A Common Asthma Drug May Help the Immune System Fight Cancer Again
Some tumors do more than hide from the immune system. They can actually manipulate immune cells to help cancer survive and spread. Now, researchers say an asthma drug could interrupt this process.
In a new study published in Natural cancerNorthwestern Medicine researchers have found that many tumors appear to use a molecule called CysLTR1 to suppress immune attacks. When researchers blocked this pathway using montelukast in preclinical models, the generic version of the asthma drug Singulair®, tumor growth slowed in several types of cancer and some tumors began to respond to immunotherapy again.
This could be particularly important for aggressive cancers like triple-negative breast cancer, for which immunotherapy often doesn’t work as well as doctors hope.
“When we turned off this switch, either genetically or with existing drugs, we not only slowed tumor growth, but also helped the immune system regain its ability to fight cancer,” said the study’s lead author, Bin Zhang, in a press release.
How an asthma drug helped tumors respond to immunotherapy again
At the center of the discovery are neutrophils, white blood cells that the body rapidly produces during infections and injuries. Tumors appear capable of redirecting this emergency response to generate large numbers of immunosuppressive cells.
When researchers blocked CysLTR1 in mice, the immune system appeared better able to recognize and attack tumors.
The effect has been shown in several cancers, including triple negative breast cancer, melanoma, ovarian cancer, colon cancer and prostate cancer.
In several cases, tumors that had stopped responding to anti-PD1 immunotherapy have started responding again. Anti-PD1 drugs work by removing some of the biological “brakes” used by cancers to stop immune cells from attacking tumors, although many cancers eventually adapt and become resistant.
CysLTR1 could help drive some of this resistance, potentially giving researchers a new target to make immunotherapy effective over longer periods of time.
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Asthma drug did more than slow tumor growth
The treatment didn’t just destroy the problematic immune cells. Instead, it seems to push them out of their role in protecting against tumors.
“Instead of just eliminating these harmful white blood cells, we were able to reprogram them into cells that support immune attacks,” Zhang explained. “This means we’re not just targeting the cancer, we’re recycling a type of immune cell that’s abundant in the body to fight the tumor again.”
Since neutrophils help fight infections, preserving them can help avoid weakening normal immune defenses.
The team combined experiments in mice with studies of human immune cells, tumor samples and large datasets of cancer patients.
Researchers also found that patients with higher CysLTR1 activity tended to have poorer responses to immunotherapy and poorer survival rates across several cancer types.
Why results could be quickly transferred to human trials
Since doctors have been prescribing montelukast for asthma and allergies for years, the drug could move into cancer trials much faster than a brand new treatment, since we already understand much of the drug’s safety profile and side effects.
The next step is to determine which patients are most likely to benefit and how drugs like montelukast might work alongside existing immunotherapy treatments before moving into clinical trials.
“We may be able to quickly and safely test it in cancer patients to improve immunotherapy. Particularly in aggressive cancers, such as triple negative breast cancer, where new options are urgently needed,” Zhang said.
This article does not offer medical advice and should be used for informational purposes only.
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