Inclusion Criteria:

- Patients must have a diagnosis of NB as defined by international criteria,45 i.e.,
histopathology (confirmed by the MSKCC Department of Pathology) or BM metastases plus
high urine catecholamine levels.

- Patients must have refractory or relapsed high-risk NB (including MYCNamplified stage
3/4/4S and MYCN-nonamplified stage 4 >18 months old) resistant to standard therapy.

- Prior treatment with 3F8 is allowed.

- Age <21 years.

- Signed informed consent indicating awareness of the investigational nature of this
program.

Exclusion Criteria:

- Existing major organ dysfunction should be grade 2 or less, with the exception of
myelosuppression (neutrophil count >500/ul and platelet count >10,000/ul are
acceptable), alopecia, hearing loss. Patient cannot be taking antihypertensive
medication.

- History of allergy to mouse proteins.

- Active life-threatening infection.

- Human anti-mouse antibody (HAMA) titer >1000 ELISA units/ml.

- Prior treatment with 3F8 is NOT an exclusion criterion.

- Inability to comply with protocol requirements.

- Pregnant women are excluded for fear of danger to the fetus. Therefore negative
pregnancy test is required for all women of child-bearing age, and appropriate
contraception is used during the study period.