Mesothelioma is a very rare kind of malignant tumor that is caused by inhaled asbestos fibers and forms in the lining of the lungs, abdomen or heart. While there are some treatments for this disease, there is no cure, and life expectancy for most mesothelioma patients is a mere 12 months following a diagnosis. Over 30,000 people per year are diagnosed with mesothelioma and over 25,000 die from it annually.
However, new research presented at the 2019 European Society for Medical Oncology Congress reports how novel developments regarding treatment for mesothelioma. The research was based on data from the PROMISE-meso trial and compared the results of immunotherapy with the checkpoint inhibitor, pembrolizumab, with those from standard chemotherapy in patients with mesothelioma who had relapsed on or after first-line treatment. They found that such patients often responded better to immunotherapy than to chemotherapy.
"In PROMISE-meso, nearly four times more patients responded to immunotherapy than standard chemotherapy, but unfortunately these responses did not delay progression or improve survival. These findings are disappointing but, as in previous studies, some patients benefitted from immunotherapy for long periods. If we can find out how this happens, we will have a better idea of which patients should preferentially receive this treatment over chemotherapy," said study author Dr. Sanjay Popat, Royal Marsden Hospital NHS Foundation Trust, London, UK. "Nevertheless, whilst pembrolizumab was not superior to chemotherapy, survival was similar, and so pembrolizumab may represent an alternative."
As the authors of the study explain, the danger of mesothelioma stems from exposure to asbestos, and although 66 nations to date have totally or partially banned asbestos, lower and middle-income countries are taking the hit in terms of mesothelioma incidences. Furthermore, explains Dr. Federica Grosso, from the Mesothelioma and Rare Cancers Unit in Alessandria, Italy, "The worldwide number of deaths is expected to rise as people exposed to asbestos before it was banned continue to be diagnosed many years later. Mesothelioma is a huge problem because asbestos powder from the plants pollutes large areas. It isn't just people who worked in the plant who are being diagnosed, it is their families and unrelated people, some of whom are only 40-50 years old -- much younger than we would expect to see with mesothelioma.”
Popat says that this study is just the tip of the iceberg, leaving more questions than answers. "In studies of lung cancer, we have already learned that we can improve results with immunotherapy by combining it with chemotherapy and the same may be true with mesothelioma. I would advise clinicians to enroll their patients into one of the large ongoing trials of first-line combination treatment so we can get answers as soon as possible about how to improve mesothelioma treatment," urged Popat. "Meanwhile, we need to better understand which patients benefit most from immunotherapy."