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Good Adherence to Vaginal Ring and
Daily PrEP in Half of Young African Women
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IAS 2021, 11th IAS Conference on HIV Science, July 18-21, 2021
Mark Mascolini
About half of 16- to 21-year old women in an African trial of the dapivirine vaginal ring and a preexposure prophylaxis (PrEP) pill had objectively measured high use of these HIV prevention tools [1]. The dapivirine ring outdid oral PrEP in full adherence rate-50% to 22%-in the Microbicide Trials Network (MTN)-034 REACH study. Researchers rated adherence "higher than anticipated" in these young women.
Previous trials of tenofovir-based PrEP and the dapivirine ring found worrisome evidence that younger Africans might not use these HIV prevention methods consistently enough to protect themselves from HIV. The MTN-003 (VOICE) and FEM-PrEP placebo-controlled efficacy trial determined that fewer than one quarter of young African women adhered well to a daily oral PrEP regimen. HPTN 082 found that drug levels linked to high PrEP efficacy dwindled from 25% to 9% between study months 3 and 12. In MTN-020 (ASPIRE) dapivirine ring efficacy reached 61% in women older than 25 but only 10% in those younger than 25. The trial found this vaginal ring had "no efficacy" in women 18 to 21 years old.
The World Health Organization now recommends the dapivirine ring for women "at substantial risk" of HIV infection. Oral tenofovir-based PrEP is available in many countries. MTN-034 (REACH) aimed to test both strategies in HIV-negative African girls and women 16 to 21 years old who were not pregnant and were using a reliable contraceptive method for at least 70 days. This randomized, open-label, crossover trial began enrollment in February 2019 and should complete follow-up in October 2021. Goals are to assess dapivirine ring and oral PrEP safety, adherence, acceptability, and preference. The PrEP pill was coformulated tenofovir disoproxil fumarate/emtricitabine (TDF/FTC). At IAS 2021 MTN-034 researchers presented interim results from the first two study periods, February 2019 through April 2021.
Adherence encouragement included text message reminders, support groups, counseling, and monthly adherence feedback to all participants. Researchers determined PrEP adherence by measuring drug levels in dried blood spots; they estimated ring adherence by measuring residual drug levels in returned rings.
The MTN team enrolled 60 participants in Cape Town, 60 in Harare, 67 in Johannesburg, and 60 in Kampala. Age averaged 18.2 years, 87% of participants were not married, 40% had ever been pregnant, 37% were in school, and 21% had an income-earning job. A big majority of participants, 89%, reported having a primary sex partner who averaged 23 years in age. Three quarters of participants knew their primary partner's HIV status, and one quarter thought their primary partner had other partners. These girls and young women averaged 2.5 sex partners in the past 3 months. A substantial minority, 39%, were "not at all worried" about getting HIV infection, and only 7% were "very worried." One third of study participants, 35%, began the trial with 1 or more sexually transmitted infections, including 29% with chlamydia and 8.5% with gonorrhea.
About half of participants, 54%, had at least 1 product-related adverse event. They averaged 5.1 adverse events and 1.3 product-related adverse events. Total adverse event numbers did not differ between the vaginal ring and PrEP. The most frequent adverse events were decreased creatinine clearance (a well-known kidney-related effect of TDF), chlamydia, and headache. No adverse events led participants to stop using the ring or PrEP, and there were no product-related serious adverse events.
Through the first 12 months of study, researchers confirmed high use of PrEP in 58.6% of participants (at least 700 fmol tenofovir per punch) and high ring use in 50.2% (more than 4 mg per month). High use of PrEP meant drug levels indicated taking the pill at least 4 times a week; high use of the ring meant leaving it in place for a full month. Lower proportions had "some use" of PrEP (16.6 to 699 fmol tenofovir per punch) and the ring (0.9 to 4.0 mg per month): 39.9% and 45.4%. Some use of PrEP meant taking the pill 1 to 3 times weekly. The investigators determined no use or little use of PrEP in 1.5% of participants (below 16.6 fmol tenofovir per punch) and no use or little use of the dapivirine ring in 4.4% (0.9 mg or less). While 50.2% of participants had full adherence to the ring (leaving it inserted for a full month), only 22.4% had full adherence to PrEP (6 or more doses per week).
A large majority of participants, 88.5%, reported finding the ring acceptable, while 63.9% rated oral PrEP acceptable. Only 1 of 247 girls or women became infected with HIV for an incidence of 0.5 per 100 person-years. Four participants became pregnant for an incidence of 1.8 per 100 person-years.
"Not only are we seeing high adherence," said trial cochair Connie Celum of the University of Washington, "but persistence appears to be high as well." She attributed higher rates of adherence in REACH than in earlier studies to "the ongoing support and individual attention paid to participants." Despite high acceptability of both the ring and PrEP, however, only 50% to 60% of participants reached the "high use" threshold set for each strategy.
Reference
1. Nair G, Ngure K, Szydlo D, et al. Adherence to the dapivirine vaginal ring and oral PrEP among adolescent girls and young women in Africa: interim results from the REACH study. IAS 2021, 11th IAS Conference on HIV Science, July 18-21, 2021. Abstract OALC01LB01.
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