A groundbreaking immunotherapy drug that effectively treats skin cancer stopped tumor growth in 76 percent of patients diagnosed with malignant pleural mesothelioma, a recent study shows.
Researchers at the University of Pennsylvania School of Medicine reported their findings involving pembrolizumab, a drug marketed under the brand name Keytruda, earlier this week at the American Association of Cancer Research (AACR) annual meeting in Philadelphia.
Twenty-five patients with mesothelioma whose disease had progressed after receiving first-line or standard chemotherapy participated in the study. Researchers administered pembrolizumab as a second-line treatment.
Results were impressive: Seven patients experienced tumor shrinkage, and 12 reported no tumor growth. Only four patients experienced tumor growth after taking the drug, and two others were not assessed at time of analysis.
“The 76 percent disease control rate is very promising and represents a signal of efficacy in the treatment of this disease,” lead study researcher Dr. Evan Alley said in a press release. “The study has provided an early glimpse of the potential benefits.”
The University of Chicago Medical Center also recently opened a phase II clinical trial involving pembrolizumab and malignant mesothelioma and currently is recruiting new patients.
Patients will receive the drug every 21 days for up to 24 months in the absence of disease progression. Researchers are hoping for an estimated 65 patients, including those whose disease has progressed following standard chemotherapy. The trial is expected to conclude March 2018.
U.S. Food and Drug Administration regulators have not approved mesothelioma treatment that progresses after first-line therapy, which typically includes a combination of surgery, chemotherapy and radiation.
However, the FDA did approve pembrolizumab in 2014 for the treatment of metastatic melanoma, a rare form of skin cancer. The drug now is being tested on a variety of other cancers, including mesothelioma.
Patients in the University of Pennsylvania study received pembrolizumab every two weeks. Researchers assessed their progress every eight weeks.
The U.S. National Institutes of Health shows there are currently 88 clinical trials testing pembrolizumab.
In addition to announcing the success of using pembrolizumab, AACR officials reported the drug’s success in treating lung cancer. It stopped cancer growth in 19 percent of 495 lung cancer patients, according to Dr. Edward Garon of the UCLA Medical Center.
Pembrolizumab works by inhibiting the ability of PD-1 and PD-L1, which are gene mutations that allow the tumor cells to grow undetected by the body’s immune system. The drug unmasks the tumor cells and activates the immune system to destroy the foreign cells. Last year, it became the first FDA approved, anti-PD-1 drug on the market.
Pembrolizumab is part of a broad, immunotherapy trend in cancer treatment today. Most researchers and oncologists agree the future of cancer care will involve more immunotherapy and less toxic chemotherapy and radiation.
Unlike chemotherapy, immunotherapy has few serious side effects. UPenn researchers reported that none of the 25 subjects of their study left because of side effects. Reports of fatigue and rash are typical of immunotherapy.
“We managed all adverse events without discontinuing treatment,” Alley said. “It was very encouraging.”
A year ago, Spanish researchers identified PD-1 and PD-L1 as being especially susceptible to pembrolizumab, but also emphasized less than 25 percent of mesothelioma patients have those mutations at high levels. Patients with those mutations have shorter survival times, according to that Spanish study.
It was unclear whether the patient selection process for the UPenn study was based on first identifying PD-1 and PD-L1 levels, which would have given researchers a much clearer target.