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Immune checkpoint inhibitors in dMMR-MSI-H colorectal cancer: rationale, progress and prospects
Guangre Xu1, Die Liang2, Lei Li3
1Department of Gastroenterology and Hepatology, Sichuan Provincial People's Hospital, School of Medicine, University of Electronic Science and Technology of China, Chengdu, China.
Abstract:
Colorectal cancer (CRC) with a deficient mismatch repair and high microsatellite instability (dMMR-MSI-H) phenotype represents a biologically distinct subtype characterized by elevated tumor mutational burden and strong immunogenicity. These features contribute to their exceptional responsiveness to immune checkpoint inhibitors (ICIs), especially those targeting the PD-1 and CTLA-4 pathways. Although dMMR-MSI-H tumors constitute only a small fraction of CRC cases, their response to ICIs has redefined therapeutic standards. In this review, we discuss the immunological underpinnings that render these tumors susceptible to immune modulation, summarize key clinical trial findings, and analyze emerging resistance mechanisms. Furthermore, we highlight the evolving landscape of predictive biomarkers and ongoing efforts to increase treatment efficacy through combination strategies and biomarker-driven approaches.
Insights
Colorectal cancer (CRC) with deficient mismatch repair (dMMR) and high microsatellite instability (MSI-H) shows exceptional response to immune checkpoint inhibitors (ICIs). This review explores the mechanisms, clinical data, and future strategies for treating this distinct CRC subtype.
Area of Science:
- Oncology
- Immunology
- Genetics
Background:
- Colorectal cancer (CRC) exhibits distinct subtypes, including those with deficient mismatch repair and high microsatellite instability (dMMR-MSI-H).
- The dMMR-MSI-H phenotype is associated with increased tumor mutational burden and immunogenicity.
- These characteristics predict a heightened sensitivity to immune checkpoint inhibitors (ICIs).
Purpose of the Study:
- To review the immunological basis for dMMR-MSI-H CRC response to ICIs.
- To summarize clinical trial outcomes for ICIs in this CRC subtype.
- To analyze resistance mechanisms and explore future therapeutic strategies.
Main Methods:
- Literature review of immunological mechanisms, clinical trials, and resistance patterns.
- Analysis of predictive biomarkers and combination therapy approaches.
- Synthesis of current knowledge on dMMR-MSI-H CRC and ICI treatment.
Main Results:
- dMMR-MSI-H CRC exhibits unique immunobiology making it highly responsive to PD-1 and CTLA-4 inhibitors.
- Clinical trials demonstrate significant efficacy of ICIs in this specific CRC subgroup.
- Emerging resistance mechanisms necessitate further research and novel therapeutic combinations.
Conclusions:
- The dMMR-MSI-H phenotype represents a paradigm shift in CRC treatment, highlighting the success of ICIs.
- Understanding resistance and optimizing biomarker-driven strategies are crucial for improving patient outcomes.
- Combination therapies and novel approaches hold promise for enhancing ICI efficacy in dMMR-MSI-H CRC.
