An NIH-funded Cleveland Clinic study found testosterone may suppress glioblastoma growth in men, potentially opening new paths for brain cancer treatment research and future clinical trials.
A new Cleveland Clinic study backed by the National Institutes of Health challenges long-held assumptions and perceptions about male hormones and brain cancer growth. The study, published this week in Nature, has found evidence suggesting testosterone may help suppress the growth of aggressive brain tumors in men, a finding researchers say could eventually reshape treatment approaches for glioblastoma.
As part of the study, scientists examined how androgen hormones such as testosterone interact with glioblastoma, one of the deadliest forms of brain cancer. Researchers at the Cleveland Clinic found that lowering testosterone levels in male mice accelerated tumor growth and weakened immune responses inside the brain. Glioblastoma occurs more frequently in men than women, leading scientists for years to suspect male hormones may contribute to the disease. The new findings point in the opposite direction.
“This outcome is a welcome surprise and may potentially offer a lead for new treatments for a kind of cancer that is deadlier in men,” said Anthony Letai in a statement released by the NIH.
Researchers said testosterone appeared to help regulate immune activity in the brain. When androgen levels dropped in laboratory models, a stress-response system known as the hypothalamus-pituitary-adrenal axis became overactive. That triggered inflammation and created an immunosuppressive environment that allowed tumors to grow more aggressively.
The team also analyzed medical data from more than 1,300 men with glioblastoma using the NIH’s SEER cancer database. Men who were already receiving supplemental testosterone for unrelated medical reasons showed a 38% lower risk of death compared with patients not taking testosterone supplements, according to the study. Researchers cautioned that the findings do not prove that testosterone directly improves survival in humans.
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Justin Lathia, the study’s senior author, said the brain’s immune environment differs sharply from other parts of the body, making hormone effects harder to predict. The findings arrive as researchers continue exploring why certain cancers behave differently in men and women. NIH-funded studies have recently also examined how sex chromosomes and hormones influence tumor biology and immune responses. Researchers said the next step will involve clinical trials to determine whether testosterone-based therapies could safely help certain glioblastoma patients.
An industry expert welcomed the study’s findings. Himanshu Shah, Executive Chairman of Marius Pharmaceuticals, the company behind the testosterone therapy Kyzatrex, described the study as “momentous.”
“Though testosterone supplementation is not a standard of care yet, it should be based on such an influential large study results. The patients will be better off.”
Kyzatrex, which was approved by the U.S. Food and Drug Administration, is used to treat adult men with low or deficient testosterone levels. Marius announced earlier this year that it plans to launch a new post-marketing clinical study to evaluate a potential label expansion for Kyzatrex CIII capsules in men between the ages of 65 and 80 who suffer from hypogonadism. As men grow older, low testosterone levels can compound many age-related health challenges, affecting energy, muscle strength, mobility, metabolism, and overall quality of life. Through the study, researchers hope to better understand how Kyzatrex may help improve health outcomes and daily functioning in older patients.
Testosterone therapy has been used successfully for nearly a century, including in women undergoing menopause treatment, but its progress slowed after testosterone was classified as a Schedule III controlled substance in the US in 1980’s. Critics of the move have long argued that the decision was shaped by political pressure than scientific evidence, despite opposition at the time from the FDA and the American Medical Association.