PHILADELPHIA -- Doug Olson had been living with chronic lymphocytic leukemia, or CLL, for 14 years. By 2010, after four rounds of chemotherapy, his only option seemed to be a bone marrow transplant with a 50 percent chance of success.
"You know, it's sort of standing at the edge of a cliff with a parachute that may or may not open," Olson says.
That's when he became Patient Number Three in a gene therapy experiment designed to manipulate his immune system.
"I didn't hesitate for a second," he says. "They talk about cancer being a battle -- you're fighting cancer, and that's exactly what it feels like."
The weapon is drawn from a patient's own body. Doctors at the University of Pennsylvania remove "T cells," or white blood cells that help fight infections. The cells are then genetically modified to recognize and attack cancer cells.
"The T cell can grow and divide," says oncologist Dr. David Porter, who is part of the team overseeing the therapy. "In fact, we've seen for every T cell that we genetically modify and put into a patient's body, it has the ability to kill up to 93,000 leukemia cells."
In Olson's case, it took just three weeks to work.
"Dr. Porter said 'hot off the press.' He said, 'We can't find any CLL in your blood at all,'" Olson recalls. "It was amazing. You can imagine, only a few weeks before, you're not sure you have a future."
Fifty-nine patients were treated for two types of leukemia. Fifteen of 32 adults with CLL have responded to the therapy, and seven have no evidence of leukemia. In the second type of leukemia, ALL, the patients were mostly children, and the results were even more dramatic: no detectible cancerous cells in 24 of 27 treated patients.
"The fact that these cells can survive for so long and continue to be biologically active really is quite remarkable to all of us," Porter says.
More than three years later, Olson is still in complete remission, and the modified T cells are still circulating.
The hope is to use this same technique to make other types of cancer cells more visible to the body's immune system. In the next few months, doctors will start using this sophisticated immunotherapy in patients with non-Hodgkin's lymphoma.