IGR_MERCHER_LAM7

Acute megakaryoblastic leukemia (AMKL) is a heterogeneous disease generally associated with poor prognosis. Gene expression profiles indicate the existence of distinct molecular subgroups and several genetic alterations have been characterized in the past years, including the t(1;22)(p13;q13) and the trisomy 21 associated with GATA1 mutations. However, the majority of patients do not present with known mutations and the limited access to primary patient leukemic cells also prevents efficient development of novel therapeutic strategies. Using a xenotransplantation approach, we have modeled human pediatric AMKL in immunodeficient mice. High-throughput sequencing of engrafted cases identified recurrent fusions genes that define new molecular subgroups. A group of patients present with MLL or NUP98 fusion genes leading to upregulation of the HOX A cluster genes as described in other subtypes of AML. Also, a novel CBFA2T3-GLIS2 fusion gene resulting from a cytogenetically invisible inversion of chromosome 16 was identified and observed in 31% of non Down syndrome AMKL. These data provide new markers that will be useful for the diagnosis and follow-up of patients. Finally, we show that AMKL xenograft models constitute a relevant preclinical screening platform to validate the efficacy of novel therapies such as dimethylfasudil, a novel small molecule ploidy inducer.