Follow-up Subjects who have a response and proceed with stem cell transplant will be followed weekly for the first three months and then every month for six months, then every two months for 12 months, then every three months for 18 months. The stem cell transplant will be done 21-30 days after first receiving Clofarabine. Subjects who do not go on to stem cell transplant will be followed for 3 months following administration of Clofarabine.