Author: Maja Belamaric

Mesothelioma Treatment News: Delivering therapies directly into the pleural space

• Maja Belamaric
• Mesothelioma, Pleural Mesothelioma, Research, Treatments

In a new article published in the medical journal The Lancet (Leveraging the pleural space for anticancer therapies in pleural mesothelioma by Blythe at al., 2024), authors make an argument for renewed focus toward therapies that can be delivered directly into the intrapleural space.

The benefit of such therapies is that by targeting the tumor directly, doctors are able to use higher doses of medication for increased likelihood of success while limiting toxicity to the patient.

Pleural mesothelioma is a cancer of the lining that surrounds the lung, which is called the pleura. So far, most attention has been devoted toward finding systemic treatments that work – a feat that has proven to be quite challenging. Systemic treatments are treatments such as chemotherapy or immunotherapy, which are administered through a vein, that travel throughout the entire body to kill the cancer cells wherever they may be. These treatments are currently the standard of care, but many patients’ tumors still don’t respond to them well. Because most patients’ cancer is quite advanced at diagnosis, this approach is often the only option anyway.

However, some patients receive a very early diagnosis either incidentally, meaning they underwent a surgical procedure for a different issue when mesothelioma was found; or because they presented with fluid buildup in the pleural space (called a pleural effusion) that prompted further testing. Recent staging studies suggest that this population of patients is significantly larger than previously thought and might include anywhere between 15% to 40% of diagnoses. For such patients, benefits of systemic therapies are unclear because studies that led to the FDA approval of chemotherapy and immunotherapy predominantly included unresectable (non-surgical candidates) stage 3 and 4 patients. Typically, early-stage patients are either offered surgery, or watchful waiting. But in the past year, this approach has been further complicated by a somewhat controversial surgical study called MARS 2 which showed limited benefits of surgery in the management of mesothelioma. Therefore, the expectation is that the number of early-stage patients who receive no immediate treatment will increase.

For this reason, the authors suggest that development of studies to test the effectiveness of localized intrapleural treatment is important and feasible and can be performed during the wait period between diagnosis and standard treatment, called window of opportunity.

In its early stages, mesothelioma’s only symptom might be a pleural effusion, either symptomatic or not. If symptomatic, once the effusion is drained, the patient feels better. But as long as mesothelioma is present on the pleura, it is rare for the fluid to stop building up. Currently, there are two ways to manage this problem:

1. With a procedure called pleurodesis. The purpose of the procedure is to close the space in the pleura where fluid accumulates. This procedure makes the pleural space mostly inaccessible.
2. By inserting a drain catheter into the pleural space to drain the fluid as it builds up, thus leaving the pleural space accessible.

Critically, administering intrapleural therapy will require access to the pleura, so the initial course of action for palliation of the pleural fluid will need to be reviewed and will require consensus among providers. It is important to note that a previous pleurodesis might not necessarily be a disqualifying factor as long as pleural pockets of air/fluid are still present.

This article is a summary of a research study and does not constitute medical advice.