The findings, presented at the Conference on Retroviruses and Opportunistic Infections, also showed the drug was well tolerated, with 2 of 182 people developing drug-resistant mutations to lenacapavir and one person developing a nodule at the injection site.
Laura Waters, MD, consulting physician in HIV and sexual health at Central and Northwest London NHS Trust, who was not involved in the trial, called the findings “hugely exciting,” especially given its unique mode of administration. Right now it’s formulated as a subcutaneous injection, not an intramuscular injection like cabotegravir and rilpivirine (Cabenuva, ViiV Healthcare).
“Clearly it’s incredibly exciting to have the option for a subcutaneous drug that could be given at home every 6 months,” Dr. Waters said in an interview. With phase 3 trials and long-term follow-up still to come, she said she’s looking forward to how the treatment evolves.
CALIBRATE is a phase 2, four-arm, open-label, active-control study. Of the 182 participants, 25 were randomized to the active control arm, in which participants took daily oral bictegravir, emtricitabine, and tenofovir alafenamide (Biktarvy, Gilead Sciences) as standard of care. The rest of the 182 participants were divided evenly between three arms. In one of those, treatment group three, participants took a daily oral version of 50-mg LEN with emtricitabine and tenofovir alafenamide (F/TAF, Descovy, Gilead Sciences).
The other two arms, treatment groups one and two, were the arms in which Samir K. Gupta, MD, of Indiana University, Indianapolis, and colleagues tried the twice-yearly subcutaneous shots of LEN (LEN SC). Participants in those arms underwent a 2-week lead-in period in which they took 600 mg of LEN orally on days 1 and 2 and then a 300-mg pill on day 8 before starting the shots on day 15. As currently formulated, LEN SC shots can be given into the stomach and are designed to be simple enough to administer at home.
“It’s like doing an insulin shot,” Dr. Gupta said in an interview.
In addition to LEN SC, participants in treatment group one took a daily Descovy lead-in and then engaged in dual therapy of LEN plus TAF. In group two, they took a daily Descovy lead-in and then switched to LEN SC plus bictegravir (BIC) daily at 28 weeks.
Study results presented at the meeting were the results at 54 weeks. Researchers had previously presented 28-week results for CALIBRATE at the International AIDS Society Conference on HIV Science 2021.
Of the participants, 7% were cisgender women, 52% were Black, and 45% were Latinx. A total of 15% of participants had baseline viral loads of more than 100,000 copies, and median CD4 counts were 437. None of the participants in either the active-control arm or the LEN SC plus Descovy group had a history of AIDS, defined as fewer than 200 cells/mcL. In the LEN SC plus Biktarvy group, two did, and there were six people with a history of AIDS in the oral LEN plus Descovy group.
At 54 weeks, 88% of participants in groups one and two – the LEN SC arms – had undetectable viral loads (viral loads below 50 copies/mL). Specifically, 90% of those in the LEN SC plus TAF arm had viral loads below 50 copies. Those taking LEN SC plus BIC had an 85% viral suppression rate. The best performing of all was the control arm, in which 92% had undetectable viral loads. The protocol didn’t allow for analysis of statistical significance between the arms, so it’s unclear if any of the treatments really surpassed the others, Dr. Gupta said.
When they looked only at people whose viral loads became undetectable early, by week 28, the results were slightly better, with 93% of people between the two subcutaneous arms having undetectable viral loads at week 54. Again, the results were slightly higher in the LEN SC plus TAF arm (94%) than the LEN SC plus BIC (92%). People taking daily oral LEN plus Descovy had the lowest rate of viral suppression, but it was still at 90% if they were virally suppressed early. Again, it’s unclear whether those differences were statistically significant.