Differential dosing of high-dose MTX based on risk stratification
| BFM risk group . | MTX dose . | Infusion time, h . | FAB/LMB risk group . | MTX dose . | Infusion time, h . |
|---|---|---|---|---|---|
| R1: stage I/II resected | 1000 mg/m2 × 2 | 4 | Group A: stage I/II resected | None | None |
| R2: unresected stage I/II, stage III with low LDH | 1000 mg/m2 × 4 | 4 | Group B low risk: not in groups A or C, low LDH | 3000 mg/m2 × 4 | 3 |
| R3: stage III and CNS− stage IV with intermediate LDH | 5000 mg/m2 × 4* | 24 | Group B high risk: not in groups A or C, high LDH | 3000 mg/m2 × 4 | 3 |
| R4: stage III/IV with high LDH or any CNS+ stage IV | 5000 mg/m2 × 4* | 24 | Group C: bone marrow ≥ 25% and/or CNS+ | 8000 mg/m2 × 3* | 4 for CSF−and 24 for CSF+ |
| BFM risk group . | MTX dose . | Infusion time, h . | FAB/LMB risk group . | MTX dose . | Infusion time, h . |
|---|---|---|---|---|---|
| R1: stage I/II resected | 1000 mg/m2 × 2 | 4 | Group A: stage I/II resected | None | None |
| R2: unresected stage I/II, stage III with low LDH | 1000 mg/m2 × 4 | 4 | Group B low risk: not in groups A or C, low LDH | 3000 mg/m2 × 4 | 3 |
| R3: stage III and CNS− stage IV with intermediate LDH | 5000 mg/m2 × 4* | 24 | Group B high risk: not in groups A or C, high LDH | 3000 mg/m2 × 4 | 3 |
| R4: stage III/IV with high LDH or any CNS+ stage IV | 5000 mg/m2 × 4* | 24 | Group C: bone marrow ≥ 25% and/or CNS+ | 8000 mg/m2 × 3* | 4 for CSF−and 24 for CSF+ |
CSF+ is defined by the presence of blasts on CSF cytology. LDH thresholds for BFM: low is <2 times the upper limit of normal (ULN), intermediate is 2 to 4 times the ULN, high is >4 times the ULN. LDH thresholds for FAB/LMB: low LDH is <2 times the ULN, and high LDH is >2 times the ULN.
Patients in risk groups R3, R4, and C also received high-dose cytarabine.