Cytarabine and clofarabine after high-dose cytarabine in relapsed or refractory AML patients.

Clofarabine has been shown to be effective in AML patients, either as single agent or, mainly, in association with intermediate dose cytarabine. Based on these reports, we conducted a preliminary study combining clofarabine and intermediate dose cytarabine in AML patients who relapsed or failed to respond to at least two induction therapies. We treated 47 patients affected by relapsed/refractory AML with a regimen including clofarabine at 22.5 mg/m2 daily on days 1–5, followed after 3 hr by cytarabine at 1 g/m2 daily on days 1–5. Ten patients received a further consolidation cycle with clofarabine at 22.5 mg/m2 and cytarabine at 1 g/m2 day 1–4. Among the 47 patients, 24/47 (51%) achieved a complete remission, 5/47 (10.5%) a partial response, 10/47 (21%) had a resistant disease, and 6/47 (13%) died of complications during the aplastic phase. The most frequent nonhematologic adverse events were vomiting, diarrhea, transient liver toxicity, febrile neutropenia, and infections microbiologically documented. Among the 24 patients who obtained a CR 13 underwent allogeneic bone marrow transplantation. In 14 patients, complete remission duration was shorter than 12 months, whereas 10 patients experienced longer complete remission duration. These very preliminary results suggest that clofarabine-cytarabine regimen is effective in this particularly poor prognosis category of patients, representing a potential ‘‘bridge’’ toward bone marrow transplant procedures. Safety data were consistent with previously reported salvage therapies. Further studies and a longer follow up are warranted.