Transcenta's Osemitamab Combination Shows Promising 16.6-Month Median PFS in First-Line Gastric Cancer Trial
Key Insights
Transcenta Therapeutics (search) reported updated Phase I/II trial data showing osemitamab plus nivolumab and CAPOX (search) achieved a median progression-free survival of 16.6 months in first-line gastric/gastroesophageal junction cancer (search) patients.
The triple combination demonstrated a 68% objective response rate and 18-month median duration of response in 26 patients with high CLDN18.2 (search) expression at 25.8-month median follow-up.
Clinical benefit remained consistent across different PD-L1 (search) expression levels, with better outcomes observed in patients with higher CLDN18.2 (search) expression regardless of PD-L1 status.
Transcenta Therapeutics (search) has unveiled encouraging updated efficacy data from its Phase I/II Transtar102 trial, demonstrating that the combination of osemitamab, nivolumab, and CAPOX (search) achieved a median progression-free survival of 16.6 months in first-line treatment of gastric and gastroesophageal junction cancer (search). The findings were presented at the ESMO Asia Congress 2025 in Singapore.
Strong Efficacy Signals Across Patient Subgroups
The updated analysis focused on Cohort G, examining 26 patients with CLDN18.2 (search) expression ≥40%, ≥2+ and known PD-L1 (search) CPS. At a median follow-up of 25.8 months, the triple combination regimen demonstrated an objective response rate of 68% and a median duration of response of 18 months.
"The exploratory efficacy analysis continues to show promising clinical benefit with osemitamab when combined with standard-of-care therapy," said Professor Lin Shen, Director of the Department of Gastrointestinal Oncology and Phase I Clinical Trial Center at Peking University Cancer Hospital and Principal Investigator of the trial. "The consistency of benefit across different PD-L1 (search) subgroups is particularly noteworthy and suggests that this regimen may offer meaningful improvement for a broad population of patients with advanced G/GEJ cancer."
CLDN18.2 Expression Drives Treatment Benefit
A key finding from the analysis revealed that patients with higher CLDN18.2 (search) expression experienced better progression-free survival outcomes compared to those with lower CLDN18.2 expression. This benefit was observed consistently in both PD-L1 (search) CPS<1 and ≥1 subgroups, indicating that osemitamab's therapeutic potential remains consistent regardless of PD-L1 expression levels.
The safety profile remained similar to that previously presented at ASCO 2025, with the combination continuing to demonstrate tolerability as a first-line regimen for patients with advanced gastric and gastroesophageal junction cancer (search).
Novel CLDN18.2-Targeting Approach
Osemitamab represents the second CLDN18.2 (search)-targeting antibody in global development. The humanized monoclonal antibody was developed using Transcenta's Immune Tolerance Breaking Technology platform and features enhanced antibody-dependent cellular cytotoxicity. Through advanced bioprocessing technology, the fucose content of osemitamab was significantly reduced during production, further enhancing NK cell-mediated ADCC activity.
The drug has received Orphan Drug Designation from the FDA for treating patients with gastric or gastroesophageal junction cancer (search) and pancreatic cancer (search).
Clinical Development Progress
Dr. Charlie Qi, Executive Vice President and Head of Global Clinical Development at Transcenta, emphasized the significance of the continued clinical signals. "We are encouraged to see the continued strength of the clinical signals in this study, which reinforce the potential of osemitamab to deliver meaningful benefit to patients in need of more effective treatment options," he said.
The company continues to advance its diverse pipeline of more than a dozen novel biologic therapies for oncology and selected non-oncology indications, including bone and kidney disorders, through its fully integrated capabilities in antibody-based biotherapeutics discovery, research, development, and manufacturing.