The U.S. Food and Drug Administration recently upgraded its approval of pembrolizumab (Keytruda) for metastatic non-small cell lung cancer, inching it closer to becoming an accepted treatment option for pleural mesothelioma.
Pembrolizumab, produced by pharmaceutical giant Merck & Co., also is marketed as Keytruda.
The FDA's announcement last week converted its previous “accelerated” approval in second-line treatment of lung cancer to regular first-line treatment for tumors that express the PD-L1 protein.
This is the first FDA approval of a checkpoint inhibitor - a drug that unleashes an immune system attack on cancer cells - for first-line treatment of lung cancer.
The approval has fueled the growing belief that help also is on the way in the form of Keytruda for mesothelioma patients who have run out of options after chemotherapy, radiation and surgery.
“It could take a while yet, and we still don't have enough data to say for sure, but yes, [Keytruda] could become the next big thing for mesothelioma,” Dr. Tawee Tanvetyanon, oncologist at the Moffitt Cancer Center in Tampa, told Asbestos.com. “It might not be the home run, but it seems to work well in certain cases.”
Clinical Trials Demonstrate Effectiveness
The FDA approval of pembrolizumab was based on two clinical trials that showed significant improvements in overall survival and progression-free survival in comparison to chemotherapy.
There are more than 90 active clinical trials across the country today involving various cancers and pembrolizumab, but the University of Chicago has the only one in the U.S. specifically targeting pleural mesothelioma. The phase II study is expected to close March 2018.
The Moffitt Cancer Center is part of a multicenter clinical trial involving pembrolizumab and various other solid tumors. Lung cancer patients also are receiving the drug there.
Even without a trial, mesothelioma patients at several cancer centers can receive the drug through Merck's special Patients Access Program.
Keytruda worked wonders through that program for mesothelioma survivor Walter Merth, who was treated at the Abramson Cancer Center in Philadelphia. He started taking the drug earlier this year when his cancer started regrowing two months after aggressive surgery to remove it.
He credits the drug to a dramatic turnaround in his health.
“I'm getting stronger every day,” Merth said in September. “This therapy has given me a new window. It's like getting my life back, like a restart.”
Impressive Earlier Reports of Keytruda for Mesothelioma
Researchers from the Abramson Cancer Center in 2015 reported a 76 percent disease control rate with mesothelioma patients treated the previous year with pembrolizumab.
Their findings were based on 25 patients with tumors expressing the PD-L1 protein. The results were presented at the American Association for Cancer Research annual meeting.
The PD-L1 protein is what prevents a person's own immune system from killing the tumor cells. It is typically expressed in almost 50 percent of mesothelioma tumors.
“It's a treatment in its own class. It has the potential to work well with these rare cancers,” Tanvetyanon said. “With mesothelioma, when chemotherapy is no longer working, you're out of options. This could become one.”
There currently is no FDA-approved second-line treatment for mesothelioma that has progressed beyond standard therapy.
Keytruda First Approved in 2014
The FDA first approved pembrolizumab in 2014 for the treatment of melanoma. Since then, it has shown promising early results in clinical trials for several different cancers.
Former President Jimmy Carter brought considerable attention to the drug in 2015 when he credited it for stopping the melanoma cancer that had spread to his brain.
In the Chicago trial, patients are receiving pembrolizumab through a 30-minute intravenous procedure, and receiving it every 21 days for up to 24 months.
Side effects have been minimal compared to those taking chemotherapy, which is typical with most immunotherapy drugs.
In one of the non-small cell lung cancer trials, the median progression-free survival was 10.3 months, compared to just six months for those receiving chemotherapy. In the larger of the two trials, the median overall survival was 12.7 months compared to 8.5 months with chemotherapy.
“There is a lot of encouraging data out there about this drug right now,” Tanvetyanon said. “There is great potential.”