[A prospective study on nephrotoxicity induced by continuous infusion of high-dose ifosfamide (15/m2)].

Background: A good response rate to high-dose ifosfamide (HDIFO) has been reported in metastatic osteosarcoma and soft tissue tumors. As standard dose of IFO (< 12 g/m2) can give several renal complications and patients previously treated with nephrotoxic drugs are at high risk of nephrotoxicity, a prospective study to evaluate the pattern of nephrotoxicity induced by HDIFO was carried out.

Methods: Twelve patients (11 metastatic osteosarcoma, 1 synovial sarcoma; mean age 17, R 14-34) were treated with 4 courses of HDIFO/ MESNA (15 g/m2, IV 5 day continuous infusion with bicarbonate and K supplements). All but two were previously treated with cisplatin and methotrexate. Several parameters of renal function were measured before treatment, after each HDIFO course and two months after chemotherapy completion.

Results: Significant changes in the urinary excretion of beta 1-microglobulin, beta 2-microglobulin, Alanine Aminopeptidase, N-Acetil-beta, D-glucosaminidase and a significant reduction in phosphate tubular absorbtion according to the cumulative dose of IFO infused, were observed. Phosphaturia and hypophosphatemia occurred in all the patients studied. In 5 patients, CrCl fell below 70 ml/min with normal serum creatinine level after 45 g/m2 IFO. Plasma bicarbonate concentration less than 20 mmol/l was observed in 5 of 48 HDIFO courses. Glycosuria was detected in 4 patients. Two months after chemotherapy completion, mild glycosuria and slightly reduced CrCl persisted in two patients, whereas the other parameters of renal function studied were similar to the baseline values. An acute, usually reversible subclinical nephrotoxicity involving glomerule and renal tubule was demonstrated in all the patients treated with HDIFO. A persisting subclinical renal impairment was shown with mild glycosuria (2/12 patients) and slightly reduced CrCl (2/12 patients).