Risk-oriented postremission strategies in adult acute lymphoblastic leukemia: prospective confirmation of anthracycline activity in standard-risk class and role of hematopoietic stem cell transplants in high-risk groups.

Abstract

Although definite risk classes are well known, risk-adapted modulation of first-line therapy is seldom attempted in adult ALL. So, a prospective validation of the therapeutic efficacy of a protocol (or a component thereof) in specific risk groups is uncommon. From 1996-1999 a risk-oriented program (08/96) was evaluated in 102/121 unselected patients (median age 35 years, blast count 0-450 x 10(9)/l, 100 B(lin) (lineage), 21 T(lin)) responsive to induction therapy. The standard risk (SR) class was B(lin) CD10+ Ph- with blasts < 10 x 10(9)/l (prior studies: disease-free survival (DFS) rate 52% at five years with dose-intensive anthracycline-containing programs). The SR protocol was therefore anthracycline-rich (early consolidation cycles with total idarubicin 96 mg/m2), and comprised long-term maintenance. High-risk (HR) patients were eligible to the following three options: allogeneic hematopoietic stem cell transplantation (HSCT) from related family donor; short sequence with high-dose cyclophosphamide-cytarabine-methotrexate followed by melphalan/total body irradiation with autologous HSCT; or T(lin) ALL chemotherapy regimen inclusive of high-dose cytarabine and methotrexate. Treatment realization and three-year DFS rates according to risk class, HR subset and postremission treatment intensity were the following. SR group (n = 28): realization rate 93%, DFS 68.5%. HR group (n = 74): realization rate 80%, DFS 39% (P = 0.052 vs SR category). In HR group, three-year DFS rates by disease subtype were the following. B(lin) Ph- (n = 35) 43%; Ph+ (n = 19) 13% at 2.7 years (P = 0.006 vs other HR subtypes); T(lin) (n = 18) 59.5%. And DFS rates by treatment intensity were: allograft (n = 21) 40%; autograft (n = 28) 27%; shift to SR protocol (n = 13) 52% (P = ns vs allograft/autograft); T(lin) program (n = 10) 57%. Matched analyses of treatment protocols and disease subtypes suggested a possible therapeutic role of the autograft regimen in B(lin) Ph- ALL with a blast count < 25 x 10(9)/l, and of T(lin) protocol for T(lin) ALL. Comparisons with retrospective control cohorts were confirmatory of anthracycline activity in SR subclass. The intended strategy was applicable to the majority of study patients, confirming the value of anthracyclines in SR class and, preliminarily, the usefulness a T(lin)-specific treatment. Apart from the case of Ph+ ALL, the indications for high-dose procedures with HSCT remains largely undetermined in this study.