Defective DNA Mismatch Repair as a Biomarker in Cancer Diagnosis and Immunotherapy: Review Article

Authors

  • Mahmoud A. Aloriby Department of Pathology, University Medical center, Libyan International Medical University, Benghazi, Libya Author
  • Mohammed shultami Department of Otolaryngology, Medical Collage, University of Benghazi,Libya Author
  • Yousef M.A. Hasen Department of Pathology, University Medical center, Libyan International Medical University, Benghazi, Libya Author
  • Salem Aldrsy Department of Pathology, University Medical center, Libyan International Medical University, Benghazi, Libya Author
  • Soad Ibrahim Eldruki Department of Histopathology, Benghazi Medical Center, Benghazi, Libya Author
  • Omar Mussa Emhmed Department of Cytogenetic, Fuclaty of Applied Medical Science, Libyan International Medical University, Benghazi, Libya Author
  • Abeer H. Amer Department of Cytogenetic, Fuclaty of Applied Medical Science, Libyan International Medical University, Benghazi, Libya Author
  • Ahmed .S.Mikael Department Laboratory Tobruk Medical Center Author
  • Hanadi A. Mohamed Department of Histopathology, Saray Salam Diagnostic center, Tripoli, Libya Author
  • Moataz F. Gebril Department of Health Care Administration, Faculty of Human and Social Science, Libyan international Medical University Author
  • Farag A. Bleiblo Department of Microbiology, Faculty of Science, University of Benghazi, Benghazi, Libya Author

DOI:

https://doi.org/10.54361/LJMR.20.2.57

Keywords:

DNA mismatch repair, Microsatellite instability, dMMR, Immunotherapy, Lynch syndrome, colorectal cancer

Abstract

The DNA mismatch repair (MMR) system is essential for maintaining genomic integrity by correcting base–base mismatches and insertion–deletion loops generated during DNA replication. Defects in this pathway result in microsatellite instability (MSI) and a hypermutated tumor phenotype with profound biological and clinical consequences. Over the past decade, deficient mismatch repair (dMMR) and MSI-high (MSI-H) status have emerged as robust biomarkers for cancer screening, molecular diagnosis, prognostic stratification, and prediction of response to immune checkpoint blockade (ICB). This narrative review summarizes the molecular biology of the MMR system, mechanisms leading to MMR deficiency, current diagnostic strategies for MSI/MMR assessment, and the pivotal role of dMMR as a predictive biomarker for immunotherapy across multiple cancer types. Emphasis is placed on clinical applications, limitations, and emerging directions in precision oncology.

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Published

27-06-2026

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How to Cite

1.
Aloriby M, shultami M, Hasen Y, Aldrsy S, Eldruki S, Emhmed O, et al. Defective DNA Mismatch Repair as a Biomarker in Cancer Diagnosis and Immunotherapy: Review Article. LJMR [Internet]. 2026 Jun. 27 [cited 2026 Jun. 27];20(2):386-95. Available from: https://ljmr.ly/index.php/ljmr/article/view/578

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