This article, from MIT's Technology Review
, offers a terrific layman's summary of the history, hype, tragedy, and hope attending the search for effective gene therapy treatments.
As Fischer and his team had expected, the number of treated precursor cells able to generate T cells was very low. However, he said, it was sufficient to produce a normal number of T cells. "After a few months, these children could leave the hospital and start to live normally with their parents. And except for those who had the complication I'm going to describe in a moment, they are living normally still today."
After the first three years, three of the ten children treated developed a severe complication, an uncontrolled proliferation of T lymphocytes. "I would call it a leukemia–like disease," said Fischer. Childhood leukemia can usually be cured with massive doses of chemotherapy, and that's how Fischer and his colleagues treated the three patients. One died. "The other two kids today are doing well, as well as the other seven," Fischer said.
How much did all this cost? "A lot!" Fischer laughed abruptly. "A lot; but the treatment of a child with such a disease, without gene therapy, costs a lot, too." Yes, he said, per patient, the cost of the research is huge. But "the cost of the therapy itself is not that big. Let's assume it's commercialized. I would assume the cost of the therapy itself, with the cost of the vector—the cell treatment ex vivo—shouldn't cost more than maybe somewhere between $30,000 and $50,000, something like that. Per patient." About the same as a heart transplant? "Exactly!" he said. "As it moves toward being a kind of, quote, ‘routine therapy,' this is not much higher than many other therapies."
And those complications? "We'll see when we have enough follow-up to be sure," he said, adding that if the chances of such a complication were reduced by a factor of 10, he'd consider the risk-benefit ratio "perfectly acceptable." Fischer said he does not yet know whether his methods can be generalized to other types of genetic defects; he is not making any sweeping claims. His group is moving first to two other immune–deficiency diseases, involving other genes. "So we want to go step by step from the ones that are easiest to the most complex."
From the first glimmer of possibility to the present day, Theodore Friedmann has written and spoken as gene therapy's most ardent advocate. He has seen medicine enter a new era, which offers "new and definitive approaches to therapy that were previously only the stuff of dreams and scientific fantasy." His has also been a voice of caution, of reason. He has had to warn his colleagues that they must openly address their discipline's difficulties, its limitations, its failures. Yet he continues to marvel at the unprecedented possibilities raised by gene transfer. For the first time, he says, and one can sense his quiet exultation, medicine can do more than treat the signs and symptoms. It can reach the underlying causes. It can cure. "It's going to be difficult," he says. "Yet medicine has always had to work with imperfect knowledge and technology."