Validation of a Triplex Pharmacokinetic Assay for Simultaneous Quantitation of HIV-1 Broadly Neutralizing Antibodies PGT121, PGDM1400, and VRC07-523-LS

Abstract

The outcome of the recent Antibody Mediated Prevention (AMP) trials that tested infusion of the broadly neutralizing antibody (bnAb) VRC01 provides proof of concept for blocking infection from sensitive HIV-1 strains. These results also open up the possibility that triple combinations of bnAbs such as PGT121, PGDM1400, as well as long-lasting LS variants such as VRC07-523 LS, have immunoprophylactic potential. PGT121 and PGDM1400 target the HIV-1 V3 and V2 glycan regions of the gp120 envelope protein, respectively, while VRC07-523LS targets the HIV-1 CD4 binding site. These bnAbs demonstrate neutralization potency and complementary breadth of HIV-1 strain coverage. An important clinical trial outcome is the accurate measurement of in vivo concentrations of passively infused bnAbs to determine effective doses for therapy and/or prevention. Standardization and validation of this testing method is a key element for clinical studies as is the ability to simultaneously detect multiple bnAbs in a specific manner. Here we report the development of a sensitive, specific, accurate, and precise multiplexed microsphere-based assay that simultaneously quantifies the respective physiological concentrations of passively infused bnAbs in human serum to ultimately define the threshold needed for protection from HIV-1 infection.

Safety and antiviral activity of triple combination broadly neutralizing monoclonal antibody therapy against HIV-1: a phase 1 clinical trial

“…(1) BAMA: PGT121, PGDM1400 and VRC07-523LS levels were determined on a Bio-Plex 200 system (Bio-Rad) that measures the ability of each monoclonal antibody to bind to their specific anti-idiotype antibody captured on fluorescent magnetic microspheres (MagPlex, Luminex), using a customized and standardized HIV-1 assay 32 – 35 . PGT121, PGDM1400 and VRC07-523LS concentrations were representative of three separate assays where each sample was run in duplicate.…”

Pharmacokinetic serum concentrations of VRC01 correlate with prevention of HIV-1 acquisition

“…The PK-BAMA method demonstrated accuracy, precision, and specificity for detection of VRC01 in human serum samples. 29 Accuracy of VRC01 IgG concentration measurements by PK-BAMA was evaluated by testing a blinded panel of 78 spiked samples with known VRC01 concentrations (0 mcg/ml–700 mcg/ml). Sample concentrations measured by the PK-BAMA method demonstrated excellent concordance with the true (known) concentration of VRC01 in serum.…”

“…Generally, HIV-1 bnAbs are dosed by body weight in clinical trials. 5 , 8 , 9 , 10 , 11 , 12 , 13 , 14 , 15 , 16 , 17 , 18 , 19 , 20 , 21 , 22 , 23 , 24 , 25 , 26 , 27 , 28 , 29 Weight-based dosing has historically been assumed to adjust for participant differences in pharmacokinetics (PK), yet body weight does not substantially affect monoclonal antibody (mAb) distribution and elimination as reported for oncology mAbs, 30 and HIV-1 mAbs in adults. 17 , 18 In AMP, VRC01 dose amount was directly proportionate to body weight, so we assessed the association between body weight and HIV-1 acquisition likelihood.…”

Impact of LS Mutation on Pharmacokinetics of Preventive HIV Broadly Neutralizing Monoclonal Antibodies: A Cross-Protocol Analysis of 16 Clinical Trials in People without HIV

“…The BAMA assay derived on a Bio-Plex instrument was used to quantify concentrations in human serum for VRC07-523LS [20,28], PGDM1400 [24,36], and PGT121 [29,33,38] under the oversight of the Quality Assurance for Duke Vaccine Immunogenicity Programs. This anti-idiotype (anti-ID) assay measured concentrations by its ability to bind anti-idiotype antibody captured on fluorescent magnetic beads.…”