This microscopy image provided by Dr. Carl June on Wednesday, Aug. 10, 2011 shows immune system T-cells, center, binding to beads which cause the cells to divide. The beads, depicted in yellow, are later removed, leaving pure T-cells which are then ready for infusion to the cancer patients. Scientists are reporting the first clear success with gene therapy to treat leukemia, using the patients’ own blood cells to hunt down and wipe out their cancer. They’ve only done it in three patients so far, but the results were striking: two appear cancer-free up to a year after treatment, and the third had a partial response. Scientists are already preparing to try the approach in other kinds of cancer. (AP Photo/Dr. Carl June) |
NEW
YORK (AP) — Scientists are reporting the first clear success with a new
approach for treating leukemia — turning the patients’ own blood cells
into assassins that hunt and destroy their cancer cells.
They’ve
only done it in three patients so far, but the results were striking:
Two appear cancer-free up to a year after treatment, and the third
patient is improved but still has some cancer. Scientists are already
preparing to try the same gene therapy technique for other kinds of
cancer.
“It
worked great. We were surprised it worked as well as it did,” said Dr.
Carl June, a gene therapy expert at the University of Pennsylvania.
“We’re just a year out now. We need to find out how long these
remissions last.”
He led the study, published Wednesday by two journals, New England Journal of Medicine and Science Translational Medicine.
It
involved three men with very advanced cases of chronic lymphocytic
leukemia, or CLL. The only hope for a cure now is bone marrow or stem
cell transplants, which don’t always work and carry a high risk of
death.
Scientists
have been working for years to find ways to boost the immune system’s
ability to fight cancer. Earlier attempts at genetically modifying
bloodstream soldiers called T-cells have had limited success; the
modified cells didn’t reproduce well and quickly disappeared.
June
and his colleagues made changes to the technique, using a novel carrier
to deliver the new genes into the T-cells and a signaling mechanism
telling the cells to kill and multiply.
That
resulted in armies of “serial killer” cells that targeted cancer cells,
destroyed them, and went on to kill new cancer as it emerged. It was
known that T-cells attack viruses that way, but this is the first time
it’s been done against cancer, June said.
For
the experiment, blood was taken from each patient and T-cells removed.
After they were altered in a lab, millions of the cells were returned to
the patient in three infusions.
The
researchers described the experience of one 64-year-old patient in
detail. There was no change for two weeks, but then he became ill with
chills, nausea and fever. He and the other two patients were hit with a
condition that occurs when a large number of cancer cells die at the
same time — a sign that the gene therapy is working.
“It was like the worse flu of their life,” June said. “But after that, it’s over. They’re well.”
The
main complication seems to be that this technique also destroys some
other infection-fighting blood cells; so far the patients have been
getting monthly treatments for that.
Penn
researchers want to test the gene therapy technique in leukemia-related
cancers, as well as pancreatic and ovarian cancer, he said. Other
institutions are looking at prostate and brain cancer.
Dr.
Walter J. Urba of the Providence Cancer Center in Portland, Oregon,
called the findings “pretty remarkable” but added a note of caution
because of the size of the study.
“It’s
still just three patients. Three’s better than one, but it’s not 100,”
said Urba, one of the authors of an editorial on the research that
appears in the New England Journal.
What happens long-term is key, he said: “What’s it like a year from now, two years from now, for these patients.”
But
Dr. Kanti Rai, a blood cancer expert at New York’s Long Island Jewish
Medical Center, could hardly contain his enthusiasm, saying he usually
is more reserved in his comments on such reports.
“It’s an amazing, amazing kind of achievement,” said Rai, who had no role in the research.
One
of the patients, who did not want to be identified, wrote about his
illness, and released a statement through the university. The man,
himself a scientist, called himself “very lucky,” although he wrote that
he didn’t feel that way when he was first diagnosed 15 years ago at age
50.
He was successfully treated over the years with chemotherapy until standard drugs no longer worked.
Now,
almost a year since he entered the study, “I’m healthy and still in
remission. I know this may not be a permanent condition, but I decided
to declare victory and assume that I had won.”
Chimeric Antigen Receptor–Modified T Cells in Chronic Lymphoid Leukemia
SOURCE: The Associated Press
