Comparative effects of citrovorum factor and carboxypeptidase G1 on cerebrospinal fluid-methotrexate pharmacokinetics

A comparison between citrovorum factor (CF) and carboxypeptidase G1 (CPDG1) rescue with respect to cerebrospinal fluid (CSF)-methotrexate (MTX) disappearance was studied in a patient with recurrent medulloblastoma who had a ventriculoperitoneal shunt. CPDG1 rescue resulted in a prolonged CSF-MTX half-life of 16.5-23 hours in comparison with CF rescue where the CSF-MTX half-life was 6.5-7.2 hours. There was a positive clinical response measured by loss of bone pain, increased physical activity, and almost complete clearing of CSF blast cells. CPDG1 rescue after high-dose MTX may provide more intense and selective treatment for meningeal neoplasms.