WASHINGTON -- An advisory committee to the National Institutes of Health, while endorsing the "extraordinary potential" of human gene therapy for the treatment of serious diseases, urged yesterday that federally funded research shift its emphasis away from human experiments and back to the laboratory.
Panel members, hinting that scientists may have moved too rapidly into testing gene therapy theories in humans, said they believed that more can be gained from investing time and money into basic science that precedes application into humans.
And they said the gene therapy -- in its current immature state -- has been "oversold" to create the widespread public misperception that "it is further developed and more successful than it actually is."
Human gene therapy, which many researchers regard as the most innovative and promising therapeutic approach for treating diseases in the future, involves repairing or replacing defective genes in the body that cause disease, rather than using drugs.
Each of the approximately 50 trillion cells in the human body contains information that directs its function. This information is stored in the genes, which are made up of DNA, the genetic blueprint of life. When a gene is destroyed or broken, the cell's function is disrupted or eliminated, and disease may occur.
There are several basic approaches to gene therapy. Scientists can introduce a normal gene in an attempt to correct a defective gene, or replace a missing gene. Or genes can be used to assign a cell a new function, or enhance its current function.
The panel was created last spring by NIH Director Harold Varmus, who asked its members to study ways to improve NIH's investment in human gene therapy, and report back to him. Mr. Varmus said their recommendations will be reviewed by several institute directors within NIH before any decisions is made.
Since the human studies began in 1990, 106 human gene therapy studies have been launched involving nearly 600 patients, but they have produced no definitive results, the panel said. Some of these studies have involved cancer, cystic fibrosis and inherited immune disorders.
Moreover, the studies have raised some problems that only basic science can solve, the committee said.
NIH currently spends nearly $200 million annually to fund research into gene therapy approaches.
Panel members said more work was needed at the basic level to refine the ways in which genes are transferred into the human body. Most scientists use harmless viruses as "vectors" to deliver genes to the appropriate blood or tissues, or introduce cells that have been manipulated in the laboratory to harbor foreign DNA. Problems can occur if the body's immune system, primed to fight microbial invaders, attacks the transferred material.
Also, better ways need to be found to "turn on" the gene once it is in the body, a process known as gene "expression," the panel said.
