Safety of Clofarabine With Multiagent Chemotherapy in Childhood Acute Lymphoblastic Leukemia

Inclusion Criteria:

* 1 to 21 years old at the date of acute lymphoblastic leukemia initial diagnosis
* Very early medullary first relapse occurring during the first 18th months after complete remission OR patients with second relapse OR a relapse occurring 6 months or more after myeloablative stem cell transplantation will be eligible.
* Have a Karnofsky Performance Status (KPS) of ≥70 for patients \>10 years of age or a Lansky Performance Status (LPS) of ≥60 for patients ≤10 years of age.
* No concomitant malignant disease.
* No active uncontrolled infection.
* Have adequate renal and hepatic functions
* absence of concomitant severe cardiovascular disease, i.e. congestive heart failure
* Female patients of childbearing potential must have a negative serum pregnancy test within 2 weeks prior to enrollment.
* Male and female patients must use an effective contraceptive method during the study and for a minimum of 6 months after study treatment.

Exclusion Criteria:

* Current concomitant chemotherapy, radiation therapy, or immunotherapy other than as specified in the protocol.
* Use of any investigational agent within 30 days.
* Known hypersensitivity to clofarabine or excipients.
* Known hypersensitivity to mitoxantrone, etoposide or excipients.
* Allergy to both E Coli-Asparaginase and Erwinia Asparaginase
* Prior transplant less than 6 months ago.
* Trisomy 21
* Have any other severe concurrent disease, or have a history of serious organ dysfunction or disease involving the heart, kidney, liver, or other organ system that may place the patient at undue risk to undergo treatment.
* Patients with a systemic fungal, bacterial, viral, or other infection not controlled (defined as exhibiting ongoing signs/symptoms related to the infection and without improvement, despite appropriate antibiotics or other treatment).
* Pregnant or lactating patients.
* Any significant concurrent disease, illness, or psychiatric disorder that would compromise patient safety or compliance, interfere with consent, study participation, follow up, or interpretation of study results.