Three hits are superior than one: multiple Akt inhibition as a new therapeutic strategy in T-ALL

T-cell acute lymphoblastic leukemia (T-ALL) is an aggressive neoplastic disorder of T lymphocytes characterized by a poor clinical outcome, especially for relapsed patients [1]. The PI3K/Akt/mTOR signaling pathway is crucial for cell growth and survival in many types of solid and blood tumors, including T-ALL, influencing the response to therapeutic treatments [2]. The PI3K/Akt/mTOR network is often hyperactivated in T-ALL and therefore could constitute a target of inhibitory strate- gies, such as those that use small molecules inhibitors (SMI). The combined administration of multiple drugs is an attractive attempt to overcome drug resistance and to improve clinical outcome [3]. We tested in a panel of T-ALL cell lines three drugs directed against Akt with totally different modes of action: GSK690693, ATP- competitive, MK-2206, allosteric, and Perifosine, alkylphospholipid-Akt inhibitor. We showed that multiple Akt inhibition with this drug combination in T-ALL cell lines was cytotoxic and displayed a synergistic effect which was also related to the timing and the sequence of every drug administration. In fact, our findings showed that 6h of Perifosine pre-treatment followed by the combined administration of MK-2206 and GSK690693 for 30 min was necessary for the complete switch off of the activated protein. This combination caused a potent cell cycle arrest in G0/G1 phase and induced apoptosis and autophagy with more efficacy than single or double drug administration. In conclusion, our data demonstrated that this pharmacological strategy could represent a new promising treatment for patients affected by T-ALL with hyperacti- vated PI3K/Akt/mTOR signaling pathway