Reduced Intensity Haploidentical BMT for High Risk Solid Tumors

This study tests whether a bone marrow transplant from a half-matched family member (called a haploidentical transplant) can help children and young adults with high-risk solid tumors — cancers with a very poor prognosis — that have not responded to standard treatment. **You may be eligible if...** - You are between 1 and 50 years old with a confirmed high-risk solid tumor (such as high-risk neuroblastoma, stage 4 rhabdomyosarcoma, metastatic Ewing sarcoma, or other advanced solid tumors with less than 10% expected survival) - You have received standard upfront treatment and your disease is stable - You have a half-matched family member willing to donate bone marrow - Your heart, liver, kidney, and lung function are within acceptable limits **You may NOT be eligible if...** - You are HIV positive - You are pregnant or not using adequate contraception - You have an uncontrolled active infection (viral, bacterial, or fungal) - There are certain immune incompatibilities with your donor (positive crossmatch) Talk to your doctor to see if this trial is right for you.