DR-251 Characterization of the oncogenic fusion landscape of microsatellite instability high solid tumors

Microsatellite instability (MSI) is a genomic phenomenon characterized by a high number of mutations in tumor DNA. This is due to an error in the DNA repair mechanism, either germline or somatic. MSI-high has been extensively researched in colorectal cancer. MSI-H CRC is enriched for oncogenic fusions, of which some are responsive to targeted therapy e.g., NTRK fusions. In this study, we want to describe the occurrence of oncogenic fusions in MSI-H solid tumors. The second research question is to describe the (co)-occurrence of oncogenic driver mutations in in MSI-H solid tumors. If we find that MSI-H tumors are enriched for oncogenic fusions and/or driver mutations, this could potentially improve treatment possibilities for these patients. Some of these patients might have already been treated with targeted therapy, so we would also be interested to investigate treatment responses.

Barend Sikkema, Erasmus MC, The Netherlands