BackgroundDespite great efforts to identify druggable molecular targets for AML, there remains an unmet need for more effective therapies.MethodsAn in silico screening was performed using Connectivity Maps to identify FDA-approved drugs that may revert an early leukaemic transformation gene signature. Hit compounds were validated in AML cell lines. Cytotoxic effects were assessed both in primary AML patient samples and healthy donor blood cells. Xenotransplantation assays were undertaken to determine the effect on engraftment of hit compounds. The mechanism of action responsible for the antileukaemic effect was studied focussing on lysosomes and mitochondria.FindingsWe identified a group of antihistamines (termed ANHAs) with distinct physicochemical properties associated with their cationic-amphiphilic nature, that selectively killed leukaemic cells. ANHAs behaved as antileukaemic agents against primary AML samples ex vivo, sparing healthy cells. Moreover, ANHAs severely impaired the in vivo leukaemia regeneration capacity. ANHAs' cytotoxicity relied on simultaneous mitochondrial and lysosomal disruption and induction of autophagy and apoptosis. The pharmacological effect was exerted based on their physicochemical properties that permitted the passive targeting of both organelles, without the involvement of active molecular recognition.InterpretationDual targeting of lysosomes and mitochondria constitutes a new promising therapeutic approach for leukaemia treatment, supporting the further clinical development.FundThis work was funded by the (RMR), (RMR), the (RMR), the (RMR), (RMR), and (IJC).

This study was supported in part by a grant from FIS-PI11/01560 and FIS-PI11/00977 within the 'Plan Nacional de I + D + I' and co-funded by the 'ISCIII-Subdirección General de Evaluación' and 'Fondo Europeo de Desarrollo Regional (FEDER)' and by the grant 'Premi Fi de Residència Emili Letang 2015' from the Hospital Clínic of Barcelona. The authors have no competing interests to disclose.

BackgroundTreatment for acute myeloid leukemia (AML) has not significantly changed in the last decades and new therapeutic approaches are needed to achieve prolonged survival rates. Leukemia stem cells (LSC) are responsible for the initiation and maintenance of AML due to their stem-cell properties. Differentiation therapies aim to abrogate the self-renewal capacity and diminish blast lifespan.MethodsAn in silico screening was designed to search for FDA-approved small molecules that potentially induce differentiation of AML cells. Bromocriptine was identified and validated in an in vitro screening. Bromocriptine is an approved drug originally indicated for Parkinson’s disease, acromegaly, hyperprolactinemia and galactorrhoea, and recently repositioned for diabetes mellitus.ResultsTreatment with bromocriptine reduced cell viability of AML cells by activation of the apoptosis program and induction of myeloid differentiation. Moreover, the LSC-enriched primitive AML cell fraction was more sensitive to the presence of bromocriptine. In fact, bromocriptine decreased the clonogenic capacity of AML cells. Interestingly, a negligible effect is observed in healthy blood cells and hematopoietic stem/progenitor cells.ConclusionsOur results support the use of bromocriptine as an anti-AML drug in a repositioning setting and the further clinical validation of this preclinical study.Electronic supplementary materialThe online version of this article (doi:10.1186/s12967-016-1007-5) contains supplementary material, which is available to authorized users.