A sub-study of the landmark clinical trial evaluating the safety and efficacy of the twice-yearly injectable HIV prevention drug, Lenacapavir, has found that it provides 100 percent protection against HIV infection among pregnant and breastfeeding women using it as pre-exposure prophylaxis (PrEP).
The Phase 3 PURPOSE 1 trial results, published in the Lancet Medical Journal last week and presented at the ongoing International AIDS Conference that opened on Sunday, show the injection to be safe for use in pregnancy.
While Lenacapavir was previously studied and demonstrated high efficacy and safety as PrEP in cisgender women, its use during pregnancy and lactation, when women are disproportionately vulnerable to HIV acquisition, was not described in the initial studies that formed the World Health Organisation’s global recommendation for the drug.
Now, in the latest study, Dr Flavia Matovu Kiweewa, a Senior Research Scientist at MUJHU, says they checked for drug traces in breast milk and exposure to an unborn baby and found drug exposure levels across all trimesters and postpartum were comparable to non-pregnant participants, confirming no dose adjustments are needed for this group.
Among 5345 women enrolled between Sept 28, 2021, and Sept 15, 2023, 487 participants, 184 allocated to Lenacapavir and 303 allocated to oral PrEP, had one or more pregnancies, resulting in 509 total pregnancies with 512 pregnancy outcomes, including three sets of twins.
While the study involved women aged between 16 and 26 years in both South Africa and Uganda, 80 percent of all the pregnancies recorded were in Uganda. Results show Lenacapavir was present in breast milk, but exposure in breastfed infants was minimal. Drug concentrations were measured in the blood of the mothers, breast milk, and breastfed infants’ blood.
Kiweewa says these results are a breakthrough as pregnant and postpartum women face elevated vulnerability of HIV acquisition, yet historically they have been excluded from early prevention trials, leading to years-long evidence gaps. The study compared twice-yearly Lenacapavir with daily oral PrEP in women who were not pregnant at enrollment.
But, unlike previous studies, women who got pregnant while participating in the study were, for the first time, left on their allocated study drug. Now, because of the new findings, Kiweewa says at one of their study sites in Mityana District Hospital, they have decided to dedicate seventy percent of their drug supplies to women.
Generally, she says other options such as condom use and daily PrEP have been challenging for certain groups of people.
Figures by the Uganda AIDS Commission show that of the 1.5million people living with HIV, over nine hundred thousand are women. Dr Vincent Bagambe who heads planning and strategic information at the Commission, explains that young women are still the biggest number when it comes to new infections. Last year, he says, the country recorded 37,000 new infections, of which 21, 000 are women. According to him, Lenacapavir will go a long way in cutting such infections.
