Leads Biolabs' PD-L1/4-1BB Bispecific Antibody Wins Pivotal Phase III Approval, Set to Reshape the Frontline Treatment Landscape for Advanced EP-NEC

NANJING, China, May 18, 2026 /PRNewswire/ -- Nanjing Leads Biolabs Co., Ltd. ("Leads Biolabs" or the "Company," Stock Code: 9887.HK) today announced that its proprietary PD-L1/4-1BB bispecific antibody, Opamtistomig (LBL-024), has received approval from the Center for Drug Evaluation (CDE) of China's National Medical Products Administration (NMPA) to initiate a pivotal Phase III clinical trial for the first-line treatment of advanced extrapulmonary neuroendocrine carcinoma (EP-NEC). This approval marks the successful advancement of Opamtistomig's clinical development in EP-NEC from late-line monotherapy to first-line combination therapy — Opamtistomig had previously received CDE approval for a pivotal single-arm registration trial in 3L+ EP-NEC patients; this Phase III approval further expands Opamtistomig's addressable patient population in EP-NEC, potentially reshaping the treatment landscape for this malignancy.

This randomized, double-blind, multicenter Phase III study is led by Professor Lin Shen of Peking University Cancer Hospital. The approval was based on the promising efficacy and favorable safety profile demonstrated by Opamtistomig in a successfully completed Phase Ib/II proof-of-concept study. Detailed results are planned to be presented at the 2026 ESMO Congress.

As an integral part of the overall EP-NEC development strategy, Leads Biolabs plans to submit a Biologics License Application (BLA) in the third quarter of 2026 for Opamtistomig as a single agent for the treatment of advanced EP-NEC in the third-line or later setting. In parallel, Leads Biolabs is advancing multiple proof-of-concept studies and preparing to initiate at least two additional Phase III clinical trials for Opamtistomig, exploring its application across 13 solid tumor indications, including first-line NSCLC, first-line BTC, small cell lung cancer, and ovarian cancer, thereby building a comprehensive, multi-tumor, multi-stage development layout. To date, Opamtistomig has demonstrated first- or best-in-class potential in Phase II or registrational clinical trials across four indications: non-small cell lung cancer (NSCLC), small cell lung cancer (SCLC), biliary tract cancer (BTC) and extrapulmonary neuroendocrine carcinoma (EP-NEC).

Executive Commentary

Dr. Charles Cai, Chief Medical Officer of Leads Biolabs, stated: "The Phase Ib/II data for Opamtistomig in first-line treatment of EP-NEC are encouraging. In our communications with the CDE, we have seen the regulatory agency's strong focus on unmet clinical needs and its recognition of Opamtistomig's clinical value. Based on the clear regulatory feedback, we are rapidly implementing the pivotal Phase III study protocol, and we look forward to validating its potential to extend patient survival through a high-quality trial, bringing this innovative therapy to EP-NEC patients as soon as possible."

About EP-NEC

EP-NEC is a highly aggressive, immunologically "cold" tumor. To date, no drug has received regulatory approval for this indication worldwide. The current first-line standard treatment for advanced EP-NEC remains platinum-based chemotherapy, with an objective response rate (ORR) of 30%-50% and a median overall survival (mOS) of approximately 1 year, underscoring a pressing unmet need for new therapeutic options.

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. Developed using Leads Biolabs' proprietary X-Body bispecific platform, Opamtistomig is designed to simultaneously block PD-1/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. To date, Opamtistomig has demonstrated first- or best-in-class potential in Phase II or registrational clinical trials across four indications: non-small cell lung cancer (NSCLC), small cell lung cancer (SCLC), biliary tract cancer (BTC), and extrapulmonary neuroendocrine carcinoma (EP-NEC).

As the first 4-1BB–targeting bispecific antibody globally to advance to a single-arm pivotal trial as monotherapy, Opamtistomig has been evaluated in 13 solid tumor indications in China, including 1 pivotal registration trial and 8 proof-of-concept studies. These cover EP-NEC, NSCLC, SCLC, BTC, ovarian cancer (OC), esophageal squamous cell carcinoma (ESCC), hepatocellular carcinoma (HCC), gastric cancer (GC), triple-negative breast cancer (TNBC), malignant melanoma, and other areas with high unmet medical needs.

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. 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.

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.

We are a front-runner in next-generation immuno-oncology treatments with a differentiated pipeline of 14 innovative drug candidates, including four clinical-stage drug candidates and one registration-stage asset.

We adopt a science-driven R&D approach and have successfully established comprehensive R&D capabilities spanning antibody discovery and engineering, in vivo and in vitro efficacy evaluation, as well as druggability assessment. We have also developed multiple proprietary technology platforms, including LeadsBody platform (a CD3 T-cell engager platform), X-body platform (a 4-1BB engager platform), TOPiKinectics (ADC platform) and ImBiTDC (TDC Platform), which serve as the cornerstone for our continued innovation and have been validated by the clinical outcomes of our bispecific antibody portfolios.

We have established integrated capabilities across early discovery, translational medicine, clinical development, CMC and business development. The innovative nature and competitive strengths of our drug candidates, coupled with our global perspectives, proactive strategy, and efficient clinical validation, have made us an attractive partner for leading industry players and investment institutions. For more information, please visit https://en.leadsbiolabs.com/

SOURCE Nanjing Leads Biolabs Co., Ltd.