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A new study has revealed that dexamethasone, a commonly prescribed anti-swelling drug, may significantly hinder the effectiveness of immunotherapy in brain cancer patients by suppressing the immune system for weeks after its administration.
Swelling, or edema, caused by brain cancer is a serious medical issue that can lead to severe side effects and even death. While controlling swelling is crucial, researchers have now identified a potential downside to using dexamethasone in treatment. The study, conducted by an international team of scientists from Canada and the United States, found that the drug alters immune cells in a way that weakens the body’s ability to fight cancer.
The research, published in Nature, is titled “Programs, Origins, and Immunomodulatory Functions of Myeloid Cells in Gliomas.” Scientists analyzed myeloid cells from over 100 brain tumors using single-cell and spatial transcriptomics, advanced techniques that reveal both cellular function and positioning within tissue. Their findings showed a highly organized distribution of myeloid cells within tumors, with each type of cell found in specific regions based on its role.
Most notably, the study identified two types of immunosuppressive myeloid cells in brain tumors: one associated with areas of dead tissue and the other linked to anti-swelling therapy. Patients who had received dexamethasone exhibited a significantly stronger immunosuppressive effect, with higher doses exacerbating the impact.
Further experiments confirmed that exposing non-immunosuppressive myeloid cells to dexamethasone caused them to become immunosuppressive—a transformation that persisted for weeks after the drug was discontinued. This suggests that even if a patient stops taking dexamethasone before starting immunotherapy, its effects may still compromise the body’s natural ability to combat cancer.
Given that some brain cancer treatments rely on enhancing the immune response to attack malignant cells, the study raises concerns about the widespread use of dexamethasone in these patients.
“Doctors should ask themselves if dexamethasone is truly needed in each case it’s prescribed,” said Dr. Charles Couturier, a neurosurgeon-scientist at The Neuro (Montreal Neurological Institute-Hospital) of McGill University and one of the study’s lead authors. “It is important to balance the need to reduce swelling with the need for a healthy immune response. We need to start developing alternatives to dexamethasone that do not inhibit immune response in patients.”
The study highlights the importance of re-evaluating treatment approaches for brain cancer and encourages further research into alternative therapies that can manage swelling without compromising immune function.
Disclaimer: This article is for informational purposes only and does not constitute medical advice. Patients should consult their healthcare providers before making any changes to their treatment plans.
More Information: Bradley Bernstein, “Programs, Origins, and Immunomodulatory Functions of Myeloid Cells in Gliomas,” Nature (2025). DOI: 10.1038/s41586-025-08633-8. www.nature.com/articles/s41586-025-08633-8.
