ATLANTA » Jimmy Carter is receiving ground-breaking treatment at Emory University’s Winship Cancer Institute, but it’s not just because he’s a former president.

Indeed, the prognosis for Carter may have been much more grim if he had been diagnosed with late-stage melanoma just two years earlier, cancer specialists say. But the former president’s recent announcement in Plains that he is cancer-free comes after decades of trial and error by researchers.

That work finally paid off in September 2014, when the Food and Drug Administration granted special approval for a drug, pembrolizumab, to treat late-state melanoma for patients who are no longer responding to other drugs.

“There have been decades of research, where you build the knowledge one step at a time,” said Dr. Len Lichtenfeld, deputy medical officer for the American Cancer Society. “What we lose sight of is that the knowledge base took an incredibly long time to develop, and a substantial amount of investment.”

It’s important to note that not all patients with Stage IV melanoma will have similar results to Carter’s, medical experts said in interviews with The Atlanta Journal-Constitution. In clinical trials, about 24 percent of those who received the drug experienced tumor shrinkage, the FDA has reported.

Cancer claims more than half a million lives a year. And, doctors say, prevention is still key for many cancers, such as melanoma, where sun exposure and tanning beds dramatically raise a person’s risk.

Yet those who work in laboratories and clinics all their lives to overcome the nation’s No. 2 killer said that Carter’s cancer and his response to it are reasons for great hope in the fight against the disease. They also praised the way the former president has shared his diagnosis and treatment openly.

“This is extremely important because it allows our patients to feel hope and to allow him to continue to do his very important work,” said Dr. Jedd Wolchok, chief of the melanoma and immunotherapeutics program at Memorial Sloan Kettering Cancer Center in New York. “He’s doing something now — showing such enormous grace, courage and transparency — that may be just as important as anything he’s done.”

Wolchok said he feels great personal satisfaction in the president’s response to treatment because Wolchok was a principal investigator on one of the many worldwide Phase I clinical trials to test the safety of the drug.

While the story might sound like an overnight success, it is not. It is the result of years of painstaking and expensive research, clinical trials with successes and failures — with millions of lives lost along the way, despite researchers’ best efforts.

The War on Cancer

The fight against cancer began in earnest with then-President Richard Nixon’s proclamation of the War on Cancer in 1971.

“There was the thinking that ‘if we can put a man on the moon, we can cure cancer,’ ” Lichtenfeld said.

But that goal has been harder to reach than many people anticipated.

First, there are many types of cancer — it is not all one disease. Even within certain types of cancer that are designated by organ site, such as lung cancer or breast cancer, there are many genetic subtypes.

Researchers also have been confounded because of how “smart” the cancer cells are.

“If you treat them with a targeted therapy, they may or may not respond, but then they figure that out, and they change,” Lichtenfeld said.

For those who began practicing medicine about the time the War on Cancer was proclaimed, there was a lot of disappointment.

“You start to scratch your head, and you want to have something to offer your patients,” Lichtenfeld said.

Patients, their families, researchers and doctors across the country — and around the world — felt the same way. Work continued. And while today there are more than 14 million cancer survivors across the country, millions of others died as cancer fought back in the war against it.

Success in fight

One of the ways cancer fights back is by mutating, said Dr. Amod Sarnaik, an associate professor at Moffitt Cancer Center in Tampa, who specializes in melanoma.

“Melanoma is one of the most heavily mutated cancers there is,” Sarnaik said. Melanoma cells have mutated in thousands of ways, outfoxing many of the drugs that were developed to destroy it.

For more than a decade, not a single new drug to treat melanoma was approved, Sarnaik said. Then in 2011 came the immunotherapeutic drug Yervoy, and at least five other drugs to fight melanoma have gained approval since then.

These drugs differ from traditional chemotherapy drugs in that they help the body’s own immune system to fight the cancer; they do not destroy the cancer cells themselves.

The immune system typically recognizes cells that are bad for the body, such as bacteria that cause infections.

“But the immune system has a tough time with cancer cells because they look very much like a normal cell,” Wolchok said. The immunotherapeutic drugs turn off certain “brakes” within the immune system that tell it to leave the cancer cells alone.

“We’ve waited many decades for the scientific understanding of the immune system,” Wolchok said.

Those years of trial and error are producing significant advances in a disease that once brought a life expectancy of just a few months, he said. “Many, many patients have given of themselves to participate in clinical trials, and none of this would be happening without them.”

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©2015 The Atlanta Journal-Constitution (Atlanta, Ga.)