On September 28, 2026 Nanjing Leads Biolabs Co., Ltd. ("Leads Biolabs" or the "Company," Stock Code: 9887.HK) reported that opamtistomig (LBL-024), the Company’s proprietary PD‑L1/4‑1BB bispecific antibody, has been granted Orphan Drug Designation (ODD) by Japan’s Ministry of Health, Labour and Welfare (MHLW) for the treatment of extrapulmonary neuroendocrine carcinoma (EP-NEC). This is the third Orphan Drug Designation for opamtistomig, following designations in the U.S. Food and Drug Administration (FDA) and the European Commission (EC), marking a further expansion of its global regulatory recognition into a strategically important Asian market.

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The designation provides opamtistomig with access to a range of regulatory and development incentives in Japan, which may include:

Financial support and subsidies for clinical development.
Regulatory consultation and advice from Japan’s Ministry of Health, Labour and Welfare (MHLW) and other relevant authorities.
Potential access to priority consultation and expedited review pathways, as applicable.
Reduction or exemption of certain application and examination fees, and
An extended re‑examination period following marketing authorization.

These incentives are expected to facilitate and potentially accelerate the clinical development, regulatory submission, and commercialization of opamtistomig in Japan, particularly for EP-NEC and other high-potential indications.

Japan is one of the world’s major pharmaceutical markets, with a market size of over $73 billion in 2025, of which the immuno‑oncology segment accounted for over $8 billion, ranking behind only the United States, China, and Europe. By securing orphan drug designation in this strategic market, opamtistomig not only represents a breakthrough for the EP‑NEC indication but also establishes priority consultation and accelerated review pathways within Japan’s regulatory framework, paving the way for the subsequent development and registration of opamtistomig for other tumor indications in Japan.

Since October 2024, opamtistomig has received Breakthrough Therapy Designation from the National Medical Products Administration (NMPA) of China, Orphan Drug Designation and Fast Track designation from the U.S. FDA, and Orphan Drug Designation from the European Commission. In July 2026, its New Drug Application (NDA) was granted Priority Review by the NMPA. In August 2026, NDA submitted to NMPA and now under technical review. To date, opamtistomig has demonstrated promising and durable efficacy signals across seven tumor types, including EP‑NEC (first‑line and post‑line), 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).

Clinical results from multiple studies of opamtistomig in EP‑NEC, NSCLC, and BTC have been presented at the American Society of Clinical Oncology (ASCO) (Free ASCO Whitepaper) Annual Meeting, the World Conference on Lung Cancer (WCLC), and the European Society for Medical Oncology (ESMO) (Free ESMO Whitepaper) Annual Congress. The clinical data and innovative value of opamtistomig have been widely recognized, further validating opamtistomig as an "IO 2.0" backbone therapy with survival benefit across immunologically ‘cold tumors’ and a broad range of indications.

Executive Commentary
Dr. Charles Cai, Chief Medical Officer of Leads Biolabs, commented: "The orphan drug designation in Japan represents an important milestone in the global development of opamtistomig and further strengthens its regulatory recognition across the four key markets of China, the United States, Europe, and Japan. It underscores the innovative value and global development potential of opamtistomig, particularly in EP-NEC, a tumor type with substantial unmet medical needs. We look forward to leveraging the regulatory incentives associated with this designation to accelerate the development and registration of opamtistomig in Japan, while advancing additional high-potential indications and bringing this innovative therapy to more patients in Japan and around the world."

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, 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) in November 2024. Additionally, in January 2026, opamtistomig was granted Fast Track Designation (FTD) by the FDA and ODD by the European Commission, further underscoring its potential to address unmet medical needs in this patient population. 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.

(Press release, Nanjing Leads Biolabs, SEP 28, 2026, View Source [SID1234671136])