PDCD1 and COVID-19: The addition of ipilimumab, an antibody targeting cytotoxic T-lymphocyte-associated protein 4 (CTLA-4), significantly increases the risk of immune-related adverse events (iRAEs) from 15%–20% to 50%–60% compared to anti-PD1 monotherapy; this often leads to the need for immunosuppressive therapies and hospitalization, which in turn potentially increases the rate of COVID-19 transmission and severe disease [23].