Phase I study on the safety, pharmacokinetic profile, and efficacy of the combination of TSU-68, an oral antiangiogenic agent, and S-1 in patients with advanced hepatocellular carcinoma

Purpose We aimed to investigate the recommended dose for the combination of TSU-68, a multiple-receptor tyrosine kinase inhibitor targeting vascular endothelial growth factor receptor-2 and platelet-derived growth factor receptor-beta, and S-1, an oral fluoropyrimidine, in patients with advanced hepatocellular carcinoma (HCC) based on its associated dose-limiting toxicity (DLT) frequency. We also determined the safety, tolerability, pharmacokinetics (PK), and efficacy of the combination treatment. Patients and methods Patients without any prior systemic therapy received 400 mg/day TSU-68 orally and 80 mg/day (level 1) or 100 mg/day (level 2) S-1 for 4 or 2 weeks followed by a 2- or 1-week rest period (groups A and B, respectively). According to the treatment, patients progressed from level 1B to level 2A, then level 2B. Safety and response rates were assessed. Results Eighteen patients were enrolled. Two patients at levels 1B and 2A but none at level 2B showed DLTs. The common adverse drug reactions were a decrease in hemoglobin levels, hypoalbuminemia, and anorexia, which were mild in severity (grades 1-2). PK data from levels 1B and 2A indicated that the area under the curve for TSU-68 and 5-fluorouracil was unlikely to be affected by the combination treatment. Response rate, disease control rate, median time to progression, and median overall survival were 27.8 %, 61.1 %, 5.3 months, and 12.8 months, respectively. Conclusion The recommended dose for advanced HCC should be 400 mg/day TSU-68 and 100 mg/day S-1 for 4 weeks followed by 2-week rest.