<qa>  What is the name of the group that you will receive clofarabine?If you are found to be eligible, you will be randomly assigned as in the roll of dice to one of 2 treatment groups. Participants in Group 1 will take a lower dose of clofarabine than Participants in Group 2. You have an equal chance of being assigned to either of the 2 treatment groups. Neither you nor your study doctor can choose your assignment. Later after the first 40 patients, the assignment will favor the better treatment arm until one arm is selected as the significantly better one, or until 80 patients are treated in total. When you have been assigned to a treatment group, you will receive clofarabine as tablets once a day for 5 days in a row. This will be repeated every 4-8 weeks. Each 4-8 week period is considered 1 cycle of treatment. 