Pembrolizumab Proves Effective in Fighting Pleural Mesothelioma

A new study led by investigators from the Perelman School of Medicine at the University of Pennsylvania and published this month in The Lancet Oncology, is the first to show a positive impact from checkpoint inhibitor immunotherapy drugs on malignant pleural mesothelioma, the most common form of the disease.

PembrolizumabPleural mesothelioma, the study points out, accounts for about 90 percent of all mesothelioma cases and most victims pass away within a year of diagnosis.

Currently, the standard first-line therapy is chemotherapy, usually involving the drum pemetrexed (brand name: Alimta™).

There is no approved second-line therapy for the disease. Hence, researchers and doctors are excited about the possibility of using immunotherapy drugs to combat mesothelioma, which is almost always caused by exposure to asbestos.

“There have been a lot of studies looking at different drugs, but researchers have not seen positive results,” said the study’s lead author Evan Alley, MD, PhD, chief of Hematology and Medical Oncology at Penn Presbyterian Hospital.

“But we’ve found this new class of drugs, checkpoint inhibitors, seems to be more effective than what’s been available in the past.”

Such drugs are crafted so that they free the body’s immune system so it can fight cancer cells. Pembrolizumab, which is the drug studied in this particular research, has already been used to treat melanoma, non-small cell lung cancer, and some head and neck cancers.

It’s better known by its brand name, Keytruda™. It’s likely many patients are already familiar with the name of the drug, which is seen regularly in direct-to-consumer ads on television.

The Penn study involved 25 patients over the age of 18 who had already received chemotherapy or, for some reason, were unable to be treated with chemo.

Patients received one dose of the immunotherapy drug every two weeks. In 14 of the patients, the tumor was reduced in size. Most patients went about six months without disease progression. Overall survival was 18 months although 14 patients passed during the study.

To most, those statistics still appear grim. But researchers see it as a huge step in the right direction for patients with a disease that nearly always takes lives quickly.

“Most patients who receive a second-line 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.

“One great sign in this study is that none of the patients had to stop treatment because of side-effects,” Alley said. “Some had temporary stoppages, but they were able to continue.

The drug appears to be well-tolerated,” he added, noting that the most common side effects were fatigue, nausea, loss of appetite, and dry mouth.

“This study provides evidence that some patients can have long-term disease control with this drug, which we haven’t seen before,” Alley said. “We need to better understand what we can do next to make immunotherapy more effective for more patients.”