Sirolimus With Cyclophosphamide and Topotecan for Pediatric/Adolescent Relapsed and Refractory Solid Tumors

This is a Phase I study of the combination of three drugs: sirolimus, cyclophosphamide, and topotecan. This is the first study to evaluate the safety and clinical activity of the combination of oral sirolimus, oral cyclophosphamide and oral topotecan in pediatric and young adult patients with relapsed and refractory solid tumors. In this phase I study, the mTOR inhibitor sirolimus will be administered in combination with oral cyclophosphamide and oral topotecan to children with relapsed or refractory solid tumors. The primary aim of this study is to recommend a phase II dose schedule and describe the toxicity of this combination. Myelosuppression will be a targeted toxicity.