Standard Biomarkers for Pleural Mesothelioma “Not Useful” for Immunotherapy

Two of the most important biomarkers for pleural mesothelioma are not much help when it comes to tracking response to immunotherapy.

Top mesothelioma researchers at the University of Pennsylvania drew that conclusion based on data from a cohort of 58 patients. 

They focused on two primary biomarkers for pleural mesothelioma: SMRP and fibulin-3. Doctors use both of these markers to diagnose and plan treatment for mesothelioma. 

The study confirms the correlation between these markers and mesothelioma tumor volume. But the Penn Medicine researchers say these biomarkers of pleural mesothelioma were “not useful” for measuring immunotherapy response.

Understanding Biomarkers for Pleural Mesothelioma

A biomarker is a substance produced by the body that indicates a biological process or condition. Most mesothelioma biomarkers – including the two in a current study – are proteins. 

Doctors can find biomarkers for pleural mesothelioma in lung fluid. They can also find them in blood serum. Biomarker tests may be combined with biopsies, imaging studies, physical exams, and work history to make a mesothelioma diagnosis. 

Biomarkers give doctors a fast, non-invasive way to predict how a patient will respond to a mesothelioma treatment. They can also use these markers to see if the treatment is having an effect on the cancer. If the patient does not respond the way they were hoping, they can try another approach.

In 2020, some of the world’s top mesothelioma experts again confirmed the best biomarkers for pleural mesothelioma. They concluded that Soluble Mesothelin-Related Proteins (SMRPs) are the most reliable mesothelioma biomarkers. The MESOMARK assay tests for SMRPs in the blood. 

SMRP, FIbulin-3, and Immunotherapy

Mesothelioma treatment has been the same for many years. Most patients have chemotherapy. The healthiest may also have surgery. The most effective treatments use a combination of therapies. 

But mesothelioma treatment is starting to change. New treatments like the Optune Lua device and immunotherapy drugs are playing a bigger role. Last year, the FDA approved two immunotherapy drugs – Opdivo and Yervoy – for first-line treatment of pleural mesothelioma. 

To make the most of any treatment, doctors need reliable biomarkers for pleural mesothelioma response. The new University of Pennsylvania study analyzed the data on 58 mesothelioma patients. The patients enrolled in either a photodynamic therapy trial or an immunotherapy clinical trial. 

Researchers compared their SMRP and fibulin-3 levels to their tumor size. Then they compared them to their treatment response. 

“There was a strong correlation between tumor volume and serum SMRP levels, and a moderate correlation between tumor volume and serum fibulin-3 levels,” states the report in the journal Lung Cancer. 

Unfortunately, the two substances fell short as biomarkers for pleural mesothelioma immunotherapy treatment. 

“Although our data show correlations of SMRP and fibulin-3 with initial tumor volumes as measured by CT scanning, the use of SMRP and fibulin-3 as serological biomarkers in the immunotherapy trial were not useful in following tumor response longitudinally,” the researchers conclude. 

An estimated 2,500 Americans get sick with mesothelioma every year. Asbestos exposure is the primary cause.  

Source:

Katz, S, et al, “Serum soluble mesothelin-related protein (SMRP) and fibulin-3 levels correlate with baseline malignant pleural mesothelioma (MPM) tumor volumes but are not useful as biomarkers of response in an immunotherapy trial”, April 1, 2021, Lung Cancer, Volume 154, pp. 5 – 12, https://www.lungcancerjournal.info/article/S0169-5002(21)00029-5/fulltext