Phase 1 Trial of a Therapeutic Anti–Yellow Fever Virus Human Antibody

Copyright © 2020 Massachusetts Medical Society. BACKGROUND Insufficient vaccine doses and the lack of therapeutic agents for yellow fever put global health at risk, should this virus emerge from sub-Saharan Africa and South America. METHODS In phase 1a of this clinical trial, we assessed the safety, side-effect profile, and pharmacokinetics of TY014, a fully human IgG1 anti–yellow fever virus monoclonal antibody. In a double-blind, phase 1b clinical trial, we assessed the efficacy of TY014, as compared with placebo, in abrogating viremia related to the administration of live yellow fever vaccine (YF17D-204; Stamaril). The primary safety outcomes were adverse events reported 1 hour after the infusion and throughout the trial. The primary efficacy outcome was the dose of TY014 at which 100% of the participants tested negative for viremia within 48 hours after infusion. RESULTS A total of 27 healthy participants were enrolled in phase 1a, and 10 participants in phase 1b. During phase 1a, TY014 dose escalation to a maximum of 20 mg per kilogram of body weight occurred in 22 participants. During phases 1a and 1b, adverse events within 1 hour after infusion occurred in 1 of 27 participants who received TY014 and in none of the 10 participants who received placebo. At least one adverse event occurred during the trial in 22 participants who received TY014 and in 8 who received placebo. The mean half-life of TY014 was approximately 12.8 days. At 48 hours after the infusion, none of the 5 participants who received the starting dose of TY014 of 2 mg per kilogram had detectable YF17D-204 viremia; these participants remained aviremic throughout the trial. Viremia was observed at 48 hours after the infusion in 2 of 5 participants who received placebo and at 72 hours in 2 more placebo recipients. Symptoms associated with yellow fever vaccine were less frequent in the TY014 group than in the placebo group. CONCLUSIONS This phase 1 trial of TY014 did not identify worrisome safety signals and suggested potential clinical benefit, which requires further assessment in a phase 2 trial

Neutralization of antibody-enhanced dengue infection by VIS513, a pan serotype reactive monoclonal antibody targeting domain III of the dengue E protein

<div><p>Dengue virus (DENV) infection imposes enormous health and economic burden worldwide with no approved treatment. Several small molecules, including lovastatin, celgosivir, balapiravir and chloroquine have been tested for potential anti-dengue activity in clinical trials; none of these have demonstrated a protective effect. Recently, based on identification and characterization of cross-serotype neutralizing antibodies, there is increasing attention on the potential for dengue immunotherapy. Here, we tested the ability of VIS513, an engineered cross-neutralizing humanized antibody targeting the DENV E protein domain III, to overcome antibody-enhanced infection and high but brief viremia, which are commonly encountered in dengue patients, in various <i>in vitro</i> and <i>in vivo</i> models. We observed that VIS513 efficiently neutralizes DENV at clinically relevant viral loads or in the presence of enhancing levels of DENV immune sera. Single therapeutic administration of VIS513 in mouse models of primary infection or lethal secondary antibody-enhanced infection, reduces DENV titers and protects from lethal infection. Finally, VIS513 administration does not readily lead to resistance, either in cell culture systems or in animal models of dengue infection. The findings suggest that rapid viral reduction during acute DENV infection with a monoclonal antibody is feasible.</p></div

PRNT₅₀ (ng/mL) values for anti-DENV antibodies.

<p>PRNT₅₀ (ng/mL) values for anti-DENV antibodies.</p

Structural analysis of escape mutations.

<p>A. Molecular interactions of E-DENV1 protein (shown in rainbow color cartoon) are shown with the 14c10 antibody (shown in transparent surface and cartoon diagram with heavy and light chains shown in green and cyan color, respectively). In the complex, the Lys136 residue of the E-DENV1 protein is found in the vicinity of the HCDR3 loop of the mAb. Mutation of Lys136 to a Glu is expected to cause loss of mAb binding due to the change in charge of the residue. B. Molecular interactions of Lys308/310 of EDIII-DENV3/4 protein (shown in magenta cartoon) are shown with VIS513 (shown in transparent surface and cartoon diagram with heavy and light chains shown in green and cyan color, respectively). The Lys308 of E-DENV3 or Lys310 of E-DENV4 residues are the same and it is found to form hydrogen bonding and salt bridges with the VIS513 heavy chain residues Asp52 and Glu54 (left panel). The right panel shows the modeling of mutation Lys308Arg. C. Modeling of position E311 of E-DENV4 region found to be mutated in virus from mouse samples. A hydrogen bond with the antibody molecule is shown with dotted line.</p

Identification of VIS513 escape mutants.

<p>A. Neutralization profile of a titration of 14c10 with DENV1 population passaged in presence of 14c10 at 100 μg/ml, 10 μg/ml, or trastuzumab at 150 μg/ml for 5 passages. B-C. Neutralization profile of a titration of VIS513 with DENV3 (passage 7) (B) or DENV4 (passage 5) (C) passaged in the presence of indicated concentrations of VIS513 or trastuzumab. For DENV4, passaging in the presence of 150 μg/ml VIS513 yielded insufficient virus for subsequent neutralization assays and hence could not be assayed. The solid lines and error bars represent mean ± SEM of experiment performed in triplicate.</p

Summary of escape mutations observed from cell culture studies.

<p>Summary of escape mutations observed from cell culture studies.</p