LEADS BIOLABS-B (09887) has announced that the Phase II clinical study of its self-developed investigational drug Vilitrin (Opasotiumumab, a PD-L1/4-1BB bispecific antibody, LBL-024) for the first-line treatment of locally advanced or metastatic esophageal squamous cell carcinoma (ESCC) has completed the safety run-in phase and successfully advanced into the extension phase, building on observed positive efficacy signals alongside a favorable safety and tolerability profile.

The study is led by Professor Shen Lin from Beijing Cancer Hospital. During the safety run-in period, Vilitrin in combination with chemotherapy demonstrated promising efficacy signals in first-line ESCC patients, with an overall well-tolerated safety profile. Based on a comprehensive assessment by both the sponsor and investigators, the study has now moved into the combination dosing extension phase. This extension phase employs a randomized, controlled design to conduct a head-to-head comparison of Vilitrin plus chemotherapy versus tislelizumab plus chemotherapy as first-line treatment for ESCC, aiming to further enhance the clinical benefits of the current standard of care.

Vilitrin is currently being evaluated across 11 clinical studies, including one single-arm pivotal registration study, one confirmatory Phase III trial, and nine proof-of-concept (POC) studies. To date, three POC studies evaluating Vilitrin in first-line extrapulmonary neuroendocrine carcinoma (EP-NEC), small cell lung cancer (SCLC), and biliary tract cancer (BTC) have fully completed patient enrollment, with the first-line EP-NEC indication having already progressed to the confirmatory Phase III stage. Two additional POC studies in hepatocellular carcinoma (HCC) and ESCC have smoothly entered their expansion phases, continuously validating Vilitrin's pan-tumor efficacy potential.

Leveraging the conditionally activated design of the company's proprietary X-body platform, Vilitrin has demonstrated clear and durable efficacy signals across multiple indications. Clinical data from seven indications have shown meaningful clinical value and broad therapeutic potential. Vilitrin has also maintained a good safety and tolerability profile across approximately 800 subjects treated to date, laying a solid foundation for its continued development as a next-generation cornerstone immuno-oncology therapy.

Vilitrin is a bispecific antibody that simultaneously targets PD-L1 and 4-1BB, representing a potential survival-benefit pan-tumor IO2.0 cornerstone therapy. Developed using the company's proprietary X-body platform with wholly owned intellectual property, Vilitrin enables conditional activation of 4-1BB, which strengthens 4-1BB-mediated T-cell activation while relieving PD-1/PD-L1 immunosuppression, achieving synergistic tumor elimination. Vilitrin exhibits a safety profile comparable to PD-1/PD-L1 inhibitors alongside broader spectrum anticancer potential, having demonstrated first-in-class (FIC) or best-in-class (BIC) potential in tumors such as non-small cell lung cancer (NSCLC), SCLC, EP-NEC, and BTC.

As the world's first molecule targeting the costimulatory receptor 4-1BB to have entered a single-arm pivotal registration clinical stage, Vilitrin is positioned to potentially become the first drug approved for the treatment of EP-NEC. Vilitrin has initiated clinical studies across 13 solid tumor indications in China, including one pivotal registration study and eight POC studies, covering high unmet medical need areas such as EP-NEC, NSCLC, SCLC, BTC, ovarian cancer (OC), ESCC, HCC, gastric cancer (GC), triple-negative breast cancer (TNBC), and malignant melanoma. Notably, activating the 4-1BB costimulatory pathway can restore and enhance the activity of apoptotic T cells and promote their expansion, potentially making 4-1BB-targeted therapies applicable to immunologically "cold tumors" that are resistant or non-responsive to PD-1/PD-L1 inhibitors, with potential for long-tail durable survival benefits.

In October 2024, Vilitrin received Breakthrough Therapy Designation from the NMPA Center for Drug Evaluation. In November 2024, it received Orphan Drug Designation from the U.S. Food and Drug Administration (FDA). In January 2026, Vilitrin was granted Fast Track Designation by the FDA and Orphan Drug Designation by the European Union.