Dynamics of MSI and Genomic Profile of Colorectal Cancer In the Course of Immune Checkpoint Inhibitor Therapy (BLOOMSI)

This was 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 included in the study. MSI/dMMR positivity was confirmed with polymerase chain reaction-based (PCR) assays or immunohistochemistry (IHC). Pre-treatment FFPE and liquid biopsy (LB) samples were collected, as well as LB samples collected until treatment discontinuation (at day 14 and 28 after treatment and at each visual control). Collected samples were subjected to amplicon panel sequencing covering common cancer-related genes and short tandem repeats for MSI detection to trace correlation of dynamics of MSI and genomic profiles with the treatment outcomes.