Common Asthma Drug May Fight Aggressive Cancers

Millions of people take a common asthma drug every day, and scientists just discovered it might also save lives in a completely different way.

Researchers at Northwestern University found that montelukast, sold as Singulair for asthma and allergies, could help fight aggressive cancers like triple-negative breast cancer. The drug blocks a molecule called CysLTR1 that tumors exploit to hide from the immune system.

The discovery came when scientists figured out how tough cancers evade immunotherapy treatments. Tumors trick a type of white blood cell called neutrophils into protecting them instead of attacking them. A molecule acts like an on/off switch for this process, and existing asthma drugs can flip that switch.

"When we turned off this switch, either genetically or with existing drugs, we not only slowed tumor growth, but also helped the immune system recover its ability to fight the cancer," said Professor Bin Zhang, who led the study.

The team tested their theory in mice with five different cancer types, including breast cancer, melanoma, ovarian cancer, colon cancer, and prostate cancer. When they blocked CysLTR1 with montelukast or removed it genetically, tumors grew slower and mice lived longer. Even cancers that had stopped responding to immunotherapy started responding again.

Human immune cells showed the same promising results in lab tests. Instead of just killing the harmful white blood cells, the treatment reprogrammed them to support the immune system's attack on cancer.

The researchers also analyzed data from human tumor samples and large patient databases. Patients with higher CysLTR1 activity had worse survival rates and poorer responses to immunotherapy across multiple cancer types.

The Bright Side

The most exciting part of this discovery is how quickly it could help patients. Because montelukast is already FDA-approved and has been prescribed safely for decades, doctors can start testing it in cancer patients much faster than a brand new drug. Years of development and safety testing are already complete.

Professor Zhang plans to begin carefully designed clinical trials soon. The goal is to confirm the results in patients, figure out who will benefit most, and determine the best way to combine the drug with existing immunotherapy treatments.

For people battling triple-negative breast cancer and other aggressive cancers where new options are desperately needed, this research offers real hope that help could arrive sooner rather than later.