LAUSR

We report a case of multiple high-grade and rare immune-related adverse events (irAEs) in a patient with microsatellite instability-high (MSI-H) metastatic colorectal cancer (mCRC). A middle-aged MSI-H mCRC patient with metastases to the lungs and lymph nodes received several lines of chemotherapy and immunotherapy and developed five different high-grade irAEs during immunotherapy, including lymphadenitis, pneumonitis, hypophysitis, thyroiditis and transverse myelitis. Genomic profiling revealed high tumor mutational burden of 43 Muts/Mb. Cytokine profiling showed a threefold increase in MMP-9 shortly prior to the onset of lymphadenitis and a fourfold increase of Ang-1 1 week after the resolution of lymphadenitis. Further studies are warranted to investigate the association of MSI-H mCRC with irAEs and the role of cytokines in predicting irAEs.