|THE CHANGING FACE OF AIDS
The fight against AIDS shifts to the developing nations.
July 17, 1998
in this forum:
Are we using the third world as guinea pigs? What is the status of vaccine research? Will funding for a vaccine limit ressearch into drug treatments? Do drug-resistant AIDS viruses mean that drug treatments will become obsolete? Has a drop in public attention hurt the fight against AIDS? Susan Darlen of Mecklenberg, NC asks: Is there a point to continuing funding drug treatments? I ask this because with the emergence of a drug resistant strain of HIV, it seems that any drug treatment's effectiveness is on borrowed time.
Dr. Anthony Fauci, director of the National Institute of Allergy and Infectious Diseases, responds:Our initial success with highly active antiretroviral therapy (HAART) in controlling HIV-1 replication and slowing disease progression is actually providing more, not less, incentive for antiretroviral drug clinical development.
It is now clear that with the appropriate drugs, HIV replication can be controlled for far longer periods than was possible even a few years ago. We now need to develop drugs that decrease the likelihood of the virus developing resistance and thereby sustain the proven benefit of therapy.
Some of the approaches for overcoming drug resistance under evaluation are:
- Increasing the potency of antiretroviral drugs available to patients. For example, an experimental drug called Abacavir, a nucleoside reverse transcriptase inhibitor in the same class as AZT, ddI, ddC and D4T, is considerably more potent than the older drugs.
- Improving adherence to the drug regimens. The complicated nature of the current antiretroviral regimens makes adherence difficult. Omitting doses of antimicrobial medications is a recipe for inducing drug resistance. Therefore, investigators are working to introduce regimens that can improve adherence by decreasing the number and frequency of pills that a patient must take each day. In this regard, an experimental drug called Efavirenz, a potent non-nucleoside reverse transcriptase inhibitor (NNRTI), can be given once a day in combination with other anti-retroviral drugs. Several clinical studies also are evaluating the efficacy of less frequent administration of protease inhibitors. The development of less toxic combination regimens is also being evaluated.
- Developing drugs that target other stages of the viral life cycle will make it increasingly difficult for the virus to develop resistance. Only 2 viral proteins (i.e.reverse transcriptase and protease) are targeted by the 11 drugs that are currently available for the treatment of HIV infection. New drugs that target the ability of the virus to use chemokine receptors to enter cells, and that target the viral integrase enzyme are in development.