A medication commonly used to treat asthma and allergies may also help fight some of the most difficult cancers, according to a new study from Northwestern Medicine.
Researchers discovered that tumors can hijack certain immune cells to protect themselves from treatment, but an existing asthma drug may help reverse this process and allow the immune system to attack the cancer again.
The study was published in the journal Nature Cancer and focused on a molecule called CysLTR1. This molecule is already well known in asthma research because it plays an important role in inflammation and allergic reactions.
Drugs that block CysLTR1, such as montelukast, which is commonly sold under the brand name Singulair, have been prescribed safely for many years to help people manage asthma and allergies.
Now scientists believe these drugs may also have potential in cancer treatment.
The research team found that many cancers appear to use the CysLTR1 pathway to weaken the body’s immune response and avoid being destroyed by immunotherapy. Immunotherapy is a type of cancer treatment that helps the immune system recognize and attack cancer cells.
While immunotherapy has transformed treatment for many cancers, it does not work well for every patient, especially in aggressive cancers such as triple-negative breast cancer.
Triple-negative breast cancer is considered particularly difficult to treat because it grows quickly and lacks several common treatment targets used in other breast cancers. Patients with this form of cancer often have fewer treatment options and poorer outcomes.
The Northwestern researchers discovered that tumors can manipulate white blood cells called neutrophils. Neutrophils are among the most common immune cells in the body and normally help fight infections.
However, tumors appear able to reprogram these cells and turn them into helpers that protect cancer rather than destroy it.
The scientists found that the molecule CysLTR1 acts almost like an on-off switch controlling this harmful process.
Dr. Bin Zhang, senior author of the study and professor of cancer immunology at Northwestern University Feinberg School of Medicine, explained that blocking this switch helped restore the immune system’s ability to fight cancer.
The researchers used several different approaches in the study. They carried out experiments in mice, examined human immune cells, analyzed human tumor samples, and studied large public cancer databases.
The mouse experiments included several aggressive cancers, including triple-negative breast cancer, melanoma, ovarian cancer, colon cancer, and prostate cancer.
In some mice, researchers genetically removed the CysLTR1 pathway. In others, they blocked the pathway using medications such as montelukast.
The results were encouraging. In multiple cancer models, blocking CysLTR1 slowed tumor growth, improved survival, and restored the effectiveness of immunotherapy. This even worked in tumors that had already become resistant to treatment.
One particularly important finding was that the treatment did not simply eliminate neutrophils. Instead, it appeared to reprogram them.
According to Dr. Zhang, the harmful neutrophils were converted into immune cells that once again supported anti-cancer activity.
This means the treatment may not only target cancer directly but may also retrain the immune system itself.
The researchers then studied human immune cells and found similar effects. Blocking CysLTR1 prevented the formation of immune-suppressing neutrophils that help tumors survive.
Finally, the team examined human cancer samples and large patient databases. They found that patients with higher CysLTR1 activity often had worse survival and poorer responses to immunotherapy across several different cancer types.
These findings suggest that CysLTR1 may play a major role in helping tumors resist treatment.
One reason the discovery is exciting is because montelukast and related drugs are already approved by the U.S. Food and Drug Administration for asthma treatment. This could potentially speed up the process of testing the drugs in cancer patients because their safety profiles are already well understood.
Researchers say this may allow clinical trials to move forward more quickly compared to developing entirely new drugs from the beginning.
The scientists now hope to identify which patients may benefit most from this approach and determine how these medications work best alongside immunotherapy treatments.
They also want to better understand exactly how tumors manipulate neutrophils and whether similar strategies could help in other diseases involving immune system dysfunction.
The findings reflect a growing shift in cancer research toward understanding the tumor microenvironment, which refers to the surrounding immune cells, blood vessels, and tissues that interact with cancer.
Scientists increasingly believe cancer survival often depends not only on the cancer cells themselves but also on how tumors manipulate the immune system around them.
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Source: Northwestern Medicine.
