Figure 2.

Combination of external beam radiotherapy and immune checkpoint inhibiting antibodies. The optimal timing of immune checkpoint inhibition appears to be in the early phase of radiotherapy. Preclinical models indicate that cytotoxic T-lymphocyte-associated protein 4 (CTLA-4) blockade may be more effective when administered days before irradiation. The optimal dose of radiation as determined in mouse models is indicated. The red gradient indicates suggested variability in cancer-specific clinical settings. Preliminary clinical studies have reported improved outcomes when irradiating multiple sites.