SCH 727965 in Patients With Acute Myelogenous Leukemia and Acute Lymphoblastic Leukemia (P04717AM2)(TERMINATED)

Inclusion Criteria:

* For participants with AML:

  * Age \>=60 years, either sex, any race.
  * Diagnosis of CD33-positive AML by World Health Organization criteria.
  * Must be in first or second relapse, or have primary refractory or refractory disease at first salvage, and not be considered a candidate for transplant.
  * Acute promyelocytic leukemia who has relapsed following treatment with both all trans retinoic acid (tretinoin) and arsenic trioxide-based therapy is eligible.
* For participants with ALL:

  * Age \>=18 years, either sex, any race.
  * Diagnosis of ALL by World Health Organization criteria.
  * Must be in first or second relapse, or have primary refractory or refractory disease at first salvage, and not be considered a candidate for potentially curative therapy.
  * Eastern Cooperative Oncology group performance status of 0 or 1.
  * Adequate hematologic, renal, and hepatic organ function and laboratory parameters.
  * Receiving treatment with hydroxyurea or leukapheresis to reduce elevated white blood cell count to \<=30 x 10\^9 is eligible, provided hydroxyurea and leukapheresis are discontinued at least 24 hours before initiation of study drug.

Exclusion Criteria:

* Known central nervous system leukemia.
* Previous hematopoietic stem cell transplantation.
* Previous treatment with SCH 727965 or other cyclin-dependent kinase inhibitors.
* For AML, previous treatment with gemtuzumab ozogamicin.
* Known HIV infection.
* Known active hepatitis B or C.