Axitinib in patients with advanced/metastatic soft tissue sarcoma (Axi-STS): an open-label, multicentre, phase II trial in four histological strata

Background Axitinib is an oral vascular endothelial growth factor receptor inhibitor with anti-tumour activity in renal, thyroid, and pancreatic cancer. Methods Axi-STS was a pathologically-stratified, non-randomised, open-label, multi-centre, phase II trial of continuous axitinib treatment in patients ≥16 years, performance status ≤2, with pathologically-confirmed advanced/metastatic soft tissue sarcoma (STS). Patients were recruited within four tumour strata, each analysed separately: angiosarcoma, leiomyosarcoma, synovial sarcoma, or other eligible STSs. The primary outcome was progression-free survival at 12 weeks (PFS12). A Simon’s two-stage design with activity defined as PFS12 rate of 40% determined a sample size of 33 patients per strata. Results Between 31-August-2010 and 29-January-2016, 145 patients were recruited: 38 angiosarcoma, 37 leiomyosarcoma, 36 synovial sarcoma, and 34 other subtypes. PFS12 rate for each stratum analysed was 42% (95% lower confidence interval (LCI); 29), 45% (95% LCI; 32), 57% (95% LCI; 42), and 33% (95% LCI; 21), respectively. There were 74 serious adverse events including two treatment-related deaths of pulmonary haemorrhage and gastrointestinal bleeding. Fatigue and hypertension were the most common grade 3 adverse events. Conclusions Axitinib showed clinical activity in all STS strata investigated. The adverse event profile was acceptable, supporting further investigation in phase III trials. Clinical Trial Registration ISRCTN 60791336