Orlistat (Tetrahydrolipstatin) is a lipase inhibitor and a fatty acid synthase (FASN) inhibitor. Orlistat has been shown to promote weight loss.

METHODS: Prostate cancer cells PC3, DU145 and LNCaP were treated with Orlistat (10-300 µM) for 24 h and cell proliferation was detected by MTT assay.
RESULTS: Increasing concentrations of Orlistat resulted in a dose-dependent decrease in cell viability of the three PCa cell lines tested. [1]
METHODS: Breast cancer cells SK-Br3 were treated with Orlistat (40 µM) for 6-72 h. Cell cycle was measured by Flow cytometry.
RESULTS: The time-dependent response of SK-Br3 breast cancer cells to Orlistat was characterized by the absence of G2-M populations and the accumulation of cells in the S phase of the cell cycle. Importantly, Orlistat exposure significantly promoted apoptosis, as evidenced by the time-dependent accumulation of sub-G1 populations with <2N DNA and representing dead cells. [2]

METHODS: To detect anti-tumor activity in vivo, Orlistat (240 mg/kg, 33% ethanol and 66% PEG 400) was injected intraperitoneally into athymic nude mice bearing PC-3 xenografts once daily for three weeks.
RESULTS: Orlistat prevented PC-3 tumor growth. In five separate experiments, tumor growth was blocked by 63%, 62%, 46%, 41%, and 16%. [3]