Another study knocked out the PCSK9 gene in four malignant mouse cancer cell lines (B16F10, 4T1, MC38, and CT26) using CRISPR-Cas9 technology, and tumor growth was significantly attenuated or blocked in mice in a CTL-dependent manner and the efficacy of PD-1 inhibitors was enhanced [48]. Here, PCSK9 is linked to neoplasm.