Influence of the Novel ATP-Competitive Dual mTORC1/2 Inhibitor AZD2014 on Immune Cell Populations and Heart Allograft Rejection.

Background: Little is known about how new generation adenosine triphosphate (ATP)-competitive mechanistic target of rapamycin (mTOR) kinase inhibitors (TORKinibs) affect immunity and allograft rejection. Methods: mTOR complex (C) 1 and 2 signaling in dendritic cells (DC) and T cells was analyzed by Western blotting, while immune cell populations in normal and heart allograft recipient mice were analyzed by flow cytometry. Alloreactive T cell proliferation was quantified in MLR; intracellular cytokine production and serum antidonor IgG levels were determined by flow analysis and immunofluorescence staining used to detect IgG in allografts. Results: The novel TORKinib AZD2014 impaired DC differentiation and T cell proliferation in vitro and depressed immune cells and allospecific T cell responses in vivo. A 9-day course of AZD2014 (10 mg/kg ip twice daily) or rapamycin (RAPA; 1mg/kg ip daily) prolonged median heart allograft survival time significantly (25 days for AZD2014; 100 days for RAPA; 9.5 days for control). Like RAPA, AZD2014 suppressed graft mononuclear cell infiltration, increased regulatory T cell (Treg) to effector memory T cell (Tem) ratios and reduced T follicular helper (Tfh) and B cells 7 days posttransplant. By 21 days (10 days after drug withdrawal), however, Tfh and B cells and donor-specific IgG1 and IgG2c antibody titers were significantly lower in RAPA- compared with AZD2014-treated mice. Elevated Treg to Tem ratios were maintained after RAPA, but not AZD2014 withdrawal. Conclusions: Immunomodulatory effects of AZD2014, unlike those of RAPA, were not sustained after drug withdrawal, possibly reflecting distinct pharmacokinetics or/and inhibitory effects of AZD2014 on mTORC2. Copyright (C) 2017 Wolters Kluwer Health, Inc. All rights reserved.

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