This is a multicenter observational trial designed to evaluate the dynamics of microsatellite instability and the genomic profiles of CRC during immune checkpoint inhibitor treatment.
Patients with MSI/dMMR-positive tumors who are candidates for the ICI treatment will be included in the study. MSI/dMMR positivity should be confirmed with polymerase chain reaction-based (PCR) assays, immunohistochemistry (IHC) or Next-generation sequencing (NGS). Treatment with any ICI will be allowed. Upon inclusion in the study, patients will be asked to provide the pre-treatment FFPE tumor and liquid biopsy (LB) samples along with LB samples on the 14th, 28th days of ICI, and at every control study. LB samples will be collected until treatment discontinuation.
The pre-treatment FFPE samples will be tested with an alternative routine method (PCR and/or IHC, depending on what method was used for initial testing), as well as with the Solo Atlas Pro NGS panel covering common cancer-related genes and short tandem repeats for MSI detection. All LB samples will be tested with the Solo Atlas Pro NGS panel. Dynamics of MSI and genomic profiles will be correlated with the treatment outcomes.
Disease response to study treatment will be evaluated by imaging methods. Response to treatment will be determined by RECIST v1.1.
