(Reuters) -- Former U.S. President Jimmy Carter said on Sunday that he will no longer need treatment for melanoma, a type of skin cancer that had spread to his liver and brain, the Atlanta Journal-Constitution newspaper reported.
The 91-year-old Nobel Peace Prize winner will continue to be observed by doctors, but will not need treatment with a promising immunotherapy drug that helps the body's immune system target cancer cells, the newspaper said, quoting his nonprofit public policy center, the Carter Center.
Click though images of Jimmy Carter through the years:
Jimmy Carter through the years
Former US President Carter says he no longer needs cancer treatments
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)
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A spokeswoman for the Carter Center told the newspaper in an email that if doctors find that the former president's cancer returns, he will resume treatment.
The former president shared his news at a Sunday school class he teaches in his hometown of Plains, Georgia, the newspaper said, quoting Carter's niece, Mandy Flynn.
Carter started treatment in August for melanoma that had spread from his liver to his brain. In December, he said he was cancer-free but that he would continue to receive treatment.
At the time, Carter said he would continue to receive regular doses of pembrolizumab, a new treatment that is part of a promising class of drugs that harness the body's immune system to fight cancer. The immunotherapy is manufactured by Merck & Co under the brand name Keytruda.
While about 30 percent of patients treated with the drug experience significant shrinkage of their cancer, only approximately 5 percent experience complete remission, said Dr. Marc Ernstoff, director of the melanoma program at the Cleveland Clinic's Taussig Cancer Institute in Ohio who is familiar with the drug but has not been involved with Carter's care.