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CROI 2023: HIV PrEP
PrEP Data From CROI 2023: Protecting Patients From HIV

Released: March 20, 2023

Expiration: March 18, 2024

Monica Gandhi
Monica Gandhi, MD, MPH
Activity Information

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Key Takeaways
  • LA CAB for PrEP is highly effective but underused.
  • Long-acting early viral inhibition (LEVI) syndrome was described in a subset of individuals who became infected with HIV after exposure to LA CAB PrEP and further supports the recommendation for HIV-1 RNA testing while receiving LA CAB PrEP.
  • CAB concentrations were found to remain above the PA-IC90 for most women after delays in dosing of up to 8-10 weeks in HPTN 084.
  • Effectiveness of FTC/TDF daily for protection against HIV infection was found to be similarly high for cisgender women who received ≥4 doses each week and those who received all 7 doses each week.

CROI 2023 was exciting in terms of the number of HIV prevention updates of importance to HIV and primary care healthcare professionals.  

Frequency of LA CAB for PrEP Use
Data on the use of long-acting (LA) cabotegravir (CAB) for pre-exposure prophylaxis (PrEP) administered every 8 weeks in different populations were presented in various abstracts and posters. Despite the number of studies describing use of LA CAB for PrEP, a study by Zhu and colleagues noted that, as of September 2022, only 0.5% of individuals receiving PrEP in the United States were receiving injectable CAB (1353 people out of a population of 186,367 in a large insurance database). Given the superior efficacy of LA CAB vs oral PrEP, attempts to increase accessibility in the United States should be pursued. 

Subanalyses of HPTN 083 and HPTN 084
A substudy of HPTN 083 and HPTN 084-2 clinical trials that proved the efficacy of LA CAB for PrEP-demonstrated the challenges of diagnosing a new HIV infection while receiving LA CAB. In a phenomenon dubbed long-acting early viral inhibition (LEVI) syndrome by Eschelman and colleagues, acute HIV seroconversions while receiving LA CAB for PrEP often were accompanied by negative HIV antigen and antibody results, reinforcing the need for HIV-1 RNA testing to diagnose new HIV infections in people receiving this regimen. 

A study by Marzinke and colleagues demonstrated that among cisgender African women enrolled on HPTN 084, CAB concentrations were above target concentrations of the PA-IC90, the protein-adjusted concentration required for 90% viral inhibition, in 98%, 95%, and 90% of cisgender African women after an LA CAB dose delay of 4-6 weeks, 6-8 weeks, and 8-10 weeks, respectively. Although the authors do not recommend increasing dosing intervals beyond the every-8-week approved dosing regimen, there is likely pharmacokinetic “forgiveness” in this population when an LA CAB injection is delayed.

Oral PrEP Adherence in Cisgender Women
A study by Marrazzo and colleagues pooled analyses of >6200 cisgender women on PrEP trials and demonstration projects that used oral emtricitabine (FTC)/tenofovir disoproxil fumarate (TDF) to examine levels of adherence required for PrEP effectiveness over an 8-year period. Adherence data were available for 2954 individuals, and effectiveness for protection against HIV infection was similarly high for cisgender women who received ≥4 doses each week and those who received all 7 doses each week. Previous analyses demonstrated similar findings that in men who have sex with men (MSM), 4 doses each week of FTC/TDF-based PrEP are adequate for protection against HIV acquisition. This large study by Marrazzo and colleagues alleviates concerns that cisgender women need higher levels of FTC/TDF adherence to maintain the same level of protection against HIV compared with MSM. 

Your Thoughts?
What do you think are the most compelling HIV PrEP data? Which data are likely to change your practice? Join the discussion by posting a comment below.