Treat HIV infection to protect partners

New research indicates that early initiation of antiretroviral treatment in people infected with HIV prevents them from transmitting the virus to their partners.

Results from a study set to run until 2015 were released early in May 2011 by an independent data safety monitoring board after findings indicated that HIV-infected men and women with relatively healthy immune systems who received immediate oral antiretroviral therapy were 96.3% less likely to pass on the infection to their uninfected partners and remained healthier than those whose treatment was delayed. The findings of the Phase III clinical trial, conducted by the HIV Prevention Trials Network as HPTN 052 and sponsored by the National Institute of Allergy and Infectious Diseases, were released early after data indicated the benefits of early treatment were clear. The results represent the first findings from a major randomized clinical trial to indicate that treating an HIV-infected individual can reduce the risk of sexual transmission of HIV to an uninfected partner.

What the science shows is what many HIV clinicians have long suspected: Earlier treatment is not only better for patient outcome, but it also is better for lowering transmission, says Michael Horberg, MD, vice chair of the Arlington, VA-based HIV Medicine Association (HIVMA) and director of HIV/AIDS at Kaiser Permanente in Rockville, MD. "The earlier you test, the earlier you screen for HIV risk and other sexually transmitted disease risk, diagnose early, and get patients into care, there is now not only a treatment, but a public health imperative," states Horberg, who serves on the Presidential Advisory Council on HIV/AIDS.

Look closer at results

To conduct the study, researchers began in 2007 to enroll discordant patients at 13 study sites in nine countries, including Botswana, Brazil, India, Kenya, Malawi, South Africa, Thailand, the United States and Zimbabwe. All participants were at least 18 years of age with a median age of 33 at the time of enrollment; 52% of the participants were male, and 97% of the couples were heterosexual. A total of 1,763 couples were enrolled in the study.

Couples randomly were assigned to two study groups: 886 were placed in the "immediate" arm, where the HIV-infected partners began receiving a three-drug HIV treatment combination, with the other 877 assigned to the "deferred" arm, where the HIV-infected partners received antiretroviral therapy only after their CD4 count dropped below a pre-determined level or an AIDS-related event occurred. Both groups received regular HIV testing, safe-sex counseling, free condoms, testing and treatment for sexually transmitted infections, and treatment for any HIV-related complications.

The study retained 90% of its participants, with only one case of HIV infection occurring among the couples assigned to receive immediate treatment, compared to 27 cases of HIV infection among those who delayed treatment. Seventeen cases of previously undiagnosed extrapulmonary tuberculosis also occurred among the HIV-infected partner in the deferred treatment arm, with only three cases occurring in the immediate arm.

The HIV drugs that were used in various combinations in the trial included atazanavir (300 mg once daily), didanosine (400 mg once daily), efavirenz (600 mg once daily), emtricitabine/tenofovir disoproxil fumarate (200 mg emtricitabine/300 mg tenofovir disoproxil fumarate once daily), lamivudine (300 mg once daily), lopinavir/ritonavir 800/200 mg once daily or lopinavir/ritonavir 400/100 mg twice daily, nevirapine (200 mg taken once daily for 14 days, followed by 200 mg taken twice daily), ritonavir (100 mg daily, used only to boost atazanavir), stavudine (weight-dependent dosage), tenofovir disoproxil fumarate (300 mg once daily), and zidovudine/lamivudine (150 mg lamivudine/300 mg zidovudine taken orally twice daily). A separate non-affiliated study is looking at the optimal time for asymptomatic HIV-infected individuals to begin antiretroviral treatment.

What happens next?

While the study findings were released early, the study will continue for at least one year, with all infected subjects being offered antiretroviral therapy while researchers consider the best way forward, says Myron Cohen, MD, J. Herbert Bate Distinguished Professor of Medicine, Microbiology and Immunology, and Public Health at the University of North Carolina at Chapel Hill. Cohen serves as lead investigator of the HPTN 052 trial. At press time, full findings of the study were scheduled to be presented at the July 2011 annual session of the International AIDS Society in Rome, Italy.

"Confirmation of the protective effect of treatment on HIV transmission to sexual partners is a giant step forward in confronting the HIV epidemic," said Wafaa El-Sadr, MD, MPH, professor of clinical epidemiology at the Mailman School of Public Health at Columbia University and a member of HIVMA's Center for Global Health Policy's Scientific Advisory Committee in a statement accompanying news of the study findings. "The finding of a protective effect of HIV treatment on the development of extrapulmonary tuberculosis may play an important role in avoiding this deadly complication in HIV-infected individuals."

While research continues on HIV prevention, clinicians can continue to emphasize the consistent and correct use of condoms by all women and men infected with HIV, notes Robert Hatcher, MD, MPH, professor of gynecology and obstetrics at the Emory University School of Medicine in Atlanta.