"It exceeded our wildest expectations," said Carl June, a gene therapy pioneer at Penn's Abramson Cancer Center who led the work.
On Wednesday, two prestigious journals - New England Journal of Medicine and Science Translational Medicine - simultaneously published the Penn breakthrough. June's team genetically engineered each patient's T cells - the big guns of the immune system - to recognize and attack the malignant cells, then stand guard against the disease.
Although chronic lymphocytic leukemia is rare and slow-growing, the study has implications for a large group of blood cancers, including many lymphomas, that are diagnosed in 87,000 Americans a year. In these cancers, malignancy arises in B cells, which are the target of the Penn gene therapy.
In an editorial in the New England Journal, two oncologists called the results of the new study impressive. But they warned that toxic effects, known and unknown, "could pose substantial problems."
Only wider testing will show if the breakthrough is "an authentic advance" toward a novel medicine for B-cell malignancies, or yet another "lead that runs into a barrier," wrote lead editorialist Walter Urba of the Chiles Research Institute in Oregon.
For the 64-year-old patient, the answer is already clear. Although he did not want to be identified by name, he wrote an essay about his experience for Penn's website.
"I'm healthy and still in remission," he said. "I know this may not be a permanent condition, but I decided months ago to declare victory." (A second patient also declined to be named. The third patient, William Ludwig, 65, declined an interview.)
