Etanercept (Enbrel) for Juvenile Myelomonocytic Leukemia

Etanercept blocks a hormone called Tumor Necrosis Factor (TNF), which has been shown to play a role in helping the growth of leukemic cells in JMML. Before participants can start treatment on this study, they will have what are called "screening tests". These tests will help the doctor decide if patients are eligible to take part in the study. You will have a complete medical history and physical exam. About two tablespoons of blood and urine will be collected for routine tests as well as to test for the liver and kidney function. You will have a bone marrow biopsy performed to monitor disease activity. To collect a bone marrow biopsy, an area of the hip or chest bone is numbed with anesthetic and a small amount of bone marrow and bone is withdrawn through a large needle. You will have cells from inside of the mouth tested for genetic changes by swabbing the side of the cheeks. If you are found to be eligible, etanercept will be given as an injection under the skin once a week for up to 90 days. During the study, you will have weekly follow-up tests that will include physical exam and lab tests. About 2 tablespoons of blood will be collected each time. Urine will also be collected for testing at least every 3 weeks while on the study. If the disease gets worse or intolerable side effects occur, you will be taken off study and alternative treatment options will be discussed. This is an investigational study. The FDA has approved etanercept for use in adults and children with rheumatoid arthritis and juvenile rheumatoid arthritis. Its use in this study is experimental. A total of up to 30 patients will take part in this study. All will be enrolled at M. D. Anderson.