Trial results for an umbrella study (NCT05251948) evaluating atezolizumab in combination therapies for gastric or gastroesophageal junction carcinoma were posted on ClinicalTrials.gov on 2026-04-15. The atezolizumab + capecitabine + oxaliplatin (CAPOX) arm demonstrated an objective response rate (ORR) of 55.6%, which was higher than the 40.9% observed in the atezolizumab + CAPOX + tiragolumab arm.
Background
This study investigated treatment combinations for participants with advanced gastric carcinoma (GC) or gastroesophageal junction carcinoma (GEJC). The trial was designed as an umbrella study to allow flexibility in evaluating new and existing treatment arms.
Trial design
The study (NCT05251948) was a Phase 1/Phase 2, open-label, multicenter, randomized umbrella study. It enrolled 40 participants with advanced gastric carcinoma or gastroesophageal junction carcinoma, with adenocarcinoma confirmed as the predominant histology. The study was designed to evaluate the efficacy and safety of multiple treatment combinations. Interventions included atezolizumab, capecitabine, oxaliplatin, and tiragolumab in various combinations. The study's overall status is TERMINATED.
Key results
The trial results compared two treatment arms: atezolizumab + capecitabine + oxaliplatin (CAPOX) and atezolizumab + CAPOX + tiragolumab across several key outcomes.
- For Objective Response Rate (ORR):
- The Atezo + CAPOX arm showed an ORR of 55.6 percentage of participants.
- The Atezo + CAPOX + Tira arm showed an ORR of 40.9 percentage of participants.
- For Progression-free Survival (PFS) After Randomization:
- The median PFS for the Atezo + CAPOX arm was 9.51 months.
- The median PFS for the Atezo + CAPOX + Tira arm was 6.65 months.
- For Overall Survival (OS) After Randomization:
- The median OS for the Atezo + CAPOX arm was 20.85 months.
- The median OS for the Atezo + CAPOX + Tira arm was 12.67 months.
- For OS Rates at Specified Timepoints:
- At an unspecified early timepoint, the Atezo + CAPOX arm showed 93.75 percentage of participants, while the Atezo + CAPOX + Tira arm showed 86.36 percentage of participants.
- At an unspecified later timepoint, the Atezo + CAPOX arm showed 68.75 percentage of participants, while the Atezo + CAPOX + Tira arm showed 50.00 percentage of participants.
- For Duration of Response (DOR):
- The median DOR for the Atezo + CAPOX arm was 10.38 months.
- The median DOR for the Atezo + CAPOX + Tira arm was 8.08 months.
An analysis of the difference in Overall Response Rates between the two arms was -14.65 (95.0% CI: -50.5 to 21.21), indicating a lower ORR for the triple therapy arm compared to the dual therapy arm, though the confidence interval is wide.
What this means
The results from this Phase 1/Phase 2 umbrella study suggest that the combination of atezolizumab with CAPOX (capecitabine and oxaliplatin) may offer a more favorable efficacy profile compared to the addition of tiragolumab to the same regimen in participants with advanced gastric or gastroesophageal junction carcinoma. The dual therapy arm demonstrated higher objective response rates, longer median progression-free survival, longer median overall survival, and longer duration of response. These findings, while from a terminated study with a relatively small enrollment, provide insights into potential treatment strategies and the impact of adding a third agent in this patient population.
Source
The information regarding these trial results was obtained from ClinicalTrials.gov, a public database of clinical studies. The results for study NCT05251948, titled "An Umbrella Study Evaluating the Efficacy and Safety of Multiple Treatment Combinations in Patients With Gastric or Gastroesophageal Junction Carcinoma," were posted on 2026-04-15 on clinicaltrials.gov.