CD274 and neoplasm: In mouse liver metastasis tumor models, STAT3 inhibitors markedly promoted Bax-dependent apoptosis of MDSCs and further enhanced the antitumor efficiency of chimeric antigen receptor T-cell (CAR-T) therapy.210 Currently, a phase II clinical trial testing AZD9150 coupled with anti-PD-L1 mAb (MEDI4736) and anti-CTLA-4 mAb (tremelimumab) in patients with advanced solid tumors and relapsed metastatic HNSCC is ongoing (NCT02499328).