Assessment of systemic toxicity in children receiving chemotherapy with cyclosporine for sarcoma.

BACKGROUND: Overexpression of P-glycoprotein in malignant tumors has been associated with poor responses to chemotherapy. It appears biologically plausible that addition of the P-glycoprotein inhibitor cyclosporine (CsA) to standard chemotherapy may improve the outcome. The protective functions of P-glycoprotein in healthy tissues, however, have not been fully elucidated. Addition of CsA may lead to increased systemic chemotherapy toxicity, so we compared the rate and severity of chemotherapy-associated systemic toxicity in the presence and absence of CsA.

PROCEDURE: Standard chemotherapy consisted of etoposide/ifosfamide (VP16/IFOS) cycles, alternating with vincristine/dactinomycin/cyclophosphamide (VAC) cycles. CsA was given at a median dose of 20 mg/kg with unaltered doses of the antineoplastic drugs. The analysis of toxicity was performed by comparing clinically significant toxicity events recorded during and after chemotherapy cycles with and without CsA.

RESULTS: Toxicity-related hospital admissions occurred after 93% of VAC cycles with CsA compared to 40% of the cycles without CsA (P < 0. 0001); 29% of VP16/IFOS cycles with CsA led to admissions vs. 12% with non-CsA cycles (P = 0.04). Infections or fever and neutropenia were the main reasons for these admissions. Thirty-seven percent of the VAC cycles with CsA were complicated by culture-proved sepsis, which did not occur in cycles without CsA (P < 0.0001). Requirements for blood and platelet transfusions were greatly increased after VAC cycles with CsA compared to VAC cycles without CsA.

CONCLUSIONS: The chemosensitizer CsA increases the systemic toxicity of VAC chemotherapy in patients with sarcomas. Future trials of chemotherapy with chemosensitizers will have to take into account a potential increase in systemic toxicity. Careful monitoring of chemotherapy-related toxicity becomes mandatory in such studies.