<qa>  What is the starting dose of clofarabine?A cohort of 3-6 patients receives the starting dose of clofarabine. If 1 of 6 patients experiences dose-limiting toxicity DLT, a subsequent cohort of patients receives clofarabine at the next higher dose. If 2 of 6 patients experience DLT, the dose of cytarabine is reduced and subsequent cohorts of patients receive cytarabine at reduced doses and clofarabine as per the dose-escalation scheme above. 