Early Results of Gene Therapy Show Promise Against Leukemia
Article date: August 12, 2011
By Stacy Simon
A form of gene therapy is showing promising results against a type of leukemia in a small new study, though it is still likely years away from being available as a standard treatment.
The clinical trial at the University of Pennsylvania involved only 3 patients with advanced chronic lymphocytic leukemia (CLL) who had already received several other treatments. (CLL is a type of cancer that usually starts in white blood cells called B cells.) A year after the new treatment, two of the patients had complete remission of leukemia, while the third had a partial response to treatment.
Researchers plan to monitor the patients for years to come, to watch for complications related to the therapy. And the treatment will need to be studied in much larger groups of patients to make sure it is safe and effective.
The therapy involved treating patients with genetically engineered versions of their own T cells, which are a kind of white blood cell. Patients’ T cells were removed and modified using a harmless virus to give them new genes to help them target B cells in the body. The cells were then injected back into the patients, where they began killing CLL tumor cells and normal B cells. On average, each infused T cell led to the killing of thousands of tumor cells, which led to the destruction of at least 2 pounds of tumor in each patient.
"Within three weeks, the tumors had been blown away, in a way that was much more violent than we ever expected," said senior author Carl June, MD, director of Translational Research and a professor of Pathology and Laboratory Medicine in the Abramson Cancer Center. "It worked much better than we thought it would."
The patients temporarily experienced severe flu-like symptoms as a result, including high fever, chills and nausea. A potentially serious long-term concern is the killing of patients’ B cells, which the body needs to help fight off infection. The long-term effects of the treatment are still being studied.
Treatment May Be Years Away
American Cancer Society Chief Medical Officer Otis Brawley, MD says if the therapy proves successful, it will still likely take 5 to 10 years of work before it can be made available to large groups of people.
The researchers are not currently enrolling new patients into the leukemia study. It is expected to reopen within the next few months, but will enroll only a small number of people. The researchers are hoping the technology will be helpful in developing effective treatments for other types of cancer as well.
The study is published in both The New England Journal of Medicine and Science Translational Medicine.
Reviewed by: Members of the ACS Medical Content Staff
ACS News Center stories are provided as a source of cancer-related news and are not intended to be used as press releases.
Citation: Chimeric Antigen Receptor-Modified T Cells in Chronic Lymphoid Leukemia. Published in the Aug. 10, 2011 issue of The New England Journal of Medicine. First author: David L. Porter, MD, University of Pennsylvania, Philadelphia.
Citation: T Cells with Chimeric Antigen Receptors Have Potent Antitumor Effects and Can Establish Memory in Patients with Advanced Leukemia. Published in the Aug. 10, 2011 issue of Science Translational Medicine (Vol. 3, No. 95). First author: Michael Kalos, PhD, University of Pennsylvania, Philadelphia.
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