Safety, Tolerability, and Pharmacokinetics of Long-Acting Broadly Neutralizing HIV-1 Monoclonal Antibody VRC07-523LS in Newborn Infants Exposed to HIV-1.

Background: Vertical HIV-1 transmission despite antiretroviral therapy may be mitigated by the use of long-acting, broadly neutralizing, monoclonal antibodies (bNAb) such as VRC07-523LS. The present study was designed to determine the safety and pharmacokinetics of VRC07-523LS.

Methods: VRC07-523LS, 80 mg/dose, was administered subcutaneously after birth to non-breastfed (cohort 1; N = 11, enrolled in USA) and breastfed (cohort 2; N = 11, enrolled in South Africa and Zimbabwe) infants exposed to HIV-1. Breastfed infants (cohort 2) received a second 100-mg dose at 12 weeks if still receiving breastmilk. All infants received antiretroviral prophylaxis in addition to VRC07-523LS. VRC07-523LS levels were compared to VRC01 levels, as determined previously in this study.

Results: Local reactions (all grade ≤ 2) occurred after dose 1 in 18% of infants in cohort 1 and after doses 1 and 2 in 100% of infants in cohort 2. The VRC07-523LS dose at birth (mean 26 mg/kg) achieved a mean ± SD plasma level of 222.3 ± 71.6 mcg/mL by 24 hours and 18.4 ± 7.2 mcg/mL at week 12, prior to dose 2. The pre-established target of ≥ 10 mcg/mL at week 12 was met in 94% of infants. The terminal half-life of VRC07-523LS was observed to be 39.2 ± 5.0 days. At week 4 and week 8, bNAb levels were significantly higher (P ≤ .002) after one dose of VRC07-523LS, compared to one dose of VRC01 (20 mg/kg). No infant included in the study acquired HIV-1.

Conclusions: VRC07-523LS was well tolerated with pharmacokinetics that support further studies of potent long-acting bNAbs together with antiretrovirals to prevent HIV-1 acquisition in infants.