A phase II and pharmacodynamic study of sunitinib in relapsed/refractory oesophageal and gastro-oesophageal cancers

Abstract

BACKGROUND: Blockade of the vascular endothelial growth factor (VEGF) pathway shows evidence of activity in gastro-oesophageal (GE) and oesophageal cancer. We investigated the efficacy of sunitinib, a multikinase VEGF inhibitor, in patients with relapsed/refractory GE/oesophageal cancer. METHODS: This was a single-stage Fleming phase II study. The primary end point was progression-free survival (PFS) at 24 weeks. If five or more patients out of a total of 25 were free of progressive disease at 24 weeks, sunitinib would be recommended for further study. Patients received sunitinib 37.5 mg orally daily and imaged every 6 weeks. Exploratory correlative analysis included serum growth factors, tumour gene expression and dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI). RESULTS: Twenty-five evaluable patients participated in the study. Progression-free survival at 24 weeks was 8% (n=2 patients; confidence interval (CI): 95% 1.4-22.5%), and the duration of best response for the patients was 23 and 72 weeks. Ten patients (42%) had stable disease (SD) for >10 weeks. Overall response rate is 13%. Median PFS is 7 weeks (95% CI: 5.6-11.4 weeks) and the median overall survival is 17 weeks (95% CI: 8.9-25.3 weeks). Most common grade 3/4 toxicities included fatigue (24%), anaemia (20%) thrombocytopenia (16%), and leucopenia (16%). No patients discontinued therapy due to toxicity. Serum VEGF-A and -C levels, tumour complement factor B (CFB) gene expression, and DCE-MRI correlated with clinical benefit, defined as SD or better as best response. CONCLUSION: Sunitinib is well tolerated but only a select subgroup of patients benefited. Serum VEGF-A and -C may be early predictors of benefit. On this study, patients with clinical benefit from sunitinib had higher tumour CFB expression, and thus has identified CFB as a potential predictor for efficacy of anti-angiogenic therapy. These findings need validation from future prospective trials.