The U.S. Food and Drug has approved Merck's drug Keytruda for the treatment of advanced melanoma.

Keytruda will be used to treat melanoma in patients who have stopped responding to other treatments. The drug, chemically known as pembrolizumab, uses patients' own immune system to fight cancer.

Melanoma is a rare, but deadly type of skin cancer. It accounts for 5 percent of all new cancers in the United States. Keytruda works by blocking a cellular pathway called as PD-1, which prevents the body's immune system from killing cancer cells.

The newly approved drug helps immune system recognize and attack the cancerous cells.

"This drug is a game changer, a very significant advance in the treatment of melanoma," said Dr. Antoni Ribas, lead author of the study from University of California, Los Angeles. "For patients who have not responded to prior therapies, this drug now provides a very real chance to shrink their tumors and the hope of a lasting response to treatment."

Keytruda was tested on 600 patients with advanced melanoma. A majority of the patients showed improvements in their condition after the drug therapy. The success of the drug in the initial clinical trials, the FDA chose to accelerate its approval and has given Keytruda "breakthrough therapy" status.

"Keytruda is the sixth new melanoma treatment approved since 2011, a result of promising advances in melanoma research," said Richard Pazdur, M.D., from FDA's Center for Drug Evaluation and Research, according to a news release.

The drug is for use in melanoma patients who have earlier been treated with ipilimumab, a type of immunotherapy, the agency said. Patients whose tumors express a gene mutation called BRAF V600 will need to use a BRAF inhibitor.

New Jersey-based Merck & Co., said that the price of its drug will be around $12,500 a month for the average U.S. patient or around $150,000 a year. Bristol-Myers's Yervoy, a drug used to treat melanoma, costs about $120,000 per course, Bloomberg reported.

The company plans to find whether or not pembrolizumab can be used to treat lung and bladder cancer.

Survivors                                                                

Tom Stutz, 74, of Sherman Oaks, California, who was part of the clinical trial, said that Keytruda saved his life.

"It's the little things that make me happy now," Stutz said in a news release. "I'm very appreciative that I get to get up in the morning, go into my backyard and see my garden. I'm able to be with my children and grandchildren, go on vacations with them. I was close to the end of the road, as far as you can get to the edge of the cliff, and I was pulled back by this treatment."

Another patient, Kathy Thomas, 59, of Torrance, California was able to defeat the deadly cancer and can now go on vacations with her grandchildren. "I just enjoy life now, really enjoy it," she said.