Anlotinib Exerts Potent Antileukemic Activities in B-Cell Acute Lymphoblastic Leukemia Via Attenuation of PI3K/AKT/mTOR Signaling Cascade

Abstract Background: Adult patients with B-cell acute lymphoblastic leukemia (B-ALL) have unfavorable prognosis. Recurrent disease is the major challenge for treatment success and has limited effective therapeutic strategies, suggesting that alternative therapeutics are unmet medical needs. Anlotinib, a novel multi-target inhibitor, is capable of blunting the proangiogenic activity of VEGFR, PDGFR and FGFR, and has shown strong antitumor effects across distinct solid tumors. No study to date has investigated the antileukemic efficacy of Anlotinib in B-ALL, thus prompting us to initiate this study.Methods: A published B-ALL microarray data was analyzed to identify the novel potential treatment choice using Expression2Kinases program. Cell viability was determined by Cell Counting Kit-8 (CCK-8). Annexin V/PI staining kit and staining kit were used to assess cell apoptosis and cell cycle distribution, respectively. The mechanism of action of Anlotinib was investigated with Quantitative real-time polymerase chain reaction (qRT-PCR) and Western blotting. A B-ALL Patient Derived Xenograft (PDX) animal model was generated and then use to analyze the in vivo antileukemia activity of Anlotinib.Results: In this study, we observed that recurrent B-ALL patients exhibited high proangiogenic activity relative to newly-diagnosed patients, as evidenced by upregulation of VEGF/VEGFR signaling and its downstream targets, including PIK3/AKT/mTOR pathway. In vitro studies demonstrated that Anlotinib was potent to reduce cell viability, induce cell apoptosis and block cell cycle at G2/M phase in B-ALL cells. In a patient-derived-xenograft (PDX) model, Anlotinib dramatically attenuated leukemia burden and improved prognosis as compared to the control group. Mechanistically, blockade of three important proangiogenic mediators, comprising VEGFR2, PDGFR-beta and FGFR3, played a critical role in the cytotoxicity of Anlotinib against B-ALL. Moreover, Anlotinib significantly dampened the activity of PI3K/AKT/mTOR pathway which resides in the convergence of these proangiogenic signals, manifested by dephosphorylation of PI3K, AKT and mTOR.Conclusions: In summary, our results indicate that Anlotinib exerts potent anti-leukemic efficacy in B-ALL preclinical models via perturbation of proangiogenic signalings and inactivation of the common downstream PI3K/AKT/mTOR signaling. This work provides evidence and a rationale for future evaluation of Anlotinib in B-ALL management in clinical settings.