Beyond Psychotropic: Repurposing of Fluoxetine Toward Cancer Management and Its Molecular Mechanisms

Drug repurposing, rebranding an existing drug for a new therapeutic indication, is deemed a beneficial approach for a quick and cost-effective drug discovery process by skipping preclinical, Phase 1 trials and pharmacokinetic studies. Several psychotropic drugs including selective serotonin reuptake inhibitors (SSRIs) and tricyclic antide-pressants (TCAs) were studied for their potential application in different diseases es-pecially in cancer therapy. Fluoxetine (FLX) is one of the most prescribed psychotropic agents from SSRIs class for the treatment of several neuropsychiatric disorders with a favourable safety profile. FLX exhibited different oncolytic effects via mechanisms dis-tinct from its main serotonergic activity. Taking advantage of its ability to rapidly pen-etrate the blood-brain barrier, FLX could be particularly useful in brain tumors. This was proved by different in vitro and in vivo experiments using FLX as a monotherapy or combination with temozolomide (TMZ) or radiotherapy. In this review of literature, we summarize the potential pleiotropic oncolytic roles of FLX against different cancers highlighting the multifaceted activities of FLX and its ability to interrupt cancer prolif-eration via several molecular mechanisms and even surmount multidrug resistance (MDR). We elaborated on the successful synergistic combinations such as FXR/temozolomide and FXR/raloxifene for the treatment of glioblastoma and breast cancer, respectively. We showcased beneficial pharmaceutical trials to load FLX on car-riers to enhance its safety and efficacy on cancer cells. This is the first review article ex-tensively summarizing all previous FLX repurposing studies for the management of cancer.