Seoul, South Korea – July 15 – AbClon announced today that its Licensee, Henlius has completed the first patient dosing in the United States for the global Phase 3 clinical trial (HLX22-GC-301) of an innovative anti-HER2 monoclonal antibody, AC101 (Henlius code name HLX22). This multi-center trial compares AC101 with the current first-line standard care (trastuzumab + chemotherapy ± pembrolizumab).

The trial is jointly led by Professor Lin Shen of Beijing Cancer Hospital and Professor Zafard Azani of MD Anderson Cancer Center in the United States. The first patient dosing has already been completed in China, Japan, Australia, and South Korea, and Investigational New Drug (IND) approvals have been obtained in numerous other countries, including Chile, Brazil, and Argentina. AC101 has previously been granted Orphan Drug Designation (ODD) by the U.S. FDA and the European Commission (EC) for the treatment of gastric cancer. To date, no dual HER2 blockade therapy for HER2-positive gastric cancer has received commercial approval worldwide.

AC101 is designed to bind to the epitope in HER2 extracellular domain IV, a different binding site from trastuzumab, allowing both antibodies to act simultaneously on HER2 homodimers and HER2-EGFR heterodimers. This mechanism increases the intracellular internalization of the HER2 protein by 40-80%. Interim results from the Phase 2 clinical trial (HLX22-GC-201) were presented at ASCO this year and continue to show excellent efficacy even beyond two years of median follow-up.

The double-blind, randomized, controlled, multi-center Phase 3 study (HLX22-GC-301) compares HLX22 (15 mg/kg) + trastuzumab + chemotherapy with placebo + trastuzumab + chemotherapy (± pembrolizumab) in a 1:1 ratio for patients with HER2-positive locally advanced or metastatic gastroesophageal junction/gastric cancer.

In addition to gastric cancer, Henlius is also conducting a clinical trial combining Enhertu and AC101 as a second-line treatment for HER2-low, hormone receptor-positive locally advanced and metastatic breast cancer. The Phase 2 trial (HLX22-BC201) recently initiated in China, with the first patient dosed.

A company official stated, "Gastric cancer is a major global health issue, with approximately 1 million new patients and 660,000 deaths worldwide each year. We expect that accelerating the global development of AC101 will provide more effective HER2-targeted treatment options for patients worldwide."

Meanwhile, gastric cancer is typically diagnosed at an advanced stage, with a five-year relative survival rate of only 6%. Despite recent advancements in anti-HER2 therapies and immune checkpoint inhibitors (anti-PD-1/PD-L1), significant variations in patient response to treatment exist due to high molecular heterogeneity. In particular, immunotherapy has shown limited efficacy only in PD-L1 positive patient groups, highlighting the urgent need for new treatment options across the spectrum of HER2-positive gastric cancer.