Drug Shows Early Promise Against Advanced Melanoma
Helps immune system recognize, kill cancer cells, researchers explain
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.
In the end, there were four patients who showed a "partial response" to the drug, which meant their tumors shrunk. One patient continued to see a regression with further treatment, and is still stable after more than 10 months, according to Middleton.
The most common side effects were rash, fever and "tumor flare" -- swelling and tenderness at the site of a tumor. Two of four patients who got the highest drug dose did have an immediate drop in blood pressure, so the researchers have since set the maximum dose below that.
Middleton said his team is now studying the drug in a larger group of patients, and trying to find the most effective regimen.
"The other obvious question is, where would this drug fit in?" Middleton said.
Besides Yervoy and other immunotherapies under development, there are also newer "targeted" drugs that directly attack proteins found on some melanomas -- including drugs called BRAF inhibitors.
Weber said researchers will have to figure out whether combinations of different therapies work better than a single one -- and which patients stand to benefit from a particular combination.
Middleton agreed. "We now have a whole range of therapies coming out, which is exciting," he said. But the difficult part, he added, will be understanding how to best use them.
In the United States, about 76,000 people will be diagnosed with melanoma this year, and 9,700 will die of the disease, according to the American Cancer Society. While melanoma is relatively uncommon, its incidence has been rising for the past few decades, the cancer society notes.