LEADS BIOLABS-B(09887): First Patient Dosed in Phase IB/II Clinical Trial of Vilixin (Opatilimab, PD-L1/41BB Bispecific Antibody) in Combination Therapy for Metastatic Colorectal Cancer

LEADS BIOLABS-B(09887) announced that the Company is pleased to announce the completion of first patient dosing in the open-label, multicenter Phase Ib/II clinical trial evaluating the Company's independently developed Vilixin (Opatilimab, PD-L1/4-1BB bispecific antibody) in combination therapy for metastatic colorectal cancer (mCRC). This marks a further extension of the Company's strategy of targeting immunologically "cold tumors" with Vilixin, following 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 mismatch repair proficient ("pMMR") status account for approximately 95%. Due to insufficient T-cell infiltration in the tumor microenvironment, this patient population responds poorly to traditional immune checkpoint inhibitors, and standard treatment remains primarily chemotherapy combined with targeted therapy, highlighting an urgent need for new therapeutic strategies. Vilixin can conditionally activate 4-1BB, thereby relieving PD-1/PD-L1 immunosuppression while simultaneously reactivating and massively expanding T cells, potentially filling the immunotherapy gap for this patient population and delivering long-tail survival benefits. The Phase Ib/II clinical trial is led by Academician Xu Ruihua of Sun Yat-sen University Cancer Center and will be conducted simultaneously at multiple hospitals across China, aiming to evaluate the efficacy and safety of Vilixin combination therapy in mCRC patients. The translational medicine research of Vilixin for MSS colorectal cancer has been selected for poster presentation at the 2026 European Society for Medical Oncology ("ESMO") Annual Meeting. Meanwhile, Vilixin has demonstrated a trend of significantly prolonged survival benefits compared to historical data across multiple typical immunologically "cold tumor" indications, including EP-NEC, BTC, HCC, and PROC, providing mechanistic and clinical support for the development prospects of Vilixin in the mCRC indication. CRC is the most common malignant tumor of the digestive system worldwide. According to data from the International Agency for Research on Cancer ("IARC"), there were approximately 1.93 million new CRC cases and approximately 904,000 deaths globally in 2022, making CRC the third most commonly diagnosed cancer and the second leading cause of cancer-related death worldwide. According to data released by China's National Cancer Center, there were 517,000 new CRC cases and 240,000 deaths in China in 2022, with incidence and mortality rates ranking second and fourth, respectively, among all malignant tumors. Approximately 15% to 30% of CRC patients have distant metastasis at initial diagnosis, and 20% to 50% of patients with initially localized CRC eventually develop mCRC. Despite therapeutic advances, mCRC continues to have a poor prognosis, with a 5-year survival rate of only approximately 15%. Currently, immunotherapy is primarily approved for CRC patients with microsatellite instability-high (MSI-H) or mismatch repair deficient (dMMR). However, in mCRC, such patients account for only approximately 5%, while approximately 95% are microsatellite stable (MSS) or mismatch repair proficient (pMMR), who generally have limited response to traditional immunotherapy, representing a huge unmet medical need. Vilixin is a bispecific antibody simultaneously targeting PD-L1 and 4-1BB, with the potential to become a pan-tumor IO 2.0 backbone therapy with survival benefits. Currently, Vilixin has initiated clinical studies across 14 indications, including 1 single-arm pivotal registration study, 1 confirmatory Phase III clinical study, and 9 proof-of-concept studies, covering multiple major cancer types and "cold tumors." Among the 7 cancer types with existing clinical data support, Vilixin has demonstrated outstanding clinical value and broad therapeutic prospects, including extrapulmonary neuroendocrine carcinoma (EP-NEC), non-small cell lung cancer (NSCLC), small cell lung cancer (SCLC), biliary tract cancer (BTC), hepatocellular carcinoma (HCC), esophageal squamous cell carcinoma (ESCC), and ovarian cancer (OC). Developed using the Company's independently developed platform X-body with fully proprietary intellectual property rights, Vilixin achieves conditional activation of 4-1BB, strengthening 4-1BB-mediated T-cell activation while relieving PD-1/PD-L1 immunosuppression, thereby achieving synergistic tumor elimination. Vilixin has safety comparable to PD-1/PD-L1 inhibitors and greater broad-spectrum cancer treatment potential. Notably, activation of 4-1BB can reactivate exhausted T cells and induce massive expansion, making 4-1BB-targeting therapies potentially suitable for treating immunologically "cold tumors" that are resistant or unresponsive to PD-1/PD-L1 inhibitors, and capable of delivering long-tail survival benefits. In October 2024, Vilixin received Breakthrough Therapy Designation from the NMPA; in November 2024, it received Orphan Drug Designation from the U.S. Food and Drug Administration ("FDA"). In January 2026, Vilixin received Fast Track Designation from the FDA and Orphan Drug Designation from the European Union. In September 2026, Vilixin received Orphan Drug Designation from Japan's Ministry of Health, Labour and Welfare ("MHLW"). In July 2026, the innovative biologic marketing application for Vilixin was included in the NMPA's priority review and approval process, and was officially accepted in August 2026, with the potential to become the world's first approved 4-1BB antibody drug, the world's first approved agonist-class antibody drug, and the world's first approved treatment for EP-NEC.