5 Facts you should know about

Advanced MSI⁠-⁠H/dMMR Cancers

There are three different testing methods available for detecting MSI-H/dMMR status: PCR and next-generation sequencing (NGS) for MSI-H, and immunohistochemistry (IHC) for dMMR (1)

Although not routinely tested, MSI can be found in other cancer types outside the more common Lynch syndrome-associated gastrointestinal and endometrial cancers, at a frequency of around 2%–4% (1)

Mismatch repair deficiency (dMMR) results in microsatellite instability (MSI) and is strongly associated with responsiveness to programmed death-1 receptor (PD-1)-blocking antibodies

MSI CRC comprises around 15% of all primary CRCs (1)

The approval of MSI-H immunotherapy has historical significance, because it was the first ‘orphan’ approval of a biomarker, regardless of histology and tumor type (2)

1. Kok M, Chalabi M, Haanen J. How I treat MSI cancers with advanced disease. ESMO Open. 2019 May 21;4(Suppl 2):e000511. doi: 10.1136/esmoopen-2019-000511. PMID: 31231574; PMC6555602. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6555602

2. Alessandro Rizzo, Angela Dalia Ricci & Gennaro Gadaleta-Caldarola (2021) MSI-H/dMMR and cancer immunotherapy: current state and future implications, Expert Review of Precision Medicine and Drug Development, 6:6, 345-347, DOI: 10.1080/23808993.2021.1946391 https://www.tandfonline.com/doi/full/10.1080/23808993.2021.1946391

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