It was fitting that the 13th International AIDS Conference was held last month in Durban, South Africa, the country most infected with this disease. Drawing more than 12,000 researchers and public health officials, the conference offered many presentations addressing ways to tame the epidemic that continues to ravage the African continent. But there were also findings galore that could be used stateside. Here are some of the highlights:
•The potential for drug resistance and adverse effects always requires a therapeutic backup plan, so continued availability of new treatment options is vital. Ideally, these would involve fewer doses than earlier regimens, making it easier for patients to adhere to therapy. For the first time, the Atlantic study directly compared agents from the three existing classes of HIV/AIDS drugs.
The study involved 298 patients given the Bristol-Myers Squibb nucleoside analog reverse transcriptase inhibitors (NRTIs) didanosine (Videx) and stavudine (Zerit). At the same time, patients took either once-daily nevirapine (Viramune, Boehringer Ingelheim), a non-nucleoside reverse transcriptase inhibitor (NNRTI); thrice-daily indinavir (Crixivan, Merck & Co.), a protease inhibitor (PI); or twice-daily lamivudine (Epivir, Glaxo Wellcome), an NRTI. While the use of a PI in a regimen is generally considered the standard of care, researchers found HIV levels undetectable in 49% of the nevirapine group, 49% of the indinavir patients, and 40% of the lamivudine arm after 48 weeks of treatment. Indinavir calls for six tablets per day; nevirapine requires only two.
•AZT (zidovudine, Retrovir, Glaxo Wellcome) isn't the only drug that can prevent mother-to-child transmission (MTCT) of HIV. Several studies concluded that other antiretrovirals are equally effective. In one study, 373 pregnant HIV-infected women were given didanosine, stavudine, didanosine plus stavudine, or AZT. Preliminary results for the infants showed that MTCT rates were 1.9% for didanosine, 4.2% for stavudine, and 2.0% for both didanosine and stavudine, making them comparable to AZT (6.3%).
In another study—the SAINT trial—1,300 women were administered two doses of nevirapine (one in labor and one after delivery, plus one to the baby) or a seven-day course of AZT plus lamivudine. The overall rates of MTCT of HIV were 14% for nevirapine and 10.8% for AZT plus lamivudine, so similar results for both drugs were observed.
The positive nature of these findings was dampened, however, by the news that many HIV-infected mothers in Africa are still passing on the virus through breastfeeding. Breastfeeding is common in Africa for cultural and economic reasons.
•Another PI therapy could be in the offing—Abbott Laboratories' ABT-378/r (lopinavir/ritonavir). In one phase I/II study involving 100 patients aged six months to 12 years who either had never taken or had taken a PI or an NRTI before, treatment included ABT-378/r in one of two liquid doses—230/57.5 mg/m2 or 300/75 mg/m2 twice daily. After three weeks, all patients were continued on the 300/75 mg/m2 twice-daily regimen. Patients who were new to therapy also received stavudine and lamivudine, while patients who had tried other therapies took nevirapine and up to two NRTIs. The researchers found reduced HIV levels in their blood and increased CD4 cell counts at 24 weeks of treatment.
Other studies of ABT-378/r were done among adults who were either treatment-naive or PI-experienced. All of them showed that the investigational PI suppressed HIV in both groups. Abbott submitted a New Drug Application for this drug with the Food & Drug Administration this past June.
•Considering that many patients must change their drug regimen over time, since few benefit from long-term combination therapy, many studies sought to determine if one agent could take the place of another. For instance, one study of 165 patients focused on whether the NNRTI efavirenz (Sustiva, DuPont Pharmaceuticals) could spare patients from taking a PI. The results demonstrated that 97% of patients on efavirenz plus two NRTIs maintained the viral load suppression originally achieved with a PI and two NRTIs at 24 weeks of treatment versus 83% of patients continuing on a PI and two NRTIs. The difference, according to researchers, is statistically significant.
•New national data on AIDS were released by Helene Gayle, director of the Centers for Disease Control & Prevention's National Center for HIV, STD, and TB Prevention. Gayle said that while the number of AIDS infections today is lower than in the 1980s, she is "scared" by some trends she's starting to see. Among them are increasing risk-taking behavior in homosexuals and a rise in gonorrhea in HIV patients. Unless this risky behavior is curbed, we could expect a resurgence of this scourge, she warned.
