Targeted gene therapy for HIV/AIDSSaturday, 5 March, 2011
Some scientists (I still have no idea who) reported treating six patients with ex vivo gene therapy for the treatment of HIV/AIDS. Researchers used zinc finger nucleases to edit out the CCR5 gene from CD4-positive T-cells. Because HIV (or, most strains of it) uses the CCR5 protein to infect CD4+ T-cells, this essentially creates white blood cells that are immune to HIV. People with a deletion in their CCR5 gene (5-14% of Europeans have at least one such deletion, the CCR5-Δ32 allele) are essentially immune to AIDS (though they can sometimes get asymptomatic HIV infections).
All six patients showed some immune recovery, with five showing up to 6% of their cells modified, so that’s progress, I guess. Side effects were just a couple days of flu-like symptoms. In this study, the cells were removed from the patient and edited outside the body, probably because the ridiculous safety standards required for gene therapy that I recently blogged about pretty much rule out modifying the patient’s genes directly (i.e. in vivo). And I suppose the zinc finger nucleases probably aren’t as efficient as using a virus, so it wouldn’t really work in vivo just yet.
This is, however, the first time that human gene therapy has actually deleted a gene, rather than adding one. Pretty soon, addition, deletion, modification, replacement…it’ll all be possible.
Some scientists are, I think sensibly (with just 6% of cells modified), trying to avoid the work being overhyped as a ‘cure’. For example, Dr Michael Kolber, professor of medicine at the University of Miami:
“[This study] was a proof-of-principle that they could go in and do this. They demonstrated that the [genetically engineered] cells stayed in the patients, but the patients were not cured”
Of course this gets reported as:
Experts are reacting with cautious optimism…but they say the jury is out on whether the technique might ever spell an end to AIDS.
No, the jury isn’t out on whether the technique might ever work, just whether it has worked. It’s obvious beyond a reasonable doubt that gene therapy could provide both immunity and cures for HIV infections. And I’d say it’s obvious that gene therapy could cure all disease (and I’m not overhyping, just don’t expect these cures tomorrow and without side-effects during their early stages of development).