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Microsatellite Instability: A Predictive Biomarker for Cancer Immunotherapy
Liisa Chang1, Minna Chang2, Hanna M Chang2
1Department of Medicine, Medway NHS Foundation Trust, Gillingham, Kent.
Abstract:
Immunotherapy has shown promising results in various types of cancers. Checkpoint inhibitor drugs developed for cancer immunotherapy have been approved by the US Food and Drug Administration (FDA) for patients with advanced melanoma, non-small cell lung cancer, renal cell carcinoma, bladder cancers, and refractory Hodgkin lymphoma. In the latest announcement, the FDA has granted accelerated approval to pembrolizumab for pediatric and adult patients with microsatellite instability-high (MSI-H) or mismatch repair-deficient solid tumors. This is the first time the agency has approved a cancer treatment based on a common biomarker rather than organ-based approach. MSI-H, either due to inherited germline mutations of mismatch repair genes or epigenetic inactivation of these genes, is found in a subset of colorectal and noncolorectal carcinomas. It is known that MSI-H causes a build up of somatic mutations in tumor cells and leads to a spectrum of molecular and biological changes including high tumor mutational burden, increased expression of neoantigens and abundant tumor-infiltrating lymphocytes. These changes have been linked to increased sensitivity to checkpoint inhibitor drugs. In this mini review, we provide an update on MSI-related solid tumors with special focus on the predictive role of MSI for checkpoint immunotherapy.
Insights
The FDA approved a new cancer immunotherapy based on a common biomarker, microsatellite instability-high (MSI-H), not tumor location. This advance offers new hope for patients with MSI-H solid tumors, improving cancer treatment options.
Area of Science:
- Oncology
- Immunotherapy
- Molecular Biology
Background:
- Cancer immunotherapy has demonstrated significant success across various malignancies.
- Checkpoint inhibitor drugs are approved for several advanced cancers, including melanoma and lung cancer.
- The US Food and Drug Administration (FDA) has expanded approvals for these therapies.
Purpose of the Study:
- To provide an update on microsatellite instability-related (MSI-related) solid tumors.
- To highlight the predictive role of MSI status in response to checkpoint immunotherapy.
- To discuss the recent FDA approval of a biomarker-based cancer treatment.
Main Methods:
- Review of current literature on MSI and cancer immunotherapy.
- Analysis of FDA approvals and clinical trial data for MSI-targeted therapies.
- Discussion of the molecular underpinnings of MSI-H tumors and their response to immunotherapy.
Main Results:
- The FDA granted accelerated approval to pembrolizumab for MSI-high (MSI-H) or mismatch repair-deficient solid tumors.
- This marks the first FDA approval of a cancer treatment based on a common biomarker (MSI-H) rather than organ site.
- MSI-H tumors exhibit specific molecular characteristics, including high tumor mutational burden and increased neoantigen expression, correlating with immunotherapy sensitivity.
Conclusions:
- Biomarker-based treatment selection, specifically MSI status, represents a paradigm shift in cancer therapy.
- MSI-H solid tumors are particularly responsive to checkpoint inhibitor immunotherapy.
- Further research into MSI-related tumors will likely enhance personalized cancer treatment strategies.
