Early intensification of chemotherapy for childhood acute nonlymphoblastic leukemia: improved remission induction with a five-drug regimen including etoposide.

We tested the value of early intensification of chemotherapy in 68 consecutive children with acute nonlymphocytic leukemia (ANLL) who were admitted to St. Jude Children's Research Hospital from November 1983 through March 1987. Fifty-eight patients (85%) entered complete remission after treatment with etoposide (VP-16)/cytarabine (ara-C) (A), followed by daunorubicin (Dauno)/ara-C/thioguanine (6-TG) (B) and then VP-16/azacytidine (5-AZ) (C). Thirty percent of the complete responders, mainly those with an M4 or M5 leukemia subtype, attained M1 marrow status after component A, 60% after A + B, and 10% after A + B + C. Induction failures resulted primarily from absolute or relative drug resistance; there was only one death during this phase of therapy. Postremission treatment consisted of three pairs of drugs (vincristine [VCR]/amsacrine [m-AMSA], or doxorubicin [Doxo]/6-TG/ara-C, and VP-16/cyclophosphamide [CTX]) administered sequentially in 6-week cycles for 22 months. Despite the high rate of remission induction, only 33% +/- 7% SE of the patients are expected to be failure-free survivors at 2 years. Remission durations were not significantly affected by the majority of factors examined in this study, with the exception of marrow cellularity after VP-16/ara-C induction therapy. Patients with less than or equal to 5% leukemic cells survived relapse-free for a median of 36.1 months, compared with 11.3 months for the group with a larger infiltrate (P = .01). Although postremission therapy did not improve the percentage of long-term failure-free survivors, the induction regimen we used appears highly effective, and its components should be considered for inclusion in other treatment programs.