Epitranscriptomic regulation via m6A RNA methylation: a determinant of cancer immunotherapy response

To the Editor, We read with great interest the recent advances highlighting epitranscriptomic regulation, particularly N6-methyladenosine (m6A) RNA modification, as a pivotal determinant of cancer progression and therapeutic response. The role of m6A regulators in modulating tumor immune evasion and checkpoint inhibitor efficacy is now emerging as a transformative paradigm in precision oncology[1]. The m6A modification dynamically influences RNA splicing, translation, and decay through the coordinated actions of “writers” (METTL3/14), “erasers” (FTO, ALKBH5), and “readers” (YTHDF proteins)[2]. In cancer, aberrant m6A signaling affects tumor immunogenicity, antigen presentation, and T-cell infiltration. A recent Nature Cancer study by Liu et al demonstrated that loss of METTL3 in tumor cells enhances PD-L1 expression via interferon-γ signaling, thereby promoting immune evasion[3]. Conversely, high METTL3 activity correlates with reduced checkpoint inhibitor efficacy across multiple solid tumors. Mechanistically, m6A methylation regulates the stability of mRNAs encoding immune checkpoint and interferon pathway mediators. Zhang et al showed that ALKBH5 overexpression stabilizes PD-L1 and VEGFA transcripts, impairing antitumor immunity[4]. These findings suggest that targeting m6A modifiers could enhance tumor immunogenicity and improve immune checkpoint blockade (ICB) outcomes. Indeed, selective FTO inhibitors have been shown to synergize with anti–PD-1 therapy in preclinical melanoma and NSCLC models[5]. A 2025 Cell Reports Medicine study extended these insights to clinical practice by identifying an m6A immune response score (m6A-IRS) that stratifies ICB responders from nonresponders in real-world melanoma cohorts[6]. Integrating this score with tumor mutational burden and microsatellite instability (MSI) improved predictive accuracy beyond existing biomarkers, underscoring the translational relevance of m6A profiling. Therapeutically, combining epitranscriptomic modulators with immunotherapy represents a novel and rational strategy. Early-phase trials of FTO inhibitors (FB23-2, CS1) and METTL3/14 activators are underway, aiming to restore immune sensitivity and reduce tumor heterogeneity[7]. However, challenges persist regarding drug selectivity, tissue-specific off-target effects, and the lack of standardized m6A quantification methods. Development of single-cell m6A-seq and imaging-based mapping tools may help clarify tumor microenvironment heterogeneity and optimize combinatorial regimens. In conclusion, m6A-mediated RNA methylation represents a new regulatory dimension in cancer immunotherapy, bridging transcriptomic plasticity with immune dynamics. Incorporating m6A profiling into biomarker panels and clinical trial designs could enable epitranscriptome-guided immunotherapy, moving the field toward more precise and durable oncologic outcomes. This letter to the editor adheres to the Transparency in the Reporting of Artificial Intelligence in Research (TITAN) guideline[8].