A recent study could give birth to a new kind of expensive drug for boosting immunity to prolong the lives of people suffering from a fatal form of skin cancer for two to three years.

655 people suffering from this kind of skin cancer called advanced melanoma took a new drug called Keytruda by Merck & Co. in a clinical trial. Three years after the treatment was started, they were still alive. The Merck funded study shows that among older patients the 3-year survival rate was 10 to 20 percent. The average survival rate among patients was two years.

Keytruda, along with other "immunotherapy" drugs, work to enhance the functioning of the immune system and are more successful than the older kind of medicines in destroying cancer cells. For melanoma and certain kinds of tumors, these drugs have high success rates.

Back in April, researchers revealed that out of the number of melanoma patients who took Bristol-Myers Squibbs Co.'s Opdivo, 34 percent were still alive after five years since the beginning of treatment. As revealed by the American Cancer Society, the general 5-year survival rate of people suffering from advanced melanoma has been 15 to 20 percent

According to Wall Street Journal, "Patients with advanced melanoma are often very reasonably scared about the diagnosis, based on reading old statistics about long-term survival probabilities," said Michael Postow, a medical oncologist at Memorial Sloan Kettering Cancer Center in New York.

"All of these statistics are now being rewritten in a favorable way with these new drugs," added Postow.

Jimmy Carter, the former U.S. president, said that he took Keytruda to treat melanoma that was spreading to other parts of his body. The new scans in December showed that there were no new signs of cancer. However, there have been no recent updates on his condition.

However, the incredible treatment comes at an incredible price. Both Keytruda and Opdivo cost more than $12,500 a month for an average patient. There have been no clear answers on the length of the drug intake.

The results of the Keytruda study and other cancer trials will come out in June at ASCO's annual meeting which will be taking place in Chicago.