In addition to the medications listed above, you will also be receiving intrathecal (IT) chemotherapy that is given directly into your spinal fluid to treat the leukemia that may have spread to your brain and spinal fluid. The medicines we will be giving in your spinal fluid are listed below. The number of times we give chemotherapy into the spinal fluid will depend on whether or not we see leukemia cells in your spinal fluid on the sample we take on the first day of the study.