Summer inspires many people to think about their vacation plans; it makes Montaser Shaheen, MD, think about melanoma. Shaheen is a medical oncologist at the University of New Mexico Cancer Center. He and colleagues from around the country recently published a paper in the New England Journal of Medicine about a promising new treatment for melanoma. Shaheen ran the UNM Cancer Center's portion of the clinical trial from which the paper's data was collected. He hopes to be able to offer the melanoma treatment to more people.
Melanoma doesn't strike often but it can be deadly when it does: it accounts for only two percent of all skin cancers but causes most skin cancer deaths. Once it has spread from the original tumor site, melanoma is particularly difficult to treat. Chemotherapy, the standard treatment, causes the tumor to shrink in only about 10 percent of the people treated.
The treatment Shaheen and his colleagues tested in the clinical trial caused tumors to shrink in 61 percent of the people treated. In another 22 percent, the tumors disappeared completely. "This is a revolutionary therapy," Shaheen says. "The efficacy is dramatic for melanoma. More than 70 percent [of people treated] benefit."
The treatment consists of two drugs, Nivolumab and Ipilmumab. Both are antibodies, which are natural proteins the immune system uses to kill disease-causing invaders. Ipilmumab disables certain receptors, called CTLA-4 receptors, on the surface of melanoma cells. The effect is akin to removing an invisibility cloak; when these CTLA-4 receptors become disabled, the immune system attacks the tumor cells. Nivolumab blocks the PD-1 receptors on the cytotoxic T-cells, allowing the immune system to act against cancer cells. Although both drugs work well on their own, the clinical trial showed that they are especially potent when combined. "By giving the drugs together, you give a much higher benefit to patients," says Shaheen.
Some of the people taking part in the clinical trial had side effects. "The immune system attacks the cancer cells as a primary target," explains Shaheen. "But patients can get immune-mediated side effects from these drugs." The most frequent side effect in the clinical trial was diarrhea, which doctors treated with the steroid drug prednisone. "Prednisone does not suppress the reaction against the tumor," Shaheen says, so the diarrhea could be managed during the treatment.
The side effects stopped when the treatments stopped, but the tumors stayed away. Some people who took part in the clinical trial are still in full remission. "The cool thing about immune therapy is its durability," says Shaheen. "For the first time in history, we can talk about a potential cure for a subset of patients with metastatic melanoma."
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