Inclusion Criteria:

        Procurement and T-cell production eligibility*

        *a previously collected, autologous leukapheresis product can be used for T-cell production

          -  Age ≤21 years old

          -  B7-H3+ solid tumor with measurable disease; B7-H3 expression will be evaluated by
             standard immunohistochemistry (IHC) using a previously obtained biopsy; a tumor is
             considered B7-H3 positive with an H-score ≥100

          -  Estimated life expectancy of >12 weeks

          -  Karnofsky or Lansky (age-dependent) performance score ≥50

          -  For females of child bearing age:

          -  Not pregnant with negative serum pregnancy test within 7 days prior to enrollment

          -  Not lactating with intent to breastfeed

          -  Meets eligibility criteria to undergo autologous apheresis, or have previously
             undergone autologous apheresis

        Exclusion Criteria:

          -  Known primary immunodeficiency

          -  Known HIV positivity

          -  Severe intercurrent bacterial, viral or fungal infection (e.g. active hepatitis B or C
             infection or adenovirus infection)

          -  History of hypersensitivity reactions to murine protein-containing products

          -  Rapidly progressive disease (in the opinion of the study PIs)

        Inclusion criteria

        Treatment eligibility

          -  Age ≤21 years old

          -  B7-H3+ solid tumor with measurable disease

          -  Evidence of relapsed or refractory disease after standard first-line therapy

          -  Estimated life expectancy of >8 weeks

          -  Karnofsky or Lansky (age-dependent) performance score≥50

          -  Echocardiogram with a ventricular ejection fraction

          -  >40%; or shortening fraction ≥25%

          -  Adequate renal function defined as creatinine clearance or radioisotope GFR 50
             ml/min/1.73m2 (GFR 40 ml/min/1.73m2 if < 2 years of age)

          -  Adequate pulmonary function defined as pulse oximetry ≥92% on room air or forced vital
             capacity (FVC) ≥50% of predicted value

          -  Total Bilirubin ≤3 times the upper limit of normal for age, except in subjects with
             Gilbert's syndrome

          -  Alanine aminotransferase (ALT) or aspartate aminotransferase (AST) ≤5 times the upper
             limit of normal for age

          -  Hemoglobin≥ 7g/dL (can be transfused)

          -  Platelet count >50,000/uL (can be transfused)

          -  Absolute neutrophil count (ANC) ≥ 1000/uL

          -  Has recovered from all NCI CTAE grade III-IV, non-hematologic acute toxicities from
             prior therapy

          -  For females of child bearing age:

          -  Not pregnant with negative serum pregnancy test within 7 days prior to enrollment

          -  Not lactating with intent to breastfeed

          -  If sexually active, agreement to use birth control until 3 months after T-cell
             infusion. Male partners should use a condom.

          -  Available autologous transduced T-cell product that has met GMP release criteria

          -  Agreement to participate in long-term follow-up protocol for patients, who have
             received genetically modified cell products

        Exclusion criteria

          -  Known primary immunodeficiency

          -  History of HIV infection

          -  Severe, uncontrolled intercurrent bacterial, viral or fungal infection

          -  History of hypersensitivity reactions to murine protein-containing products

          -  Receiving systemic steroid therapy exceeding the equivalent of 0.5 mg/kg/day of
             methylprednisolone, in the 7 days prior to B7-H3-CAR T-cell infusion

          -  Receiving systemic therapy in the 14 days prior to CAR T-cell infusion, which will
             interfere with the activity of the B7-H3-CAR product (in the opinion of the study
             PIs).

          -  Rapidly progressing disease (in the opinion of the study PIs)