The histone H3K4 methyltransferase KMT2D (also called MLL4) is an important chromatin regulator frequently inactivated by mutation across multiple cancers, including colorectal cancer (CRC). Prior evidence suggests connections between chromatin regulation, tumor immunity and drug sensitivity. The study summarized here evaluated whether KMT2D mutational status is associated with immune activity and therapy efficacy in CRC.
The authors analyzed genomic and clinical datasets from The Cancer Genome Atlas (TCGA) and from Memorial Sloan Kettering Cancer Center (MSKCC) across multiple cancer entities, with a focus on CRC. Transcriptomic analyses, immune gene signature assessment and immune cell deconvolution from bulk RNA data were used to compare KMT2D-mutant versus KMT2D wild-type tumors. Clinical response data for immune checkpoint inhibitor (ICI) therapy were compared between KMT2D-mutant and wild-type CRC patients. Additionally, epithelial cells with wild-type or inactive KMT2D were treated with cancer drugs to probe differential chemosensitivity and DNA damage.
Note: the abstract did not report specific cohort sizes, exact mutation classifications, or detailed statistical methods; those details were not provided in the source summary.
Compared with KMT2D wild-type CRCs, tumors carrying KMT2D mutations exhibited significantly higher expression of immune checkpoint regulators, including PD-L1 and CTLA4, and higher levels of CD8 expression. Mutated tumors showed enrichment of T-effector and interferon-γ (IFN-γ) gene signatures, consistent with activation of adaptive immune responses in the tumor microenvironment. These transcriptomic patterns indicate that loss-of-function mutations in KMT2D are associated with increased immune activity within CRC tumors.
Immune cell deconvolution of transcriptomic data indicated that CRCs harboring KMT2D mutations have increased infiltration of CD8+ T cells, natural killer (NK) cells and macrophages. Conversely, these tumors displayed relatively low abundance of regulatory T cells (Tregs). Together, these observations support classification of KMT2D-mutant CRC as an immunologically “hot” tumor phenotype characterized by active effector cell infiltration and elevated immune checkpoint expression.
In clinical cohorts of CRC patients treated with immune checkpoint inhibitors, those with KMT2D-mutant tumors demonstrated better clinical responses and improved overall survival compared with patients whose tumors were KMT2D wild type. Importantly, this beneficial association between KMT2D mutation status and outcome was not observed in CRC cohorts that had not received immunotherapy, indicating the effect is specific to ICI-treated patients.
To explore mechanisms underlying differential drug response, the investigators treated epithelial cells with either wild-type or inactive KMT2D using a panel of cancer drugs. Cells lacking functional KMT2D exhibited increased DNA damage and displayed higher sensitivity to cisplatin relative to KMT2D wild-type cells. These in vitro results suggest that KMT2D loss may render tumor cells more susceptible to DNA‑damaging chemotherapy.
The study concludes that KMT2D (MLL4) loss-of-function mutations in colorectal cancer associate with an immune‑active tumor microenvironment and predict improved efficacy of immune checkpoint inhibitors. In vitro data also indicate enhanced sensitivity of KMT2D-mutant cells to cisplatin, implying potential combined or alternative therapeutic avenues. Stratifying CRC patients by KMT2D gene status may therefore help identify subgroups more likely to benefit from ICIs and from cisplatin-containing regimens, enabling more personalized treatment approaches.
This report is a preprint and has not been peer reviewed. The abstract did not provide detailed methodological parameters such as cohort sizes, mutation types and frequencies, statistical analyses, or full experimental protocols; those specifics were not reported in the source summary. As a preprint, findings should be interpreted cautiously until validated and peer reviewed.