Nothing else has been very effective either in the metastatic melanoma setting, the researchers said, noting that enrollment in a clinical trial for an experimental treatment is considered the standard of care once chemotherapy or other commonly used treatments fail.
"Melanoma is one of the cancers that is relatively chemoresistant and does not have any options so far," Rietschel said.
However, Rietschel warned, the targeted agent isn't without its side effects.
"You have to be very careful with this and pay attention to stop it in time," Rietschel said.
Immune-related adverse events were most common with the drug, and seven of the 14 deaths in the study were associated with immune-related adverse events.
"Adverse events can be severe, long-lasting, or both, but most are reversible with appropriate treatment," Hodi's group wrote in the New England Journal of Medicine, where the results were published.
Ipilimumab works by removing the "brakes" on the immune system's attack on melanoma by blocking a specific molecule that acts as a checkpoint in the body's destruction of cancer cells.
Hodi's trial involved 676 patients with stage III or IV melanoma that could not be removed through surgery. The researchers reported that ipilimumab reduced risk of progression of the disease, and it also appeared to improve survival rates in the patients taking the drug.
These data will likely be enough to approach the U.S. Food and Drug Administration for an indication in refractory metastatic melanoma, study coauthor Dr. Jedd Wolchok of Memorial Sloan-Kettering Cancer Center in New York City said in an interview.
"If [ipilimumab] gets approved, I think it will be used for the majority of people with metastatic melanoma in the United States," he said.