Inclusion Criteria:

          -  Consent/Assent: all patients and/or their parents or legally authorized
             representatives must sign written informed consent; assent, when appropriate, will be
             obtained according to institutional guidelines

          -  Age: patients must be ≥12 months of age at the time of study enrollment

          -  Diagnosis: patients must have histologically documented locally advanced or metastatic
             desmoplastic small round cell tumor or rhabdomyosarcoma (confirmed at MSK)

          -  Therapeutic options: patient's current disease state must be one which has failed
             standard therapy and for which there is no known curative therapy

          -  Disease Status: patients must have measurable disease based on RECIST 1.1

          -  Performance level: Karnofsky ≥ 50% for patients > 16 years of age and Lansky ≥ 50 for
             patients ≤ 16 years of age

          -  Prior Therapy: patients may have had any number of prior therapies, but must have
             recovered from the acute toxic effects of all prior anti-cancer therapy (other than
             alopecia) as described below and must meet the following minimum duration from prior
             anti-cancer directed therapy prior to enrollment

             °patients who have previously received irinotecan and/or temozolomide will be allowed

               -  21 days must have elapsed after the last dose of cytotoxic or myelosuppressive
                  chemotherapy

               -  7 days must have elapsed after the last dose of anti-cancer agents not known to
                  be myelosuppressive

               -  14 days must have elapsed after radiation therapy, and toxicity related to prior
                  radiation therapy must be recovered to grade ≤ 1

               -  21 days must have elapsed after the last dose of antibody therapy, and toxicity
                  related to prior antibody therapy must be recovered to grade ≤ 1

          -  Organ Function Requirements: Adequate bone marrow function defined as:

               -  absolute neutrophil count (ANC) ≥ 1500/mm^3

               -  platelet count ≥ 100,000/ mm^3

               -  hemoglobin ≥ 8 g/dl

          -  Adequate renal function defined as:

               -  Creatinine clearance or radioisotope glomerular filtration rate ≥ 70
                  mL/min/1.73m2 OR

               -  Serum creatinine based on age/gender derived from the Schwartz formula for
                  estimating GFR53

          -  Adequate liver function defined as:

               -  Bilirubin (sum of conjugated + unconjugated) ≤ 1.5 x upper limit of normal for
                  age

               -  AST or ALT ≤ 5 x upper limit of normal for patients with liver metastases

               -  Serum albumin ≥ 2.5 g/dl

          -  Adequate cardiac function defined as:

               -  echocardiogram with left ventricular ejection fraction (LVEF) >45%

               -  QTc < 470 ms on screening 12 lead electrocardiogram

          -  Pregnancy/Contraception

               -  post-menarchal females must have a negative urine or serum pregnancy test at
                  screening and ≤ 24 hours prior to study treatment

               -  males or females of reproductive potential must be willing to use a barrier
                  method of contraception throughout the course of the study and for 6 months after
                  participation

        Exclusion Criteria:

          -  Patients for whom the investigator deems that irinotecan and temozolomide are not
             appropriate are not eligible.

          -  Patients who have an uncontrolled infection are not eligible.

          -  Patients who are pregnant or breast feeding are not eligible.

          -  Patients who have a history of Torsades de Pointes, carry a diagnosis of congestive
             heart failure, or have a family history of prolonged QT syndrome are not eligible.

          -  Patients who, in the opinion of the investigator, may not be able to comply with the
             safety monitoring requirements of the study are not eligible.

          -  Patients with known hypersensitivity to irinotecan or its excipients are not eligible.