LEADS BIOLABS-B (09887) released an announcement that the company is pleased to announce the completion of first patient enrollment in an open-label, multicenter Phase Ib/II clinical trial evaluating the company's independently developed Viresin (Oplatilimab, a 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 Viresin, building upon prior development 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 mismatch repair proficient (pMMR) status account for approximately 95% of cases. 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, creating an urgent need for new therapeutic strategies.
Viresin can conditionally activate 4-1BB, simultaneously releasing PD-1/PD-L1 immune suppression while 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 across multiple hospitals nationwide, aiming to evaluate the efficacy and safety of Viresin combination therapy in mCRC patients.
Translational medicine research of Viresin for MSS colorectal cancer has been selected for poster presentation at the 2026 European Society for Medical Oncology (ESMO) Annual Congress. Meanwhile, Viresin has demonstrated survival benefit trends significantly longer than historical data across multiple typical immunological "cold tumor" indications including EP-NEC, BTC, HCC, and PROC, providing mechanistic and clinical support for the development prospects of Viresin 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 ranking second and fourth among all malignant tumors, respectively. Approximately 15% to 30% of CRC patients already have distant metastasis at initial diagnosis, while 20% to 50% of patients with initially localized CRC eventually develop mCRC. Despite therapeutic advances, mCRC still carries a poor prognosis, with a 5-year survival rate of only approximately 15%.
Current immunotherapies are primarily approved for CRC patients with microsatellite instability-high (MSI-H) or mismatch repair deficient (dMMR) status. However, these patients account for only about 5% of mCRC cases, while the approximately 95% who are microsatellite stable (MSS) or mismatch repair proficient (pMMR) generally have limited response to traditional immunotherapy, representing a huge unmet medical need.
Viresin is a bispecific antibody simultaneously targeting PD-L1 and 4-1BB, with the potential to become a foundational IO 2.0 therapy with survival benefits across tumor types. Currently, Viresin has initiated clinical studies across 14 indications, including 1 single-arm pivotal registrational clinical 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, Viresin has demonstrated exceptional 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, Viresin achieves conditional activation of 4-1BB, simultaneously releasing PD-1/PD-L1 immune suppression while enhancing 4-1BB-mediated T-cell activation, achieving synergistic tumor elimination. Viresin has safety comparable to PD-1/PD-L1 inhibitors and stronger broad-spectrum cancer treatment potential. Notably, activation of 4-1BB can reactivate exhausted T cells and massively expand them, making 4-1BB-targeting therapies potentially suitable for treating immunologically "cold tumors" that are resistant or unresponsive to PD-1/PD-L1 inhibitors, and can deliver long-tail survival benefits.
In October 2024, Viresin 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, Viresin received Fast Track Designation from the FDA and Orphan Drug Designation from the European Union. In September 2026, Viresin received Orphan Drug Designation from Japan's Ministry of Health, Labour and Welfare (MHLW). In July 2026, Viresin's innovative biologics marketing application 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.
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