- Intensification therapy: Beginning 4 weeks after the completion of the second induction therapy, patients receive high-dose MTX IV over 2 hours on days 1, 8, and 22; leucovorin calcium IV every 6 hours for 4 doses and then orally every 6 hours for 12 doses beginning 22-24 hours after each MTX infusion; and ASP IV over 30 minutes on days 2, 9, and 23.