RS Oncology has dosed the first subject in the dose expansion part of its multicentre Phase II MITOPE clinical trial of RSO-021 to treat malignant pleural mesothelioma and metastatic disease to the lung, in the UK.

This development marks a significant milestone in the development of the company’s investigational anti-cancer treatment, RSO-021.

The therapy has been designed to act on malignant cells selectively by disrupting their antioxidant defences.

A small molecule that irreversibly binds to mitochondrial peroxiredoxin 3 (PRX3), it is administered every week into the pleural space after MPE [malignant pleural effusion] drainage through an indwelling pleural catheter.

The Phase II portion of the MITOPE trial follows the successful completion of the Phase I dose escalation, which established the recommended dose and safety profile for RSO-021.

Preclinical studies have demonstrated that its mechanism of action can kill malignant cells by increasing oxidative stress, while healthy cells remain unaffected.

The expanded Phase II portion of the MITOPE trial will now investigate the anti-cancer activity of RSO-021 in various patient groups.

These subjects include those with MPE due to malignant pleural mesothelioma, relapsed disease post-first-line standard-of-care treatment, and local metastatic lung disease.

The therapy will also be analysed for MPE in advanced metastatic breast, ovarian, and non-small cell lung cancer patients, along with systemic paclitaxel.

A buildup of fluid in the pleural lining of the lungs, MPE is a symptom in approximately 15% of end-stage cancer patients, causing significant morbidity.

RS Oncology focuses on improving the lives of patients with aggressive cancers, with an initial focus on pleural mesothelioma and cancers with metastatic disease to the lung.

RS Oncology CEO Jarrett Duncan said: “RSO-021 is an exciting novel anti-cancer treatment that can potentially help a global population of cancer patients who are left with little to no options.

“Commencing the Phase II portion of our trial presents a major milestone for patients and their caregivers.”