PCSK9 and neoplasm: This effect was associated with a noticeable increase in CD8+ and GZMB+CD8+ T cells and a reduction in Tregs.356 In a 4MOSC1 syngeneic mouse HNSC model, inhibiting PCSK9 boosted the infiltration of CTLs in tumor immune microenvironment (TIME) and decreased the myeloid-derived suppressor cells (MDSCs).