Safety, pharmacokinetics, and immunological activities of multiple intravenous or subcutaneous doses of an anti-HIV monoclonal antibody, VRC01, administered to HIV-uninfected adults: Results of a phase 1 randomized trial

Abstract

Background: VRC01 is an HIV-1 CD4 binding site broadly neutralizing antibody (bnAb) that is active against a broad range of HIV-1 primary isolates in vitro and protects against simian-human immunodeficiency virus (SHIV) when delivered parenterally to nonhuman primates. It has been shown to be safe and well tolerated after short-term administration in humans; however, its clinical and functional activity after longer-term administration has not been previously assessed.

Methods and findings: HIV Vaccine Trials Network (HVTN) 104 was designed to evaluate the safety and tolerability of multiple doses of VRC01 administered either subcutaneously or by intravenous (IV) infusion and to assess the pharmacokinetics and in vitro immunologic activity of the different dosing regimens. Additionally, this study aimed to assess the effect that the human body has on the functional activities of VRC01 as measured by several in vitro assays. Eighty-eight healthy, HIV-uninfected, low-risk participants were enrolled in 6 United States clinical research sites affiliated with the HVTN between September 9, 2014, and July 15, 2015. The median age of enrollees was 27 years (range, 18-50); 52% were White (non-Hispanic), 25% identified as Black (non-Hispanic), 11% were Hispanic, and 11% were non-Hispanic people of diverse origins. Participants were randomized to receive the following: a 40 mg/kg IV VRC01 loading dose followed by five 20 mg/kg IV VRC01 doses every 4 weeks (treatment group 1 [T1], n = 20); eleven 5 mg/kg subcutaneous (SC) VRC01 (treatment group 3 [T3], n = 20); placebo (placebo group 3 [P3], n = 4) doses every 2 weeks; or three 40 mg/kg IV VRC01 doses every 8 weeks (treatment group 2 [T2], n = 20). Treatment groups T4 and T5 (n = 12 each) received three 10 or 30 mg/kg IV VRC01 doses every 8 weeks, respectively. Participants were followed for 32 weeks after their first VRC01 administration and received a total of 249 IV infusions and 208 SC injections, with no serious adverse events, dose-limiting toxicities, nor evidence for anti-VRC01 antibodies observed. Serum VRC01 levels were detected through 12 weeks after final administration in all participants who received all scheduled doses. Mean peak serum VRC01 levels of 1,177 μg/ml (95% CI: 1,033, 1,340) and 420 μg/ml (95% CI: 356, 494) were achieved 1 hour after the IV infusion series of 30 mg/kg and 10 mg/kg doses, respectively. Mean trough levels at week 24 in the IV infusion series of 30 mg/kg and 10 mg/kg doses, respectively, were 16 μg/ml (95% CI: 10, 27) and 6 μg/ml (95% CI: 5, 9) levels, which neutralize a majority of circulating strains in vitro (50% inhibitory concentration [IC50] > 5 μg/ml). Post-infusion/injection serum VRC01 retained expected functional activity (virus neutralization, antibody-dependent cellular cytotoxicity, phagocytosis, and virion capture). The limitations of this study include the relatively small sample size of each VRC01 administration regimen and missing data from participants who were unable to complete all study visits.

Conclusions: VRC01 administered as either an IV infusion (10-40 mg/kg) given monthly or bimonthly, or as an SC injection (5 mg/kg) every 2 weeks, was found to be safe and well tolerated. In addition to maintaining drug concentrations consistent with neutralization of the majority of tested HIV strains, VRC01 concentrations from participants' sera were found to avidly capture HIV virions and to mediate antibody-dependent cellular phagocytosis, suggesting a range of anti-HIV immunological activities, warranting further clinical trials.

Trial registration: Clinical Trials Registration: NCT02165267.

Fig 1. HVTN 104 CONSORT flow diagram (A) and specimen collection schedule (B).

T1: 20 mg/kg IV q 4 weeks with 40 mg/kg IV loading; T2: 40 mg/kg IV q 8 weeks; T3 (P3): 5 mg/kg SC q 2 weeks with 40 mg/kg IV loading; T4: 10 mg/kg IV q 8 weeks; T5: 30 mg/kg IV q 8 weeks. ADCC, antibody-dependent cellular cytotoxicity; ADCP, antibody-dependent cellular phagocytosis; CONSORT, Consolidated Standards of Reporting Trials; HVTN, HIV Vaccine Trials Network; IV, intravenous; P3, placebo group 3; q, quodque; SC, subcutaneous; T1, treatment group 1; T2, treatment group 2; T3, treatment group 3; T4, treatment group 4; T5, treatment group 5.

Fig 2. Frequency of maximum severity of systemic (A) and local (B) reactogenicity symptoms by group in the MITT cohort.

T1: 20 mg/kg IV q 4 weeks with 40 mg/kg IV loading; T2: 40 mg/kg IV q 8 weeks; T3 (P3): 5 mg/kg SC q 2 weeks with 40 mg/kg IV loading; T4: 10 mg/kg IV q 8 weeks; T5: 30 mg/kg IV q 8 weeks. Grading per DAIDS Table for Grading the Severity of Adult and Pediatric Adverse Events, Version 1.0, December 2004; clarification August 2009 [36]. DAIDS, Division of AIDS; MITT, modified intent-to-treat; P3, placebo group 3; q, quodque; SC, subcutaneous; T1, treatment group 1; T2, treatment group 2; T3, treatment group 3; T4, treatment group 4; T5, treatment group 5.

Fig 3. VRC01 serum concentrations over time in the PP cohort, measured by ELISA and TZM-bl assays.

ELISA measured anti-idiotypic binding. TZM-bl measured neutralization against 3 Env-pseudotyped virus strains (MN.3, MW965.26, and PVO.4). Each dot (bar) indicates the geometric mean (± standard error) concentrations across participants in each group. A double tick on the x-axis denotes a time interval of 3 days, representing visit days 3, 17, 31, 59, 115, and/or 157. Peak concentrations were measured at 1 hour after the last IV infusion in treatment groups T1, T2, T4, and T5 and 3 days after the first and last SC injections in group T3/P3. Concentrations were truncated at the limit of quantification of the least sensitive assay. T1: 20 mg/kg IV q 4 weeks with 40 mg/kg IV loading; T2: 40 mg/kg IV q 8 weeks; T3 (P3): 5 mg/kg SC q 2 weeks with 40 mg/kg IV loading; T4: 10 mg/kg IV q 8 weeks; T5: 30 mg/kg IV q 8 weeks. Env, HIV-1 envelope glycoprotein; PP, per-protocol; P3, placebo group 3; q, quodque; SC, subcutaneous; T1, treatment group 1; T2, treatment group 2; T3, treatment group 3; T4, treatment group 4; T5, treatment group 5.

Fig 4. Serum neutralizing activity against multiple isolates at 4 weeks after the first, second, and third infusions and at 1 hour and 8 weeks following the third infusion in 6 T5 participants.

(A) MB curves based on TZM-bl neutralization assay results against 11 tier 2 viruses for each of the 6 individuals in T5. Two individuals who missed their second infusion are indicated by an * at the red line (4 weeks post infusion 2). MB curves based on results with HIV-1 Env-pseudotyped viruses PVO.4, 398F1, CNE8, X2278, 246-F3, TRO.11, CNE55, CH119, 25710, X1632, and Ce0217. Response rate on the y-axis is the percent of the 11 viruses neutralized at serum dilutions (Log10 ID50 titer) shown on the x-axis. (B) Serum ID50 neutralization titers against the 11 tier 2 and 2 tier 1 isolates. Shown are the geometric mean and standard error of the mean over the ID50 titers of 4 T5 individuals, excluding the 2 individuals who missed their second infusion. (C) VRC01 serum concentration measured by ELISA and TZM-bl against tier 1 and tier 2 isolates. Shown are the geometric mean and standard error of the mean over the estimated concentration of VRC01 in 4 T5 individuals, excluding the 2 individuals who missed their second infusion. Individual level neutralization data for participants can be found in S5 Table. Env, HIV-1 envelope glycoprotein; ID50, 50% infectious dose; MB, magnitude-breadth; T5, treatment group 5.

Fig 5. VRC01 mAb retains nonneutralizing Fc effector functions postintravenous or postsubcutaneous administration in the PP cohort.

(A) ADCC using the Luciferase-HIV CH0505.LucR T2A.ecto/293T/17 assay, (B) average phagocytosis score, and (C) average virus capture percentage are presented (average of 2 replicate experiments). Grey squares indicate baseline (preadministration) time points; red circles represent positive responses at postadministration time points; open blue triangles represent negative responses at postadministration time points. Horizontal dashed lines represent the positivity cutoff based on the 95th percentile of all baseline visits. Percent responders and the number of positive responders/total number are shown above each treatment group. T1: 20 mg/kg IV q 4 weeks with 40 mg/kg IV loading; T2: 40 mg/kg IV q 8 weeks; T3 (P3): 5 mg/kg SC q 2 weeks with 40 mg/kg IV loading; T4: 10 mg/kg IV q 8 weeks; T5: 30 mg/kg IV q 8 weeks. ADCC, antibody-dependent cellular cytotoxicity; Fc, fragment crystallizable; mAb, monoclonal antibody; PP, per-protocol; P3, placebo group 3; q, quodque; SC, subcutaneous; T1, treatment group 1; T2, treatment group 2; T3, treatment group 3; T4, treatment group 4; T5, treatment group 5.

Fig 6. Correlations between functional activities and VRC01 level in the PP cohort (all treatment arms).

Lower diagonal squares show scatterplots of each pair of assay variables. A Lowess smoother line using locally weighted polynomial regression with a span of 2/3 was added. Upper diagonal squares show rank-based Spearman correlation coefficients for each pair of assay variables. Diagonal squares show histograms of each variable. ADCC, antibody-dependent cellular cytotoxicity; PP, per-protocol.