The long-acting drug lenacapavir, a first-in-class capsid inhibitor, shows sustained viral suppression in a small cohort of heavily treatment-experienced patients with multidrug-resistant HIV at 26 weeks when combined with an optimized antiretroviral therapy. With regulatory approval, lenacapavir could become the only HIV-1 treatment option given every 6 months.
“These data support the use of lenacapavir in patients with multidrug-resistant viruses, and according to its long half-life of two subcutaneous injections per year, [it] could help reduce pill burden,” first author Jean-Michel Molina, MD, PhD, professor of infectious diseases and head of the infectious diseases department at the Saint-Louis and Lariboisière Hospitals, Paris, France, told Medscape Medical News.
Presenting the updated findings from the phase 2/3 CAPELLA trial at the International AIDS Society Conference on HIV Science (IAS 2021), Molina underscored the need for longer-term treatments.
“These patients with multidrug resistances are usually those who have not been fully adherent to their regimen,” he said. “Being able to provide the drug, given every 6 months subcutaneously, provides an ideal treatment for overcoming resistance and lack of adherence.”
The study showed that, after 26 weeks, 81% of heavily treatment-experienced people with HIV in a randomized cohort who were treated with a subcutaneous injection of lenacapavir (927 mg) combined with an optimized background antiretroviral regimen achieved sustained virologic suppression, with an undetectable viral load (< 50 copies/mL).
In addition, the lenacapavir-treated patients had a clinically meaningful mean increase in CD4 counts of 81 cells/μL over the 26 weeks.
The drug was well-tolerated, with no drug-related serious adverse events or adverse events leading to discontinuation. The most common adverse events were injection-site reactions, which occurred in 56% of participants, with most being mild or moderate.
Importantly, four participants developed emergent resistances to lenacapavir. One was suppressed with a change in the background regimen and two others were suppressed without a change in regimen.
“We know that these mutations affect viral fitness,” Molina told Medscape Medical News. “We need more studies to assess the real impact of these mutations.”
Molina noted that a phase 2 study is already underway to evaluate how a pairing of lenacapavir with fellow investigational long-acting drug islatravir (Merck) could offset the risk of developing resistances.
Asked by an audience member whether a two-drug regimen with something like islatravir is likely to successfully prevent resistances, Molina responded that “it’s too early to know what’s going to happen with (combinations), but these first results are really encouraging when you see the very high rate of being fully suppressed after 26 weeks.”
“The efficacy that we’ve seen after [a previous 2-week analysis] is long lasting.”
Lenacapavir Targets Multiple Viral Stages
Unlike other antiviral drugs that target just a single stage of viral replication, lenacapavir takes aim at multiple steps in the viral lifecycle, including capsid-mediated uptake of HIV-1 proviral DNA, virus assembly and release, and capsid core formation, Molina explained.
The CAPELLA trial included participants at research centers in North America, Europe, and Asia, with a median age of 52 years; 25% were female, 38% were Black, and their mean HIV-1 RNA (viral load) was 4.17 log copies/mL.
Overall, 72 patients were divided into two cohorts of 36 patients each, including a randomized and nonrandomized cohort. Molina primarily reported results from the randomized group.
In that group, patients received either a lead-in of oral lenacapavir (600 mg on day 1 and 2 and 300 mg on day 8) or placebo, in combination with patients’ current failing drug regimens in both groups.
At day 15, all participants were switched to the investigator-selected, optimized background treatment regimen, tailored according to patients’ drug-resistance profiles, and those in the lenacapavir group received the subcutaneous injection of lenacapavir, while those in the placebo group were switched to the oral lead-in, followed by subcutaneous lenacapavir every 6 months.
Combined data that included six patients from the nonrandomized cohort showed that 79% of patients had a viral load of < 50 copies/mL at week 26. The 81% viral suppression rate represented the randomized group (29 of 36).
IAS co-chair Hendrik Streeck, MD, director of the Institute of Virology and Institute for HIV Research at the University Bonn, Germany, said a twice-a-year drug could possibly have profound benefits with a reduction in daily pill burden.
“What makes this an interesting drug is that it is long acting, so one can imagine it has the potential to treat individuals such as those who are not very adherent to the antiretroviral therapy, or who can’t easily access treatment, for example in resource-limited settings,” he told Medscape Medical News.
“The option to treat patients for the next months in advance could be a very important next step,” he said.
Further Data From CALIBRATE
Additional data on lenacapavir from the phase 2 CALIBRATE study, presented in a separate session, further showed the drug, given orally or subcutaneously in combination with oral daily emtricitabine/tenofovir alafenamide (F/TAF), resulted in high rates of viral suppression among 94% of 157 treatment-naive patients after 28 weeks.
Commenting on the research, session moderator Alexandra Calmy, MD, PhD, of the HIV/AIDS Unit and LIPO & Metabolism Group, Infectious Diseases Division, Geneva University Hospitals, Switzerland, noted the study offered “interesting data indeed” — with some caveats: “Why position a new drug class in naive patients [when] we already have good options, available for a large range of various populations?” she said in an interview with Medscape Medical News.
Calmy noted that, in general, lenacapavir “would certainly be an added value with an adapted 6-monthly companion drug.”
But she raised another key issue: “When will we have data on pregnancy that would allow lenacapavir to really be a game changer worldwide?”
The study was funded by Gilead Sciences. Molina has reported receiving research funding from Gilead and being on advisory boards for Gilead, Merck, ViiV, and Janssen. Calmy and Streeck have reported no relevant financial relationships.
IAS 2021. Abstract #2605. Presented July 20, 2021.
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