Despite supporting studies on PCSK9 inhibition for example as a combinatory treatment with immune checkpoint inhibition in murine 4T1 mammary cancer cell xenografts [130] and in targeting the OVCAR3 HGSC ovarian cancer cells [131] exist, generally studies with PCSK9 inhibition in cancer contain controversialities and are thus pending for more thorough studies for its usability as a cancer-treatment, since it could also induce LDLR expression in tumors, and thus increase tumor growth [132]. Here, PCSK9 is linked to breast cancer.