PI3K-AKT-mTOR inhibition in cancer immunotherapy, redux

Cancer therapies will increasingly be utilized in combination to treat advanced malignancies so as to increase their long-term efficacy in a greater proportion of patients. In particular, much attention has focused on developing targeted therapies that inhibit the PI3K-AKT-mTOR signaling network which is dysregulated in many cancer types. In addition, there is now a growing appreciation that targeting of these pathways can impact not only on cancer cells, but also host immunity. The clinical success of cancer immunotherapies targeting T-cell immune checkpoint receptors PD-1/PD-L1 has demonstrated the importance of immunoevasion as a hallmark of cancer. In this review, we discuss how PI3K-AKT-mTOR inhibitors target cancer cell biology, attenuate immune cell effector function and modulate the tumor microenvironment. We next discuss how the immunomodulatory potential of these inhibitors can be exploited through rational combinations with immunotherapies and targeted therapies.