On April 9, 2026 Nanjing Leads Biolabs Co., Ltd. ("Leads Biolabs" or the "Company," Stock Code: 9887.HK) reported that its proprietary PD-L1/4-1BB bispecific antibody, Opamtistomig (LBL-024), has successfully completed the safety run-in stage of a Phase II clinical trial in the first-line treatment of advanced biliary tract cancer (BTC). Based on favorable safety and encouraging preliminary efficacy data, the study has progressed into the expansion phase, with the first patient already enrolled.
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The study is led by Dr. Jian Zhou from Zhongshan Hospital, Fudan University, and is being conducted across multiple clinical sites in China. A total of 20 patients were included in the safety run-in cohort and completed preliminary evaluation. Results demonstrated that Opamtistomig in combination with chemotherapy was generally well tolerated, with a favorable safety profile and no new safety signals observed. Preliminary efficacy assessments indicated encouraging tumor reduction trends. Based on these results, the study has advanced to the expansion phase with accelerated enrollment underway.
Opamtistomig is a uniquely engineered bispecific antibody designed to simultaneously block PD-1/L1-mediated immune suppression and selectively activate the 4-1BB co-stimulatory pathway. By restoring T-cell functionality and expanding effector T-cell populations within the tumor microenvironment, Opamtistomig has the potential to deliver more potent and durable anti-tumor activity than PD-1/PD-L1 blockade alone, particularly in difficult-to-treat and immunotherapy-resistant tumors. To date, Opamtistomig has demonstrated first- or best-in-class potential in Phase II or registrational clinical trials across three indications: non-small cell lung cancer (NSCLC), small cell lung cancer (SCLC), and extrapulmonary neuroendocrine carcinoma (EP-NEC).
Executive Commentary
Dr. Charles Cai, Chief Medical Officer of Leads Biolabs, commented: "Based on favorable safety and encouraging efficacy signals from the safety run-in cohort, Opamtistomig has advanced into the expansion phase of the Phase II BTC study, with strong support from investigators unanimously. This represents an important milestone for the program and reinforces our confidence in its clinical potential. As additional efficacy data mature, we plan to initiate a confirmatory study, leveraging our extensive clinical network to accelerate development and bring a differentiated immunotherapy option to patients with advanced biliary tract cancer as early as possible."
About Biliary Tract Cancer
Biliary tract malignancies primarily include gallbladder cancer and intrahepatic/extrahepatic cholangiocarcinoma, with approximately 419,100 new cases globally in 2024. These malignancies are predominantly adenocarcinomas with high invasiveness, and most cases are diagnosed at advanced stages, leading to poor prognosis (5-year survival rate <5%). Currently, global incidence of biliary tract malignancies is rising, with the highest prevalence observed in Asian countries.
Although PD-1/L1 inhibitors combined with chemotherapy have been approved as first-line treatment for advanced biliary tract malignancies, clinical benefits remain limited: Modest improvement in median overall survival (OS) (from ~11.5 to 12.8 months) and Low objective response rate (ORR) (<30%). These gaps highlight unmet medical needs for more effective therapies.
About Opamtistomig (LBL-024)
Opamtistomig (LBL-024) is a potential first-in-class bispecific antibody that simultaneously targets PD-L1 and the co-stimulatory receptor 4-1BB. It is the first 4-1BB–targeting bispecific antibody globally to advance to a single-arm pivotal trial as monotherapy, and it holds promise to become the first approved therapy specifically for extrapulmonary neuroendocrine carcinoma (EP-NEC)—a rare malignancy with substantial unmet clinical need.
Developed using Leads Biolabs’ proprietary X-Body bispecific platform, Opamtistomig features a 2:2 molecular format, incorporating two binding domains each for PD-L1 and 4-1BB with an optimized affinity ratio. This unique design enables dual functionality: reversing PD-L1–mediated immune suppression while selectively enhancing T-cell activation, resulting in a potent and synergistic anti-tumor immune response.
In two ongoing clinical studies in China, Opamtistomig has demonstrated promising efficacy and a favorable safety profile in patients with advanced EP-NEC, both as monotherapy and in combination with chemotherapy. Given the absence of a globally accepted standard of care for EP-NEC, these results support the advancement of a single-arm pivotal study toward potential accelerated approval.
Recognizing its clinical potential, Opamtistomig received Breakthrough Therapy Designation (BTD) 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) for the treatment of neuroendocrine carcinoma in November 2024. Additionally, in January 2026, Opamtistomig was granted Fast Track Designation (FTD) by the FDA and ODD by the European Commission for the treatment of EP-NEC, further underscoring its potential to address unmet medical needs in this patient population.
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. Beyond EP-NEC, Opamtistomig has received clinical trial approvals across multiple tumor types with high unmet medical needs, including small cell lung cancer (SCLC), biliary tract cancer (BTC), ovarian cancer (OC), non-small cell lung cancer (NSCLC), esophageal squamous cell carcinoma (ESCC), hepatocellular carcinoma (HCC), gastric cancer (GC), triple-negative breast cancer (TNBC), and malignant melanoma. Encouraging clinical activity has already been observed in NSCLC, SCLC, BTC, OC, and other indications, underscoring Opamtistomig’s potential as a broad-spectrum immuno-oncology therapy.
(Press release, Nanjing Leads Biolabs, APR 9, 2026, View Source [SID1234664288])