A. Tumor PD-L1 expression B. Tumor mutational burden C. DNA mismatch-repair status D. Immunoscore E. Unsure

A. Colitis can be attributed to ipilimumab, which should be stopped, but nivolumab can be continued. B. Ipilimumab and nivolumab should be discontinued and high-dose corticosteroids initiated. C. After resolution of the colitis, the nivolumab and ipilimumab can be safely resumed. D. The colitis should resolve promptly with just discontinuing nivolumab and ipilimumab. E. Unsure

A. Pembrolizumab is FDA-approved as first-line treatment of patients with unresectable or metastatic MSI-H or dMMR CRC. B. Compared to FOLFOX chemotherapy for initial treatment of MSI-H/dMMR metastatic CRC, pembrolizumab is associated with a higher objective response rate but progression-free survival rates are similar. C. The combination of standard chemotherapy to pembrolizumab as initial therapy for metastatic CRC is inactive against MSS/pMMR tumors. D. Pembrolizumab should be administered as frequently as every 3 weeks to maintain efficacy. E. Unsure