The pre-exposure prophylaxis (PrEP) regimen of long-acting cabotegravir injections is 89 percent more effective than daily oral Truvada pills for preventing HIV infection, researchers from the HIV Prevention Trials Network announced on Monday.
“The results are incredibly important for women in Africa where lowering HIV incidence remains a priority,” said Dr Sinead Delany-Moretlwe, a research professor at the University of the Witwatersrand in Johannesburg who headed the study.
“We know that adherence to a daily pill continues to be challenging, and an effective injectable product such as long-acting cabotegravir is a very important additional HIV prevention option for them.”
An independent Data and Safety Monitoring Board recommended the study sponsor ― the United States National Institute of Allergy and Infectious Diseases ― should stop the trials early “in the interest of public health” after finding that a shot of the experimental medicine every two months worked better than daily pills to help prevent women from contracting HIV from an infected sexual partner.
The study was originally designed to continue through 2022.
The news is a boon for HIV/AIDS prevention efforts – especially in Africa, where the study took place and where women have few discreet ways of protecting themselves from infection.
The study, known as HPTN 084, was jointly-funded through by the Bill & Melinda Gates Foundation, and ViiV Healthcare. Study drugs are provided by ViiV Healthcare and Gilead Sciences, Inc.
Researchers enrolled 3,223 women at research sites in Botswana, Eswatini, Kenya, Malawi, South Africa, Uganda, and Zimbabwe. The average age of study participants was 26 years and 57 percent of participants were 18-25 years old. Eighty-two percent of the women enrolled were not living with a partner, 55 percent reported two or more partners in the past month, with 34 percent having a primary partner who is reported to be living with HIV or having an unknown HIV status.
A total of 38 HIV infections occurred during follow-up, with four infections in women receiving the shots (0.21 percent) and 34 infections in women taking the daily pill (1.79 percent). Women taking Truvada had approximately nine times more incident HIV infections.
The researchers said the higher-than-expected level of adherence to the daily pill throughout the study and overall low incidence rate in both arms of the study clearly demonstrates that both drugs were highly effective at preventing HIV acquisition.
“After years of evaluating HIV prevention strategies for women, I am thrilled that we have found cabotegravir so effectively reduces HIV acquisition and provides women more choices in how to protect themselves,” said Dr Mina Hosseinipour, the HPTN 084 protocol co-chair and professor of medicine at the University of North Carolina (UNC) who is currently the scientific director of UNC Project-Malawi in Lilongwe, Malawi.
Earlier this year, the HPTN 083 clinical trial showed that a PrEP regimen containing cabotegravir injected once every eight weeks was superior to daily oral Truvada for HIV prevention among men and transgender women who have sex with men.
“The results from HPTN 084 along with the HPTN 083 results released earlier this year show how far we have come in the fight against HIV,” said Dr Myron Cohen, HPTN co-principal investigator and director of the Institute for Global Health at the University of North Carolina in Chapel Hill.
“A highly effective product like cabotegravir that does not require a daily pill can be an important part of ending the epidemic globally.”
Dr Wafaa El-Sadr, HPTN co-principal investigator and professor of epidemiology and medicine at Columbia University in New York said he was “thrilled by these outstanding results”, calling them “a milestone for the prevention of HIV among women.”
He added: “These findings motivate continued evaluation of the safety of cabotegravir in adolescents, a group at substantial risk from HIV infection. Defining the safety of cabotegravir in adolescents will hopefully lead to faster access to cabotegravir, once approved for use as PrEP.”
“The urgent work now” is to make all prevention medicines affordable and more widely available, said Mitchell Warren, who heads AVAC, formerly known as the AIDS Vaccine Advocacy Coalition, a non-profit focused on prevention efforts that had no role in the study.
Condoms remain widely recommended because they help prevent a host of sexually spread diseases, not just HIV.
“People need choices for HIV prevention,” and this gives a new option, Warren said in a statement.