BAP1 May Be Valuable for Peritoneal Mesothelioma Prognosis

There is new evidence that the same genetic mutation that is common in people with pleural mesothelioma may be present in many cases of peritoneal mesothelioma, too.

BAP1 is a tumor suppressing protein encoded by the BAP1 gene. People with a mutation in this gene are less likely to produce the protein and are more likely to develop certain kinds of cancer, including pleural mesothelioma.

Although there is a great deal of information linking BAP1 loss and pleural mesothelioma, which occurs on the lining of the lungs, much less is known about the link between BAP1 and peritoneal mesothelioma, which occurs in the lining of the abdomen.

BAP1 and Peritoneal Mesothelioma

To better understand the potential role of BAP1 mutation and protein expression in people with peritoneal mesothelioma, French researchers used data from an extensive national database of mesothelioma patients.

The team collected biological samples and clinical epidemiological data for 46 peritoneal mesothelioma patients.

The data was subjected to several different kinds of tests to evaluate the status of the BAP1 gene and the expression of the BAP1 protein and their relationship to mesothelioma survival.

Mutations Common Among Study Subjects

The results showed that pleural mesothelioma patients are not the only ones with genetic abnormalities. Seventy-one percent of the malignant peritoneal mesotheliomas analyzed carried at least one inactivated BAP1 allele. Fifty-seven percent exhibited a complete loss of the BAP1 protein.

But the most exciting news to come out of the new study was the fact that BAP1 loss in people with peritoneal mesothelioma was related to mesothelioma survival.

“A better overall survival was observed for patients with BAP1 mutations, protein expression loss, or at least one of these alterations, independently of tumor histology, age, and gender,” write the authors in an article in the Journal of Thoracic Oncology.

The authors conclude that not only is BAP1 inactivation common in peritoneal mesothelioma, but that it can also be a helpful prognostic marker.

Similar to Pleural Mesothelioma Research

The results are similar to those of studies on BAP1 loss and pleural mesothelioma. A 2016 study published in the journal Oncotarget found BAP1 loss in 63 percent of pleural mesothelioma biopsies, a figure consistent with previous data.

That report suggested that BAP1 staining could help distinguish pleural mesothelioma from lung cancer; the two produce similar symptoms but may respond differently to treatment.

In 2015, a separate study found that pleural mesothelioma patients with BAP1 mutations may live longer than those without these genetic alterations.

Sources:

Leblay, N, et al, “BAP1 is altered by copy number loss, mutation, and/or loss of protein expression in more than 70% malignant peritoneal mesotheliomas”, December 27, 2016

Carbone, M, et al, “Positive nuclear BAP1 immunostaining helps differentiate non-small cell lung carcinomas from malignant mesothelioma”, July 18, 2016, Oncotarget, Epub ahead of print