CELLULAR EXPRESSION OF ANTIAPOPTOTIC BCL-2 ONCOPROTEIN IN NEWLY-DIAGNOSED CHILDHOOD ACUTE LYMPHOBLASTIC-LEUKEMIA - A CHILDRENS CANCER GROUP-STUDY

We found a marked variation in BCL-2 oncoprotein expression levels of primary leukemic cells from 338 children with newly diagnosed acute ly mphoblastic leukemia (ALL). None of the high-risk features predictive of poor treatment outcome in childhood ALL, such as older age, high wh ite blood cell (WBC) count, organomegaly, T-lineage immunophenotype, a bility of leukemic cells to cause overt leukemia in severe combined im munodeficient (SCID) mice, presence of MLL-AF4, and BCR-ABL fusion tra nscripts were associated with high levels of BCL-2 expression, overall , high BCL-2 levels were not associated with slow early response, fail ure to achieve complete remission, or poor event-free survival. High B CL-2 levels in primary leukemic cells predicted slow early response on ly in T-lineage ALL patients, which comprised approximately 15% of the total patient population. Even for this small subset of patients, the level of BCL-2 expression did not have a significant impact an the sh ortterm event-free survival. (C) 1997 by The American Society of Hemat ology.