Our findings support and build on previous preclinical reports demonstrating enhanced radiosensitization using CTLA‐4 and/or PD‐1/PD‐L1 immune checkpoint inhibitors in melanoma, breast, and colorectal cancer, and glioblastoma multiforme (Demaria et al, 2005; Deng et al, 2014; Dovedi et al, 2014; Sharabi et al, 2015b; Twyman‐Saint Victor et al, 2015; Rodriguez‐Ruiz et al, 2016). The gene discussed is CTLA4; the disease is melanoma.