At the Crossroads: COVID-19 and Immune-Checkpoint Blockade for Cancer

Abstract

The immunomodulatory effects of immune-checkpoint blockade (ICB) therapy for cancer may act at the crossroads between the need to increase antiviral immune responses to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and to decrease the inflammatory responses in severe cases of coronavirus disease 2019 (COVID-19). There is evidence from preclinical models that blocking programmed death receptor 1 (PD1) protects against RNA virus infections, which suggests that patients with cancer receiving ICB may have lower rates of viral infection. However, given the heterogeneity of patient characteristics, this would be difficult to demonstrate using population-based registries or in clinical trials. Most studies of the impact of ICB therapy on the course of COVID-19 have centered on studying its potential detrimental impact on the course of the COVID-19 infection, in particular on the development of the most severe inflammatory complications. This is a logical concern as it is becoming clear that complications of COVID-19 such as severe respiratory distress syndrome are related to interferon signaling, which is the pathway that leads to expression of the PD1 ligand PD-L1. Therefore, PD1/PD-L1 ICB could potentially increase inflammatory processes, worsening the disease course for patients. However, review of the current evidence does not support the notion that ICB therapy worsens complications from COVID-19, and we conclude that it supports the continued use of ICB therapy during the COVID-19 pandemic provided that we now collect data on the effects of such therapy on COVID-19 vaccination.

Figure 1.

ICB therapy in patients with cancer has the potential to have beneficial or detrimental effects on infection with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and the course of coronavirus disease 2019 (COVID-19). Blocking immune-checkpoint proteins like programmed death 1 (PD1) or cytotoxic T lymphocyte antigen 4 (CTLA4) may improve antiviral responses against SARS-CoV-2, decreasing the rate of infection or mounting a stronger immune response to the virus leading to lack of viral replication and less serve COVID-19 outcomes. Conversely, blocking immune checkpoints may result in enhanced inflammatory responses to the host induced by increased interferon pathway signaling, resulting in severe complications such as acute respiratory distress syndrome (ARDS).