In the largest study ever performed in patients with advanced melanoma, researchers showed that the immunotherapy medication pembrolizumab (Keytruda) put the cancer in regression with treatment effects lasting up to three years. With pembrolizumab available on the market, the numbers mean hope to melanoma patients worldwide.
The study, “Association of Pembrolizumab With Tumor Response and Survival Among Patients With Advanced Melanoma,” published recently in JAMA Oncology, is a follow-up trial of a Phase 1 study performed before theU.S. Food and Drug Administration (FDA) approved the drug in 2015.
Pembrolizumab belongs to a class of new anticancer drugs known as checkpoint inhibitors, which block the checkpoint protein PD1 on immune cells. Unchecked, the protein prevents the immune system from turning on – cancer cells use it to evade attacks by immune T-cells. With Pembrolizumab to block the factor, the immune system can use its full potential to destroy the cancer.
Led by professor of hematology and oncology Dr. Antoni Ribas, director of the University of California, Los Angeles Jonsson Comprehensive Cancer Center Tumor Immunology Program, the study included 655 patients with advanced disease and little hope of benefit from traditional approaches.
Testing three different dosing regimens, the trial concluded no difference in effects between the doses but the drug led to a regression of cancer in 33% of patients. Looking only at a group of patients who had not received prior melanoma treatment, regression was observed in 45%.
The durability of the drug was also noted: 44% of patients responded for at least one year; the 12-month progression-free survival was 35% in the whole group and 52% among first-time treated patients. Median survival time among the first-time patients also was considerable: 31 months versus 23 months for the entire group.
The treatment was generally well tolerated, with adverse events occurring in 14% of participants. Only 4 percent experienced side effects severe enough to motivate discontinuation of treatment – much lower than associated with chemotherapy approaches. In all, 74% continued to respond from one to more than three years.
“The early data from this research showed the unprecedented activity of pembrolizumab in people with advanced melanoma, and we can now report the full results of the study,” Ribas said in a press release.