Absence of Chromosomal Abnormalities Corresponds to Better Survival in Adult Ph-Negative ACUTE Lymphoblastic Leukemia – Results of the Russian ACUTE Lymphoblastic Leukemia (RALL) Study Group.

Abstract 2572

Adult ALL regardless recent advantages in adolescents and young adults is still considered to be a therapeutical problem. So called “a pediatric-like approach” applied in adult ALL is reported to be more reasonable even in the older adults (up to 55 y).

RALL has initiated a prospective multicenter trial for adult Ph-neg ALL based on: 1) evaluation of b/m blast clearance after 7 days of Prednisolone (PRD) prephase and its substitution by Dexamethasone (DEXA) if b/m blast count was >25%; 2) continuous 2,5 years treatment schedule with prolonged L-asparaginase (Σ=590.000 IU); 3) evaluation of the impact of the late intensification (2 courses of HD of methotrexate and ARA-C) on MRD clearance. The study is registered on the ClinicalTrials.gov public site; NCT01193933.

From Nov, 2008, till June, 2012, 24 centers enrolled 173 pts: median age 28 y (15–55), 71f/101m, 112 (64,7%) = B-lin, 54 (31,2%) = T-lin, 1 pt -undifferentiated AL (0,6%), 6 - uknown phenotype (3,5%), median LDH=848 ME (72–13061), median L=13,5 (0,6–556*10⁹/l). Cytogenetics was evaluable in 58,3% of pts (n=101) and 46,5% of them (n=47) had normal karyotype (NK). Initial risk group was evaluated in 154 pts among whom 46 patients (29,9%) were in the standard risk (SR) group (WBC <30 for B-Lin, <100 for T-Lin, EGIL BII-III, T-III; LDH < 2N, No late CR, t(4;11)-negative), 109 (60,1%) - in the high risk (HR) group (WBC >30 for B-Lin, >100 for T-Lin, EGIL BI, T-I-II-IV; LDH > 2N, No late CR, t(4;11)-positive). 19/173 pts (11%) were not qualified. The analysis was performed in June, 2012. +8 day b/m blast count was reported in 149 pts and b/m blasts less than 25% were detected in 36,2% of pts. The portion of PRD non-responders was statistically different in SR and HR groups: 24/45 (53,3%) and 68/101 (67,3%) (p=0,01), confirming the initial risk groups identification.

Induction results were obtained in 150 pts, and CR rate was identical in both risk groups (SR=86,9%; HR=84,1%) with total 12 induction deaths (8,0%) and 6 resistant leukemias (4,0%). With a median follow-up of 12 mo (1–36 mo) death in CR was reported in 9/132 (6,8%) pts. OS at 36 mo was 58,6%, DFS-68,3%.

MRD analysis for clonal IgH and TCR rearrangements was carried out in 25 pts. And as in our previous studies (ASH 2006, abstr 2294) the clearance was slow with only 41,6% pts negative for MRD at day +133 (4mo) of the protocol. Two late intensification courses (day +157 = 5 mo) increased MRD negativity only up to 50%. Such slow MRD clearance did not correspond to higher relapse rate so far.

Age, WBC, immunophenotype, LDH, risk group, +8 day b/m blast count, time to CR, time without treatment (<>8days), L-asparaginase cessation did not influence survival. OS and DFS differed in pts with NK vs all other abnormalities: 87,4% vs 57,9% (p=0,002) and 88,9% vs 66,5%, respectively (p=0,02).

So, our data demonstrated that ALL-2009 protocol provided 58% 3-years overall survival and 68,3% DFS. In adult Ph-neg ALL normal karyotype predicts better survival. The MRD clearance is very slow while on this protocol.