Scientists at the University of California, Los Angeles have discovered that the commonly used antidepressant in clinical practice, selective serotonin reuptake inhibitors (SSRIs), can significantly enhance the ability of T cells to fight cancer. The latest research published in the journal Cell shows that the drug has excellent inhibitory effects on melanoma, breast cancer and other cancers in mouse and human tumor models, and can reduce the tumor volume by more than 50% on average. The research team claims that SSRI not only brings happiness to the brain, but also injects vitality into anti-cancer T cells. These antidepressants, sold as classic drugs such as Prozac and Citalopram, increase serotonin levels by blocking the activity of serotonin transporters. It not only regulates emotions, but also unexpectedly activates the anti-cancer potential of the immune system. Serotonin, the 'happiness hormone', is not only an emotional messenger, but also a key regulator of immune metabolism. The research team found that immune cells isolated from tumors have higher levels of serotonin regulatory molecules, which prompted them to further explore the anti-cancer mechanism of SSRI. Experiments have shown that SSRI can reshape the serotonin signaling pathway of T cells, enabling them to regain their ability to kill cancer cells. What is even more exciting is that when SSRI is combined with PD-1 immunotherapy, some experimental groups even observed a therapeutic effect of complete tumor regression. At present, PD-1 immunotherapy is only effective for less than 1/4 of patients. If safe and inexpensive drugs such as SSRI can improve their efficacy, it will bring revolutionary breakthroughs to cancer treatment. The research team plans to conduct clinical trials to verify the anti-cancer effect of SSRI on cancer patients, especially those receiving immunotherapy. (New Society)