Cell therapy shows promise for acute type of leukemia

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NEW YORK -- A treatment that genetically alters a patient's own immune cells to fight cancer has, for the first time, produced remissions in adults with a deadly type of acute leukemia that resisted chemotherapy and left little hope of survival, researchers are reporting.

In one severely ill patient, all leukemia traces vanished in eight days.

"We had hoped but couldn't have predicted that the response would be so profound and rapid," said Renier Brentjens, first author of a new study of the therapy and a leukemia specialist at New York City's Memorial Sloan-Kettering Cancer Center.

The treatment is experimental and has been used in only a small number of patients, but cancer experts consider it a highly promising approach for a variety of cancers. The study, in five adults with acute leukemia, was published 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 last year, and that has had astounding success in several adults with chronic leukemia in whom chemotherapy had failed. Emma and those adults were treated at the University of Pennsylvania.

But this cell-therapy approach had not been tried before in adults with the disease Emma had, acute lymphoblastic leukemia. This blood cancer type is worse in adults than children, with an adult cure rate of only about 40 percent, compared with 80 percent to 90 percent in children.

In adults, this leukemia type is a "devastating, galloping disease," said Michel Sadelain, the new study's senior author and director of Memorial Sloan-Kettering's Center for Cell Engineering and the Gene Transfer and Gene Expression Laboratory.

Patients such as those in the study, who relapse after chemotherapy, usually have only a few months to live, Dr. Sadelain said. Now, three of the five adults in the study have been in remission for five to 24 months.

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 carrying a particular protein on its surface.

The protein, called CD19, is found on B-cells, part of the immune system. This target was chosen because patients had a leukemia type that affects B-cells, so the goal was to train their 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.

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