In addition, PH-894 silencing of BRD4 not only inhibited tumor growth at the local site of therapy, but also elicited an abscopal effect toward distal tumors, with efficacy similar to that provided by systemically administered anti-PD-1 mAb. These results indicate that IT PH-894 can potentiate the efficacy of systemic anti-PD-1 mAb, warranting further investigation of clinical applications in combination with anti-PD-1 mAbs toward improving patient outcomes.