Tenofovir gel fails to prevent HIV infection in women
SEATTLE — Pericoital vaginal tenofovir 1% gel once again was found to be ineffective at preventing HIV acquisition among women, according to data from the FACTS 001 trial presented at CROI 2015.
“The results are very disappointing,” Helen Rees, MD, executive director of the Wits Reproductive Health and HIV Institute, University of Witwatersrand in Johannesburg, South Africa, said during her presentation. “Tenofovir gel has demonstrated a reduction in HIV acquisition in a proof of concept phase II2 trial, but there are now two phase 3 trials showing no benefit.”
Rees and colleagues evaluated the gel among HIV-negative, sexually active women aged 18 to 30 years. The study included 2,059 women who were randomly assigned to tenofovir gel or placebo. Baseline characteristics between the two groups were similar. The modified intent-to-treat analysis included 1,015 women in the tenofovir arm and 1,014 in the placebo arm, after participants were excluded for HIV-positivity at enrollment or not having a follow-up visit after randomization.
There were 61 HIV infections over 1,515 person-years of follow-up among women in the tenofovir arm and 62 HIV infections over 1,521 person-years of follow-up in the placebo arm. The incidence rate was the same in both: 4.0 per 100 person-years, an incidence rate ratio of 1.0 (95% CI, 0.7-1.4).
The researchers estimated the use of the gels by dividing the number of returned used applicators by the number of reported sex acts and cutting that in half. By these estimates, participants in both arms used the gel in 50% to 60% of sex acts per month, on average.
In a pre-specified, case-cohort substudy in the tenofovir arm, the researchers measured tenofovir levels in cervicovaginal lavage samples taken quarterly. This study included 56 seroconverters and 158 controls. Among the 1,075 samples, 64% had any tenofovir detected. Tenofovir was detected at all quarterly visits for 22% of the women and never detected in 13% of the women. In an adjusted model, detection of tenofovir was associated with 52% protection (HR = 0.48; 95% CI, 0.23 – 0.97).
“HIV prevention in women is a major public health priority,” Rees said. “Pericoital vaginal tenofovir 1% gel was safe, but not effective in preventing HIV acquisition in this population. There is an urgent need for a range of HIV prevention options for young women, which may be easier to integrate into their lives.” – by Emily Shafer
Rees H, et al. Abstract 26LB. Presented at: Conference on Retroviruses and Opportunistic Infections; Feb. 23-26, 2015; Seattle.
Disclosure: Rees reports no relevant disclosures.