The more than 300 transgender women in the pivotal iPrEx pre-exposure prophylaxis (PrEP) trial had similar overall HIV infection rates whether they were randomized to take Truvada or placebo, but those with drug levels indicating consistent PrEP use appeared to be protected, researchers reported in the November 5 advance online edition of The Lancet.
"While this analysis did not include a large enough sample group to draw firm conclusions, we did find strong evidence pointing to efficacy," said senior study author Robert Grant from the University of California at San Francisco. "Additional research designed specifically for transgender women is needed to confirm this finding."
U.S. Food and Drug Administration approval of Truvada (tenofovir/emtricitabine) for PrEP in July 2012 was based in part on data from the Phase 3 iPrEx trial, which enrolled 2499 mostly gay and bisexual men from Brazil, Ecuador, Peru, South Africa, Thailand, and the U.S. (Boston and San Francisco) between 2007 and 2009. Participants were randomly assigned to take oral Truvada or a placebo once-daily. Follow-up in the randomized portion of the study continued for a median of 1.2 years. Afterwards participants had the option to receive Truvada in an open-label extension of the study, which ended in 2013.
Primary results, published in December 2010, showed that once-daily Truvada reduced the risk of HIV infection by 42% overall compared to placebo, rising to 73% among participants who reported good adherence and 92% among those with blood drug level measurements indicating regular use. In the open-label extension, no one who took Truvada at least 4 times a week became infected.
Transgender women have one of the highest rates of HIV infection. One meta-analysis of 22 studies found that 28% of transgender women in the U.S. are HIV-positive, while a 2013 meta-analysis looking at 15 countries found that 19% of trans women were living with HIV, the researchers noted as background.
To date, no randomized clinical trials have looked specifically at PrEP for transgender women, and it is not known whether hormone use or other factors might affect its safety and effectiveness for this group. This is the first separate analysis of trans women in a Truvada PrEP trial.
Grant, Madeline Deutsch, and fellow investigators performed an unplanned analysis of PrEP efficacy, overall effectiveness, and adherence among trans women in iPrEx, comparing PrEP outcomes between trans women and men who have sex with men (MSM).
While most of the 2499 iPrEx participants were gay and bi men, a total of 339 (14%) were classified as transgender women, including 29 (1%) who identified as women, 296 (12%) who identified as trans or "travesti," and 14 (1%) who identified as men but reported use of feminizing hormones. Of these, 192 joined the open-label extension, 79% of whom opted to take Truvada.
This excerpt was cross-posted with the permission of HIVandHepatitis.com. Read the full article.