N⁶-Methyladenosine in Cancer Immunotherapy: An Undervalued Therapeutic Target

N⁶-methylation of adenosine (m⁶A), a post-transcriptional regulatory mechanism, is the most abundant nucleotide modification in almost all types of RNAs. The biological function of m⁶A in regulating the expression of oncogenes or tumor suppressor genes has been widely investigated in various cancers. However, recent studies have addressed a new role of m⁶A modification in the anti-tumor immune response. By modulating the fate of targeted RNA, m⁶A affects tumor-associated immune cell activation and infiltration in the tumor microenvironment (TME). In addition, m⁶A-targeting is found to affect the efficacy of classical immunotherapy, which makes m⁶A a potential target for immunotherapy. Although m⁶A modification together with its regulators may play the exact opposite role in different tumor types, targeting m⁶A regulators has been shown to have wide implications in several cancers. In this review, we discussed the link between m⁶A modification and tumor with an emphasis on the importance of m⁶A in anti-tumor immune response and immunotherapy.