The results from the Danish reanalysis are modest yet promising. However, they need to be interpreted cautiously, at least for the following reasons:
- Reanalyzing data from a study designed for a different purpose can, at best, yield interesting results. However, such reanalysis cannot produce definitive results. The findings from the Danish study can be used to design a clinical trial to assess the impact of CpG 7909 on changes in the proportion of HIV-infected cells, perhaps with more participants and over a longer period.
- The reanalysis had additional gaps: The study was not formally designed to assess the impact on the immune system's ability to detect and destroy HIV-infected cells. Therefore, the scientists are not certain how repeated exposure to CpG 7909 apparently reduced the burden of HIV-infected cells.
What is clear is that no one has yet been cured of HIV by repeated exposure to CpG 7909 over a period of 10 months. Also, such a cure -- with this or any other therapy -- is not imminent. Rather, much more study is required of this exciting compound, perhaps in combination with other experimental drugs in HIV-positive people who are taking ART.
Problems With Access to CpG 7909
CpG 7909 was developed by the Coley Pharmaceutical Group, which was then acquired by the pharmaceutical company Pfizer in 2011, along with all of the rights for commercially testing and using CpG 7909 in people. Pfizer is developing a new CpG molecule that recently entered clinical trials, but they have not been providing this to outside groups for testing. CpG 7909 is in cancer vaccines being developed by GlaxoSmithKline as well as in several other cancer vaccines being developed by university-based scientists. Although clinical trials with CpG 7909 are ongoing in HIV-negative people, Pfizer has not continued Coley's policy of providing the compound to academic researchers for their research. Until this situation changes, it is not likely that CpG 7909 will be tested in clinical trials in HIV-positive people.
Not Giving Up
Although the Danish scientists cannot currently access CpGs for clinical trials in people, they are not giving up on cure research. They have at least another approach to a potential cure for HIV. In collaboration with other scientists in Australia, Sweden and the United States, they are testing a drug that will hopefully help to drive HIV out of hiding. This approach has the potential to reduce the burden of HIV-infected cells in the body and make future attempts at a cure perhaps easier. The drug being tested is an experimental cancer therapy called panobinostat, made by the pharmaceutical company Novartis. Panobinostat belongs to a class of drugs called HDAC inhibitors. Interim results from their study of panobinostat will be released later this year. To find out more about HDAC inhibitors and their potential and challenges for curing HIV, see TreatmentUpdate 196.
Cure Research in Context
The journey toward a cure will not be easy and many challenges lie ahead. Some of the challenges are known, others may only become known as experiments proceed. As with any great scientific endeavour, there will be setbacks. The initial wave of cure research experiments over the next five to 10 years should be viewed as exploratory and their results highly preliminary. This research will seek to answer important scientific questions that can then be used to build a foundation toward a cure. In the meantime, research funding agencies need to show patience and sustained funding as hardworking scientists struggle against the many challenges that lie in their path as they search for avenues to explore in the quest for an HIV cure.
We thank Ole Søgaard, M.D., and colleagues at Aarhus University, Denmark, and Arthur Krieg, M.D., RaNA Therapeutics, Cambridge, Massachusetts, for their helpful comments, research assistance and expert review.
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