Two Randomized Trials of Neutralizing Antibodies to Prevent HIV-1 Acquisition

BACKGROUND

Whether a broadly neutralizing antibody (bnAb) can be used to prevent human immunodeficiency virus type 1 (HIV-1) acquisition is unclear.

METHODS

We enrolled at-risk cisgender men and transgender persons in the Americas and Europe in the HVTN 704/HPTN 085 trial and at-risk women in sub-Saharan Africa in the HVTN 703/HPTN 081 trial. Participants were randomly assigned to receive, every 8 weeks, infusions of a bnAb (VRC01) at a dose of either 10 or 30 mg per kilogram (low-dose group and high-dose group, respectively) or placebo, for 10 infusions in total. HIV-1 testing was performed every 4 weeks. The VRC01 80% inhibitory concentration (IC80) of acquired isolates was measured with the TZM-bl assay.

RESULTS

Adverse events were similar in number and severity among the treatment groups within each trial. Among the 2699 participants in HVTN 704/HPTN 085, HIV-1 infection occurred in 32 in the low-dose group, 28 in the high-dose group, and 38 in the placebo group. Among the 1924 participants in HVTN 703/HPTN 081, infection occurred in 28 in the low-dose group, 19 in the high-dose group, and 29 in the placebo group. The incidence of HIV-1 infection per 100 person-years in HVTN 704/HPTN 085 was 2.35 in the pooled VRC01 groups and 2.98 in the placebo group (estimated prevention efficacy, 26.6%; 95% confidence interval [CI], -11.7 to 51.8; P = 0.15), and the incidence per 100 person-years in HVTN 703/HPTN 081 was 2.49 in the pooled VRC01 groups and 3.10 in the placebo group (estimated prevention efficacy, 8.8%; 95% CI, -45.1 to 42.6; P = 0.70). In prespecified analyses pooling data across the trials, the incidence of infection with VRC01-sensitive isolates (IC80 <1 μg per milliliter) per 100 person-years was 0.20 among VRC01 recipients and 0.86 among placebo recipients (estimated prevention efficacy, 75.4%; 95% CI, 45.5 to 88.9). The prevention efficacy against sensitive isolates was similar for each VRC01 dose and trial; VRC01 did not prevent acquisition of other HIV-1 isolates.

CONCLUSIONS

VRC01 did not prevent overall HIV-1 acquisition more effectively than placebo, but analyses of VRC01-sensitive HIV-1 isolates provided proof-of-concept that bnAb prophylaxis can be effective. (Supported by the National Institute of Allergy and Infectious Diseases; HVTN 704/HPTN 085 and HVTN 703/HPTN 081 ClinicalTrials.gov numbers, NCT02716675 and NCT02568215.).

Review of preventative HIV vaccine clinical trials in South Africa

New HIV infections continue relentlessly in southern Africa, demonstrating the need for a vaccine to prevent HIV subtype C. In South Africa, the country with the highest number of new infections annually, HIV vaccine research has been ongoing since 2003 with collaborative public-private-philanthropic partnerships. So far, 21 clinical trials have been conducted in South Africa, investigating seven viral vectors, three DNA plasmids, four envelope proteins, five adjuvants and three monoclonal antibodies. Active vaccine candidates have spanned subtypes A, B, C, E and multi-subtype mosaic sequences. All were well tolerated. Four concepts were investigated for efficacy: rAd5-gag/pol/nef showed increased HIV acquisition in males, subtype C ALVAC/gp120/MF59 showed no preventative efficacy, and the trials for the VRC01 monoclonal antibody and Ad26.Mos4.HIV/subtype C gp140/ aluminum phosphate are ongoing. Future trials are planned with DNA/viral vector plus protein combinations in concert with pre-exposure prophylaxis, and sequential immunization studies with transmitted/founder HIV envelope to induce broadly neutralizing antibodies. Finally, passive immunization trials are underway to build on the experience with VRC01, including single and combination antibody trials with an antibody derived from a subtype-C-infected South African donor. Future consideration should be given to the evaluation of novel strategies, for example, inactivated-whole-virus vaccines.

1272. Feasibility and Successful Enrollment in Proof-of-Concept Trials to Assess Safety and Efficacy of a Broadly Neutralizing Monoclonal Antibody, VRC01, to Prevent HIV-1 Acquisitionin in Uninfected Individuals

Background

The Antibody-mediated Prevention (AMP) trials (HVTN 704/HPTN 085 and HVTN 703/HPTN 081) are the first efficacy trials to evaluate whether VRC01, a broadly neutralizing antibody (bnAb) that targets CD4 binding site of HIV envelope, prevents HIV acquisition in uninfected individuals. In these ongoing trials, 10 intravenous (IV) infusions of VRC01 are given every 8 weeks over a period of 2 years. We report on interim operational feasibility, enrollment and safety.

Methods

Participant recruitment was enhanced by extensive community engagement and education. Eligible participants were randomly assigned 1:1:1 to 10mg/kg, 30mg/kg of VRC01 or saline placebo. HVTN 704/HPTN 085 enrolled high-risk men (MSM) and transgender (TG) individuals who have sex with men at 26 sites in United States, Peru, Brazil, and Switzerland. HVTN 703/HPTN 081 enrolled high-risk heterosexual women at 20 sites in Botswana, Kenya, Malawi, Mozambique, South Africa, Tanzania, and Zimbabwe. HIV testing occurs monthly.

Results

In October 2018, the AMP trials completed enrollment of 4,625 participants. Enrollment met or exceeded targets throughout the trial period, peaked at 298 participants/month, and was slowed mid-trial to allow for sufficient drug supply at trial sites. In HVTN 704/HPTN 085, 2701 (target N = 2700) MSM/TG participants 18–50yrs were enrolled with median age of 28; 99% born male; 90% identified as male gender and 5% TG female. Race/ethnicity was 32% White, 15% Black and 57% Hispanic/Latino/a. 28% had a sexually transmitted infection (STI) including gonorrhea (GC), chlamydia (CT) or syphilis at enrollment. In HVTN 703/HPTN 081,1924 (target N = 1900) women 18–40yrs were enrolled with median age of 26;100% were born female (53% female gender, 47% gender not assessed); 99% were Black. 26% had a STI at enrollment including GC, CT, trichomonas or syphilis. Overall 36,945 infusions have been given so far with no serious procedural complications due to IV administration. Retention and adherence to the rigorous study schedule (monthly visits for 2 years) remain within an acceptable range.

Conclusion

The AMP trials have exceeded enrollment of target populations and are maintaining high rates of retention. With exceptional safety and operational feasibility, they are paving the way for future large-scale bnAb trials for HIV prevention and/or treatment.

Disclosures

All authors: No reported disclosures.

Neonatal Cryptococcosis: Beware of False-positive Results

Although cryptococcal meningitis is uncommon in children and rare in neonates, it does occur. We highlight circumstances in which the diagnosis should be considered and methods required to confirm the diagnosis in young patients.