RSO-021 drug shows 67% disease control in mesothelioma trial

A phase one clinical trial for the experimental drug RSO-021 has shown promising results in treating mesothelioma, a rare and aggressive cancer often linked to asbestos exposure. According to research published in Nature Communications, the drug controlled disease progression in 67% of participants. In some cases, tumors also shrank, and patients receiving the treatment lived longer than those on standard therapies.

The drug utilizes a unique mechanism that turns the cancer cells' own defenses against them. Mesothelioma cells produce high levels of reactive oxygen species to manage their metabolism, and they rely on antioxidant enzymes like peroxiredoxin 3 (PRX3) to survive the resulting oxidative stress. RSO-021, a small molecule derived from the antibiotic thiostrepton, irreversibly binds to mitochondrial PRX3. This prevents the enzyme from neutralizing hydrogen peroxide, causing oxidative damage that triggers cancer cell death.

Developed by researchers at the University of Vermont and an international team, the drug is administered weekly into the pleural space via an indwelling catheter. This method aims to concentrate the medication near the tumor while minimizing systemic exposure. The trial was sponsored by RS Oncology, LLC.