The treatment is similar to one that pulled a 7-year-old girl, Emma Whitehead, from death’s door into remission nearly a year ago, and that has had astounding success in several adults with chronic leukemia in whom chemotherapy had failed. The treatment regimen that saved Emma and those adults was developed at the University of Pennsylvania. Related studies have also been done at the National Cancer Institute.

But this cell-therapy approach had not been tried before in adults with the disease that Emma had, acute lymphoblastic leukemia. This type of blood cancer is worse in adults than in children, with a cure rate in adults of only about 40 percent, compared with 80 percent to 90 percent in children. The disease is not common. Each year in the United States, it affects about 2,400 people older than 20, and 3,600 younger. Though there are fewer cases in adults, there are more deaths: about 1,170 adults die each year compared with 270 deaths in people under 20.

In adults, this type of leukemia is a “devastating, galloping disease,” said Dr. Michel Sadelain, the senior author of the new study and director of the Center for Cell Engineering and the Gene Transfer and Gene Expression Laboratory at Memorial Sloan-Kettering Cancer Center in Manhattan.

Patients like the ones in the study, who relapse after chemotherapy, usually have only a few months left, Dr. Sadelain said. But now, three of the five have been in remission for 5 to 24 months. Two others died: one was in remission but died from a blood clot, and the other relapsed. The survivors have gone on to have bone-marrow transplants. Their prognosis is good, but relapse is still possible, and only time will tell.

Experts not connected with the study said it was an important advance in an emerging field. Dr. Carl June of the University of Pennsylvania, who led the team that treated Emma and the other patients, said, “This is the first report showing some real, clinically beneficial activity in adult acute lymphoblastic leukemia.” He said his team was also starting to test its version of the cell therapy on patients with the disease.