Doctors from Seattle, Washington have for the first time successfully treated a malignant melanoma skin cancer patient with cells cloned from his own immune system.

The ground-breaking treatment for advanced melanoma (Stage 4), or skin cancer, led to a long remission for the patient who was given his own cloned infection-fighting T-cells, according to Dr. Cassian Yee,  lead author of the study in the New England Journal of Medicine.

Yee and associates from the Clinical Research Division at Fred Hutchinson Cancer Research Center in Seattle removed CD4+ T-cells, a type of white blood cell, from a 52-year-old man whose melanoma had spread to a groin lymph node and to one of his lungs.

The T-cells which specifically fight melanoma were modified and expanded in the laboratory and  five billion cells were then infused into the patient, who received no other kind of treatment.

Two months later no tumors were found during scans of the patient’s organs. He has been cancer free for two years, according to Yee.

“We were surprised by the anti-tumor effect of these CD4 T cells and its duration of response,” Yee said. “For this patient we were successful, but we would need to confirm the effectiveness of therapy in a larger study.”

It was the first case to show that cloned cells from a patient’s own immune system can successful combat skin cancer. If further tests confirm the efficiency of the method, it could be used in some 25 percent of patients with late-stage skin cancer, the study said.

Using a patient’s own immune system to combat cancer, called immunotherapy, is a growing area of research that aims to develop less-toxic cancer treatments than standard chemotherapy and radiation.

About 160,000 cases of melanoma are diagnosed around the world every year, particularly affecting white men living in very sunny climates. According to the World Health Organization, about 48,000 people die from melanoma every year.

Although it usually affects the skin, in rare cases it can also infect the eyes and intestines.