CREB engages C/EBPδ to initiate leukemogenesis.

cAMP response element binding protein (CREB) is frequently overexpressed in acute myeloid leukemia (AML) and acts as a proto-oncogene; however, it is still debated whether such overactivation alone is able to induce leukemia as its pathogenetic downstream signaling is still unclear. We generated a zebrafish model overexpressing CREB in the myeloid lineage, which showed an aberrant regulation of primitive hematopoiesis, and in 79% of adult CREB-zebrafish a block of myeloid differentiation, triggering to a monocytic leukemia akin the human counterpart. Gene expression analysis of CREB-zebrafish revealed a signature of 20 differentially expressed human homologous CREB targets in common with pediatric AML. Among them, we demonstrated that CREB overexpression increased CCAAT-enhancer-binding protein-δ (C/EBPδ) levels to cause myeloid differentiation arrest, and the silencing of CREB-C/EBPδ axis restored myeloid terminal differentiation. Then, C/EBPδ overexpression was found to identify a subset of pediatric AML affected by a block of myeloid differentiation at monocytic stage who presented a significant higher relapse risk and the enrichment of aggressive signatures. Finally, this study unveils the aberrant activation of CREB-C/EBPδ axis concurring to AML onset by disrupting the myeloid cell differentiation process. We provide a novel in vivo model to perform high-throughput drug screening for AML cure improvement

Outcome of adolescent patients with acute lymphoblastic leukaemia aged 10-14 years as compared with those aged 15-17 years: Long-term results of 1094 patients of the AIEOP-BFM ALL 2000 study

BACKGROUND: Adolescents (aged 10-17 years) with acute lymphoblastic leukaemia (ALL) have unfavourable disease features and an inferior outcome when compared with younger children, but it is still unclear if differences in disease biology and prognosis exist between adolescents older or younger than 15 years. METHODS: We retrospectively analysed outcomes of 1094 adolescents with ALL, aged 10-17 years, treated within the AIEOP-BFM ALL 2000 trial, overall and by the age groups 10-14 and 15-17 years. FINDINGS: Compared with younger children (aged 1-9 years, n = 3647), adolescents had a statistically inferior 5-year event-free survival (EFS) [74.6% (1.3) vs. 84.4% (0.6)] and overall survival (OS) [83.4% (1.1) vs. 92.7% (0.4); p < 0.001]. Clinical and biological disease characteristics did not differ between the two subgroups of adolescents, including minimal residual disease (MRD) results during initial therapy, except for ETV6-RUNX1 frequency and gender. With a median follow-up of 8.8 years, the 5-year EFS and OS were 76.2% (1.5) and 84.9% (1.3), respectively, for those aged 10-14 years and 70.0% (2.8) and 78.8% (2.5) for those aged 15-17 years (p = 0.06; 0.05). There was no significant difference in the cumulative incidence of relapses [17.8% (1.4) and 18.3% (2.4); p = 0.98], while the incidence of treatment-related deaths as a first event was 2.6% (0.6) versus 7.4% (1.6) (p < 0.001) with, in particular, a higher incidence in the high-risk arm. INTERPRETATION: Further prospective studies and biological investigations are required to define optimal treatment for adolescents, in particular for those aged 15-17 years. Newer agents (immunotherapy, targeted therapy) in early treatment phases of patients at higher risk of treatment failure could replace most toxic treatment elements, with the aim of reducing both toxicity and the risk of relapses