Long-acting antiretroviral therapy (ART) for HIV involving injections every 1 or 2 months not only shows non-inferiority to a standard daily oral treatment regimen, it also suppresses HIV even in patients who do not already have virologic suppression, as is typically required before initiation, results from two new studies suggest.
Meanwhile, a third study shows early promise of a long-acting ART regimen that could require injections only twice yearly.
“Instead of having the burden of taking a pill every day, patients with HIV can now have these choices of being able to forget about their treatment for up to 2 months at a time,” Moti N. Ramgopal, MD, first author of one of the three studies, said in a press conference this week at the Conference on Retroviruses and Opportunistic Infections (CROI) 2023. “My patients tell me that it’s game-changing for them.”
First Head-to-Head Comparison
The injectable intramuscular combination of cabotegravir and rilpivirine, administered once every 1 or 2 months, is the first and only long-acting ART to be approved by the US Food and Drug Administration (FDA) for people with HIV. At the meeting, Ramgopal, from the Midway Immunology and Research Center in Fort Pierce, Florida,
reported the results from the first head-to-head study comparing the regimen with the standard daily oral regimen of bictegravir/emtricitabine/tenofovir alafenamide (B/FTC/TAF).
For the phase 3b SOLAR trial, adults with HIV who were already virologically suppressed and treated with daily B/FTC/TAF were randomly assigned to remain on the oral regimen (n = 223) or switch to the long-acting injections every 2 months, either with an oral lead-in (n = 173) or without a lead-in (n = 274).
The results after 12 months showed non-inferiority between the groups, with 90% of the long-acting ART group and 93% in the oral daily pill group maintaining viral suppression, defined as plasma HIV-1 RNA <50 c/mL.
Two patients (0.4%) receiving the long-acting ART in a modified-intention to treat and 3 (0.6%) in the intention-to-treat populations had confirmed virologic failure, and rates of adverse events leading to withdrawal were 6% with the long-acting ART group vs 1% with the oral treatment group.
As many as 90% of subjects reported preferring the long-acting ART over their previous oral therapy at the end of the study, and those in the long-acting group also reported significantly greater improvements in quality of life on the HIV Treatment Satisfaction Questionnaire status version compared with the oral therapy group at the end of the study (P < .001).
Prior to the randomization, as many as 47% of patients on the oral regimen reported “always” or “often” having psychosocial challenges with the daily therapy, including worries of having their HIV status revealed and forgetting to take the medication.
“These data demonstrate that [the long-acting regimen] addresses important unmet needs for people with HIV who are virally suppressed on oral daily HIV therapy, while improving the quality of life,” said Ramgopal.
Suppression at Onset Not Necessarily Required
For all of its benefits, a key caveat of the cabotegravir and rilpivirine long-acting regimen is that it is approved only for patients who have already achieved viral suppression and are currently on oral ART, meaning some of the people most in need, including those with unstable housing, mental illness, or substance abuse disorders, may be excluded.
To evaluate the therapy’s efficacy among those patient types, Monica Gandhi, MD, MPH, professor of medicine and associate division chief at the University of California San Francisco, enrolled 133 participants between June 2021 and November 2022 at the Ward 86 HIV Clinic, a safety-net clinic in San Francisco, to initiate long-acting ART. Participants included 57 patients (43%) with untreated or unsuppressed HIV, and 76 who were virally suppressed on oral ART.
Of the whole study group, 66% reported unstable housing, 8% reported experiencing homelessness, 38% reported having a mental illness, and 33% reported substance use.
Although all of the subjects (100%) who started with viral suppression remained suppressed over the study’s 26-week follow-up, the rate of viral suppression at the study’s end was nearly as high — 55 of 57 subjects (96.5%) — among those who started long-acting ART without having viral suppression.
Of note, the overall rate of study participants who did not achieve or maintain viral suppression (1.5%) was consistent with rates reported in clinical trials of long-acting ART in people with HIV who had previously achieved viral suppression on daily oral ART.
“Our patient population does not look like the patient population that got enrolled in the clinical trials to determine the approval criteria for long-acting ART,” Gandhi said in presenting the findings.
“If 10% of the population carries 90% of the HIV virus — which we see in modeling — then we need innovations for this population if we want to end the HIV epidemic,” she added.
“We tried long-acting ART in our diverse, urban, low-income population and we saw very high virologic suppression rates equal to those that were seen in the clinical trials,” Ghandi reported. “This shows that long-acting ART, used creatively and used boldly, could really make a dent in the [efforts] to end the HIV epidemic movement.”
Commenting on the study in a press statement, Nora Volkow, MD, director of the National Institute on Drug Abuse, said “Dr Gandhi and her team have made state-of-the-art HIV treatment finally available to people with unique challenges, like those who use drugs, and have found success.”
“This is the sweet spot for addressing HIV ― thinking outside the box to deliver care in a way that meets people’s needs, even when that means it happens outside the clinic walls, by phone, or on neighborhood streets,” she said.
“This can be done ― but it requires creativity and resolve.”
Twice-Yearly Dosing Option?
Looking ahead, an even more intriguing scenario of a long-acting ART requiring injections only once every 6 months may be getting closer to fruition. Researchers at CROI 2023 reported early but promising safety and efficacy results of an innovative combination of the first-in-class HIV-1 capsid inhibitor lenacapavir with teropavimab and zinlirvimab, two broadly neutralizing antibodies (bNAbs).
To achieve the goal of the longer-acting therapy, Joseph J. Eron, MD, of the University of North Carolina at Chapel Hill, and colleagues modified both antibodies to extend their half-lives and allow less frequent dosing.
For the phase 1b trial, 20 adult patients with virologically suppressed HIV for at least 18 months were randomly assigned to one of two doses of the ART, both groups receiving lenacapavir at 927 mg subcutaneous after oral loading, plus teropavimab (30 mg/kg IV) and zinlirvimab at either 10 mg/kg or 30 mg/kg.
Patients had to have a CD4 count >500 and CD4 nadir >350, and importantly, patients had to demonstrate sensitivity on DNA phenotyping to both bNAbs at baseline.
After 26 weeks, 18 of the 20 participants (90%) maintained a viral suppression of HIV-1 RNA < 50 copies/mL.
Of the remaining 2 patients, one in the 10 mg/kg zinlirvimab group had a confirmed HIV RNA of 50 copies/mL (155 copies/mL, confirmed 524 copies/mL) at Week 16 and was able to be resuppressed with re-initiation of baseline ART, and one participant in the zinlirvimab 30 mg/kg group withdrew consent at week 12, with viral suppression, and chose to go back on oral therapy
The safety profile looked favorable, with no serious adverse events and two patients with grade 3 AEs, including one experiencing an injection site cellulitis and one with injection site erythema.
Eron noted that “bNAb sensitivity is an important issue and a limitation for broad use, [because] only about 50% of people with HIV in the US would be sensitive to both antibodies.”
However, “we are doing a pilot of only 10 participants looking to see if it works with sensitivity to a single antibody, which would increase [applicability] to about 90% of people with HIV,” he told Medscape Medical News.
At a press conference, Eron commented on how far HIV treatment has come, from the early days of patients having to wake up every 4 hours to take their medication, then to having to take 15 to 20 pills a day, to the current option of long-acting ART every other month, and now the potential of just a twice-yearly treatment.
“This is a very preliminary proof-of-concept study and not a very large study, but I think it’s incredibly important,” he said.
The SOLAR study was funded by ViiV Healthcare. Ramgopal has received speaking and/or consulting fees from AbbVie, Gilead Sciences, Janssen, Merck, and ViiV Healthcare. Eron’s study was funded by Gilead Sciences.
Conference on Retroviruses and Opportunistic Infections/CROI 2023. Abstracts 191, 518, and 193.
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