Researchers at the University of Vermont published findings from a new trial showing that a new cancer drug produced a high level of disease control and improved survival rates in the treatment of relapsed mesothelioma.
A team led by University of Vermont research scientist Victoria Gibson unveiled results published in the journal Nature Communications, indicating that in a phase 1 trial examining a cohort of 15 patients with relapsed pleural mesothelioma, their new drug – from a class known as a PRX3 inhibitor – controlled disease in 67% of patients and recipients lived longer than those given standard treatments.
Although much time and effort remains before such a treatment could become more widely available, it’s an exciting start.
“Our overall survival data is very promising and will hopefully persist with additional patients,” said Dr. Brian Cunniff, a University of Vermont professor who served on the research team. “Our drug has both cytotoxic activity, it can kill the tumor cells, but it also has immunomodulatory capacity where it can modulate the immune system to now manage the tumor.”
What Is a PRX3 Inhibitor?
The term “PRX3” refers to peroxiredoxin 3, an antioxidant enzyme found in a human cell’s mitochondria. When tumor cells metabolize in the human body, they produce PRX3 in order to protect themselves from reactive oxygen molecules that could damage them.
The idea of a PRX3 inhibitor came as a response to many unsuccessful clinical efforts to fight cancer. While many studies had focused on increasing antioxidants, the Vermont team looked instead to stop the production of PRX3, thus overwhelming the cancer cell with oxidative stress.
Although much of the conventional wisdom stated that the mitochondria of a cell is too important to target, previous studies on mice showed the Vermont team that PRX3 could be inhibited in a cell’s mitochondria and the animal would show no adverse effects. This opened the door for studying the same phenomenon in humans.
How This New Drug Treats Mesothelioma
The trial drug developed by the Vermont team and RS Oncology, a private pharmaceutical company founded by members of the University of Vermont Cancer Center, uses a naturally occurring antibiotic called thiostrepton to prevent a cancer cell from generating PRX3.
The absence of PRX3 disables the mitochondria’s ability to protect itself from a buildup of hydrogen peroxide, which kills the cell. The drug is administered directly into the patient’s chest cavity through a catheter. This allows a higher local concentration of PRX3 inhibitor where the cancer is located and also reduces the systemic effects. It is designed for patients with a pleural effusion – a buildup of fluid in the lining of the lungs – which is common in most mesothelioma cases.
The Vermont team was pleased by their findings. They showed that the PRX3 inhibition worked as well in humans as it had in mice, and it met its benchmarks for safety and tolerance. Aside from the impressive result of 67% disease control, their PRX3 inhibitor also showed indications of tumor reduction and overall survival rates higher than standard treatments.
Next Steps for This Mesothelioma Study
The Vermont team has already completed phase 2 of the mesothelioma trial and results are expected to be presented later this year. In the meantime, they are expanding their research program, collaborating with other institutions to develop new iterations of the PRX3 inhibitor treatment.
Further research to maximize the drug’s effectiveness on mesothelioma will be a focus in the years to come. In their study, the team conjectured that combining their PRX3 inhibitor with other immunotherapies may enhance the drug’s effectiveness.
They are also planning on researching the PRX3 inhibitor’s effectiveness in other forms of cancer, including peritoneal mesothelioma, and finding a way to distill the treatment into an oral tablet that would make it more easily brought to market.
Sources & Author
- Preclinical characterization and phase 1 clinical testing of targeting mitochondrial peroxiredoxin 3 in cancer. Nature Communications. Retrieved from https://www.nature.com/articles/s41467-026-75153-y. Accessed on 07/15/2026.
- New Cancer Drug Shows Promise in Mesothelioma Trial. University of Vermont. Retrieved from https://www.uvm.edu/uvmnews/news/new-cancer-drug-shows-promise-mesothelioma-trial. Accessed on 07/15/2026.
