· The U.S. bridging study of serplulimab in ES-SCLC has completed the enrolment, laying a solid foundation for a future BLA submission to the U.S. FDA

· Independently managed and executed by Henlius’ U.S. clinical & RA teams, the study represents the largest ES-SCLC clinical trial conducted with full local enrolment in the U.S., marking the full maturity of Henlius’ on-the-ground clinical operations and quality management system in the U.S.

· As the world’s first anti-PD-1 mAb approved for 1L treatment of ES-SCLC, serplulimab has been approved in nearly 40 countries and regions including China, the U.K., Germany, Singapore and India, serving as a high-quality example of Chinese innovation reaching global markets

Shanghai, China, October 22, 2025 – Shanghai Henlius Biotech, Inc. (2696.HK) announced that its independently developed innovative anti-PD-1 mAb serplulimab (trade name in Europe: Hetronifly^®) has successfully completed enrolment of all 200 patients in the U.S. bridging clinical study (ASTRIDE) comparing serplulimab plus chemotherapy with atezolizumab plus chemotherapy in previously untreated patients with extensive-stage small cell lung cancer (ES-SCLC). This milestone paves the way for Henlius to submit a Biologics License Application (BLA) to the U.S. Food and Drug Administration (FDA).

The ASTRIDE study is a randomized, controlled, open-label clinical trial designed to evaluate the efficacy and safety of serplulimab plus chemotherapy versus atezolizumab plus chemotherapy in U.S. patients with ES-SCLC. The results will serve as key clinical evidence supporting the registration of serplulimab in the U.S. market. The study is fully managed and executed by Henlius’ U.S. clinical and regulatory affairs teams across more than 100 oncology centres, representing one of the largest ES-SCLC clinical trials ever conducted in the U.S. with locally enrolled patients. Serplulimab is the only anti-PD-1 mAb currently conducting a bridging trial in the U.S. Its steady progress underscores Henlius’s global leadership in clinical design, execution, and regulatory engagement.

David R. Gandara, M.D., the principal leading investigator of the ASTRIDE study, Professor Emeritus and Co-Director of the Experimental Therapeutics Program at UC Davis Comprehensive Cancer Centre (UCDCCC), said: “I’m so pleased to see this bridging study of serplulimab complete accrual. I anticipate that this trial will add a new therapeutic option for our patients with extensive stage small cell lung cancer.”

Jing Li, Vice President of Global Product Development at Henlius, said: ”The completion of patient recruitment in the ASTRIDE study not only marks a major milestone in the U.S. clinical operation of serplulimab, but also signifies the full establishment of Henlius’ local product development in the U.S., laying a solid foundation for future global multicentre studies of the company’s innovative pipeline.”

Dr. Ely Benaim, U.S. Chief Medical Officer at Henlius, said: ”Our U.S. team’s independent execution of the ASTRIDE study reflects our deep integration into the U.S. clinical ecosystem. We are committed to maintaining close collaboration with our investigator network to advance serplulimab’s registration process and bring this promising therapy to patients in need.”

Henlius previously conducted a randomized, double-blind, placebo-controlled, international Phase 3 study (ASTRUM-005) to evaluate serplulimab for first-line treatment of ES-SCLC. The results were first presented as an oral presentation at the 2022 American Society of Clinical Oncology (ASCO) Annual Meeting and subsequently published in The Journal of the American Medical Association (JAMA)—marking the first small-cell lung cancer immunotherapy study ever featured in JAMA’s main edition. At the 2025 ASCO Annual Meeting, the final analysis of ASTRUM-005 was released: as of December 31, 2024 (median follow-up 42.4 months), the four-year overall survival (OS) rate was 21.9% in the serplulimab group versus 7.2% in the control group, with a manageable safety profile—further validating its durable survival benefit for patients with ES-SCLC.

Building on these positive results, serplulimab has been granted Orphan Drug Designation (ODD) by both the U.S. FDA and the European Commission (EC) for the treatment of SCLC and has been approved for first-line treatment of ES-SCLC in nearly 40 countries and regions including China, the U.K., Germany, Singapore and India. Serplulimab’s clinical data in SCLC have been included in the ESMO Magnitude of Clinical Benefit Scale (MCBS), ranking higher than peer products, and have been featured in oral and panel sessions at leading international congresses such as ESMO and the World Conference on Lung Cancer (WCLC). Henlius continues to advance its global regulatory and clinical program for serplulimab. In addition to the ES-SCLC program, the company is conducting an international multicentre Phase 3 trial (ASTRUM-020) evaluating serplulimab with concurrent chemoradiotherapy (cCRT), in patients with limited-stage small cell lung cancer (LS-SCLC), which completed full patient enrolment in January 2025.

As one of the first Chinese biopharmaceutical companies to independently conduct innovative immuno-oncology studies in the U.S., Henlius remains committed to a science-driven approach, advancing precision treatment strategies through internationally compliant clinical practices and localized development to deliver affordable, accessible, and patient-centred therapeutic innovations to patients worldwide.

About Serplulimab

Serplulimab is a recombinant humanized anti-PD-1 mAb injection (trade name in Europe: Hetronifly^®). It is the world’s first anti-PD-1 mAb approved for first-line treatment of small cell lung cancer (SCLC) and has been approved for marketing in nearly 40 countries and regions, including China, the UK, Germany, Singapore, and India.

In March 2022, serplulimab was officially approved for marketing in China and is currently indicated for the treatment of squamous non-small cell lung cancer (sqNSCLC), extensive-stage small cell lung cancer (ES-SCLC), esophageal squamous cell carcinoma (ESCC), and non-squamous non-small cell lung cancer (nsqNSCLC).

Focusing on lung and gastrointestinal cancers, Henlius has been actively advancing the synergistic development of serplulimab with other in-house products and its combination with novel therapies. The product has received clinical trial authorizations in multiple countries and regions including China, the U.S., and the EU, and is being evaluated in over ten global, multicentre clinical trials on immuno-oncology combination therapies. To date, more than 5,000 patients have been enrolled in clinical studies of serplulimab across China, the U.S., Turkey, Poland, Georgia, and other countries, with over 30% of patients enrolled in two pivotal international studies being Caucasian, making it one of the anti-PD-1 mAbs with the most extensive international clinical data. Three pivotal clinical studies of serplulimab have been published in leading journals including The Journal of the American Medical Association (JAMA), Nature Medicine, and the British Journal of Cancer. In addition, serplulimab has been included in several authoritative clinical guidelines, such as the CSCO Guidelines for SCLC, NSCLC, ESCC, Colorectal Cancer, Clinical Application of Immune Checkpoint Inhibitors, and Chinese Guidelines for Radiotherapy in Esophageal Cancer, providing important references for oncology clinical practice. Internationally, serplulimab for the treatment of SCLC has been granted Orphan Drug Designation (ODD) by both the U.S. FDA and the European Commission (EC). Furthermore, in June 2025, Henlius initiated a bridging study in Japan to evaluate the efficacy and safety of serplulimab plus chemotherapy as first-line treatment for ES-SCLC in Japanese patients.