OBJECTIVES: I. Determine the maximum tolerated dose of fenretinide (HPR) in children with high risk solid tumors. II. Determine the toxicities of HPR in these patients. III. Determine the pharmacokinetics of HPR in these patients. IV. Determine the CSF level of HPR in patients whom cerebrospinal fluid is obtained for routine purposes while on this study. V. Determine the effect of HPR on plasma retinol levels in these patients. VI. Determine the activity of HPR in these patients. VII. Determine the antitumor activity of HPR on minimal residual bone marrow disease in neuroblastoma.

OUTLINE: This is a dose escalation study. Patients receive oral fenretinide 3 times a day on days 1-7. Treatment repeats every 3 weeks for up to 8 courses. Patients may receive an additional 22 courses of therapy in the presence of stable or responding residual tumor. Patients with recurrent neuroblastoma, after prior myeloablative therapy with no measurable disease, will stop treatment after 8 courses. Cohorts of 3-6 patients receive escalating doses of fenretinide until the maximum tolerated dose (MTD) is determined. The MTD is defined as the dose preceding that at which 2 of 6 patients experience dose limiting toxicity. Patients are followed until death.

PROJECTED ACCRUAL: Approximately 18 patients will be accrued for this study in 2 years.

DISEASE CHARACTERISTICS: Histologically confirmed malignant solid tumor that is refractory to conventional therapy or recurrent neuroblastoma treated with myeloablative therapy and autologous stem cell transplant in second complete or partial response Bone marrow metastases with granulocytopenia, anemia, and/or thrombocytopenia are eligible

PATIENT CHARACTERISTICS: Age: Under 21 at diagnosis Performance status: CCG 0-2 Life expectancy: At least 2 months Hematopoietic: Absolute neutrophil count at least 750/mm3 Platelet count at least 50,000/mm3 Hemoglobin at least 7.0 g/dL Hepatic: Bilirubin no greater than 1.5 mg/dL SGOT and SGPT less than 2.5 times normal Renal: Creatinine no greater than 1.5 g/dL OR Creatinine clearance at least 50 mL/min OR Radioisotope GFR at least 50 mL/min Other: Seizure disorders controlled with anticonvulsants allowed No CNS toxicity greater than grade 2 Not pregnant Fertile patients must use effective contraception

PRIOR CONCURRENT THERAPY: Biologic therapy: At least 1 month since prior autologous stem cell transplantation No prior allogeneic transplantation Chemotherapy: At least 2 weeks since prior chemotherapy (4 weeks for nitrosourea) and recovered No other concurrent chemotherapy Endocrine therapy: No concurrent immunomodulating agents (including steroids) Concurrent corticosteroid therapy for increased intracranial pressure allowed Concurrent dexamethasone for CNS tumor allowed Radiotherapy: At least 2 weeks since prior radiotherapy Concurrent radiotherapy to localized lesions allowed Surgery: Not specified Other: At least 2 weeks since prior retinoids Prior isotretinoin or 9-cis-retinoic acid allowed