PDCD1 and melanoma: Interestingly, ACAT1 inhibitor (avasimibe) monotherapy did enhance CD8+ TILs effector functions regardless of PD-1 expression levels and higher survival rates were observed in mouse melanoma combining anti-PD-1 mAb, suggesting that ACAT1 inhibitor might be a quality adjuvant for anti-PD-1 immunotherapy (17) (Table 2).