HIV meds, such as protease inhibitors, nucleoside inhibitors, and the upcoming integrase inhibitors act on the virus to reduce replication. Through an indirect mechanism of removing the offending virus, the immune system is facilitated to repair itself. Presently, antivirals are the mainstay of treatment for HIV infection. In the case of immunotherapy, treatments are designed to directly and effectively stimulate an immune response against HIV.
I believe that the field of immunotherapy is a sleeping giant. An example of the successful use of immune therapies can be seen with interleukin-2. Interleukin-2 stimulates the immune system to attack cancer tumors and is currently approved for metastatic kidney cancer and metastatic melanoma (a form of skin cancer).
It has also shown to be of value in increasing T-cell counts in HIV disease and perhaps limiting HIV replication, by way of its immune-stimulating characteristics.
The focus of this article is to rivet the eye: imagine the new work being conducted in the front yards of Chicago specifically at Northstar Healthcare, a progressive HIV treatment and research center devoted to care of patients with HIV. The reader will get an inside peak at how different and novel approaches are being tried. However, make note that the ongoing research of the various new antiviral targets such as integrase and entry inhibitors will not be discussed here, as they have already been written about in other recent installments of "The Buzz." Finally, in the face of progress with new inhibitors, there have been no signals that pointed to a cure for HIV. Perhaps immune-based approaches may lead us closer to this goal.
In this study patients with T-cells below 200 will get infusions of antibodies to HIV that will be harvested from goats who were exposed to the virus. It is in the beautiful rolling hills of New Zealand that these goats are found and bred. Importantly, the specific transfer of antibodies are of the polyclonal type. Polyclonal antibodies are created with multiple B-cell (immune cells that produce antibodies against infection) clones and are felt to be very effective compared to monoclonal antibodies (being of one cell line) which are not.
Why animals and why goats? As humans, if we get exposed to animal-related viruses, we do not get sick; conversely, animals getting exposed to human viruses including HIV also do not become ill with the disease. The goats mount a unique immune defense against HIV, producing antibodies to distinct regions of the virus which are dissimilar to the antibodies that humans can accumulate and develop. An observation showed that goat antibodies are sensitive to different parts (regions) of HIV, called epitopes, for which the human immune system ignores. (An epitope is a portion of a molecule to which an antibody binds).
The discovery of new epitopes on HIV and the new technology that is being used to stimulate antibody production against these new found epitopes make for a novel and alternate target for which to fight HIV. Possible side effects to receiving goat-derived antibodies are various allergic and hypersensitivity responses to the treatment. Because this treatment is being offered to individuals with T-cell counts below 200, it is felt that this problem will be minimized. Patients will be given this treatment by intravenous infusion at Northstar three times weekly for 16 weeks.
To what degree an immune-based therapy will become a significant addition to treatment is still unknown. However we must continue to search because if we don't look, we will not find. Thus as an early window's view into the future, we continue to remain on the cusp of the research. As progress continues, treatments of the future will be reshaped; they will not look like the present. Already, integrase and CCR5 (entry) inhibitors are expected to be approved shortly and will surely change our approach to treatment. We strive for ways to improve HIV therapy from different vantage points. Immune therapy and other treatments continue to evolve.
Daniel S. Berger, M.D., is the founder and Medical Director of Chicago's largest private HIV treatment and research center, NorthStar Healthcare and Clinical Assistant Professor of Medicine at the University of Illinois at Chicago. Dr. Berger serves on the Medical Issues Committee for the State of Illinois and the Board of Directors for the AIDS Foundation of Chicago. Dr. Berger can be reached at DSBergerMD@aol.com or (773) 296-2400.