Doctors in Pennsylvania reported this week that combining immunotherapy drugs with radiotherapy could help to more efficiently treat malignant pleural mesothelioma.

The analysis from the University of Pennsylvania looked at studies that combined immunotherapy drugs like Merck‘s (NYSE:MRK) Keytruda with radiation therapy. The team concluded that radiotherapy may boost the cancer-killing effects of immunotherapies.

Malignant pleural mesothelioma is a rare form of lung cancer that is closely related to asbestos exposure. It’s highly invasive and the current median survival time with standard treatment is less than 1 year.

Traditionally, patients with the rare cancer are treated using surgical resection, radiotherapy and chemotherapy. But more recently, companies have investigated the use of immunotherapy drugs, such as immune checkpoint inhibitors, in treating mesothelioma.

PD-1 inhibitors, like Keytruda, avelumab and nivolumab, block a cell surface protein that is sometimes expressed by mesothelioma tumors.

“Radiation therapy may itself be immunomodulatory,” Dr. Evan Alley of the Penn Presbyterian Medical Center wrote. “The combination of radiation therapy and immunotherapy can serve to achieve a synergistic therapeutic effect.”

The team recommended that further work be conducted regarding the combined effects of the therapies in the treatment of mesothelioma.