OBJECTIVES: I. Describe the toxic effects of combined chemotherapy with buthionine sulfoximine (BSO) and melphalan (L-PAM) in pediatric patients with progressive neuroblastoma. II. Determine the pharmacokinetics of BSO/L-PAM in pediatric patients. III. Assess the ability of BSO to deplete glutathione by at least 90% in tumor metastatic to bone marrow, in normal marrow, and in peripheral blood lymphocytes. IV. Estimate the response rate in these patients treated with BSO/L-PAM within the confines of a pilot study.