BOSTON — Results from the ASPIRE trial showed that a vaginal ring containing an antiretroviral drug was associated with a 27% reduction in HIV infection among women in sub-Saharan Africa.

Jared M. Baeten, MD, PhD, a professor in the departments of global health, medicine, and epidemiology at the University of Washington, and Annalene Nel, MD, chief medical officer for the International Partnership for Microbicides discussed the results of two separate trials on the ring during a press conference Monday at CROI 2016.

Results from the ASPIRE study were released on Monday in the New England Journal of Medicine.


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Baeten said that reduction incidence increased to 37% (95% CI, 12-56; P=.007) when researchers excluded two study sites with low adherence.

“ASPIRE demonstrates a statistically significant reduction in HIV incidence for women at risk of HIV in four African countries,” Dr Baeten said. “HIV was reduced by more than a third overall, and by more than half in women who appeared to use the ring better. This is the first demonstration of a sustained release approach for antiretroviral prevention.”

As of September 2014, The Joint United Nations Programme on HIV/AIDS (UNAIDS) estimated that nearly 25 million people in sub-Saharan Africa are infected with HIV/AIDS, 58% of whom are women. Dr Nel said the extremely high infection rate in the placebo arm suggests that more than half of the women in the communities studied are likely to become infected over the next decade without a new prevention options.

“Women in sub-Saharan Africa remain at very high risk for HIV despite the role of HIV treatment and male circumcision. That is unacceptable,” she said. “Today’s results give us hope that we must, and can, do better.”

From August 2012 through June 2015, researchers enrolled 2,629 healthy, sexually active, nonpregnant, HIV-1–seronegative women aged 18 to 45 years at 15 research sites in Malawi, South Africa, Uganda and Zimbabwe. The women were randomly assigned to a vaginal ring containing 25 mg dapivirine (n=1,113) or placebo (n-1,316).

Rings were replaced monthly. Rate of adherence was more than 70% overall, as defined by dapivirine detection in plasma, in returned rings, and in the composite of those two measures.

Median follow-up was 18 months. Rate of retention was 85% and 99.4% of women completed at least one post-randomization HIV test.

Incidence of HIV infection was 3.3% in the study group compared with 4.5% in the placebo group. Researchers determined that incidence of infection was 27% lower in the treatment population (95% CI, 1-46; P=.046).

Researchers noted a strong correlation between age and efficacy. Among women 18 to 21 years, efficacy of HIV-1 protection was −27% (95% CI, −133-31; P=0.45). Among women aged 21 years or older, the efficacy of HIV-1 protection was 56% (95% CI, 31-71; P<0.001).

“We found in a preplanned analysis that among women over 25 years old, the result was a 61% reduction in HIV incidence,” Baeten said.  

He added that the lack of protection appeared to only affect women younger than 21; in women 22 years or older, researchers found “a highly statistically significant result of” 56% reduction in HIV incidence. He added that objective measures of adherence showed that women 18 to 21 had poorer adherence compared with women 22 and older.

To learn more about this subject, view our in-depth interview with Dr. Baeten below. 

Reference

1. Baeten JM. 109LB. A Phase III Trial of the Dapivirine Vaginal Ring for HIV-1 Prevention in Women. Presented at: CROI 2016. Feb. 22-25, 2016. Boston.