The panel discussed the rationale behind the continued use of leucovorin in conjunction with glucarpidase.
Dr. Campen: We continue with leucovorin to provide a full basis for recovery of the cells. One important thing to know is that leucovorin should be given separately from glucarpidase because they do compete when given together.
Dr. Schwartzberg: If you continue to give leucovorin, could you abrogate the benefit, because it is a direct competitor for the enzyme?
Dr. Campen: We administer the leucovorin doses well before the glucarpidase and then continue every 6 hours afterward. It does drop the plasma levels of methotrexate significantly in most patients, but it is necessary to continue leucovorin to combat intracellular methotrexate levels.