A single high dose of idarubicin combined with high-dose ARA-C for treatment of first relapse in childhood 'high-risk' acute lymphoblastic leukaemia: a study of the AIEOP group.

The outcome of children with acute lymphoblastic leukaemia (ALL) and early relapse remains unsatisfactory. In January 1995, the AIEOP (Associazione Italiana di Oncologia ed Ematologia Pediatrica) group opened a trial for children with ALL in first isolated or combined bone marrow relapse defined at high risk according to the length of first remission and the immunophenotype. The treatment plan included the combination of a single high-dose idarubicin and high-dose cytarabine as induction therapy followed by an intensive consolidation and stem cell transplant (SCT). In total, 100 children from 16 Italian centres were enrolled; 80 out of the 99 evaluable patients (81%) achieved second complete remission; eight (8%) died during induction and 11 (11%) failed to respond. A total of 42 out of the 80 responders (52.5%) received a SCT: 19 from an identical sibling, 11 from a matched unrelated donor and 12 from umbilical cord blood cells. The estimated 4-year overall survival and event-free survival were 25% and 21% respectively. Disease-free survival at 4 years was 25.8% for the 80 responders. At 4 years, 39 out of 100 children remain alive, with 27 of them free of leukaemia. This induction therapy has shown antileukaemic efficacy with acceptable toxicity; moreover, all responders proved eligible for intensive consolidation

CRLF2 over-expression is a poor prognostic marker in children with high risk T-cell acute lymphoblastic leukemia

Pediatric T-ALL patients have a worse outcome compared to BCP-ALL patients and they could benefit from new prognostic marker identification. Alteration of CRLF2 gene, a hallmark correlated with poor outcome in BCP-ALL, has not been reported in T-ALL. We analyzed CRLF2 expression in 212 T-ALL pediatric patients enrolled in AIEOP-BFM ALL2000 study in Italian and German centers. Seventeen out of 120 (14.2%) Italian patients presented CRLF2 mRNA expression 5 times higher than the median (CRLF2-high); they had a significantly inferior event-free survival (41.2%±11.9 vs. 68.9%±4.6, p=0.006) and overall survival (47.1%±12.1 vs. 73.8%±4.3, p=0.009) and an increased cumulative incidence of relapse/resistance (52.9%±12.1 vs. 26.2%±4.3, p=0.007) compared to CRLF2-low patients. The prognostic value of CRLF2 over-expression was validated in the German cohort. Of note, CRLF2 over-expression was associated with poor prognosis in the high risk (HR) subgroup where CRLF2-high patients were more frequently allocated. Interestingly, although in T-ALL CRLF2 protein was localized mainly in the cytoplasm, in CRLF2-high blasts we found a trend towards a stronger TSLP-induced pSTAT5 response, sensitive to the JAK inhibitor Ruxolitinib. In conclusion, CRLF2 over-expression is a poor prognostic marker identifying a subset of HR T-ALL patients that could benefit from alternative therapy, potentially targeting the CRLF2 pathway