Taiwan study finds allergy drug ingredient boosts cancer immunity

台灣研究發現抗過敏藥物成分可增強對癌症之免疫力

TAIPEI (Taiwan News) — A Taiwanese research team has found that an ingredient in a widely used allergy medication can boost the immune system’s ability to detect and attack cancer cells, offering new possibilities for cancer treatment.

The six-year study focused on cyproheptadine, the active compound in the antihistamine Periactin. Periactin is commonly prescribed to treat allergic rhinitis, dermatitis, hives, and asthma, according to CNA and Weldricks Pharmacy.

Researchers discovered that cyproheptadine not only suppresses the growth of bladder tumors but also reshapes the tumor’s immune environment in ways that may improve treatment outcomes. The drug was shown to regulate epigenetic activity in cancer cells, enhancing the activation of natural killer cells.

Epigenetics involves changes in gene expression without altering the underlying DNA sequence. These modifications determine whether specific genes are switched on or off, ultimately influencing how cells behave.

In laboratory experiments, cancer cells treated with cyproheptadine showed a marked increase in immune recognition markers on their surfaces, making them easier for natural killer cells to identify and destroy.

Natural killer cells, or NK cells, are a type of white blood cell that originate in the bone marrow and make up about 5–10% of lymphocytes in human blood. They play a vital role in immune defense, eliminating virus-infected, aging, or cancerous cells.

Animal studies reinforced the lab results. Mice treated with cyproheptadine experienced slower tumor growth and greater infiltration of NK cells in tumor tissues, suggesting the drug both inhibits tumor progression and enhances the immune response within the tumor microenvironment.

Researchers noted that since cyproheptadine is already approved for clinical use and has a well-documented safety profile, it holds strong potential for repurposing as an immunotherapy drug — particularly for bladder cancer and potentially other difficult-to-treat tumors.

The team hopes their findings will lead to new clinical strategies that use existing medications to improve cancer treatment and patient outcomes.