Clofarabine and Cytarabine in Treating Young Patients With Refractory or Relapsed Acute Myeloid Leukemia or Acute Lymphoblastic Leukemia

DISEASE CHARACTERISTICS:

* Histologically confirmed diagnosis of 1 of the following:

  * Acute myeloid leukemia (AML) with ≥ 5% blasts in the bone marrow (M2/M3 bone marrow) with or without extramedullary disease
  * Acute lymphoblastic leukemia (ALL) with \> 25% blasts in the bone marrow (M3 bone marrow) with or without extramedullary disease
  * Acute leukemia of ambiguous lineage with ≥ 5% blasts in the bone marrow (M2/M3 bone marrow) with or without extramedullary disease
* Disease must have relapsed after or be refractory to prior induction therapy

  * Patients with AML or acute leukemia of ambiguous lineage must be in first relapse OR refractory to first induction therapy with ≤ 1 attempt at remission induction

    * Patients with AML who enroll on the phase I portion of the study must have received prior mitoxantrone hydrochloride and cytarabine for newly diagnosed AML (phase I closed to accrual as of 09/16/09)
  * Patients with ALL must be in second or third relapse (≤ 3 prior induction regimens) OR refractory to reinduction in first relapse

    * Patients with ALL refractory to first induction therapy are not eligible
* No acute promyelocytic leukemia
* No CNS 3 involvement (i.e., WBC ≥ 5/μL in the cerebrospinal fluid with blasts present on cytospin)

PATIENT CHARACTERISTICS:

* Karnofsky performance status (PS) 50-100% (\> 16 years of age) OR Lansky PS 50-100% (≤ 16 years of age) OR ECOG PS 0-2
* Life expectancy ≥ 8 weeks
* Creatinine clearance or radioisotope glomerular filtration rate ≥ 70 mL/min
* Direct bilirubin ≤ 1.5 times upper limit of normal (ULN)
* ALT \< 2.5 times ULN (unless it is related to leukemic involvement)
* Shortening fraction ≥ 27% by echocardiogram OR ejection fraction ≥ 45% by gated radionuclide study
* No evidence of dyspnea at rest or exercise intolerance
* Pulse oximetry \> 94% at room air
* Amylase ≤ 1.5 times ULN
* Lipase \< 1.5 times ULN
* No active, uncontrolled grade 3 or 4 infection
* Not pregnant or nursing
* Negative pregnancy test
* Fertile patients must use effective contraception during and for ≥ 3 months after completion of study treatment
* No known hepatitis B or C infection or history of cirrhosis

PRIOR CONCURRENT THERAPY:

* See Disease Characteristics
* Recovered from all prior therapy\*
* At least 14 days since prior cytotoxic therapy (except hydroxyurea and intrathecal chemotherapy)\*
* At least 7 days since prior biologic agent\*
* At least 14 days since prior monoclonal antibody therapy\*
* No more than 1 prior autologous or allogeneic hematopoietic stem cell transplantation

  * No evidence of active graft-vs-host disease
  * At least 4 months since transplantation
* No other concurrent chemotherapy or immunomodulating agents
* No other concurrent investigational therapy NOTE: \*Patients who relapse during ALL maintenance therapy do not require a waiting period.