Panitumumab added to docetaxel, cisplatin and fluoropyrimidine in oesophagogastric cancer: ATTAX3 phase II trial

Background: This randomised phase II study evaluated the efficacy and safety of panitumumab added to docetaxel-based chemotherapy in advanced oesophagogastric cancer. Methods: Patients with metastatic or locally recurrent cancer of the oesophagus, oesophagogastric junction or stomach received docetaxel and a fluoropyrimidine with or without panitumumab for 8 cycles or until progression. The primary end point was response rate (RECIST1.1). We planned to enrol 100 patients, with 50% expected response rate for combination therapy. Results: A total of 77 patients were enrolled. A safety alert from the REAL3 trial prompted a review of data that found no evidence of adverse outcomes associated with panitumumab but questionable efficacy, and new enrolment was ceased. Enrolled patients were treated according to protocol. Response rates were 49% (95% CI 34-64%) in the chemotherapy arm and 58% (95% CI 42-72%) in the combination arm. Common grade 3 and 4 toxicities included infection, anorexia, vomiting, diarrhoea and fatigue. At 23.7 months of median follow-up, median progression-free survival was 6.9 months vs 6.0 months and median overall survival was 11.7 months vs 10.0 months in the chemotherapy arm and the combination arm, respectively. Conclusions: Adding panitumumab to docetaxel-based chemotherapy for advanced oesophagogastric cancer did not improve efficacy and increased toxicities.