Repurposing drugs is the reintroduction of existing drugs into markets as treatments for conditions distinct from that which they were initially intended for. Examples of this include the use of heart medications for the treatment of erectile dysfunction, and the use of erectile dysfunction medications for the treatment of jet lag. Prozac® is an antidepressant that is widely prescribed for conditions such as obsessive-compulsive disorder and major depressive disorder. It functions by blocking the serotonin transporter, which delays the removal of serotonin, and leads to prolonged sensations of happiness and satisfaction. Chronic myeloid leukaemia (CML) is a white blood cell cancer that is currently treated using a drug called Gleevec®. Gleevec® successfully cures 12% of patients; however, 26% completely fail the treatment and 62% require lifelong Gleevec® to prevent the resurgence of the disease. This clearly demonstrates the necessity of developing a new drug that would address the 88% of patients who remain uncured of CML. It has recently been demonstrated that CML cells rely on signals from the nervous system, including signals from the serotonin transporter, to maintain survival. It was thus theorised that blocking the serotonin transporter using Prozac® should reduce the viability of the cells. The experiments performed demonstrate that Prozac® eliminates almost 60% of cancer cells and that combining it with Gleevec® further increases the proportion of eliminated cells up to 80%. This illustrates the possibility of repurposing Prozac® from an antidepressant to a treatment for CML.