R848 enhances the therapeutic efficacy of radiation therapy. Combination of 10 Gy local RT with a single intravenous dose of R848 (A) or weekly dosing of R848 (B). Experimental groups contained at least 7 mice and are representative of at least 2 independent experiments. *P < .05, compared with control mice (log-rank; Mantel-Cox test). ⁺P < .05, compared with monotherapy (log-rank; Mantel-Cox test). **P < .01, compared with control mice (log-rank; Mantel-Cox test). ***P < .001, compared with control mice (log-rank; Mantel-Cox test).