Gene therapy developed by Sangamo Bioscience Inc. to mimic the blocking effect of white blood cells in people naturally immune to HIV helped six patients fight off the disease without drugs, a study showed.
In most people, the CCR5 gene acts as a receptor that shepherds HIV into the body’s cells. About 5 to 15 percent of the population, though, have one or two mutant copies of the gene that disrupts entry. The therapy by Richmond, California-based Sangamo used genetically modified white blood cells to imitate the effects of the mutant DNA, the study said.
The research, reported today at the Interscience Conference on Antimicrobial Agents and Chemotherapy in Chicago, may help patients who have HIV that’s resistant to current drugs, said Pablo Tebas, a researcher at the University of Pennsylvania in Philadelphia and a study investigator. It’s exciting because no serious adverse events were seen, he said.
The study found “these cells are going where they’re supposed to go,” Tebas said in an interview at the Chicago meeting. “At this stage it’s not a cure, and it’s a complicated treatment to expand to large segments of the population.”
Sangamo rose 1.2 percent, or 7 cents, to $6 in Nasdaq Stock Market composite trading on Sept. 16, after dropping 9.6 percent since the beginning of the year.
The most common side effect cited in the gene therapy study was a persistent smell of garlic, the researchers said. After the therapy, one patient who naturally had one copy of the mutant DNA maintained undetectable levels of HIV without drug use, the study found.
About 10 percent of people have one normal and one mutant gene, and less than 5 percent have only mutant genes, Tebas said. The company has two trials ongoing using the modification method.
In the other five patients, the amount of HIV in their bodies first increased during a 12-week period in which they weren’t taking anti-viral drugs, and then the level dropped, according to the study. The patients were male, and ranged in age from 31 to 56. Three had been infected for about 20 years.
“We see a significant anti-viral effect,” said Samgamo Chief Executive Officer Edward Lanphier in a telephone interview. “That’s the big punchline here.”
In Sangamo’s process, doctors draw patients’ blood and remove white blood cells, also called T cells. They are sent to Sangamo and modified using naturally occurring proteins called zinc fingers that cut into patients’ DNA in the middle of the CCR5 gene. The modified cells are then returned to the patient through an infusion.
Base of Immunity
The therapy doesn’t remove the CCR5 protein from all of the patients’ cells, Tebas said. Instead, it provides a base of immunity that helps patients suppress the virus, he said.
The next step is to increase the number of modified cells in patients, he said.
Antiviral drugs, led by Atripla and Truvada, made by Gilead Sciences Inc., of Foster City, California, and Reyataz, sold by New York-based Bristol-Myers Squibb Co., generated $15.1 billion in worldwide sales last year, according to IMS Health Inc., a Norwalk, Connecticut-based industry research company.