Treatment of childhood acute lymphoblastic leukemia. Long-term results of the AIEOP-ALL 87 study

In March 1987 AIEOP started the AIEOP-ALL-87 study, based on the previous AIEOP-ALL-82. The aim of this new study was to evaluate, for all risk groups: a) the efficacy of treatment intensification achieved by adding a fourth drug (daunomycin) in the induction phase and a 3-drug reinduction phase for all risk groups; b) the impact of the addition of three doses of intrathecal methotrexate during cranial radiotherapy and extended exposure to weekly high-dose L-aspariginase during late intensification in high risk patients. We report the long-term results of the AIEOP ALL-87 study.

From 1987 to 1991, a total of 632 eligible and evaluable children (age 1 to < or =16 years) with non-B-cell acute lymphoblastic leukemia (ALL), were enrolled and stratified as follows: standard risk (SR, 79 patients, 12.5%) had WBC <10,000/mm3, age > or = 3 and <7 years, and FAB L1 morphology. The high risk (HR, 175 patients, 27.7%) group included patients with WBC > or =50,000/mm3 or FAB L3 morphology or T immunophenotype or acute undifferentiated leukemia (AUL) or leukemia-lymphoma syndrome. All the remaining patients formed the intermediate risk group (IR, 378 patients, 59.8%). All patients received a 4-drug induction therapy; intermediate-dose methotrexate was given to HR patients; cranial radiotherapy was given to IR and HR patients, while SR patients received extended intrathecal methotrexate; all patients received a 3-drug reinduction phase; high dose L-asparaginase (HD-L-ASP; E.Coli, Bayer) was given to HR patients; continuation therapy with 6-mercaptopurine, i.m. methotrexate, and monthly vincristine and prednisone pulses was given to all patients. Treatment duration was 2 years.

Six hundred and nineteen patients (97.9%) achieved complete remission. The remission rate was 98.7% in the SR group, 98.1% in the IR group, and 97.1% in the HR group. The overall 10-year survival and event-free survival (EFS) rates (SE) are 74.7% (1.8) and 62.8% (2.0) respectively; EFS rates by risk group are 67.5% (5.5) in SR, 62.8% (2.6) in IR, and 61.9% (3.8) for HR. The 10-year EFS for all eligible patients was 63.9% (1.9).

When compared to the results of the AIEOP-ALL-82 study, treatment intensification in the ALL-87 study has improved long-term survival and EFS from 66.4% and 53.6% to 74.7% and 62.8%, respectively. Failures were mostly due to marrow or extramedullary relapses suggesting that further treatment intensification, as being used in current therapeutic strategies, is appropriate, although patients relapsing after less intensive treatment may have better chances of rescue. These results, although obtained in a relatively large proportion of patients, in which infants were not included, indicate that the addition of high-dose L-asparaginase to a relatively non-intensive treatment may be of major benefit for HR patients and that the addition of intrathecal methotrexate during CRT, may improve the central nervous system-disease control with a marked reduction of nervous system relapses.