Phase I trial of sorafenib in combination with interferon-alpha in Japanese patients with unresectable or metastatic renal cell carcinoma

Background We investigated the safety, pharmacokinetics, tumor response, and immunological parameters of sorafenib plus interferon α-2a (IFN) in Japanese patients with advanced RCC. Patients and methods After 2 weeks of IFN-alone treatment, eligible patients received 28-day cycles of continuous sorafenib 200 mg (Cohort 1) or 400 mg (Cohorts 2 and 3) twice daily combined with intramuscular IFN 6 (Cohorts 1 and 2) or 9 (Cohort 3) million international units (MIU) three times a week. Results A total of 18 patients received at least one dose of sorafenib plus IFN. Five patients had dose-limiting toxicities (DLTs). The most common DLT was fatigue, experienced in four DLT patients. All 18 patients experienced at least one treatment-emergent adverse event (AE). The most common treatment-emergent AEs included fatigue, fever, platelets, leukocytes, hemoglobin, weight loss and anorexia. Five patients had confirmed partial response and 11 had stable disease, a response rate of 27.8%. IFN had no relevant impact on the pharmacokinetics of sorafenib. Conclusions Sorafenib administered in combination with IFN was well tolerated, with promising results in efficacy. Continuous sorafenib 400 mg twice daily in combination with IFN 6 MIU three times a week is recommended in Japanese patients with advanced RCC.