Described herein are pharmaceutical formulations comprising 4-fluoro-N-methyl-N-(1-(4-(1-methyl-1H-pyrazol-5-yl)phthalazin-1-yl)piperidin-4-yl)-2-(trifluoromethyl)benzamide, or a pharmaceutically acceptable salt thereof, wherein the pharmaceutical formulations are suitable for topical use, and methods of using such formulations in the treatment of subjects having cancer.