First-Line Immunotherapy May Be Better Than Chemo for This Mesothelioma Subtype

A new study suggests that people with sarcomatoid mesothelioma may fare better if they have first-line immunotherapy before considering chemotherapy. 

Chemotherapy is the standard first-line treatment for most people with mesothelioma. But a report in the journal Translational Lung Cancer questions the wisdom of that trend.

The study focused on the outcomes of patients with the sarcomatoid mesothelioma subtype. These patients lived longer after immunotherapy than patients with other subtypes. 

When first-line immunotherapy worked best, patients produced more white blood cells. Researchers say these patients might do well to avoid having chemotherapy first.

Chemotherapy as Standard Mesothelioma Treatment

First-line immunotherapy is not the typical mesothelioma treatment. Most mesothelioma patients have chemotherapy with Alimta (pemetrexed) before other treatments. 

Alimta is the only drug to receive FDA approval for mesothelioma. It won approval in 2004. Since then, it has been the main treatment for newly-diagnosed mesothelioma of any subtype. 

But chemotherapy is only moderately effective for most mesothelioma patients. Immunotherapy is a promising new approach to treatment. Immunotherapy uses the power of the immune system to help fight cancer. 

Most studies pair immunotherapy with other therapies. But the new report says first-line immunotherapy alone may be best for some patients. 

Sarcomatoid Mesothelioma and First-Line Immunotherapy

Doctors classify mesothelioma into three subtypes. They base the subtypes on the shape and aggressiveness of the cells. Epithelioid mesothelioma is the most common subtype. It is the most responsive to treatment. 

About 10 to 20 percent of patients have the sarcomatoid mesothelioma subtype. This type of mesothelioma grows the fastest. It is also the hardest subtype to treat. The University of Melbourne study shows first-line immunotherapy may be best for these patients.  

They analyzed the cases of 22 mesothelioma patients at their hospital. Six of them had sarcomatoid mesothelioma. These patients responded best to an immune checkpoint inhibitor (ICI). 

“Of the subtypes, sarcomatoid patients displayed the greatest median progression-free survival and overall survival post ICI compared to the epithelioid subtype,” writes lead author Natasha Brockwell.

Sarcomatoid patients who had first-line immunotherapy lived longer than those who had chemotherapy first. They had an overall survival of more than 28 months compared to 11 months for the epithelioid patients. 

Interpreting the Results

Some sarcomatoid patients responded even better to first-line immunotherapy than others. Longer survival correlated with higher levels of infiltrating CD8+, CD45RO+ and CD8+CD45RO+ cells. These cells indicate an immune system response. 

The study suggests that having chemotherapy first could hinder the effects of immunotherapy in these patients. The research team concludes that first-line immunotherapy for sarcomatoid mesothelioma deserves further study. 

“These data support the expansion of trials utilizing single and combination ICIs as first-line therapy in sarcomatoid malignant pleural mesothelioma and warrants further studies testing the impact or detriment of chemotherapy pre-ICI,” writes Dr. Brockwell.

Source:

Bockwell, N, et al, “Preliminary study highlights the potential of immune checkpoint inhibitors in sarcomatoid mesothelioma”, June 2020, Translational Lung Cancer Research, pp. 639 – 645, http://tlcr.amegroups.com/article/view/40585/html