Exposure–Toxicity Relationship of Sorafenib in Japanese Patients with Renal Cell Carcinoma and Hepatocellular Carcinoma

Background and Objectives Sorafenib has various adverse events that can cause treatment discontinuation or dose reduction. The aim of this study was to compare the safety profile between renal cell carcinoma (RCC) and hepatocellular carcinoma (HCC) patients receiving sorafenib under real-life practice conditions. Furthermore, we investigated the relationship between sorafenib exposure and clinical outcomes. Methods A total of 91 Japanese cancer patients (RCC, n = 21; HCC, n = 70) treated with sorafenib were enrolled. Toxicity was graded according to the National Cancer Institute Common Toxicity Criteria for Adverse Events (NCI-CTCAE) version 4.0. Single blood samples were collected at each clinic visit and serum sorafenib concentrations were measured by liquid chromatography–tandem mass spectrometry (LC–MS/MS). The incidence of adverse events was analyzed according to cancer type and sorafenib concentration. Results Hand-foot skin reaction (HFSR) was the most common adverse event among RCC (76 %) and HCC (66 %) patients. Elevations in hepatic transaminases and pancreatic amylase developed more frequently in patients with RCC than in those with HCC ( p