Sorafenib in Treating Young Patients With Relapsed or Refractory Solid Tumors or Leukemia

This phase I/II trial is studying the side effects and best dose of sorafenib in treating young patients with relapsed or refractory solid tumors or leukemia. Sorafenib may stop the growth of cancer cells by blocking some of the enzymes needed for cell growth and by blocking blood flow to the cancer.

PRIMARY OBJECTIVES: I. Determine the maximum-tolerated dose (MTD) and recommended phase II dose of sorafenib in pediatric patients with relapsed or refractory solid tumors. II. Determine whether pediatric patients with relapsed or refractory leukemia can tolerate the MTD of sorafenib for solid tumors. III. Determine the tolerability, active N-oxide metabolite, pharmacodynamics, and activity of sorafenib a the MTD in a subset of patients with acute myeloid leukemia (AML) and FLT3-ITD mutation. IV. Determine the toxicities of this drug in these patients. V. Determine the pharmacokinetics of this drug in these patients. SECONDARY OBJECTIVES: I. Determine, preliminarily, the antitumor activity of this drug within the confines of a phase I trial. II. Assess the biologic effect of sorafenib on circulating endothelial cells (CEC), circulating CEC precursors (CECP), VEGF, and VEGF-2 in peripheral blood. III. Assess the gene expression, proteomic profile, and ERK phosphorylation in blasts of patients with refractory leukemia treated with this regimen. IV. Assess the effect of sorafenib on solid tumor vascularity and tumor blood flow using dynamic contrast-enhanced MRI (DEMRI) in patients with measurable soft tissue tumors. V. Analyze tumor samples and leukemic blasts for the presence of ras, raf, or FLT3 (leukemias) mutations. VI. Analyze the plasma inhibitory activity for FLT3 phosphorylation in peripheral blood of patients with AML and FLT3-ITD mutation. VII. Determine the tolerability, pharmacokinetics of sorafenib and sorafenib?s active N-oxide metabolite, pharmacodynamics, and activity of sorafenib administered at the MTD for refractory leukemias in a subset of patients with AML and FLT3-ITD mutation. VIII. Analyze the plasma inhibitory activity for FLT3 phosphorylation in peripheral blood samples obtained at the time of PK studies in patients with FLT3-ITD mutation AML. OUTLINE: This is a dose-escalation, multicenter study. Patients are stratified according to diagnosis (malignant solid tumor vs leukemia). STRATUM I(REFRACTORY SOLID TUMOR PATIENTS): Patients receive oral sorafenib twice daily on days 1-28. Treatment repeats every 28 days for up to 24 courses in the absence of disease progression or unacceptable toxicity. Cohorts of 3-6 patients receive escalating doses of sorafenib until the maximum-tolerated dose (MTD) is determined. The MTD is defined as the dose preceding that at which 2 of 3 or 2 of 6 patients experience dose-limiting toxicity (DLT). Once the MTD is determined, up to 6 additional patients under 12 years of age may be treated at the MTD. The MTD dose level is also expanded to enroll up to 6 patients with refractory leukemia. STRATUM II (REFRACTORY LEUKEMIA PATIENTS): A cohort of 3-6 patients with leukemia receives treatment as in stratum 1 at the MTD determined in stratum 1. If 2 of 3 or 2 of 6 patients experience a DLT at the solid tumor MTD, sorafenib is reduced by one dose level. The leukemia MTD is defined as the dose at which \< 1/3 of patients experience DLT during course 1 of treatment. STRATUM III (ACUTE MYELOID LEUKEMIA AND FLT3-ITD MUTATION PATIENTS): Patients receive sorafenib as in stratum 1 at the MTD determined in stratum 2. Patients undergo blood sample collection for pharmacokinetics, pharmacodynamics (in leukemia blasts only), circulating endothelial cells (CEC), circulating CEC precursors (CECP), VEGF and VEGF-2 , gene expression, proteomic profile, ERK phosphorylation, and FLT3 phosphorylation activity. Tumor tissue samples may also be analyzed for the presence of ras, raf, or FLT3. After completion of study treatment, patients are followed periodically.