Sorafenib and Cyclophosphamide/Topotecan in Patients With Relapsed and Refractory Neuroblastoma

This study will combine three drugs: sorafenib, cyclophosphamide and topotecan. This study involves the use of an experimental drug, called sorafenib. Sorafenib blocks the function of a protein that is important in the growth of cancer cells. This drug has been tested by itself (as a single-agent) in children with relapsed solid tumors, including patients with neuroblastoma. In the laboratory, sorafenib appears to make neuroblastoma tumors smaller, and in addition can help immune cells to be more active in attacking tumors and blocks other harmful immune cells from promoting tumor growth and function. Sorafenib also helps to block tumor cells from developing blood vessels used to "feed" to tumor. Sorafenib is an FDA-approved drug currently widely used for adults with specific types of liver and kidney cancer. Cyclophosphamide and topotecan are both FDA-approved chemotherapy drugs. These drugs are approved for the treatment of certain adult cancers, but have also been used to treat children with cancer. These drugs have been used in combination in many people with neuroblastoma. In some neuroblastoma patients, this combination has reduced the amount of tumor burden. Adding sorafenib to cyclophosphamide and topotecan may increase the effectiveness of this combination. The investigators first need to find out the highest dose of sorafenib that can be given safely together with cyclophosphamide and topotecan. This is the first study to test giving these three drugs together and will help determine the highest dose of sorafenib that can safely be given together with cyclophosphamide and topotecan to patients with resistant/relapsed neuroblastoma.