SATURDAY, June 1, 2013 (HealthDay News) -- Nearly one-third of patients with advanced melanomas who received nivolumab, a new immune-based drug, experienced reductions in the size of their tumors, a preliminary study reveals.
Since these types of drugs have typically shrunk tumors in only 5 percent to 10 percent of patients in prior studies, the new results are a boost for immunotherapy generally, the researchers noted.
"I think nivolumab is a real breakthrough drug for patients with metastatic melanoma, and probably for other diseases, too," study author Dr. Mario Sznol, a professor of medical oncology at the Yale Cancer Center in New Haven, Conn., said in a news release.
"The high level of activity observed with this drug opens up a number of avenues for future research to understand and challenge the ways tumors evade the immune system. We're very excited that there is potential for even more activity in combination with other drugs," Sznol added.
One expert not connected to the study was also optimistic about the results.
"Nivolumab shows exciting promise for patients suffering from an otherwise fatal disease -- metastatic melanoma," said Dr. Michele Green, a dermatologist at Lenox Hill Hospital in New York City. "The fact that 30 percent of patients showed improvement from this immunotherapy drug is remarkable since these patients had some of the worse disease."
The study was funded by drugmaker Bristol-Myers Squibb and is scheduled for presentation Saturday at the annual meeting of the American Society of Clinical Oncology (ASCO) in Chicago. Findings presented at medical meetings are typically considered preliminary until published in a peer-reviewed journal.
According to the researchers, nivolumab works by honing in on PD-1 cellular receptors located on immune system T-cells. These receptors are known to function as immune system "gatekeepers," and by working to open such gates the patient's immune system is triggered into cancer-fighting action.
The new study involved 107 patients, all of whom had been previously treated with multiple forms of standard therapies that failed to halt their disease.
Following treatment with one of five different doses of nivolumab, the team found that 31 percent of the patients went on to experience a minimum tumor shrinkage of 30 percent across the various doses.
Forty-three percent of the patients are estimated to have survived two years after treatment, the researchers said, and average survival for patients across all treatment doses is now projected to be nearly 17 months.
In an ASCO news release, melanoma expert Dr. Lynn Schuchter called the results "truly remarkable."
The findings "confirm that 'revving' up the immune system is a powerful approach in shrinking melanoma," said Schuchter, who is also a spokeswoman for ASCO. "Melanoma patients are living longer and better with these new treatments."
However, although the study participants were described as being "typical" patients with advanced melanoma, the investigation's findings are tempered by the fact that it was not a randomized clinical trial and did not compare the impact of nivolumab directly against the performance of other drugs.
"[But] while this was not a randomized clinical trial, it had a considerable number of patients and the durability of responses is a sign of very promising clinical activity," Sznol said in the news release.
A randomized phase III trial has begun, aimed at confirming these initial findings.
Another expert agreed that the drug shows the promise of immunotherapies in general.
"The results of this study are truly remarkable and demonstrate that immunotherapy truly can make the difference for many melanoma patients," said Dr. Yvonne Saenger, assistant professor of hematology/oncology and dermatology at the Icahn School of Medicine at Mount Sinai Medical Center, New York City.
Saenger, who was not connected to the new study, noted that "earlier immunotherapies, such as interleukin 2 and even Yervoy, can only help a small minority of patients," but nivolumab seems to do much better.
There's more on melanoma at the U.S. National Cancer Institute.