Research: Stop Leaving Sarcomatoid Mesothelioma Patients Out of Immunotherapy Trials

When a clinical trial begins, the researchers in charge will pick specific criteria for their study. These rules may exclude a segment of people, for any number of reasons.

A quick scan of most clinical trials for mesothelioma reveals a commonality: Researchers frequently exclude people with the sarcomatoid cell type of this cancer.

It isn’t a secret why, either. Sarcomatoid mesothelioma has the most discouraging prognosis of all cell types. Researchers usually want epithelioid mesothelioma cases because this cell type is usually more responsive to treatment. In layman’s terms, their study has a better chance of success.

However, a new report published in Translational Lung Cancer Research refutes this long-held hypothesis. Studies that test new therapies, explicitly immunotherapy, may want to enroll sarcomatoid mesothelioma patients.

 

Difference in Prognosis Between Cell Types

Epithelioid mesothelioma generally has the best prognosis, and these patients are the most-sought-after for clinical trials.

Biphasic mesothelioma is a mixture of both epithelioid and sarcomatoid cells. Many studies begrudgingly accept biphasic patients or “will consider them,” as some researchers explain, simply to meet the participant goal.

Sarcomatoid mesothelioma? Very unlikely. And it’s understandable why.

Numerous studies have compared the prognosis between the three main cell types. According to a study published on UpToDate:

• The average life expectancy for people with epithelioid pleural mesothelioma is 19 months
• The average survival expectancy for people with biphasic pleural mesothelioma is 13 months
• The average prognosis for sarcomatoid pleural mesothelioma cases is just 8 months

Due to this disparity, people with sarcomatoid mesothelioma are often denied treatment opportunities. Some cancer centers won’t enroll these patients into their protocols.

If there’s evidence that refutes the stigma surrounding sarcomatoid mesothelioma, it may lead to more hope for people with this cancer.

 

Immunotherapy for Sarcomatoid Mesothelioma

The researchers pulled data from multiple studies testing immunotherapy for mesothelioma. The studies used immune checkpoint inhibitors, such as Keytruda or Opdivo. These drugs block the effectiveness of the cancerous protein PD-L1, which can trick the body’s T-cells into thinking mesothelioma tumors are harmless.

The report included 22 cases of malignant pleural mesothelioma. Most (13) were the epithelioid subtype, and six were sarcomatoid cases.

The overall survival was 11.1 months, but there was a massive difference between the two cell types:

• 28 months on average for sarcomatoid patients
• Around 11 months on average for epithelioid patients

The researchers found that patients who got immunotherapy as a first-line treatment had “greater progression-free survival” than those who received it after chemotherapy. Traditionally, sarcomatoid patients are recommended chemotherapy as the initial treatment method.

“These data support the expansion of trials utilizing single and combination (immune checkpoint inhibitors) as first-line therapy in sarcomatoid (mesothelioma),” the report concludes.