For many cancer patients, the most frightening part of the disease is not the original tumor but the possibility that cancer may return after treatment.
Doctors can often remove tumors through surgery and destroy large numbers of cancer cells with chemotherapy or radiation. Yet even when scans appear clear, a small number of cancer cells can remain hidden in the body.
These surviving cells can travel through the bloodstream and settle in distant organs. Months or years later, they may begin growing again, creating new tumors.
This process, known as metastasis, is responsible for the majority of cancer deaths worldwide. Preventing metastasis has become one of the biggest goals in cancer research.
A new study from Weill Cornell Medicine may provide a surprising new strategy. Researchers have developed a drug that releases small amounts of carbon monoxide inside the body and found that it can dramatically reduce cancer spread in animal studies. The findings were published in Advanced Science.
Carbon monoxide has a bad reputation for good reason. It is an odorless, colorless gas that can be deadly at high concentrations. Every year, accidental carbon monoxide poisoning causes serious illness and death around the world. Because of this, most people would never imagine that carbon monoxide could one day be used as a medicine.
However, biology is often more complicated than it seems. Scientists have discovered that human cells naturally generate very small amounts of carbon monoxide.
At these low levels, the molecule appears to help regulate important processes throughout the body. Researchers have been studying its effects for years and have found evidence that it may influence inflammation, immune responses, and cell survival.
Earlier research from the same team suggested that carefully controlled amounts of carbon monoxide could slow the spread of cancer. The challenge was delivering the gas safely. Direct inhalation is difficult to manage because the line between a helpful dose and a dangerous dose can be very narrow.
Other experimental approaches relied on metal-containing compounds that released carbon monoxide, but these left behind materials that could potentially create safety concerns.
The new study sought to overcome these obstacles. The researchers designed a metal-free prodrug called CO-116. A prodrug is an inactive substance that becomes active only after it enters the body. This allows scientists to create medicines that are more stable and easier to control.
Once administered through an intravenous injection, CO-116 slowly releases low levels of carbon monoxide. Because it contains no metals, it avoids the problem of leaving potentially harmful metal residues behind.
The researchers tested the treatment in several laboratory models of pancreatic cancer and triple-negative breast cancer. These two cancers were selected because they are among the most difficult forms of cancer to treat.
Pancreatic cancer is often diagnosed late and has a high risk of recurrence. Triple-negative breast cancer grows aggressively and lacks certain biological targets that many modern cancer drugs use.
The results were striking. Animals treated with CO-116 developed significantly fewer metastatic tumors than untreated animals.
The reduction was seen in major organs such as the liver and lungs, where cancer commonly spreads. Just as importantly, the treatment appeared well tolerated. Researchers found no obvious signs of toxicity, harmful behavior changes, or weight loss.
Another unexpected finding involved how the drug was given. Smaller doses delivered more frequently produced stronger results than larger doses given less often. This suggests that maintaining a steady biological effect may be more important than delivering a large amount of drug at one time.
The study also provided new insights into cancer biology. Researchers discovered that the treatment lowered levels of HRG1, a protein involved in transporting heme into cells. Heme is an iron-containing molecule that supports many cellular activities.
Cancer cells often depend heavily on these systems because they require large amounts of energy and resources to grow and spread.
When HRG1 levels were increased experimentally, cancer cells became more aggressive and responded less effectively to treatment. When HRG1 levels were reduced, cancer growth and spread slowed considerably. These findings suggest that HRG1 itself could become an important target for future anti-cancer drugs.
The discovery may have practical applications beyond the new drug. If future studies confirm the role of HRG1, doctors may eventually use the protein as a biomarker. In simple terms, measuring HRG1 levels could help identify patients who are most likely to benefit from carbon monoxide-based treatments.
Despite the excitement surrounding the results, researchers emphasize that this work remains preclinical. Human trials have not yet begun. Before any patient can receive this treatment, scientists must conduct additional studies to determine long-term safety, establish the best dosing schedule, and confirm that the benefits seen in animals also occur in people.
The research highlights an important lesson in medicine. Substances that are harmful in one context can sometimes become useful when carefully controlled. Many medicines used today originated from compounds that were once considered dangerous. The key is understanding how to use them safely and effectively.
This study provides some of the strongest evidence so far that a metal-free carbon monoxide prodrug can suppress cancer metastasis. The work combines innovative chemistry with cancer biology and offers a fresh approach to one of oncology’s most difficult challenges.
The strengths of the study include its detailed investigation of how the treatment works, successful testing in more than one cancer type, and the identification of HRG1 as a possible therapeutic target.
However, the findings should be interpreted cautiously because animal studies cannot guarantee success in humans. Future clinical trials will determine whether this promising strategy can become a real treatment.
For now, the research offers hope that scientists may have found a new way to stop cancer from spreading after initial treatment. If successful, this approach could help patients remain cancer-free longer and reduce the risk of deadly recurrences in some of the most aggressive forms of cancer.
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Source: Weill Cornell Medicine.
