- No prior exposure to immune-mediated therapy including, but not limited to, other anti CTLA-4, anti-PD-1, anti-PD-L1, and anti-programmed cell death ligand 2 (anti-PD-L2) antibodies, including therapeutic anticancer vaccines. The exception to this is those whose tumors are MSI-hi and are refractory to anti-PD1 monotherapy.