Cancer treatment has improved greatly over the past few decades.
Many people with cancer can now undergo surgery, chemotherapy, radiation therapy, or newer targeted treatments and achieve excellent results.
Yet one of the biggest challenges remains the same: preventing cancer from returning after treatment appears successful.
This problem is especially serious for pancreatic cancer and triple-negative breast cancer. Both diseases are known for their aggressive nature and their ability to spread to other parts of the body.
Even after doctors remove visible tumors and use chemotherapy to destroy cancer cells, tiny clusters of cancer cells can sometimes survive.
These hidden cells may remain undetected for months or even years before forming new tumors in organs such as the liver or lungs.
Scientists around the world have been searching for ways to stop this process, known as metastasis. Metastasis is responsible for most cancer-related deaths. Finding a treatment that can prevent cancer cells from spreading could save many lives and dramatically improve long-term survival.
Now, researchers at Weill Cornell Medicine have reported a promising new approach. Their study, published in the journal Advanced Science, describes a specially designed compound that releases small amounts of carbon monoxide inside the body. The treatment significantly reduced the spread of cancer in laboratory animal studies.
At first glance, the idea sounds surprising. Carbon monoxide is widely known as a poisonous gas. Exposure to high levels can be deadly because it prevents the blood from carrying enough oxygen.
However, scientists have learned that the human body naturally produces tiny amounts of carbon monoxide during normal biological processes. At low levels, the gas appears to play important roles in regulating inflammation, cell communication, and tissue repair.
Several years ago, the research team discovered that low doses of carbon monoxide could slow the spread of cancer in preclinical studies. The challenge was finding a safe way to deliver it. Breathing carbon monoxide directly is difficult to control and carries obvious safety concerns.
Previous attempts to develop carbon monoxide-releasing drugs often relied on compounds containing metals such as iron, manganese, or ruthenium. While these compounds could release carbon monoxide, they also left behind metal-containing substances that could potentially cause side effects.
To solve this problem, the researchers created a metal-free carbon monoxide prodrug. A prodrug is a medicine that remains inactive until it enters the body, where it is converted into its active form. This design allows scientists to control when and where the active compound is released.
The new compound, known as CO-116, was developed with help from researchers at Georgia State University. Once injected into the bloodstream, it gradually releases controlled amounts of carbon monoxide without leaving behind potentially harmful metal residues.
The team tested CO-116 in several mouse models of pancreatic cancer and triple-negative breast cancer. The results were encouraging. Animals treated with the compound developed far fewer metastatic tumors in their lungs and livers compared with untreated animals.
Importantly, researchers did not observe obvious signs of toxicity. The treated animals maintained normal body weight and behavior throughout the experiments.
One of the study’s most interesting findings involved dosing schedules. Researchers discovered that giving smaller doses more frequently worked better than administering a larger dose once a week.
Although the total amount of drug was the same, spreading the treatment over time appeared to produce stronger anti-cancer effects. This finding suggests that timing may be just as important as dosage when developing future therapies.
The scientists also wanted to understand why the treatment worked. Their investigation revealed that CO-116 reduced levels of a protein called HRG1.
This protein helps cancer cells absorb heme, a molecule that contains iron and supports many essential cellular functions. Cancer cells often depend on these biological pathways to survive, grow, and spread.
By lowering HRG1 levels, the treatment interfered with a chain of events that normally helps cancer cells move through the body and establish new tumors. Additional experiments strengthened this conclusion.
When researchers increased HRG1 levels, cancer cells became more aggressive and less responsive to treatment. When they reduced HRG1 levels, cancer growth and spread slowed significantly.
These findings suggest that HRG1 may become an important target for future cancer therapies. It may also help doctors identify which patients are most likely to benefit from treatments like CO-116.
Although the results are exciting, the research is still at an early stage. The treatment has only been tested in animal models and has not yet been evaluated in humans. Many questions remain unanswered, including the long-term safety of the compound, the best dosing schedule, and whether the benefits continue after treatment stops.
The findings represent an important advance because they demonstrate for the first time that a non-inhaled, metal-free carbon monoxide prodrug can suppress metastasis in multiple cancer models.
This opens a completely new area of cancer research and may eventually lead to treatments designed specifically to prevent cancer from returning after surgery or chemotherapy.
The study’s strengths include testing the treatment in multiple cancer models, identifying a clear biological mechanism, and demonstrating a favorable safety profile in animals. However, the research also has limitations.
Results from mice do not always translate directly to humans, and many promising cancer treatments fail during clinical trials. Further studies will be needed before doctors know whether the approach can truly benefit patients.
Even with these uncertainties, the discovery offers a hopeful glimpse into the future. If future research confirms these findings, a carefully controlled carbon monoxide-releasing treatment could become a powerful tool against one of cancer’s greatest threats: its ability to spread and return after treatment.
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