Aberrant de novo lipid synthesis is involved in the progression and treatment resistance of many types of cancers,including lung cancer;however,targeting the lipogenetic pathways for cancer therapy remains an unmet clinical need.In this study,we tested the anticancer activity of orlistat,an FDA-approved anti-obesity drug,in human and mouse cancer cells in vitro and in vivo,and we found that orlistat,as a single agent,inhibited the proliferation and viabilities of lung cancer cells and induced ferroptosis-like cell death in vitro.Mechanistically,we found that orlistat reduced the expression of GPX4,a central ferroptosis regulator,and induced lipid peroxidation.In addition,we systemically analyzed the genome-wide gene expression changes affected by orlistat treatment using RNA-seq and identified FAF2,a molecule regulating the lipid droplet homeostasis,as a novel target of orlistat Moreover,in a mouse xenograft model,orlistat significantly inhibited tumor growth and reduced the tumor volumes compared with vehicle control(P＜0.05).Our study showed a novel mechanism of the anticancer activity of orlistat and provided the rationale for repurposing this drug for the treatment of lung cancer and other types of cancer.