Phase I study of tivantinib in Japanese patients with advanced hepatocellular carcinoma: Distinctive pharmacokinetic profiles from other solid tumors

A c-Met inhibitor tivantinib is a candidate anticancer agent for patients with hepatocellular carcinoma (HCC), and CYP2C19 is the key metabolic enzyme for tivantinib. Previous Japanese phase I studies in patients with solid tumors (except HCC) recommend 360mg twice daily (BID) and 240mg BID for CYP2C19 extensive metabolizers (EM) and poor metabolizers (PM), respectively. In this study, Japanese patients with HCC in whom sorafenib treatment has failed were enrolled to evaluate the safety, tolerability and pharmacokinetics of oral tivantinib as a single agent. The dose was escalated separately in EM and PM, from 120mg BID to 240mg BID, in both capsule and tablet formulations. A total of 28 patients (EM: 21, PM: 7) received tivantinib. At a dose of 120mg BID, dose-limiting toxicities (DLT) did not develop in 12 EM (capsule: 6, tablet: 6) and 7 PM (capsule: 4, tablet: 3) during the DLT-observation period (for 29days after first dosing). At this dose, the pharmacokinetic profiles of tivantinib (AUC(0-12) and C-max) did not remarkably differ between EM and PM. When treated with 240mg BID, 5 of 9 EM (capsule: 4 of 6, tablet: 1 of 3) developed neutropenia-related DLT accompanying plasma tivantinib concentration higher than expected from the previous studies. Consequently, PM did not receive 240mg BID. In conclusion, 120mg BID of tivantinib is recommended among Japanese patients with HCC regardless of CYP2C19 phenotype. This would be one of the first manuscripts demonstrating that the recommended dose of an anti-cancer agent for patients with hepatocellular carcinoma (HCC) could be distinct from its recommended dose for patients with other solid tumors.