Leads Biolabs' Opamtistomig (PD-L1/4-1BB Bispecific Antibody) Advances to Expansion Stage in Phase II First-Line Gastric Cancer Study

Expansion Stage to Compare Opamtistomig Plus Chemotherapy Head-to-Head With Tislelizumab Plus Chemotherapy in Previously Untreated Disease

NANJING, China, Oct. 20, 2026 (GLOBE NEWSWIRE) -- Nanjing Leads Biolabs Co., Ltd. ("Leads Biolabs" or the "Company," Stock Code: 9887.HK) today announced that a Phase II study of opamtistomig (LBL-024) in first-line gastric cancer has advanced to the expansion stage, after the safety lead-in produced positive preliminary efficacy signals. The study is evaluating opamtistomig, a PD-L1/4-1BB bispecific antibody, in combination with chemotherapy in locally advanced or metastatic gastric or gastroesophageal junction (GEJ) adenocarcinoma. The expansion makes gastric cancer the fifth gastrointestinal tumor type in the opamtistomig program, alongside biliary tract cancer (BTC), hepatocellular carcinoma (HCC), esophageal squamous cell carcinoma (ESCC) and colorectal cancer (CRC). Four of the five studies have now progressed to the expansion stage.

Gastric cancer remains a major clinical challenge, as early symptoms are often nonspecific and many patients are diagnosed at an advanced stage, when prognosis is poor. Although PD-1 inhibitors combined with chemotherapy have become a standard first-line treatment approach, median progression-free survival (PFS) remains approximately seven months, while median overall survival (OS) is generally 13–17 months. Patients with a PD-L1 combined positive score (CPS) below 5 may derive limited benefit from existing immunotherapy-based regimens, underscoring the need for more effective treatment strategies.

Opamtistomig conditionally activates 4-1BB while blocking PD-1/PD-L1, reactivating and substantially expanding T cells. Because that activation does not depend on high PD-L1 expression, the approach may reach patients that checkpoint monotherapy leaves behind. Across several clinical studies, opamtistomig has produced objective responses and OS benefit even in tumors with negative or low PD-L1 expression. That profile could move first-line treatment past the current ceiling for immunotherapy combinations and deliver more durable benefits for these patients.

The study is led by Professor Shen Lin of Peking University Cancer Hospital and is being conducted at multiple sites across China. Following a comprehensive assessment of the encouraging preliminary clinical data from the safety lead-in phase, the sponsor and investigators have decided to advance the study to the combination therapy expansion stage. This stage will use a randomized, controlled design to compare the efficacy and safety of opamtistomig plus chemotherapy directly with tislelizumab plus chemotherapy. The study will also explore associations between tumor tissue biomarkers and treatment outcomes to help identify patient populations most likely to benefit from opamtistomig-based combination therapy.

Executive Commentary
Dr. Charles Cai, Chief Medical Officer of Leads Biolabs, stated: "Gastric cancer represents a significant unmet medical need, particularly for patients with low PD-L1 expression who may derive limited benefit from current first-line immunotherapy combinations. The encouraging preliminary signals observed in the safety lead-in support advancing opamtistomig into a randomized expansion stage, where its efficacy and safety will be evaluated against an established immunotherapy-based regimen. We look forward to generating more robust clinical evidence to determine whether opamtistomig can offer a differentiated first-line treatment option and improve outcomes for patients with advanced gastric cancer."

About Gastric Cancer
According to data from the International Agency for Research on Cancer of the World Health Organization in 2022, there were approximately 968,000 new cases of gastric cancer and approximately 660,000 deaths worldwide, making gastric cancer the fifth most commonly diagnosed cancer and the fourth leading cause of cancer death globally. In China, there were approximately 359,000 new cases, representing 37.1% of the global total, and approximately 260,000 deaths, representing 39.4% of the global total. Early-stage gastric cancer is often asymptomatic. In China, early gastric cancer accounts for only approximately 20% of diagnosed cases, and most patients are diagnosed with advanced disease. The overall prognosis for advanced gastric cancer remains poor, with a five-year survival rate of approximately 9%.

About Opamtistomig
Opamtistomig (LBL-024) is emerging as a next-generation pan-cancer backbone therapy with potential overall survival (OS) benefit that simultaneously targets PD-L1 and the co-stimulatory receptor 4-1BB. Currently, opamtistomig is being evaluated in 14 indications, including one pivotal single-arm registrational study, one confirmatory Phase III study, and nine proof-of-concept studies, covering major indications such as NSCLC and multiple cold tumors. To date, opamtistomig has demonstrated robust antitumor activity across seven tumor types—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)—highlighting its clinical value and broad therapeutic promise.

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 in EP-NEC, opamtistomig received Breakthrough Therapy Designation from China's National Medical Products Administration (NMPA) in October 2024, Orphan Drug Designation (ODD) from the U.S. Food and Drug Administration (FDA) in November 2024, Fast Track Designation from the FDA and ODD from the European Commission in January 2026, and ODD from Japan's Ministry of Health, Labour and Welfare (MHLW) in September 2026. In October 2026, the FDA granted a second Fast Track Designation, this one for first-line advanced or metastatic biliary tract cancer.

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
Founded in 2012, Leads Biolabs is a clinical-stage biotechnology company dedicated to the discovery, development, and commercialization of innovative therapies to address underserved medical needs in oncology, autoimmune, and other severe diseases both in China and globally.

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/

Media Contact
yizi@leadsbiolabs.com