The practical importance of getting this picture right is that immune-based therapy
that acts against HIV is not the opposite of immune-suppressive therapy.
These approaches include biologic therapy using interleukin (IL)-2, IL-12, interferon-alpha, monoclonal antibodies directed against B cell targets, cytotoxic T lymphocytes directed against viral targets, immune-based therapy
, stem cell reconstitution, angiogenesis inhibitors, therapeutic vaccines, and traditional cytotoxic chemotherapy regimens (often in combination with a biologic or immunologic approach).
But some leading HIV researchers strongly believe that further studies are important, because of opportunities to answer questions about immune-based therapy
and vaccine science now.
The development and approval of immune-based therapy (IBT) for the treatment of HIV infection and related conditions is complicated by many factors, not the least of which is a poor understanding of immune responses that promote health and prolong life in people living with HIV.
To the contrary, the first question that the FDA will ask is, "What is this particular IBT supposed to do and how does it do it?" The phrase immune-based therapy itself is vague and includes a broad range of approaches and technologies that do very different things.
Even in this case there would still be an unknown mechanism in the patient that is not easy for HIV to evolve around, and that might be exploited to develop a new kind of drug treatment -- one probably closer to immune-based therapy
than to traditional antiretrovirals.
Study 806 represents the largest randomized trial of HIV-infected persons in the last decade and the first large-scale trial to study an immune-based therapy. (An immune-based therapy is a therapy that tries to harness the body's immune system to fight a pathogen, rather than a therapy that directly fights the pathogen itself.
Without a clear understanding of what markers to look for, scientists are left to look to clinical endpoints like disease progression and death as markers for the efficacy of an immune-based therapy.
But tougher questions about how best to serve the public interest arise from the fact that today immune-based therapy
is an enormously important research area, and yet there is no satisfactory way to test such treatments for clinical efficacy in patients (see "FDA Meeting on Approving Immune Therapies: Background and Comment," AIDS Treatment News #353, October 20, 2000).
Since immune-based therapy will clearly be important not only for HIV and other infectious diseases but for cancer, autoimmune diseases, and probably a considerable number of other conditions as well, it would seem to make sense for a large company to conduct research and development in order to build position and leadership in the larger area, even if there is no visible path of return for the investment.
And another obstacle is that while one would probably expect a good immune-based therapy to substantially reduce viral load, that is a lot to ask in the early stages of development of these treatments.
We may even want to start a person upfront with an immune-based therapy
, depending on what the patient looks like at baseline.