The largest study yet on PD-L1 expression and mesothelioma prognosis shows that patients with more of this protein in their cells have poorer odds of survival.
Programmed death ligand 1 (PD-L1) helps cancer cells evade immune system attack.
Other studies have suggested a link between PD-L1 expression and mesothelioma prognosis. But the new meta-analysis performed by two Chinese researchers appears to confirm it with an even bigger data set.
Understanding Mesothelioma Prognosis
Malignant mesothelioma is an uncommon cancer that typically carries a poor prognosis. Many people diagnosed with mesothelioma lose their lives to the illness within a year.
But there are also many exceptions. Some mesothelioma survivors live for decades after a mesothelioma diagnosis. Australian Paul Kraus is an example.
Researchers have only recently made the connection between PD-L1 expression and mesothelioma prognosis. This cancer-protecting protein is one of many factors that influence mesothelioma survival.
Women, younger people, and those with few other health problems have the best survival odds. Those with the epithelioid mesothelioma subtype also tend to live longer.
The Impact of PD-L1 Expression on Mesothelioma Prognosis
PD-L1 is a protein that exists naturally in the body. It suppresses the part of the immune system that attacks foreign tissues. This is protective in a situation such as pregnancy and some auto-immune diseases.
But in the case of mesothelioma, this is not a good thing. PD-L1 expression negatively impacts mesothelioma prognosis because it protects the wrong kind of cells.
Without the immune system to help keep them in check, mesothelioma tumors can grow and spread even faster.
Mesothelioma Survival and Elevated PD-L1
The Chinese researchers combed the medical literature for studies on PD-L1 expression and mesothelioma prognosis. They focused on studies that measured PD-L1 levels in pleural mesothelioma tissue samples.
Eleven studies met their criteria. They included a total of 1,606 patients. The researchers found that “PD-L1 remained a significant prognostic indicator for worse overall survival.”
PD-L1 expression was higher in patients with non-epithelioid mesothelioma. People with non-epithelioid mesothelioma subtypes tend to have shorter survival.
“Results of this meta-analysis show that elevated expression of PD-L1 could be a factor predicting poorer survival in patients with malignant pleural mesothelioma,” write the researchers.
Zhang, F, and Gong, W, “Prognostic and clinicopathological utility of programmed death-ligand 1 in malignant pleural mesothelioma: A meta-analysis”, April 24, 2020, International Immunopharmacology, Epub ahead of print, https://www.sciencedirect.com/science/article/pii/S1567576920306639?via%3Dihub