"They gave me the medicine for five or six months and it became toxic to me," said Dixon, who began to suffer from excruciating headaches and lost 30 pounds.
But the medicine was working. Dixon watched his tumor regress, or shrink, "by 50-60 percent" in volume on CT scans.
"Now they say my adrenal gland is almost normal size," said Dixon. "At my last check-up they said it's holding steady."
His doctors have since lowered his dosage and he's since gained back the weight. There have been no improvements on his condition, but Dixon is surprised the results have held out this long. Now the only side effects seem to be a case of numb feet.
"The big picture is that people think this is a very exciting drug," said Dr. Henry Koon, an oncologist who specializes in melanoma care at the University Hospitals Case Medical Center in Cleveland. "This is something that can impact two-thirds of melanoma patients."
The other third of melanoma patients do not carry the BRAF mutation, Koon noted. And RO5185426 comes with side effects but Koon, who is not involved in the clinical trials, pointed out that administering it in pill form is much less intrusive than administering the immunotherapy, Interleukin-2.
"You actually have to come in the hospital for two out of three weeks (for immunotherapy)," said Koon. "It requires almost ICU level care."
Not to say RO5185426 is free from the typical harsh side effects of cancer treatment.
Scott Kehne, of Knoxville, Tenn., has had more severe side effects from RO5185426.
"Fluid retention. Rashes. It actually causes, for many of us, the formation of squamous cell carcinomas; another form of skin cancer," said Kehne, who had to have squamous cell carcinoma growths removed from his skin after starting the drug.
Sosman said the drug also puts people at risk for squamous cell carcinomas in their mouths, on their genitals, and anus as well. But compared to melanoma, squamous cell cancer is easier to treat.
"I also have joint soreness. Of course I have never experienced arthritis, but I'm guessing that's what it feels like," said Kehne.
Kehne, 63, is still well enough to work fulltime. But his frequent 14 mile hikes in the nearby Smokey Mountains have been cut short.
"Of course the alternative's worse," said Kehne.
Kehne's cancer started with a mole on his chest that he developed in junior high school. He remembers spending summers at the local swimming pool -- "it was my baby sitter," he joked -- but he never used, or even heard about, sunscreen.
Although Kehne went into doctors to get his mole checked throughout his life, "no one ever suggested to remove it," said Kehne. Then, in 2006, he bumped the mole while "doing something physical" and felt a pang. Doctors soon diagnosed him with Stage IV cancer.
"Immediately upon taking the drug within the first couple weeks I had something like a 30-40 percent regression. That's not unusual at all from what the doctors tell me," said Kehne, whose condition has stabilized in the seven months he has been taking the drug.
"If it [the cancer] continued to progress at the way it was going, I was going to be a very short-timer," he said.
Such success stories have made Sosman feel like there is finally some traction "a first base" in melanoma research. But he and his colleagues who cooperated across the country to study RO5185426 know it won't be a cure.