A review of mechanisms of resistance to immune checkpoint inhibitors and potential strategies for therapy

Immune checkpoint inhibitors (ICIs) have revolutionized the treatment of cancer over the last decade, bringing about a paradigm shift in systemic cancer therapy away from traditional cytotoxic and targeted therapies. While some patients have dramatic treatment responses, it is sobering to note that most tumors are either resistant at the outset, or develop resistance after initial response. A major area of translational and clinical research is in identifying therapeutic strategies to overcome resistance to ICIs. We have performed an in-depth review of the different mechanisms of resistance and potential avenues to overcome resistance through rationally designed combination treatment with ICIs.