There have been no new HIV infections in the 1628 people
taking part in a demonstration study of pre-exposure prophylaxis (PrEP) in France. Over half of participants
chose to use on-demand dosing for PrEP, with the rest opting for daily dosing,
but both have been equally effective, Jean-Michel Molina of the University of
Paris Diderot told a press conference at the 22nd International AIDS Conference
(AIDS 2018) in Amsterdam today.
The
‘Prévenir’ (prevent) study is gathering data on the best ways to deliver PrEP
in Île-de-France, which is the region of Paris and its suburbs. The researchers
hope to show that having an extra 3000 people take PrEP will result in a marked
fall in HIV diagnoses among men who have sex with men in the region.
Molina presented data on the first year (from May 2017) of
the three-year study. A total of 1628 people have enrolled, almost all of whom
(98.8%) are men who have sex with men. Twelve heterosexual men and women as
well as eight transgender people have enrolled.
Most participants are in their thirties or early forties;
just over half do not have any regular sex partners; and 57% had previously
used PrEP before enrolling in Prévenir.
Participants can choose whether to follow the on-demand
dosing schedule (sometimes referred to as ‘event-driven’ or ‘event-based’
dosing) that was validated in the IPERGAY study, or to use daily dosing, which
is more commonly used in other parts of the world. On-demand dosing involves
taking a double dose of PrEP (two pills) from 2-24 hours before anticipated
sex, and then, if sex happens, additional pills 24 hours and 48 hours after the
double dose. In the event of sex on several days in a row, one pill should be
taken each day until 48 hours after the last sexual intercourse.
At enrolment, on-demand dosing was chosen by 54.6% and daily
by 45.4%. The number choosing on-demand is much higher than in the Belgian and
Dutch studies, reported below.
There were some differences in the profiles of those
choosing the two options. Those choosing daily dosing tended to have had more
sexual partners (15 in the past three months) and more condomless sex (three
times in the past four weeks) than those choosing on-demand dosing (ten and two,
respectively).
Although the trial has been open for a year, the average
(mean) period of follow-up is seven months. Molina presented data on 506 and 443
person-years of follow-up in the on-demand and daily groups, respectively.
There have been zero infections in both groups. Annual
incidence in the on-demand group is therefore 0 (95% confidence interval 0-0.7) and in the daily group 0 (95% confidence interval 0-0.8). The
researchers estimate that, so far, 85 HIV infections have been avoided in this
cohort of 1628 people.
Based on self report, 96.2% of sexual acts reported by
people taking on-demand PrEP have been ‘covered’ by PrEP – meaning that the
person took the recommended doses before and after sex. The equivalent figure
for those taking daily PrEP is 95.8%.
Condoms have been used during 22% and 19% of sexual acts, in those using on-demand and daily PrEP, respectively.
There are indications of changes in sexual behaviour. Over the first year of the study, while average partner numbers have declined, condomless sex has increased – in on-demand PrEP users, from a median of two to
four times in the past four weeks; in daily PrEP users, from three to six
times. However, as less than one in ten people
have been in the study long enough to provide data over the full year, these
results should be interpreted with caution.
There have been eleven infections of hepatitis A, C or E (an
incidence of just over 1% in both arms). Side-effects and abnormal kidney
results have been limited, with no differences between arms. Study retention
has been good (a drop-out rate of 3.3% per year).
Molina believes these data strengthen the case for the safety and effectiveness of on-demand PrEP (currently supported by guidelines of the European AIDS Clinical Society as well as the national bodies in France, the UK, Canada and Australia). It is an option that has the potential to boost the uptake of PrEP, he told the press conference.