Retraining immune cells to fight cancer again
A common asthma medication, taken daily by millions without a second thought, may carry within it an unexpected power against cancer. Researchers at Northwestern University have found that montelukast can disrupt the molecular trick tumors use to turn the body's own immune cells into their protectors — effectively retraining those cells to fight back. Published in Nature Cancer, the findings span five cancer types in mouse models and are bolstered by patterns observed in human patient data, suggesting the mechanism may not be confined to the laboratory. Because the drug's safety is already established through decades of clinical use, the distance between this discovery and human trials may be shorter than the road usually traveled.
- Tumors have evolved a molecular switch — CysLTR1 — that hijacks neutrophils, flipping immune defenders into cancer accomplices, and montelukast appears to shut that switch off.
- The stakes are especially high for triple-negative breast cancer, one of oncology's most resistant and aggressive diseases, where standard therapies and even immunotherapy frequently fail.
- Across five cancer models in mice, blocking CysLTR1 slowed tumor growth, extended survival, and in some cases revived immunotherapy responses in tumors that had stopped responding.
- Human tumor samples and large patient databases showed the same pattern — higher CysLTR1 activity correlated with shorter survival and poorer immunotherapy outcomes — lending critical real-world weight to the mouse findings.
- Because montelukast already holds FDA approval and carries a well-documented safety record, clinical trials could launch far sooner than would be possible with an entirely new compound.
A drug that millions take daily for asthma and allergies may have a second life as a cancer weapon. Northwestern University researchers published findings in Nature Cancer showing that montelukast can reprogram immune cells to recognize and attack tumors that have learned to hide from the body's defenses.
The discovery centers on a molecular mechanism some cancers have mastered. Tumors activate a molecule called CysLTR1, which hijacks neutrophils — a type of white blood cell — converting them from cancer fighters into tumor protectors. When Northwestern immunologist Bin Zhang's team blocked that molecule, first in genetic models and then with montelukast itself, the neutrophils were retrained to resume their natural role as attackers. The drug, Zhang noted, does not assault cancer directly; it restores the immune system's own capacity to do so.
The team tested the approach across five cancer types in mice — triple-negative breast cancer, melanoma, ovarian, colorectal, and prostate cancer. In several models, montelukast halted tumor progression, extended survival, and restored immunotherapy responsiveness in previously resistant cases. Triple-negative breast cancer, notoriously difficult to treat and often unresponsive to immunotherapy, drew particular attention from specialists.
To validate the findings beyond mice, the researchers examined human tumor samples and large patient databases. The pattern held: higher CysLTR1 activity consistently correlated with shorter survival and poorer immunotherapy outcomes across cancer types.
What makes the path forward unusually short is montelukast's existing FDA approval and decades of established safety data. Researchers can move toward human trials without the lengthy preclinical groundwork new compounds require. The next steps involve confirming the mechanism in patients, identifying who benefits most, and designing trials that pair montelukast with existing immunotherapy regimens — a new chapter in cancer treatment, potentially written with a drug already sitting in medicine cabinets.
A medication that millions of people swallow each day for asthma and allergies may have a second life as a cancer fighter. Researchers at Northwestern University in Chicago published findings in Nature Cancer showing that montelukast—the generic name for a drug prescribed for decades to manage respiratory symptoms—can reprogram the immune system to recognize and attack tumors that have learned to hide from the body's defenses.
The discovery hinges on a molecular sleight of hand that some cancers have perfected. Tumors activate a molecule called CysLTR1, which functions like a switch. When flipped on, it hijacks a type of white blood cell called neutrophils, converting them from cancer fighters into tumor protectors. The Northwestern team, led by immunology professor Bin Zhang, tested what happened when they turned that switch off—first in genetic models, then with montelukast itself. The results were striking. Not only did blocking CysLTR1 slow tumor growth, but it also rewired the neutrophils, transforming them back into cells capable of recognizing and attacking cancer.
Zhang described the mechanism with precision: the drug does not simply assault the cancer directly. Instead, it retrains abundant immune cells already circulating in the body to resume their natural role as tumor fighters. This distinction matters because it suggests a path toward making immunotherapy work in cases where it currently fails.
The team tested their hypothesis across five cancer types in mice: triple-negative breast cancer, melanoma, ovarian cancer, colorectal cancer, and prostate cancer. In several of these models, blocking CysLTR1 with montelukast halted tumor progression, extended survival, and in some cases restored responsiveness to immunotherapy in tumors that had become resistant to the treatment. Triple-negative breast cancer is particularly aggressive and notoriously difficult to treat; it does not respond well to conventional therapies, and immunotherapy—which has transformed oncology over the past decade—often fails in these cases. The possibility of a new tool for this disease generated immediate interest among specialists.
To strengthen their findings, the researchers examined human tumor samples and analyzed public databases containing information from thousands of patients. The pattern was consistent: patients with higher CysLTR1 activity tended to have shorter survival times and poorer responses to immunotherapy across multiple cancer types. This human data provided crucial validation that the mechanism they observed in mice might translate to real patients.
What accelerates the path forward is montelukast's existing FDA approval and decades of clinical use. The drug's safety profile is well established, which means researchers can move toward human trials without the lengthy preclinical work typically required for new compounds. Zhang emphasized this advantage: the team could test the approach quickly and safely in cancer patients to enhance immunotherapy, particularly in aggressive cancers like triple-negative breast cancer where new options are urgently needed.
The next phase involves confirming the mechanism in actual patients, identifying which patient profiles will benefit most, and designing clinical trials that combine montelukast with existing immunotherapy regimens. The research was funded by the National Cancer Institute and the National Institutes of Health. What began as a question about how tumors evade immune detection may soon open a new chapter in cancer treatment—one written with a drug that has been sitting in medicine cabinets for generations.
Citações Notáveis
We're not just attacking the cancer, we're retraining a type of immune cell abundant in the body to fight the tumor again— Dr. Bin Zhang, Northwestern University
We could test this quickly and safely in cancer patients to improve immunotherapy, especially in aggressive cancers like triple-negative breast cancer where new options are urgently needed— Dr. Bin Zhang, Northwestern University
A Conversa do Hearth Outra perspectiva sobre a história
So the drug itself isn't new. Why does that matter so much for getting this to patients?
Because safety data already exists. Montelukast has been used for decades in millions of people. Researchers don't have to spend years proving it won't cause unexpected harm. They can move straight to testing whether it actually works against cancer.
But they only tested it in mice. How confident should we be?
The mouse data is compelling—five different cancer types showed the effect. And they backed it up by analyzing human tumor samples and patient databases. The pattern held. But you're right: mice aren't people. That's why the clinical trials matter.
What's the mechanism again? I want to make sure I understand it.
Tumors trick the immune system by activating a molecule called CysLTR1. This molecule converts neutrophils—white blood cells that should attack cancer—into protectors of the tumor instead. Montelukast blocks that molecule, which flips the neutrophils back to their original job.
So you're not killing the cancer directly. You're fixing the immune system.
Exactly. You're retraining cells that are already in the body. That's why it's different from traditional chemotherapy. It's more like waking up a sleeping defense system.
Why is triple-negative breast cancer mentioned so much?
Because it's one of the hardest cancers to treat. It doesn't respond to hormone therapies, and immunotherapy—which works well for many cancers—often fails. If montelukast can help there, it fills a real gap.
What happens next?
Clinical trials. The researchers need to confirm the mechanism works in actual patients, figure out which patients benefit most, and test whether combining montelukast with immunotherapy is safe and effective. That could start soon.