Keytruda successful in treatment of melanoma, study says, with long-lasting effects

LOS ANGELES, April 22 (UPI) -- The cancer immunotherapy drug pembrolizumab, marketed as Keytruda, was shown to have longer-lasting anti-cancer effects and fewer overall side effects than other standard treatments for advanced melanoma, according to researchers.

In a follow-up to the phase 1 clinical trial that led to FDA approval of the drug, researchers said they saw Keytruda had greater effects with less of a downside, but are just analyzing the data now.

The drug was approved by the FDA in 2014 for advanced melanoma treatment, but in the initial trials researchers reported effects against lung and kidney cancer, as well as fewer side effects.

Former President Jimmy Carter was treated with the drug in 2015 with great success, and reported along the way that there were few side effects as he continued working during treatment.

Keytruda, which has been shown to also be more effective in treating lung cancer than chemotherapy, is a checkpoint inhibitor that blocks the PD-1 protein expressed by immune cells and prevents T cells from attacking cancer cells.

For the new study, published in the Journal of the American Medical Association, researchers analyzed data from 655 people treated in the trial with one of three similar dosing regimens of Keytruda, resulting in an average tumor regression of 33 percent in the patients. Patients who had not been treated for advanced melanoma before the trial saw tumor regression of 45 percent.

Just 14 percent of patients had a significant side effect from the drug, with 4 percent having to stop taking it, but 74 percent of patients were treated for at least a year with positive response to the drug.

"The early data from this research showed the unprecedented activity of pembrolizumab in people with advanced melanoma, and we can now report the full results of the study," Dr. Antoni Ribas, a professor of hematology and oncology at the UCLA, said in a press release.