Phase I Dose Escalation Study of ON 01910.Na With Increasing Duration of an Initial 3-Day Continuous Infusion in Patients With Refractory Leukemia or MDS

Patients must have histologically documented or cytologically confirmed diagnosis of acute myelocytic leukemia refractory to standard induction treatment, or relapsed after standard therapy; acute lymphocytic leukemia refractory to induction treatment, or relapsed after effective therapy; chronic myelocytic leukemia refractory to imatinib therapy or second line tyrosine kinase inhibition, or relapsed after tyrosine kinase inhibition, in chronic, accelerated, or blastic phase; chronic lymphocytic leukemia refractory to standard therapy, or relapsed in second relapse; a myelodysplastic syndrome (including chronic myelomonocytic leukemia) refractory to azacitidine; and an int-2 or high myelodysplastic syndrome relapsed after a hypomethylating agent. Patients may not be eligible for, or must have declined, bone marrow transplantation or other chemotherapeutic regimens known to produce consistent remissions. Because hematopoietic criteria in leukemia and lymphoma are confounded by the nature of the diseases themselves, there are no hematologic exclusions from treatment. If leukopenia is clinically determined to be attributable to prior treatment, ON 01910.Na treatment may start when the leukocyte count increases on two successive determinations performed at least three days apart. Thrombocytopenia is not a criterion, and patients will be supported with platelet transfusions as clinically necessary. In the absence of leukopenia, a failed prior treatment may be succeeded immediately by entry into study of ON 01910.Na if the leukocyte count is stable or rising, on two successive determinations performed at least three days apart, in the absence of other drug toxicity.

The patient population will involve approximately 12 to 28 patients ≥ 18 years of age in the dose escalation portion of the protocol. All patients must have relapsed or refractory leukemia or poor risk MDS (i.e., int-2 or high risk MDS who have failed standard therapy). They must not be candidates for known regimens or protocol treatments of higher efficacy or priority. Patients with relapsed/refractory leukemia or poor risk MDS must have an ECOG Performance Status of 0, 1, or 2. Patients must have an expected survival, in the opinion of the Investigator, to allow a sufficient observation period for evaluating ON 01910.Na, and meet the eligibility criteria for patients with leukemia or poor risk MDS. After the maximally tolerated dose and the Recommended Phase II Dose (RPTD) and duration are determined, up to 12 additional patients with histologically documented or cytologically confirmed leukemia or poor risk MDS will be added to confirm the appropriateness of the RPTD. Inclusion criteria for the dose confirmation phase will be similar to those of the dose escalation phase of the study, but the ECOG Performance Status must be 0 or 1.

Safety data, including laboratory parameters and adverse events, will be collected for all patients in order to determine the qualitative and quantitative toxicity, and reversibility of toxicity, of ON 01910.Na. Leukemic cells and MDS cells in peripheral blood will be measured on a daily basis during infusion, and at least two times weekly during the following week. If leukemic cells disappear from the blood or blood counts improve as defined by IWG criteria in MDS patients, a bone marrow aspiration will be performed to determine response status in the bone marrow.

All patients may continue therapy for at least six cycles unless rapid disease progression is documented. Patients with an objective clinical response or stable disease can continue up to six more cycles. Further continuation will be determined by the clinical judgment of the Investigator.