The Pilot Safety portion of the study will evaluate the safety of obatoclax administered by a 3 hour infusion for 3 days in a row. The Pilot Schedule portion of the study will randomize 16 patients in to one of two cohorts: 1) patients receiving obatoclax administered by a 3 hour infusion for 3 days in a row or 2) patients receiving obatoclax administered by a 24 hour infusion for 3 days in a row. The schedule with the best overall efficacy and safety in the Pilot Schedule portion of the study will then be utilized in the Phase II portion of the study.