Prednisone response is the strongest predictor of treatment outcome in infant acute lymphoblastic leukemia

To define prognostic factors in infant acute lymphoblastic leukemia (ALL), the outcome of 106 infants (age less than or equal to 12 months) during 3 c onsecutive multicenter trials of the Berlin-Franfurt-Munster group (ALL-BFM 83, 86, and 90) was retrospectively analyzed according to presenting featu res and early in vivo response to prednisone. The prednisone response was d efined as the cytoreduction (number of blood blasts per microliter at day 8 ) to a 7-day prednisone prephase and 1 intrathecal dose of methotrexate on day 1. Prednisone good responder (PGR; <1,000 blasts/mu l) received convent ional therapy and prednisone poor responder (PPR; greater than or equal to 1,000 blasts/mu L) received intensified therapy. Infant ALL was characteriz ed by a high incidence of a white blood cell count greater than 100 x 10(3) /mu L (57%), central nervous system leukemia (24%), lack of CD10 expression (59%), 11q23 rearrangement (49%) including the translocation t(4;11) (29%) , and a comparatively high proportion of PPR (26%), which were all signific antly associated with inferior outcome by univariate analysis. The estimate d probability for an event-free survival at 6 years (pEFS) was by far bette r for PGR compared with PPR, who had a dismal prognosis despite intensified treatment (pEFS, 53% +/- 6% v 15% + 7%, P = .0001). Infant PGR, who were l ess than 6 months of age (n = 40), lacked CD10 expression (n = 43), and/or had an 11q23 rearrangement (n = 17) fared significantly better compared wit h corresponding PPR, as indicated by a pEFS of 44% +/- 8%, 49% + 8%, and 41 % +/- 12%, respectively. In multivariate analysis, PPR was the strongest ad verse prognostic factor (relative risk, 3.3; 95% confidence interval, 1.9 t o 5.8; P < .0001). Infants with PGR, comprising a major subgroup (74%) amon g infants, might successfully be treated with conventional therapy, whereas PPR require new therapeutic strategies, including early treatment intensif ication or bone marrow transplantation in first remission. (C) 1999 by The American Society of Hematology.