Vincristine, Dexamethasone, Doxorubicin, and PEG-asparaginase (VPLD) and Metformin for Relapsed Childhood Acute Lymphoblastic Leukemia (ALL)

Will be dosed orally BID as per dose level of subject as defined in dose escalation schema. Both liquid and tablet forms are allowed and can be chosen based on convenience. Metformin will be continued throughout the cycle until Day 28 or until the patient is removed from study (e.g. to pursue new lines of therapy such as transplant), whichever occurs sooner.

1.5 mg/m\^2/dose IV push (maximum single dose 2 mg) on days 2, 9, 16 and 23

"* 10 mg/m\^2/day divided BID~* Take dexamethasone by mouth days 2-15"

"* 2500 IU's/m\^2/day~* Intramuscular injection (IM) or intravenous infusion per institutional standard on days 3, 9, 16 and 23~* If the patient develops an allergic reaction to PEG while being treated on this protocol, eliminate all future doses of PEG and substitute Erwinia if not intolerant of Erwinia and has no history of pancreatitis.~* Patients will receive Erwinase® 25,000 IU/m\^2 x 6 doses intramuscularly (IM) on a Monday/Wednesday/Friday schedule as a replacement for each scheduled dose of PEG-asparaginase on the original protocol."

60 mg/m\^2/day IV over 15 minutes on day 2

"IT cytarabine given intrathecally to all patients on day 1 of each cycle. Dose defined by age. May be given with staging lumbar puncture before enrollment, but must be within 72 hours of starting therapy. If not done at study entry or before, may be done on Day 2 prior to doxorubicin administration.~* 30 mg for patients age 1-1.99~* 50 mg for patients age 2-2.99~* 70 mg for patients greater than 3 years of age IT methotrexate given Intrathecally to all patients who are CNS negative at study entry on day 16 at the dose defined by age."