Lifestyle
Antidepressants Show Promise in Boosting Cancer Defense, New Study Reveals
The prevalence of antidepressant use in the United States is significant, with the CDC estimating that one in eight adults takes these medications. Notably, the COVID-19 pandemic saw a nearly 19 percent increase in antidepressant usage, according to The New York Times. Among these medications, selective serotonin reuptake inhibitors (SSRIs) like Zoloft and Lexapro are particularly common, ranking as the 12th and 15th most prescribed drugs in the nation.
A groundbreaking study now suggests these widely used antidepressants might offer an unexpected benefit: aiding the immune system in combating cancer. SSRIs generally work by elevating serotonin levels in the brain, which can influence mood. As the Cleveland Clinic explains, “After serotonin has carried its message, nerve cells in your brain usually reabsorb the serotonin (known as reuptake). As its name—selective serotonin reuptake inhibitors—suggests, SSRIs work by blocking (inhibiting) reuptake.”
The recent study, published in the journal Cell, explored the interaction between SSRIs and T cells—key components of the immune system—in both mouse and human tumor models. The research was inspired by a 2021 study that revealed T cells produce the protein MAO-A when encountering cancer. This protein breaks down neurotransmitters like serotonin, norepinephrine, and dopamine. However, when MAO inhibitors were used, T cells showed enhanced tumor-fighting capabilities.
Given the challenges associated with MAO inhibitors, such as dietary restrictions and side effects, the researchers shifted their focus to the protein SERT, which transports serotonin. “Unlike MAO-A, which breaks down multiple neurotransmitters, SERT has one job—to transport serotonin,” explained Bo Li, PhD, a senior research scientist at UCLA. “SERT made for an especially attractive target because the drugs that act on it—SSRIs—are widely used with minimal side effects.”
The study’s findings were remarkable. In mouse and human tumor models for various cancers, including melanoma, breast, prostate, colon, and bladder, SSRI treatment reduced average tumor size by over 50 percent. This treatment also enhanced the effectiveness of T cells in destroying cancer cells. “SSRIs made the killer T cells happier in the otherwise oppressive tumor environment by increasing their access to serotonin signals, reinvigorating them to fight and kill cancer cells,” said Lili Yang, PhD, who leads the Yang Engineering Immunity Lab at UCLA.
The results were even more promising when SSRIs were combined with immune checkpoint blockade (ICB) therapy. This combination led to tumor size reduction in all treated mice, with some experiencing complete remission. James Elsten-Brown, a graduate student and co-author of the study, highlighted the potential impact: “Immune checkpoint blockades are effective in fewer than 25% of patients. If a safe, widely available drug like an SSRI could make these therapies more effective, it would be hugely impactful.”
The research team is now planning clinical trials to confirm these findings in cancer patients. Lili Yang expressed the potential of this approach, stating, “Since around 20% of cancer patients take antidepressants—most commonly SSRIs—we see a unique opportunity to explore how these drugs might improve cancer outcomes. Our goal is to design a clinical trial to compare treatment outcomes between cancer patients who take these medications and those who do not.”
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