Results from a recent phase 4 study have shown that long-acting injectable cabotegravir (CAB-LA; Apretude, ViiV Healthcare) serves as an effective HIV-1 pre-exposure prophylaxis (PrEP) option. Conducted over a year, the study focused on men who have sex with men (MSM) and transgender men, with findings presented at the Conference on Retroviruses and Opportunistic Infections (CROI) 2025 in San Francisco.
Dr. Taimur Khan, an infectious disease specialist and the associate medical research director of The Fenway Institute in Boston, emphasized the significance of these findings. “We’ve come super far in our ending the HIV epidemic war, but we’re not there yet,” he stated. “The last part is getting the prevention and treatment into the hands of the people that need it the most, and this study did two of those things and provided a new modality that is less frequent and cumbersome for patients.”
Understanding the Impact of CAB-LA
CAB-LA is administered bi-monthly, distinguishing it as the only long-acting PrEP medication approved by the FDA. Despite its efficacy, barriers to its widespread use remain, according to Dr. Patrick Sullivan, a professor of epidemiology at Emory University.
“Although the efficacy of PrEP is clear from clinical studies, we know that only about one-third of people who would benefit from PrEP are taking it,” Dr. Sullivan noted. He pointed out challenges such as lack of awareness, high out-of-pocket costs, and the stigma associated with PrEP use.
“In our own research, we have observed that some participants discontinue PrEP because they don’t have a private place to store their medications and are concerned what a roommate or others might think if they knew that a PrEP user had antiretroviral medications in their possession,” Dr. Sullivan said.
The PILLAR Study: Key Findings
The PILLAR study evaluated the administration of CAB-LA to MSM and transgender men across 17 clinics in the United States. From May 2022 to August 2023, 201 participants were enrolled, with 6% identifying as transgender men. Researchers assessed various factors, including HIV incidence, diagnostic testing, safety, tolerability, and persistence—defined as the duration participants continued receiving cabotegravir injections.
“Persistence was key because we wanted to determine if we have the capability to have people stay on the medication for a long time,” Dr. Khan explained. “The good news is that we found that 85% of people that were in the study stayed on it through six months, and then by the end of the year or six or seven injections [later], about three-quarters of people were staying on the medication.”
A total of 70% (or 141) of participants completed all of the study injections, with five patients missing an injection and receiving oral cabotegravir or an alternative PrEP, both requiring more frequent administration. Notably, no new cases of HIV were observed during the 12-month period.
Future Directions and Implications
Dr. Sullivan emphasized the importance of having convenient PrEP options. “The findings from the research about long-acting injectable PrEP speak directly to the importance of having convenient options for PrEP, and especially for the importance of PrEP formulations that don’t require daily pill taking,” he said.
A companion study to PILLAR, called EBONI, is set to conclude this year. It evaluates CAB-LA administration for Black cis- and transgender women at 20 clinics, with additional PrEP studies planned for the future.
Dr. Khan highlighted the long-term goal of making injectable PrEP less tedious with fewer requirements for access. To ensure those in need receive PrEP, both Dr. Khan and Dr. Sullivan stressed the importance of providing multiple pathways to access treatment.
“Preferences for one formulation or dosing schedule for PrEP will vary based on personal preference, out-of-pocket costs, living circumstances, and relative importance of convenience and flexibility in regimens,” Dr. Sullivan stated.
Dr. Khan received logistical support for presenting data at CROI from ViiV Healthcare, while Dr. Sullivan reported no relevant financial disclosures. This article is featured in the June 2025 print issue.
