A trial to test the safety and effectiveness of gene therapy to cure or alleviate HIV in patients has seen promising results according to a paper published yesterday in the journal Nature Medicine. When the therapy was used on 74 patients it was shown to be safe and appeared to reduce the ability of the virus to damage the patients’ immune systems. Although the results represent a notable milestone, the therapy still requires significant refinement and readers are advised to resist the hype associated with this story at other news outlets.
HIV harms its victims by systematically infecting and destroying the cells that make up the immune system, leaving them unable to defend themselves against what would normally be harmless infections. HIV sufferers currently must take a daily cocktail of medication called highly active antiretroviral therapy (HAART) to defend themselves against the virus. HAART is plagued with high costs, a daily treatment regimen, and serious negative side effects to patient health. Gene therapy holds the promise of one day completely curing patients with a once only treatment.
In the trial, 38 HIV-1-infected adults had their blood (i.e. bone marrow) “upgraded” with a gene that was expected to thwart HIV’s normal ability to destroy cells of the human immune system. The remaining 36 patients in the 74 patient trial were given a placebo. The gene therapy appears to have had some success in stopping HIV from destroying CD4+ cells, a vital component of the immune system, as evidenced by higher levels of CD4+ cell counts in adults that received the therapy. Even 100 weeks after the trial, patients that received the therapy still showed elevated CD4+ cell counts, demonstrating the long term effectiveness of the therapy.
After 48 weeks the researchers found there was no statistically significant difference in the amount of HIV circulating in the blood of the two groups of patients. This is not unexpected, as the gene therapy is not designed to attack HIV directly or to limit its pervasiveness within the body, but rather to stop it from infecting and destroying the vital cells of the immune system.
Medical News Today has one of the less hyped reports on the trial. From the report:
For the study, Mitsuyasu and colleagues took blood stem cells (CD34+ hematopoietic progenitor cells) from the patients in the treatment group, modified them to carry an enzyme called OZ1, and then reinjected them back into the patients. OZ1 targets two proteins that stop HIV replicating itself.
The trial was double blinded, so neither the patients nor the health care team treating them knew whether their stem cells carried the active enzyme or a placebo.
Although the therapy in this trial showed some success in limiting HIV’s ability to attack the immune system, the success was far short of what is needed. The problem is likely related to the fact that only part of the patients’ blood system was upgraded with the new gene instead of all of it. Researchers need to develop theories and techniques to completely upgrade the entire blood system with the new gene. They will then need to run exhaustive trials to test and develop these improvements.
Although the near term (3-5 years) prospects for this therapy seem limited, the longer term (10-20 year) prospects look very promising! Researchers know what they need to do, they just need to get better at doing it.