Help could be on the way for future mesothelioma patients who need it the most.
Researchers in Spain are the first to successfully identify a specific protein found only in mesothelioma patients with the shortest survival times.
The findings should provide a clearer target for potential therapy advances, giving those cancer patients more of a fighting chance.
The United States Food and Drug Administration (FDA) earlier this year granted accelerated approval for the drug pembrolizumab, known by its brand name Keytruda, which is designed to target skin cancers. However, the drug also targets proteins in other cancers.
“The results of our study could offer new treatment options to this population of [mesothelioma] patients,” wrote study author, Dr. Susana Cedrés, of the Vall d’Hebron Institute of Oncology in Barcelona, Spain. Cedrés presented the findings at the European Society of Medical Oncology Conference in September.
Researchers found the protein called PD-L1 in the tissue samples of 20 percent of the malignant mesothelioma patients in their recent study. Those with the highest levels of PD-L1 had the shortest survival of the 119 patients studied between 2002 and 2014.
Patients with the highest levels of PD-L1 had a median survival of just 4.79 months. The patients who tested negative for PD-L1 had a median survival of 16.3 months.
PD-L1, which works alongside another protein called PD-1, has been the target of researchers looking to slow other cancers where it was previously identified. These two proteins become immune suppressors, and they stop the body’s own immune system from fighting off the cancer.
Mesothelioma researchers believe that a drug targeting or eliminating PD-L1 and PD-1 would allow the immune system to work effectively in killing cancer cells, giving patients a better chance of survival.
“The field of inhibiting this PD-1 and PD-L1 access is one where there is a great deal of excitement right now,” said Dr. Edward Garon, an oncologist from the UCLA School of Medicine, during an interview with CurrentMedicine.Tv.
The FDA in September granted accelerated approval to pembrolizumab for advanced or untreatable melanoma, a skin cancer that is the leading cause of death of skin diseases. It is the first approved anti-PD-1 drug.
The trial that led to approval included an 8.5 month response rate to the drug. It also is used in lung cancer clinical trials, providing definitive improvement in survival times.
There are various anti-PD-L1 drugs being tested and showing similar success. They are part of the broad immunotherapy trend in cancer therapy today. Most researchers agree immunotherapy, which utilizes a body’s own immune system, is the future of cancer care. Unlike toxic chemotherapy, drugs like pembrolizumab have minimal side effects by comparison.
While PD-L1 never has been associated with mesothelioma in the past, it now presents a much clearer target for researchers looking for ways to combat this disease most often caused by exposure to asbestos.
In the recent study presented by Cedrés, factors like asbestos exposure, smoking, gender and disease stage did not have an effect on whether the patient was positive for PD-L1 expression. It was more common in nonepithelial tumors.
Of the 20.7 percent of mesothelioma patients who expressed the PD-L1 protein, 18.7 percent showed strong expression, 25.1 percent showed moderate expression and 56.2 percent showed only weak expression.
“PD-L1 is associated with poor outcomes, which suggests that this pathway could be targeted with inhibitors,” Cedrés said.