A National Institutes of Health advisory board on Monday recommended for the first time that researchers be allowed to inject cells altered with viral genes into human patients, a major step toward future gene therapy.
Dr. William J. Gartland, the executive secretary of the Recombinant DNA Advisory Committee, said the panel voted, 16 to 5, in favor of the proposal to inject the altered cells into patients to determine how well a certain form of cancer therapy is working.
He called the decision a “fairly split vote for that committee.”
The NIH director and the Food and Drug Administration still must approve the proposal before it is carried out, and Gartland said that because of the split in the vote, “the NIH director will probably want to know why those five people voted against it.”
Some Have Reservations
“The people who submitted the protocol feel it is not dangerous and that they’ve completed enough of the safety testing to say that,” Gartland said. “There are some people on the committee who have some reservations about it, but these are very terminally ill patients with cancer, so it’s probably a safe procedure in these circumstances.”
The protocol recommended by the advisory committee called for the experiment to be limited to 10 patients, and those patients would have life expectations of only about 90 days because of the advancement of their cancer, he said.
Gartland said the proposal, if given the go-ahead by the NIH director and the FDA, would be a major step toward eventual gene therapy, a much more controversial matter that would be used to treat genetic diseases.
“If this protocol were to work, I’d expect that within six to 12 months there could be a proposal to do a gene therapy experiment,” he said.
The proposal involves a so-called marker gene that would be put into patients’ cells and placed back inside the patient.
Under an already established procedure, researchers can remove tumor cells from a cancer patient and grow them in the laboratory.
“Then when they put them back in the patient, they tend to go back in and attack the tumor that they used to be a part of,” he said. “This has been done and they’ve labeled these cells with a radioactive isotope, so when they go back into the patient, they can follow it.
“The problem is the radioisotope is a short-lived isotope and they would like to be able to follow these cells that they put back into the patient for a longer period of time,” Gartland said.
In place of the radioisotope, which has a half-life of 11 days, they have proposed the use of an antibiotic resistant gene that would be traceable for months, he said.
To determine whether the cell went back to the tumor to fight the cancer, researchers would use a probe to biopsy the tumor and look for the cell marked with the gene, he said.
“They’re trying to find out how well the tumor-fighting cells go back to the tumor they were taken from and how long they persist,” he said.
The main concern for those who voted against the proposal, he said, was “what they’re using is a virus to ‘infect’ the patients’ cells and put the marker in the patients’ cells. The concern is that the virus” itself could make the patients sick, even though the virus’ ability to be infectious would be removed before it is placed in the cell.