Phase 1 dose-escalation study of apatinib and irinotecan in esophageal squamous cell carcinoma patients

Background: Apatinib, an inhibitor of vascular endothelial growth factor receptor (VEGFR), has been used to treat esophagogastric adenocarcinoma. However, the dosage of apatinib varies greatly in clinical practice, and its safety in esophageal squamous cell carcinoma (ESCC) patients is unclear. Therefore, we initiated a phase 1 dose-escalation trial to identify the maximum tolerated dose (MTD) of apatinib when combined with irinotecan in ESCC. Methods: The trial had a standard 3+3 design. The dosage of irinotecan was fixed at 150 mg/m(2) repeated every 2 weeks, while the daily dosage of apatinib was escalated from 250 mg, to 500 mg, to 750 mg. Dose-limiting toxicity (DLT) was defined as grade 4 hematological or grade 3-4 non-hematological adverse events (AEs). Results: Twelve patients were enrolled. Three DLTs occurred, comprising a grade 3 perianal abscess and a grade 3 case of kaliopenia in the level 3 cohort, and a grade 4 leukopenia in the level 2 cohort. Based on these DLTs, the MTD of apatinib was 500 mg daily. The most common AEs were leukopenia (91.7%), fatigue (91.7%), anemia (66.7%), and diarrhea (58.3%). One case of grade 2 hematochezia and one case of grade 2 subclavian vein thrombosis were observed. In the nine evaluable cases, the disease control rate (DCR) was 66.7% (6/9). The median progression-free and overall survival (OS) times were 3.6 +/- 1.2 and 6.6 +/- 3.4 months, respectively. Conclusions: This phase 1 dose-escalation trial showed that, when combined with irinotecan, a daily dose of 500 mg apatinib was the optimum dose to treat ESCC.