Background:: The administration of high-dose interleukin-2 (IL-2) seems to be a therapeutic option for children with refractory and metastatic solid malignancies.

Methods:: We prospectively studied treatment-related toxicities, quality of life and laboratory parameters in 10 children with progressive or metastatic solid tumors (metastatic osteosarcoma, n = 4; neuroblastoma stage IV, n = 3; metastatic Ewing's sarcoma, n = 2; metastatic Wilms' tumor, n = 1) during IL-2 therapy. Patients were scheduled to receive five cycles of high-dose IL-2 by continuous infusion for 5 days every 3 weeks.

Results:: All patients developed fever >39°C and influenza-like symptoms, with a significant decrease in Karnofsky score. In two patients treatment had to be stopped after three cycles because of severe side-effects. During IL-2 therapy a statistical significant increase in white blood cells (WBC), creatinine, γ-glutamyltransferase, C-reactive protein, glucose and body weight was observed. In contrast, red blood cells, platelets, protein, albumin and cholinesterase significantly decreased. When results from day 1 of the first and of the fifth cycle were compared, an increase of WBC and a decrease of alkaline phosphatase was shown. No constant quantitative changes in total lymphocytes and subsets were observed during IL-2 therapy.

Conclusions:: IL-2 treatment in children with refractory and relapsed solid malignancies is associated with severe, but reversible, side-effects. However, five of the 10 patients with diseases of worst prognosis could be rescued by this treatment.