ABSTRACT
Background. ADI is a fully human IgG1 monoclonal antibody engineered to have an extended half-life with high potency and broad neutralization against SARS-CoV-2 and other SARS-like coronaviruses. The goal of our analysis was to develop a QSP model in which ADI concentrations in upper airway (UA) epithelial lining fluid (ELF) were linked to a viral dynamic model to describe the impact of ADI on SARS-CoV-2 viral load relative to placebo. Methods. The QSP model was fit inNONMEMVersion 7.4 using PK data from a Phase 1 study (N=24, IV and IM) and from Phase 2/3 COVID-19 prevention (EVADE;N=659, IM) and treatment (STAMP;N=189, IM) studies. Saliva and NP samples were collected from STAMP study participants (pts) infected with the delta or omicron variants. The viral dynamic model was based on a published model and was modified to include both active (V) and deactivated (DV) virus (Fig). The viral dynamic model was fit to the NP swab viral load data (2 samples/pt) standardized to time since infection based upon recorded symptom onset. Saliva data (7-8 samples/ pt) was fit sequentially using a biophase compartment given the peak viral load was modestly lower and peaked later than Day 1. Viral dynamic model (A) and simulated median (90% PI) NP viral load reduction in ADI-treated or placebo participants for delta (B) and omicron (C) variants Results. The QSP model provided an excellent fit to serum ADI concentrationtime data after estimation of a transit rate to account for IM absorption, plasma volume, and the ADI-neonatal Fc receptor dissociation rate constant. The linked viral dynamic model captured the NP swab viral load data after estimating differences in within-host replication factor (R0) and viral production rate (p) by variant. Maximal ADI-induced effect (Smax) on stimulating viral clearance (c) was fixed to 0.43 based upon prior modeling. ADI concentration in UA ELF resulting in 50% of Smax (SC50) was estimated to be 0.086 for delta and 1.05 mg/L for omicron. Figure B and C show model-based simulated median (90% PI) viral load reduction in ADI-treated or placebo pts for delta and omicron variants. Conclusion. This QSP model, in conjunction with information on new variants available early in outbreaks (IC50, infectivity (R0), viral production rate [each a model parameter]), allows for rapid dose identification in response to emerging variants.
ABSTRACT
Background. ADG20 is a fully human IgG1 monoclonal antibody engineered to have high potency and broad neutralization against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and other SARS-like CoVs with pandemic potential by binding to a highly conserved epitope in the receptor-binding domain (RBD) of the spike protein. The Fc region of ADG20 has been modified to provide an extended half-life. ADG20 is in clinical development for the treatment and prevention of COVID-19. Methods. This is an ongoing Phase 1, randomized, placebo (PBO)-controlled, single ascending-dose study of ADG20 administered intramuscularly (IM) or intravenously (IV) to healthy adults aged 18-50 years with no evidence of prior or current SARS-CoV-2 infection. Participants were randomized 8:2 in 3 cohorts (N=10/cohort: n=8 ADG20, n=2 PBO): ADG20 300 mg IM, 500 mg IV, and 600 mg IM. Safety, tolerability, PK, and sVNA titers were assessed up to 3 months post dose. Serum ADG20 concentrations were measured with a validated hybrid ligand binding liquid chromatography-mass spectrometry (MS)/MS assay. sVNA titers against authentic SARS-CoV-2 were determined by a plaque reduction neutralization assay. Results. Overall, 30 participants received ADG20 (n=24) or PBO (n=6). Blinded safety data for all cohorts and PK/sVNA titer data for the 300 mg IM cohort are reported. Through a minimum of 10 weeks post dose, no study drug-related adverse events (AEs), serious AEs, injection site reactions, or hypersensitivity reactions were reported. The observed preliminary PK profile was dose proportional, consistent with an extended half-life monoclonal antibody, and well predicted by translational physiologically-based PK modeling. The measured 50% sVNA titer (MN50;geometric mean [coefficient of variation, %]) was 1382 (32.7%) 13 days after a single 300 mg IM dose. These values are within the range of peak serum neutralizing antibody titers reported for COVID-19 mRNA vaccines. Conclusion. A single dose of ADG20, up to 600 mg IM, was well tolerated. Preliminary PK and sVNA titer profiles support the ongoing Phase 2/3 trials of ADG20 at a 300 mg IM dose for the prevention of COVID-19 (EVADE: NCT04859517) and treatment of ambulatory patients with mild to moderate COVID-19 (STAMP: NCT04805671).