A new once-weekly HIV treatment has shown promising results after maintaining viral suppression as effectively as a standard daily treatment in a large phase 3 clinical trial.The study tested a combination tablet containing islatravir 2 mg and lenacapavir 300 mg in adults whose HIV had already been suppressed for at least six months while taking daily antiretroviral therapy.After 48 weeks, the weekly treatment met the study’s main goal of noninferiority compared with the daily combination of bictegravir, emtricitabine and tenofovir alafenamide.
In simple terms, the weekly pill performed closely enough to the daily treatment to be considered a potential alternative, although the study did not show that it was better.Strong Viral Suppression ResultsThe researchers measured the number of participants whose HIV-1 RNA reached 50 copies per milliliter or higher at week 48, a level used to identify loss of viral suppression.None of the participants receiving the weekly regimen reached that threshold, compared with just one participant, or 0.3 percent, among those who remained on daily treatment.The results were reported from the ISLEND-1 phase 3 trial, while a companion study, ISLEND-2, also reached the same noninferiority conclusion.Maintaining an undetectable viral load is a key goal of HIV treatment because it helps protect the immune system and, when viral suppression is maintained, prevents sexual transmission of HIV.More Than 600 People Took PartISLEND-1 involved 607 adults across 12 countries. Of these, 304 switched to the weekly treatment while 303 continued their daily therapy.The trial was randomized, double-blind and active-controlled, with participants followed for a planned 96 weeks. The results currently available cover the first 48 weeks.The study population included 21 percent women, 31 percent Black participants, 26 percent Hispanic or Latine participants and 15 percent people aged 65 or older.
However, the findings apply specifically to people whose HIV was already well controlled. Participants had to have maintained viral suppression for at least six months before entering the trial.This means the results show that the weekly treatment may work for people switching from an effective daily regimen. They do not establish whether the combination would be appropriate for someone starting HIV treatment for the first time or someone whose virus is not currently suppressed.CD4 Counts and SafetyResearchers also monitored CD4 cell counts because earlier studies involving higher doses of islatravir had raised concerns about reductions in CD4 cells and lymphocytes.At week 48, the average CD4 change was a decline of 10 cells per microliter in the weekly-treatment group and 18 cells per microliter in the daily-treatment group. Researchers did not consider the difference between the groups meaningful.Serious adverse events occurred in 5.3 percent of participants receiving the weekly regimen and 4.6 percent of those taking daily treatment.Treatment was discontinued because of adverse events in 2.0 percent of the weekly group and 1.7 percent of the daily group.The companies developing the treatment reported that no new safety concerns were identified.What Still Needs to Be LearnedThe trial results cover only 48 weeks of a planned 96-week follow-up period. Longer-term results will be important in determining whether viral suppression remains stable and whether resistance develops over time.A weekly treatment could also create a different adherence challenge. Missing one daily dose creates a relatively short gap, while missing a weekly dose could leave a longer period without medication.Researchers will therefore need to see how the treatment performs outside clinical trials, where patients may not have regular study visits and reminders.
The Weekly Pill Is Not Yet AvailableDespite the encouraging results, the treatment has not yet been approved and cannot currently be prescribed.Gilead Sciences and Merck, the companies developing the combination, have indicated that the findings will support regulatory submissions. Regulatory review must still take place before the treatment could become available.The trial results were presented at the International AIDS Conference in Rio de Janeiro.For people currently taking effective HIV treatment, the findings do not mean they should stop or change their medication. Maintaining treatment is important because interruptions can lead to viral rebound and drug resistance.What the Results MeanThe main finding is that a once-weekly pill combining islatravir and lenacapavir successfully maintained HIV viral suppression at 48 weeks in adults who were already virologically suppressed.If eventually approved, such a treatment could offer another option for people who find daily pills difficult because of pill fatigue, privacy concerns or the burden of taking medication every day.For now, however, daily antiretroviral therapy remains the established standard, and the weekly combination remains under regulatory review.
