Mercaptopurine and Dexamethasone for Acute Lymphoblastic Leukemia
Treatment Overview
- The National Comprehensive Cancer Network recommends mercaptopurine administration at 1.5-2.5 mg/kg orally once daily during maintenance therapy, combined with weekly oral methotrexate, monthly vincristine pulses, and dexamethasone 4-6 mg/m² daily for 5 days every 4 weeks, continuing for approximately 2 years total from diagnosis 1, 2
Induction and Maintenance Phases
- Dexamethasone is used during induction at 6 mg/m² daily for 28 days as part of the multi-drug backbone that includes vincristine, anthracyclines, and L-asparaginase, providing superior CNS penetration compared to prednisone, reducing isolated CNS relapse risk and improving 6-year event-free survival 3, 4, 5
- Mercaptopurine may be included during induction primarily for CNS prophylaxis, though its main role is in later phases 3, 4
- During maintenance, mercaptopurine is administered at 37.5-50 mg/m² nightly, and dexamethasone pulses are given at 4-6 mg/m² daily for 5 days on week 3 of each 4-week cycle 2, 6, 7
Critical Counseling Points
- The National Comprehensive Cancer Network suggests that dexamethasone reduces CNS relapse by 47% and improves event-free survival compared to prednisone, but carries significantly higher risks of induction mortality, neuropsychiatric events, and myopathy 3, 4
- Dexamethasone can cause common side effects such as mood changes, increased appetite and weight gain, hyperglycemia, osteonecrosis, and myopathy 3, 4, 5