highlighting a significant unmet medical need. About Opamtistomig Developed using Leads Biolabs’ proprietary X-body bispecific platform, opamtistomig is designed to simultaneously block PD-1/PD-L1 immune suppression and conditionally activate 4-1BB, an agonist pathway, resulting in a potent and synergistic anti-tumor immune response. It has a safety profile comparable to PD-1/PD-L1 inhibitors and demonstrates broader-spectrum anti-cancer potential. Mechanistically, 4-1BB agonism can reactivate exhausted T cells and promote robust T-cell proliferation, offering significant promise for PD-1/PD-L1–resistant or immunologically “cold” tumors and potentially offering durable survival benefits. Recognizing its clinical potential, opamtistomig received Breakthrough Therapy Designation from China's National Medical Products Administration (NMPA) in October 2024, and Orphan Drug Designation (ODD) from the U.S. Food and Drug Administration (FDA) in November 2024. Additionally, in January 2026, opamtistomig was granted Fast Track Designation by the FDA and ODD by the European Commission, and in September 2026, ODD from Japan's Ministry of Health, Labour and Welfare (MHLW), further underscoring its potential to address unmet medical needs in this patient population. In July 2026, its New Drug Application (NDA) was granted priority review designation by the NMPA, followed by NDA acceptance in August 2026, positioning opamtistomig as a potential world's first approved 4-1BB-targeting antibody, the first approved agonist antibody, and the first approved treatment for EP-NEC. About Leads Biolabs Leads Biolabs is a front-runner in next-generation immuno-oncology treatments with a differentiated pipeline of 15 innovative drug candidates, including five clinical-stage drug candidates and one registration-stage asset. The Company adopts a science-driven R&D approach and has successfully established comprehensive R&D capabilities spanning antibody discovery and engineering, in vivo and in vitro efficacy evaluation, as well as druggability assessment. It has also developed multiple proprietary technology platforms, including LeadsBody (a CD3 T-cell engager platform), X-body (a 4-1BB engager platform), TOPiKinectics (an ADC platform) and ImBiTDC (a TDC platform), which serve as the cornerstone for its continued innovation and have been validated by the clinical outcomes of its bispecific antibody portfolios. Leads Biolabs has established integrated capabilities across early discovery, translational medicine, clinical development, CMC and business development. The innovative nature and competitive strengths of its drug candidates, coupled with its global perspectives, proactive strategy, and efficient clinical validation, have made it an attractive partner for leading industry players and investment institutions. For more information, please visit https://en.leadsbiolabs.com/ Contact: 
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