When administered on either a weekly schedule, five out of ten patients in the 50mg/m2 and 60mg/m2 dose cohorts experienced bone marrow blast reductions of more than 95%, including one complete remission with incomplete platelet recovery, one complete remission in a patient who demonstrated partial but incomplete recovery of normal hematopoietic blood elements and one partial response.
Additionally, in the twice-weekly 40mg/m2 dose cohort, one of three patients had blast reduction of more than 95% and that patient achieved a complete remission. Several patients have gone on to receive and tolerate multiple courses of treatment with the drug, SNS-595.
SNS-595 is a replication-dependent DNA damaging agent that causes double- stranded DNA breaks, irreversible G2 arrest, and rapid apoptosis. The phase I study is designed to assess the safety, tolerability and pharmacokinetics of SNS-595 and to establish a recommended phase II dose for further testing among patients with acute leukemia. Sunesis plans to initiate a phase Ib clinical trial of SNS-595 in combination with cytarabine in patients with advanced acute leukemias in the third quarter of this year.