The treatment can cause severe flu-like symptoms and other side effects, but these have been reversible and temporary, doctors say.
Penn doctors have treated the most cases so far — 59. Of the first 14 patients with CLL, four had complete remissions, four had partial ones and the rest did not respond. However, some partial responders continue to see their cancer shrink a year after treatment.
"That's very unique to this kind of therapy" and gives hope the treatment may still purge the cancer, said Porter. Another 18 CLL patients were treated and half have responded so far.
Penn doctors also treated 27 ALL patients. All five adults and 19 of the 22 children had complete remissions, an "extraordinarily high" success rate, said Dr. Stephan Grupp at the Children's Hospital of Philadelphia.
Six have since relapsed, though, and doctors are pondering a second gene therapy attempt.
At the National Cancer Institute, Dr. James Kochenderfer and others have treated 11 patients with lymphoma and four with CLL, starting roughly two years ago. Six had complete remissions, six had partial ones, one has stable disease and it's too soon to tell for the rest.
Ten other patients were given gene therapy to try to kill leukemia or lymphoma remaining after bone marrow transplants. These patients got infusions of gene-treated blood cells from their transplant donors instead of using their own blood cells. One had a complete remission and three others had significant reduction of their disease.
"They've had every treatment known to man. To get any responses is really encouraging," Kochenderfer said. The cancer institute is working with a Los Angeles biotech firm, Kite Pharma Inc., on its gene therapy approach.
Researchers at Memorial Sloan-Kettering Cancer Center will report on 13 patients with ALL; the University of Texas MD Anderson Cancer Center will report about two-dozen patients with ALL or lymphoma, and Baylor University will give results on 10 patients with lymphoma or myeloma.
Patients are encouraged that relatively few have relapsed.
"We're still nervous every day because they can't tell us what's going to happen tomorrow," said Tom Whitehead, 8-year-old Emily's father.
Doug Olson, 67, a scientist for a medical device maker, shows no sign of cancer since gene therapy in September 2010 for CLL he had had since 1996.
"Within one month he was in complete remission. That was just completely unexpected," said Porter, his doctor at Penn.
Olson ran his first half-marathon in January and no longer worries about how long his remission will last.
"I decided I'm cured. I'm not going to let that hang over my head anymore," he said.
Online: Emily Whitehead's story: http://bit.ly/VxB0dL
Marilynn Marchione can be followed at http://twitter.com/MMarchioneAP
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