A Randomized Study of Monoclonal Antibody 3F8 Plus Granulocyte-Macrophage Colony-Stimulating Factor (GM-CSF) Compared to 13-cis-Retinoic Acid Plus GM-CSF in High Risk Stage 4, Primary Refractory Neuroblastoma Patients

Inclusion Criteria:

- Have a diagnosis of stage 4 neuroblastoma diagnosed in accordance with the
International Neuroblastoma Staging System: either (a) histologic confirmation which
may involve immunohistochemical, ultrastructural, and/or cytogenetic studies, or (b)
elevated urinary catecholamines plus tumor cells/clumps in the bone marrow.

- Have evaluable disease or biopsy-proven stable disease in BM by histology or MIBG
scan with MIBG-positive disease confined to the bone or bone marrow, plus urine
catecholamine results, documented >3 weeks after conventional chemotherapy or >6
weeks after stem-cell transplantation. CT, MRI, or bone scan (if necessary) can be
done at 2-3 weeks after conventional chemotherapy confirming that the chemotherapy,
radiotherapy, and ABMT are not realistic curative options.

- Be between 18 months to 13 years old at diagnosis.

- Have recovered to grade 2 or better toxicities since their prior therapy.

- Must, if female of childbearing potential, be willing to use two forms of medically
acceptable contraception (at least one barrier method) and have a negative pregnancy
test at screening and monthly thereafter through the first four cycles of treatment.

- Have a performance score of at least 60 from Lansky Play Performance Scale if aged up
to 16 years or at least 60 from Karnofsky Scale if aged more than 16 years.

- Have voluntarily agreed to participate.

Exclusion Criteria:

- Have measurable disease ≥ 1 cm assessed by CT or MRI.

- Have progressive disease (any new lesion; increase of any measurable lesion by >25%;
or previous negative marrow positive for tumor).

- Have disease detectable in CNS (confirmed by CT or MRI of the brain at screening or
within 8 weeks of randomization).

- Be receiving alternative therapy for the treatment of neuroblastoma, e.g.
radiotherapy or chemotherapy within 3 weeks of randomization.

- Require additional therapy (such as radiotherapy) during the first two treatment
cycles.

- Have detectable human anti-mouse antibody titers at screening.

- Have received prior anti-GD2 investigational therapies.

- Have a history of allergies to mouse proteins.

- Have an active infection requiring IV infusion of antibiotics.

- Be currently receiving long-term chronic treatment with immunosuppressive drugs such
as cyclosporine, adrenocorticotropic hormone (ACTH), or systemic corticosteroids.