PURPOSE: This study was undertaken to explore the response rate of a first-line, three-drug regimen that consisted of bortezomib, paclitaxel, and carboplatin in patients with metastatic adenocarcinoma of the esophagus, gastroesophageal junction, or gastric cardia. PATIENTS AND METHODS: Patients with the above diagnosis and acceptable organ function were treated intravenously on a 21-day cycle with the following: bortezomib 1.2 mg/m on days 1, 4, and 8; paclitaxel 175 mg/m on day 2; and carboplatin with an area under the curve of 6 on day 2. Patients received indefinite treatment unless they manifested tumor progression or severe adverse events. All were monitored for tumor response as well as other clinical outcomes. RESULTS: The cohort included 35 eligible patients with a median age of 59 years (range, 36-78) and an Eastern Cooperative Oncology Group performance score of 0, 1, and 2 in 60%, 34%, and 6% of patients, respectively. Although this regimen was well tolerated, the tumor response rate was lower than that anticipated at 23% (95% confidence interval: 10%, 40%), thereby prompting premature study closure. There were no complete responses. The median survival for the cohort was 8.9 months (95% confidence interval: 5.9, 12.8). CONCLUSION: As prescribed in this trial and for this indication, this regimen does not merit further testing.