Why cancer treatments like the one Jimmy Carter used are suddenly gaining traction

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Jimmy Carter Is Cancer-Free

We may be at the beginning of a revolution in how we treat cancer.

For years, doctors have treated patients using a combination of chemotherapy, radiation, and surgery to try and stifle the disease.

But in the past few years, doctors have started using a promising tool: immunotherapy.

Unlike chemotherapy, which involves administering powerful drugs that kill both cancerous and healthy cells (most healthy cells can repair themselves), immunotherapies harness the power of the immune system to help it identify and knock out just the cancerous cells.

Recently, former President Jimmy Carter revealed he had tested cancer free just a few months after initially sharing that he'd been diagnosed with metastatic (meaning it's spread from its primary spot) melanoma that had spread to his brain. Carter had used a combination of radiation therapy and Keytruda, one of these new immunotherapy drugs, which was delivered intravenously once every three weeks.

For more on Jimmy Carter, scroll through the gallery below:

Jimmy Carter through the years
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Why cancer treatments like the one Jimmy Carter used are suddenly gaining traction
Jimmy(James Earl) Carter as Ensign, USN, circa World War II. (Photo by PhotoQuest/Getty Images)
American politician and US Presidential candidate Jimmy Carter holds a handful of peanuts (referencing his career as a peanut farmer) during a campaign event, Boston, Massachusetts, 1976. (Photo by Mikki Ansin/Getty Images)
American politician and US Presidential candidate Jimmy Carter (center) smiles after his victory in the Pennsylvania Primary election, Philadelphia, Pennsylvania, April 27, 1976. Among those on stage with him are politicians Samuel L Evans (left) and Senator Birch Bayh (second left). (Photo by Mikki Ansin/Getty Images)
U.S. president Jimmy Carter smiling at a podium in front of an American flag, 1970s. (Photo by Hulton Archive/Getty Images)
1976: A campaign button supporting the Democratic politician Jimmy Carter for President. (Photo by MPI/Getty Images)
Jimmy Carter on his peanut farm, Plains, Georgia, 1976. (Photo by PhotoQuest/Getty Images)
Jimmy Carter (left) and Sen. Walter Mondale at the 1976 Democratic National Convention at Madison Square Garden. (Photo by James Garrett/NY Daily News Archive via Getty Images)
Photograph of President Jimmy Carter and First Lady Rosalynn Carter dancing at a White House Congressional Ball. Photographed by Marion S. Trikosko. Dated 1977. (Photo by: Universal History Archive/UIG via Getty Images)
Jimmy Carter of Plains, GA, was the 39th President of the United States and a big fan of NASCAR racing. In 1978, Carter invited a number of NASCAR Cup stars to the White House for a big dinner and entertainment provided by country star Willie Nelson. Nelson was there and so were First Lady Rosalynn Carter and the President'€™s brother Billy Carter, but President Carter was nowhere to be found. The President had gone to Camp David to meet with the leaders of Israel and Egypt, Menachem Begin and Anwar Sadat, in what ultimately would lead to a huge Middle East peace agreement known later as the Camp David Accords. (Photo by ISC Images & Archives via Getty Images)
Jean-Paul II In Washington, United States On October 06, 1979)-John-Paul II, Jimmy Carter and Rosalyn at the White House. (Photo by Pool JEAN-PAUL II AUX USA/Gamma-Rapho via Getty Images)
Photograph of President Jimmy Carter announcing new sanctions against Iran following the taking American hostages. Photographed by Marion S. Trikosko. Dated 1980. (Photo by: Universal History Archive/UIG via Getty Images)
Gerald Ford and Jimmy Carter during Humanitarian Awards Dinner - November 23, 1987 at Waldorf Astoria Hotel in New York City, New York, United States. (Photo by Ron Galella/WireImage)
Gillian Sorenson and Jimmy Carter during Benefit Dinner Dance for the Homeless - November 18, 1988 at Plaza Hotel in New York City, New York, United States. (Photo by Ron Galella/WireImage)
Musician Willie Nelson and former President Jimmy Carter at the taping of 'CMT Homecoming: Jimmy Carter in Plains,' which will premiere on CMT in December 2004. (Photo by Rick Diamond/WireImage)
ATLANTA - APRIL 22: Former President Jimmy Carter watches the game between the Philiadelphia Phillies and the Atlanta Braves at Turner Field on April 22, 2010 in Atlanta, Georgia. (Photo by Kevin C. Cox/Getty Images)
CAIRO, EGYPT - MAY 24: Former U.S. President Jimmy Carter addresses the media on the second day of Egypt's presidential election on May 24, 2012 in Cairo, Egypt. Carter Center election monitors observed the presidential election, the first of the post-Mubarak era. If no candidate wins an outright majority of the vote, the election would go to a second round June 16-17. (Photo by John Moore/Getty Images)
Former US President Jimmy Carter signs his new Book 'A Full Life: Reflections at Ninety' at Barnes & Noble on 5th avenue in New York on July 7, 2015. Photo by KENA BETANCUR/AFP/Getty Images
PASADENA, CA - JULY 30: President Jimmy Carter photographed at Vroman's Bookstore on July 30, 2015 in Pasadena, California. (Photo by Paul Redmond / Getty Images)

In cancer patients, a type of protein called PD-1 stop the immune system from doing its job and fighting the cancerous cells. Keytruda gets in the way of those dysfunctional proteins, allowing the immune system to access the cancer cells. Then, with the help of the radiation therapy to shrink tumors, it can help knock out the cancer in some people.

The incredible success of the drug in Carter's case brought the treatment into the spotlight, but the attention appears to have been a long time coming.

Recent immunotherapy successes are far from the first time researchers have explored using the immune system to fight cancer.

As NPR noted, in the 1890s a doctor named William Coley treated his cancer patients by infecting them with bacteria. The treatment worked for some of them -- with the immune system on full force to knock out the invading bacteria, the immune system could also take on the cancerous cells and kill them on the way, which wouldn't necessarily happen if the immune system wasn't stimulated.

At the time, very little was understood about the immune system, and after Coley died, his methods stopped being used in favor of radiation therapy. But in 1953, Coley's daughter Helen Coley Nauts founded the Cancer Research Institute, which works to understand the relationship between cancer and the immune system.

In the 1970s, scientists pursued an immunotherapy using a protein called tumor necrosis factor, or TNF, which the body makes in response to foreign organisms in the body, including bacteria and tumor cells.

Jan Vilcek, a microbiology professor at New York University and one of the scientists who worked on developing a TNF treatment at the time, told Business Insider that in animal testing, TNF was able to block the growth of tumors. But when put into humans, the added TNF was so toxic that it made people sick, even at doses that wouldn't kill tumors.

That was the end of immuno-oncology research for a while (though not the end of the story for TNF-related therapies).

Even so, the Cancer Research Institute stuck with it, and eventually in 2011, the first immunotherapy was approved in the US to treat melanoma. The drug, called Yervoy or ipilimumab, helps the immune system respond to cancerous cells by keeping it from pushing on the brakes before it has a chance to kill the cells. Since then, a number of other cancer treatments using the immune system have been approved, with more still in development.

"For us, the excitement that we're now seeing in the clinic is phenomenal," Cancer Research Institute CEO Jill O'Donnell-Tormey told Business Insider. "It's very validating for us."

Vilcek too is optimistic about the state of immunotherapies to treat cancer.

"I think it's really very very encouraging and in certain types of cancer, it's making a huge difference," Vilcek said.

It's working incredibly well for some cancers, such as melanoma, lung cancer, head and neck cancer, and multiple myeloma.

Yet for others, there's still a lot to learn.

"We're a long way from knowing the full story," said O'Donnell-Tormey. For example, while Keytruda, the drug Carter used, has worked "dramatically well," it still doesn't have a success rate on its own that's anywhere close to 100% for the type of cancer it targets. "We need to understand why someone like Jimmy Carter responding."

In fact, roughly 30% of metastatic melanoma patients using Keytruda alone respond completely. That's still better than the average response rate of chemotherapy treatments on their own in cases of metastatic melanoma. When the drug is combined with others, that success rate goes up, which also holds true for other medications like chemotherapy. But for those who still don't respond at all, that's the challenge. And combining different medications and therapies might be the answer.

This year was a good one for immunotherapies: In October, Keytruda was also approved to treat a form of lung cancer. It moved forward in getting developed to treat a wide variety of other cancer types as well.

In the last year, Opdivo, another drug that targets the PD-1 protein like Keytruda and was originally approved to treat patients with certain types of melanoma, was also approved to treat forms of lung cancer and kidney cancer.

In blood cancer treatment, 2015 saw the approvals of more than one multiple myeloma immunotherapy. Others went so far as to get approval for a genetically modified herpes virus that's programmed to kill tumor cells in patients with melanoma that recurs after surgery (making history as the first cancer viral therapy).

Investors expect new cancer immunotherapies to make billions of dollars in sales in the next couple of years.

So stay tuned -- more treatments are ahead.

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