Erythrocyte concentrations of metabolites or cumulative doses of 6-mercaptopurine and methotrexate do not predict liver changes in children treated for acute lymphoblastic leukemia

BACKGROUND: During therapy consisting of 6MP and MTX, metabolites accumulate in the erythrocytes. The erythrocyte levels of metabolites reflect the intensity of therapy. Whether they are associated with hepatotoxicity manifested as histological liver changes is not known. We studied the association of the metabolites and cumulative doses of 6MP and MTX with histological liver disease. METHODS: Serial measurements of E-TGN, E-MTX, and ALT during maintenance therapy were performed and cumulative doses of 6MP and MTX were calculated as g/m2 in 16 children with ALL. Each subject underwent a percutaneous liver biopsy at the end of therapy to screen for histological liver disease. RESULTS: No differences in E-TGN, E-MTX, or cumulative doses of 6MP or MTX were detected in the children with ALL with liver fibrosis compared to those without fibrosis, or in the children with less liver fatty change compared to those with more fatty change. Serum median ALT levels correlated significantly positively with cumulative doses of 6MP during therapy (rS = 0.527, P = 0.036), but not with cumulative doses of MTX, or E-TGN, or E-MTX. CONCLUSIONS: Erythrocyte levels of the metabolites or the cumulative doses of 6MP and MTX do not predict histological liver disease in children treated for ALL.