 This is a multicentre clinical study conducted in the USA and in Europe. It is an open label, dose escalation study designed to characterize the safety, tolerability, pharmacokinetics PK, and efficacy of CP-4055 as a single agent when administered as a 2 hours intravenous IV or a continuous IV CIV infusion administered daily for 5 days in a 21-day cycle, either alone or with idarubicin IV, in patients with refractoryrelapsed hematologic malignancies who have either failed potentially curative therapy or are considered unsuitable for standard therapy. 