Leads Biolabs' PD-L1/4-1BB Bispecific Antibody Opamtistomig (LBL-024) Dosed First Patient in New Indication, Paving a New Immunotherapy Pathway for TNBC Patients

Nanjing, China - February 10, 2026 - Nanjing Leads Biolabs Co., Ltd. ("Leads Biolabs" or the "Company," Stock Code: 9887.HK) today announced that the first patient has been successfully dosed in a Phase b/ clinical study evaluating Opamtistomig (LBL-024), the company's core investigational PD-L1/4-1BB bispecific antibody, for the treatment of recurrent or metastatic triple-negative breast cancer (TNBC).

Although PD-1/PD-L1-based immunotherapy in combination with chemotherapy has improved progression-free survival (PFS) and overall survival (OS) in patients with TNBC, these benefits are largely limited to the PD-L1-positive subgroup. For PD-L1-negative patients-accounting for more than half of all TNBC cases-chemotherapy remains the standard of care under current clinical guidelines. Moreover, even among PD-L1-positive groups, objective response rate (ORR) remain modest, median PFS is generally below nine months, and median OS improvements are limited, highlighting the urgent need for next-generation immunotherapies.

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).

The newly initiated open-label, multi-center Phase Ib/II clinical study, led by Professor Yin Yongmei of Jiangsu Province Hospital, is being conducted across multiple hospitals in China. The study is designed to evaluate the efficacy and safety of Opamtistomig as monotherapy or in combination with albumin-bound paclitaxel in patients with recurrent or metastatic TNBC.

Executive Commentary

Dr. Charles Cai, Chief Medical Officer of Leads Biolabs, stated: "Dosing the first patient in TNBC marks an important milestone in the clinical development of Opamtistomig and reflects our continued commitment to addressing areas of high unmet medical need. TNBC is associated with aggressive disease biology, early recurrence, and limited therapeutic options. We believe Opamtistomig's differentiated dual-mechanism approach has the potential to meaningfully improve response rates and survival outcomes, with the ultimate goal of redefining the treatment paradigm and transforming cancer into a more manageable chronic disease."

About Triple-Negative Breast Cancer (TNBC)

Cancer remains one of the leading causes of morbidity and mortality worldwide. Globally, breast cancer is the second most commonly diagnosed cancer - following lung cancer - with approximately 2.3 million new cases annually, and it ranks as the fourth leading cause of cancer-related deaths, accounting for about 670,000 deaths each year. In China, breast cancer incidence continues to rise, with an estimated 360,000 new cases and 75,000 deaths reported annually. Among these, triple-negative breast cancer (TNBC) - characterized by the absence of estrogen receptor (ER), progesterone receptor (PR), and human epidermal growth factor receptor 2 (HER2) expression - represents a highly aggressive subtype. TNBC is associated with high recurrence rates, poor prognosis, and shortened overall survival, comprising approximately 15%-20% of all breast cancer cases.

Compared with other breast cancer subtypes, TNBC is considered "immune-enriched" or a "hot tumor." Although immunotherapy combined with chemotherapy has demonstrated improvements in progression-free survival (PFS) among PD-L1 positive patients, the median PFS remains suboptimal, highlighting the need for more effective treatment options. For PD-L1 negative patients, both domestic and international clinical guidelines continue to recommend chemotherapy as the standard of care, reflecting the persistent unmet clinical needs in this population.

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.

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 seven clinical-stage drug candidates, of which four lead products are among the top-tier clinically advanced candidates globally.

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), 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/
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