What is one lesson that Dr. Bob has taught us this year? If people say something is impossible, perhaps it just has not been done yet. A recent article in the New York Times expand on the idea that finding a cure for HIV (something that is usually thought to have insurmountable challenges) may not be as far away as we think.
In 2008 a patient dubbed the “Berlin Patient” was HIV positive when he was diagnosed and treated for leukemia. He was treated with bone marrow transplants which effectively replaced his immune system with the donor’s immune system. It just so happened that his donor was one of Northern Europe’s 1% that are resistant to HIV because they lack CCR5, the human receptor for HIV that allows them to enter immune cells. With his immune system effectively replaced with an HIV resistant immune system, the Berlin Patient has been able to survive 4 years supposedly virus free.
With this knowledge scientists are trying to develop a therapy similar to the Berlin Patient’s treatment for HIV. However, bone marrow transplants are expensive, risky, and require a donor with immunologically matching bone marrow. All this makes it a very tricky process.
Nevertheless, scientists have come up with a plan: “modify a patient’s own immune cells to make them resistant to infection by eliminating CCR5” (NYTimes). Now they have succeeded in doing just that in a patient.
The Trenton patient’s white blood cells were treated with gene therapy to produce zinc-finger nucleases that effectively disrupt CCR5 gene. The treated cells were returned to the patient and a month later he stopped taking his anti-virals.
At first, the level of HIV in his body increased sharply. However, then it fell back to undetectable amounts even before the 12-week period had ended. The patient’s immune cell counts also shot up.
What’s remarkable is that only a portion of his cells became genetically altered after the treatment and it still worked. It’s amazing that it worked at all because most of his CD4 cells had CCR5 gene expression.
Five other patients who received the same treatment did not have such successful outcomes but it is an interesting start to a possible new treatment for the disease. What is most interesting is that some scientists think that getting rid of as little as 10% of CD4 CCR5 gene expression (and therefore saving them from infection) could free up the immune system to control the virus. Patients who genetically have a percentage of their immune that are resistant to HIV (lack CCR5) would be even more likely to overcome disease by this treatment.
The article, New Hope of a Cure for H.I.V. can be found at http://www.nytimes.com/2011/11/29/health/new-hope-of-a-cure-for-hiv.html?_r=1&ref=health