"While the results have been astonishing in many ways, it's also been disappointing to see patients regress after such a great response," said Sosman, who is also a professor of medicine at the Vanderbilt-Ingram Cancer Center in Nashville, Tenn.
But the success rate for the new drug makes it the first hope in a long series of therapies that target mutated genes.
"It's one of many. When it comes to melanoma we believe there are many (gene) targets that we need to turn off. The other targets that we are looking at are the MEK pathway AKT pathway," said Pavlik, who is running one of the sites for the phase III clinical trial of the drug.
"As we learn to target these mutations we may need to target more than one to get complete success. This is clearly the right step in the right direction," she said.