MTOR and cancer: In vitro studies have shown that ATP-competitive inhibitors exert a greater inhibitory effect than rapamycin analogs.218 AZD8055, one of the most recent and potent ATP-competitive mTOR inhibitors, functions by inhibiting the phosphorylation of Akt and its downstream proteins and has been shown to induce autophagy in cancer cells and inhibit tumor growth in vivo.220 In conclusion, inhibitors targeting the PI3K/Akt pathway are promising for cancer therapy, and numerous PI3K/Akt pathway inhibitors have been developed (summarized in Table 4).