For example, Acharya et al. found that combination SRS + ICI (including anti-PD-1 and anti-CTLA-4) was associated with a significant decrease in local failure (LF) compared with SRS alone [hazard ratio (HR) 0.37; 95% CI: 0.14–0.95; p = 0.04] in melanoma brain metastases [51]. Here, PDCD1 is linked to melanoma.