Protocol M 6-MP on days 1- 56, high-dose MTX (HD-MTX) on days 8, 22, 36, 50 and MTX IT on days 8, 22, 36 and 50 Protocol II Protocol IIA: DXM on days 1 to 21 (21 days); VCR on days 8, 15, 22, 29 (4 doses); doxorubicine (DOX) on days 8, 15, 22 and 29 (4 doses); PEG-L-ASP on day 8 (1 dose); MTX IT on days 1 and 18 only in patients with initial CNS involvement.