Researchers said the study is important because it represents the first long-term follow-up of survival data from a trial using an “anti-PD-1” immunotherapy drug. That approach targets the PD-1 protein, which is involved in a complex process that prevents the immune system’s T-cells from attacking cancer.
“It is very encouraging that a subset of melanoma patients is experiencing a long-term survival benefit,” said F. Stephen Hodi, director of the Melanoma Center at Dana-Farber Cancer Institute and an investigator at Harvard Medical School's Ludwig Center, who led the study. The data “provide a foundation” for using anti-PD-1 drugs as standard treatment for melanoma patients, he added. “Hopefully this would translate to other cancers as well.”
Louis Weiner, director of the Georgetown Lombardi Cancer Center, who was not involved in the study, said he was impressed by the results. “A lot more people are living longer and hitting major milestones with their loved ones because of this,” he said.
The study was released at the American Association for Cancer Research annual meeting, where thousands of scientists and physicians are gathering this week to share the latest developments. Much of the research to be presented is focused on immunotherapy, which is seen as the most promising advance in cancer treatment in decades.
Doctors used the immunotherapy drug Keytruda, along with radiation, to treat former president Jimmy Carter, who announced last year that he had contracted melanoma that had spread to his brain. In early March, Carter announced that he was stopping treatment because the treatment had been so successful.
Amid their enthusiasm, researchers caution that they have a long way to go in understanding why immunotherapy helps some people and not others and in making it more effective.
The melanoma trial led by Hodi was started in 2008 to determine what dose to use in treating patients with nivolumab. The median age of the 107 patients was 61, and more than two-thirds were men. All had been treated previously for melanoma. The beneficial impact of the drug persisted for some patients even after the treatment was discontinued.
The overall survival rate for all patients fell from about 63 percent after 12 months to a little over one-third after four years, and then plateaued. Such flattening out is indicative of a long-term benefit in some patients, although more followup is needed, Hodi said.