EACR & Bio-Rad Webinar

MSI analysis in solid and liquid biopsies: the great potential of ddPCR molecular approach

MicroSatellite Instability (MSI) phenotype is characterized by a deficiency of at least one protein of the DNA mismatch repair (MMR) system. Recent studies show the MSI status predicts the clinical benefit of immunotherapy with PD-1/PD-L1 inhibitors.

In this webinar, we will discuss published data regarding MSI analysis in solid and liquid biopsy of GastroEsophageal Adenocarcinoma (GEA) patients. Recently, The Cancer Genome Atlas Research Network proposed a simple process to characterize a GEA based on its predominant molecular profile. This provides prognostic information and suggests a benefit from targeted therapy. Currently, MSI testing for immunotherapy decision-making is commonly performed on tissue biopsies by the assessment of the MMR proteins’ expression level by immunohistochemistry (IHC). However, about 5–11% of MSI GEAs could have dysfunctional proteins due to missense mutations, leading to the erroneous exclusion of these patients from immunotherapy.

This study aimed to find a valid alternative to currently used IHC typing. We tested different molecular approaches to analyze MSI status in formalin-fixed paraffin-embedded (FFPE) tissues DNA and in cfDNA of GEA patients. Our results show the molecular analysis as an optimal alternative to IHC for the diagnostic typing and suggest that the ddPCR assay can be considered as the most reliable molecular approach to detect MSI in the cfDNA of GEA patients.