"Pembrolizumab an antibody drug already used to treat other forms of cancer can be effective in the treatment of the most common form of mesothelioma according to a new study led by investigators from the Perelman School of Medicine at the University of Pennsylvania. The study published this month in The Lancet Oncology is the first to show a positive impact from checkpoint inhibitor immunotherapy drugs on this disease.  Malignant pleural mesothelioma is a rare and aggressive cancer that represents about  percent of all malignant mesothelioma cases. Its primarily caused by the inhalation of asbestos a fiber commonly found in some forms of insulation vinyl floor tiles and other material. Tumors form in the pleura a thin membrane of cells that line the lungs and chest wall. Most patients survive less than a year. This poor prognosis is partially due to the fact that most patients are not diagnosed until they are already at a late stage of the disease. The standard firstline therapy treatment involves chemotherapy and currently there is no approved secondline therapy.  There have been a lot of studies looking at different drugs but researchers have not seen positive results said the studys lead author Evan Alley MD PhD chief of Hematology and Medical Oncology at Penn Presbyterian Hospital. But weve found this new class of drugs checkpoint inhibitors seems to be more effective than whats been available in the past.  Checkpoint inhibitors are a class of drugs designed to free the bodys immune system to fight back against cancer. Pembrolizumab in particular has been used to treat melanoma nonsmall cell lung cancer and in some cases head and neck cancers.  Alley and his team presented data from KEYNOTE an ongoing trial involving  different research sites in six different countries all looking at the effect of pembrolizumab on patients with advanced malignancies including malignant pleural mesothelioma. The study evaluated  patients with pleural mesothelioma all of whom were over the age of  and had either already been treated with chemotherapy or were unable to receive it. Patients who had already received another checkpoint inhibitor were not included in the study.  Beginning with the first enrollees two years ago doctors gave each patient a dose of pembrolizumab every two weeks. The tumor reduced in size in  of those patients. On average patients went about six months without their disease progressing and overall survival was about  months. Fourteen patients passed away during the study while four were still undergoing treatment as of the studys writing.  Most patients who receive a secondline therapy have a life expectancy of about six or seven months so to have four patients still ongoing at two years is very encouraging Alley said.  The most common sideeffects reported were fatigue nausea loss of appetite and dry mouth.  One great sign in this study is that none of the patients had to stop treatment because of sideeffects Alley said. Some had temporary stoppages but they were able to continue. The drug appears to be welltolerated.  There are multiple studies going on right now to confirm these findings which the authors note is a necessary step before the drug can become a standard secondline therapy. This study provides evidence that some patients can have longterm disease control with this drug which we havent seen before Alley said. We need to better understand what we can do next to make immunotherapy more effective for more patients.  Alley said there are already plans for trials that will test combination therapies which will utilize pembrolizumab in conjunction with other treatments. Those studies are expected to launch later this year including two at Penn.  The study was funded by Merck which manufactures pembrolizumab. Alley has no personal financial relationship with Merck.  Penn Medicine is one of the worlds leading academic medical centers dedicated to the related missions of medical education biomedical research and excellence in patient care. Penn Medicine consists of the Raymond and Ruth Perelman School of Medicine at the University of Pennsylvania founded in  as the nations first medical school and the University of Pennsylvania Health System which together form a . billion enterprise.  The Perelman School of Medicine has been ranked among the top five medical schools in the United States for the past  years according to U.S. News  World Reports survey of researchoriented medical schools. The School is consistently among the nations top recipients of funding from the National Institutes of Health with  million awarded in the  fiscal year.  The University of Pennsylvania Health Systems patient care facilities include The Hospital of the University of Pennsylvania and Penn Presbyterian Medical Center  which are recognized as one of the nations top Honor Roll hospitals by U.S. News  World Report  Chester County Hospital Lancaster General Health Penn Wissahickon Hospice and Pennsylvania Hospital  the nations first hospital founded in . Additional affiliated inpatient care facilities and services throughout the Philadelphia region include Chestnut Hill Hospital and Good Shepherd Penn Partners a partnership between Good Shepherd Rehabilitation Network and Penn Medicine.  Penn Medicine is committed to improving lives and health through a variety of communitybased programs and activities. In fiscal year  Penn Medicine provided . million to benefit our community."