The purpose of this study is to evaluate the tolerability and safety of escalating doses of metformin on a backbone of vincristine, irinotecan and temozolomide (VIT) in children with recurrent and refractory solid tumors.

Metformin is an oral anti-diabetes medication that activates AMP-activated protein kinase (AMPK). Recent data from in vitro and in vivo experiments, as well as epidemiologic retrospective analyses, suggest that metformin has anti-cancer activity. Vincristine, irinotecan, and temozolomide (VIT) is a combination of chemotherapeutic agents that have different mechanisms of action as well as disparate side effect profiles. Two recent phase 1 trials have demonstrated that this regimen is safe and well-tolerated in children with relapsed and refractory solid tumors.

Inclusion Criteria:

• Age: Patients must be > 1 year of age and ≤ 18 years of age at time of initiation of protocol therapy.

• Diagnosis: Patients have a histologically or radiographically confirmed relapsed or refractory solid tumor or primary central nervous system (CNS) malignancy.

• Disease Status: Patients must have radiographically measurable disease.

• Therapeutic Options: Patients must have relapsed or refractory cancers for which there is no known curative option or other available therapy proven to prolong survival with an acceptable quality of life.

• Performance Level: Karnofsky ≥ 50% for patients older than 16 years old, and Lansky ≥ 50 for patients 1-16 years old.

• Prior Therapy: Patients may have received prior therapy including vincristine, irinotecan, or temozolomide. Patients may not have previously been treated with combination therapy of irinotecan and temozolomide.

• Patients must be fully recovered from the acute toxic effects of all prior chemotherapy, immunotherapy, or radiotherapy prior to entering this study.

  • Myelosuppressive chemotherapy: Patients must not have received myelosuppressive chemotherapy within 3 weeks of starting protocol therapy, or a minimum of six weeks must have elapsed since prior nitrosurea chemotherapy.
  • Hematopoietic growth factor: At least 7 days must have elapsed since the last administration of filgrastim, or 14 days since administration of pegfilgrastim.
  • Biologic (anti-neoplastic agent): At least 7 must have elapsed since the last administration of any biologic agent.
  • Radiation therapy (XRT): At least 14 days since the last dose of local palliative radiation therapy. Greater than 6 months must have elapsed since the last day of treatment if given total body irradiation, craniospinal irradiation.
  • Autologous or Allogenic Stem Cell Transplant: Complete resolution of graft versus host disease and no current need for immunosuppressive medication. Greater than 3 months must have elapsed since engraftment and no longer requiring transfusion of platelets or injection of colony stimulating factors.

• Organ Function Requirements

  • Bone Marrow Function: Peripheral absolute neutrophil count (ANC) ≥ 1000/μL; Platelet count ≥ 100,000/μL (no platelet transfusion within 7 days prior to obtaining laboratory result); Hemoglobin ≥ 8.0 gm/dL
  • Adequate Renal Function: Creatinine clearance or glomerular filtration rate ≥ 70ml/min/1.73m^2
  • Adequate Liver Function: Total bilirubin ≤ 1.5x upper limit of normal (ULN) for age; alanine transaminase (ALT) ≤ 5x ULN; Serum albumin ≥ 2gm/dL

• Informed Consent: All patients ≥ 18 years of age must sign a written informed consent. For patients < 18 years old, the patient's parents or legal guardians must sign a written informed consent, unless the patient is an emancipated minor. Childhood Assent, when age appropriate as per institutional guidelines, should be signed by the participating patient.

Exclusion Criteria:

• Significant organ dysfunction, not meeting inclusion criteria.

• Pregnancy or Breast-Feeding woman will not be entered on this study due to risks of fetal and teratogenic adverse events as seen in animal/human studies.

• Concomitant Medications:

  • Growth factor: Growth factors that support platelet or white cell number of function must not have been administered within the past 7 days.
  • Steroids: Patients with CNS tumors who have not been on a stable or decreasing dose of dexamethasone for the past 7 days.
  • Investigational Drugs: Patients who are currently receiving another investigational drug.
  • Anti-cancer Agents: Patients who are currently receiving other anti-cancer agents.
  • Medication Allergy: Allergy or intolerance to agents on this protocol: vincristine, irinotecan, temozolomide, or metformin; Allergy to cephalosporins.
  • Infection: Patients who have uncontrolled infection, positive blood cultures within the past 48 hours, or receiving treatment for Clostridium difficile infection.