The vaginal ring is a silicone polymer ring containing 25mg of
the non-nucleoside anti-HIV drug dapivirine, which has never been developed as
an oral drug. Designed to be changed monthly, it sits on the cervix rather like
a diaphragm, and dapivirine diffuses out. After a month’s
continuous use, there should be about 21mg of dapivirine left in the ring if use has been continuous.
Jared Baeten of the Microbicide Trials Network made a
comparison with oral pre-exposure prophylaxis (PrEP). He pointed out that in the original iPrEx study of
PrEP, effectiveness had only been 44%, but that it had been 50% in the open-label extension study and 100% in people who took four or more doses a week.
Further PrEP studies and demo projects had been needed to demonstrate its
extremely high efficacy in circumstances where adherence was high. The
vaginal ring studies had essentially just started the second stage of this
process, he said.
The two studies are very similar. HOPE has 1407 participants,
started in August 2016 and is due to end in October 2018; DREAM has 900
participants, started a month earlier and will end by December 2018. DREAM is
taking place in six sites in South African and Uganda; HOPE has 14 sites and
adds sites in Malawi and Zimbabwe to the other two countries.
There were some differences in the trial populations. DREAM
participants were slightly younger than HOPE participants, with an
average age of 29 rather than HOPE’s 31, and 27% were below 25 compared with 13% in HOPE.
Far more women in HOPE were married – 53% compared to only 14%
in DREAM. This may be due not only to having a slightly older participant
group, but also because there were more sites outside South Africa: in that
country, among the legacies of apartheid is high levels of migrant work and transience
and consequently low levels of marriage.
There were high levels of sexually transmitted infections
(STIs) diagnosed in the women in both studies – 16% had an STI at baseline in
HOPE and 18% in DREAM – and Jared Baeten said that in HOPE, only 44% of women said they
had used condoms the last time they had sex.