Cell Therapy Shows Promise for Acute Type of Leukemia
By DENISE GRADY
Published: March 20, 2013 38 Comments
A treatment that genetically alters a patient’s own immune cells to fight cancer has, for the first time, produced remissions in adults with an acute leukemia that is usually lethal, researchers are reporting.
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In one patient who was severely ill, all traces of leukemia vanished in eight days.
“We had hoped, but couldn’t have predicted that the response would be so profound and rapid,” said Dr. Renier J. Brentjens, the first author of a new study of the therapy and a specialist in leukemia at Memorial Sloan-Kettering Cancer Center.
The treatment is experimental, has been used in only a small number of patients and did not work in all of them. But experts consider it a highly promising approach for a variety of malignancies, including other blood cancers and tumors in organs like the prostate gland. The new study, in five adults with acute leukemia, was published on Wednesday in the journal Science Translational Medicine.
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.
Dr. Richard M. Stone, the program director for adult leukemia at the Dana-Farber Cancer Institute in Boston, called the research exciting and said he hoped to begin collaborating with the team at Sloan-Kettering. He has already sent them a patient.
The treatment uses patients’ own T-cells, a type of white blood cell that normally fights viruses and cancer. The patient’s blood is run through a machine that extracts T-cells and returns the rest of the blood to the body. Researchers then do some genetic engineering: they use a disabled virus as a “vector” to carry new genetic material into the T cells, which reprograms them to recognize and kill any cell that carries a particular protein on its surface.
The protein, called CD19, is found on B-cells, which are part of the immune system. This target was chosen because the patients had a type of leukemia that affects B-cells, so the goal was to train the patients’ T-cells to destroy B-cells. Healthy B-cells — which make antibodies to fight infection — would be killed along with cancerous ones, but that side effect was treatable.
“We’re creating living drugs,” Dr. Sadelain said. “It’s an exciting story that’s just beginning.”
One of the sickest patients in the study was David Aponte, 58, who works on a sound crew for ABC News. In November 2011, what he thought was a bad case of tennis elbow turned out to be leukemia. He braced himself for a long, grueling regimen of chemotherapy.
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