Drug Shows Early Promise Against Advanced Melanoma
Helps immune system recognize, kill cancer cells, researchers explain
By Amy Norton
TUESDAY, April 8, 2014 (HealthDay News) -- An experimental cancer drug that activates the immune system has shown early promise for advanced cases of melanoma skin cancer, researchers report.
The findings come from an early stage trial of just 31 patients. But experts were cautiously optimistic about what the study showed: The drug's side effects were manageable, and four patients saw their tumors shrink.
That's a small number, but a trial like this is largely aimed at seeing whether a drug is safe and finding a tolerable dose.
"Any time you see some responders in an early study, it's encouraging," said Dr. Jeffrey Weber, a melanoma expert at the Moffitt Cancer Center in Florida, who was not involved in the research.
Much more remains to be learned about the drug -- known for now as IMCgp100. "But," Weber said, "it is good enough to show some activity in an early stage trial. It's definitely worth pursuing."
IMCgp100 is just one of several "immunotherapies" under study for advanced melanoma. The general idea behind immunotherapy is to help the body's immune system do a better job of recognizing and killing off cancer cells.
Melanoma is the rarest, but deadliest, form of skin cancer. Caught early, it's curable with surgery. But once it spreads to distant lymph nodes or other organs -- known as stage 4 melanoma -- the disease is very hard to treat.
In just the past few years, though, researchers have made headway. In 2011, the United States and Europe approved an immunotherapy drug called ipilimumab (Yervoy) -- the first treatment shown to prolong the lives of some patients with advanced melanoma.
Still, only a minority of patients respond to the drug, and it can cause severe side effects -- including life-threatening inflammation of the liver or digestive tract.
So there's an acute need for additional therapies, said Dr. Mark Middleton, who was to present the new findings on Tuesday at the annual meeting of the American Association for Cancer Research, in San Diego.
"The reality is, despite exciting advances in treatment, most of the patients we see with advanced melanoma will die of the disease," said Middleton, of Oxford University in England.
IMCgp100 targets melanoma in two ways: It attaches to a specific, tiny protein found on some melanoma cells, and it activates nearby T-cells to attack the tumor.
The catch is that a patient's cancer must be positive for that protein, called HLA A2 -- which is true in about 45 percent of melanomas, Middleton said.
The 31 patients in this study were all HLA A2-positive, and all but one had stage 4 melanoma. They were split into eight groups and given different doses of IMCgp100. Patients who were able to tolerate the first infusion received six more weekly treatments.