By Dennis Thompson
THURSDAY, May 19, 2016 (HealthDay News) -- A new drug for advanced melanoma is dramatically shifting the odds in favor of patients, extending survival for many and even curing some.
The drug also caused complete remission in 15 percent of patients, and many remained cancer-free even after they quit taking Keytruda, said Dr. Caroline Robert, head of the dermatology unit at the Institut Gustave-Roussy in Paris, France.
Keytruda already has scored one very high-profile success -- it's one of the drugs taken by former President Jimmy Carter, 91, in his successful battle last year against melanoma that had spread to his brain.
However, the drug comes with a hefty price tag -- an estimated $12,500 a month.
Prior to the advent of targeted therapies like Keytruda, advanced melanoma patients had an average survival prognosis of less than one year, Robert said.
"Pembrolizumab provides long-term survival benefit in patients with advanced melanoma, with 41 percent of patients alive at three years, which is so different from what we've come from," Robert said. "We have durable responses in one-third of the patients, and we have complete responses that are durable even after stopping the treatment."
The latest clinical trial findings, which are the first long-term follow-up results for Keytruda, are to be presented at the American Society of Clinical Oncology (ASCO) annual meeting in Chicago next month. Research presented at meetings is typically considered preliminary until published in a peer-reviewed journal.
Cancer expert Dr. Don Dizon called the results "incredibly exciting."
"I think it's incredibly encouraging that we could see a potential cure in melanoma as evidenced by the very prolonged response rate and the durability of this response," said Dizon. He is an ASCO spokesman and clinical co-director of gynecologic oncology at Massachusetts General Hospital in Boston.
Keytruda helps the body's immune system locate and destroy tumor cells by thwarting a genetic cloaking mechanism that cancer has developed to avoid immune detection.
"It teaches the body's own immune system how to fight and control melanoma," said Dr. Michael Postow, an oncologist specializing in immunotherapy with Memorial Sloan Kettering Cancer Center in New York City.
Robert's clinical trial involved 655 patients diagnosed with advanced melanoma. Three-fourths of the patients had received other treatments for their cancer prior to the study.
Participants received Keytruda either every two or three weeks. The drug is administered via IV.
Long-term follow-up showed that four out of 10 patients were alive three years after starting Keytruda, whether or not they had been previously treated.
Further, 95 patients went into complete remission after taking Keytruda, Robert said.
Of those patients, 61 stopped taking Keytruda after they were judged cancer-free, Robert said. Only two wound up relapsing.
About 8 percent of the patients dropped out of the study due to drug side effects, Robert said. The most common were fatigue (40 percent), itchiness (28 percent) and rash (23 percent).
But, Postow said, "Most patients get through the drug without any serious side effects."
The main downside is the cost of the drug. The drug's maker, Merck, has set the price at about $12,500 a month, or about $150,000 a year, according to The New York Times.
"It is pretty expensive, unfortunately," Postow said.
The clinical trial received funding and support from Merck.