CUR5g is a potent autophagy inhibitor. CUR5g selectively inhibits autophagosome degradation in cancer cells by blocking autophagosome-lysosome fusion. CUR5g blocks the recruitment of STX17 to autophagosomes via a UVRAG-dependent mechanism, resulting in the inability of autophagosomes to fuse with lysosomes. CUR5g improves the anticancer effect of Cisplatin against A549 cells both in vitro and in vivo.