AbClon said Monday that AC101 (HLX in Chinese code name), licensed to Shanghai Henlius Biotech, has demonstrated potential as a first-line treatment for patients with HER2-positive gastric cancer in a phase 2 clinical trial.

Henlius released interim results from the ongoing phase 2 clinical trial of AC101 in 53 patients with HER2-positive gastric cancer at the American Society of Clinical Oncology (ASCO) Gastroenterological Cancers Symposium in San Francisco, Calif.

Interim results from the phase 2 study of AC101 showed that the addition of AC101 to the standard of care HLX02 (a Herceptin biosimilar) + XELOX regimen demonstrated greater efficacy than the current standard of care in HER2-positive locally advanced/metastatic patients.

The trial was divided into three arms: a low-dose combination of AC101 (15 mg/kg), a high-dose combination of AC101 (25 mg/kg), and a comparator arm. At week 48, the objective response rate (ORR) was 58.8 percent in the low-dose arm, 38.9 percent in the high-dose arm, and 16.7 percent in the control arm, with more than three times the treatment effect observed in the low-dose group compared to the control group.

Median progression-free survival (PFS) was 8.2 months in the control arm vs. 15.1 months in the high-dose arm. The median has not yet been reached in the low-dose arm.

Overall survival did not reach the median level in all groups due to the ongoing nature of the trial. Still, the hazard ratio for overall survival was lower in the high-dose and low-dose arms than in the control arm. The duration of response (DOR), when a tumor responds to treatment before it grows again, was 6.8 months in the comparator arm and 12.4 months in the high-dose arm. The lower dose did not reach the median value.

"AC101 is an antibody therapy for gastric cancer targeting HER2, which has shown promise as a first-line standard of care for HER2-positive gastric cancer thanks to its enhanced efficacy in combination with Herceptin antibodies," an AbClon official said. "Henlius expects that the combination of AC101 with its Herceptin biosimilar will maximize therapeutic efficacy and provide a highly competitive advantage in the market."

AbClon will receive milestone payments as AC101 progresses through Chinese and global clinical trials and royalties on sales when it is commercialized.