Researchers at the Memorial Sloan Kettering Cancer Center are experimenting with a combination of CAR-T cell therapy and Keytruda, a PD-1 blocker for the treatment of pleural mesothelioma. This is the first time that these two therapies have been combined. The results were recently published in Cancer Discovery. Mesothelioma is an aggressive cancer of the pleural membrane, which is the mesothelium that surrounds the lungs. People diagnosed with mesothelioma typically worked with asbestos many years prior to their diagnosis. Once asbestos is inhaled, the body cannot break it down or remove it, leading to cells turning into cancer cells.
Doctors have known about mesothelioma for a long time, but there is still no cure. Different treatments are available but unfortunately the best thing they can do is extend the lives of patients and make them more comfortable. Chemotherapy and radiation are the standard treatments, and if a patient is well enough, they can undergo surgery to remove most of the cancer. Researchers have been experimenting with immunotherapy, which utilizes the body’s immune system to fight cancer. Not every type of immunotherapy for mesothelioma has been effective, but the new CAR-T cell therapy and Keytruda combination is showing real promise.
T-cells are part of the immune system. CAR-T cell therapy utilizes these cells by removing them from the body and changing them to attack cancer cells. The researchers in this study removed the T-cells and made them attack cells that express the protein mesothelin, which is the protein that is on the surface of mesothelioma cells. The problem with just using T-cells is that mesothelioma cells release a protein that repels them (PD-1). The remedy for this is Keytruda, because it is a PD-1 blocker.
The immunotherapy combination of Keytruda and CAR-T cell therapy allows T-cells to attack mesothelioma cells unincumbered. Twenty-five patients were given CAR-T cells, with 18 of them also receiving Keytruda. The patients had an overall survival of 23.9 months and 83 percent lived at least one year. Eight of the patients in the study had stable disease (no progression) for six months or more. The researchers also looked at the safety and comfort with this therapy. It was well tolerated and considered safe, meaning more studies can be done to help determine efficacy.
