Safety and Tolerability of the Adeno-Associated Virus Vector, AAV6.2FF, Expressing a Monoclonal Antibody in Murine and Ovine Animal Models

Abstract

Adeno-associated virus (AAV) vector mediated expression of therapeutic monoclonal antibodies is an alternative strategy to traditional vaccination to generate immunity in immunosuppressed or immunosenescent individuals. In this study, we vectorized a human monoclonal antibody (31C2) directed against the spike protein of SARS-CoV-2 and determined the safety profile of this AAV vector in mice and sheep as a large animal model. In both studies, plasma biochemical parameters and hematology were comparable to untreated controls. Except for mild myositis at the site of injection, none of the major organs revealed any signs of toxicity. AAV-mediated human IgG expression increased steadily throughout the 28-day study in sheep, resulting in peak concentrations of 21.4–46.7 µg/ mL, demonstrating practical scale up from rodent to large animal models. This alternative approach to immunity is worth further exploration after this demonstration of safety, tolerability, and scalability in a large animal model.

AAV-monoclonal antibody expression protects mice from Ebola virus without impeding the endogenous antibody response to heterologous challenge

“…Indeed, we have shown that AAV-mediated expression of human IgG1 mAbs is feasible in mice, 26 Syrian hamsters, 27 and sheep. 28 More recently, data from a phase 1, dose-escalation clinical trial (NCT03374202) evaluating AAV8-mediated expression of the broadly neutralizing anti-HIV mAb VRC07 from an expression cassette that we based our EBOV mAb expression platform on in this body of work is encouraging in that all eight individuals produced measurable amounts of serum VRC07, with maximal concentrations >1 mg/mL in three participants. 46 In four individuals, VRC07 serum concentrations remained stable near maximal concentration for up to 3 years of follow-up, and unlike the first human clinical trial to evaluate AAV-mediated expression of an HIV bNAb, ADA responses were observed in only three of eight participants, and only in two cases did this lead to decreased serum VRC07, demonstrating that AAV-mAb expression is potentially a viable alternative platform for protection against infectious diseases.…”

“…ZMapp was dosed at 50 mg/kg over multi-day treatment courses in humans to maintain a therapeutic threshold 9 ; however, much lower but more consistent serum mAb concentrations mediated by AAV6.2FF should be able to maintain therapeutic efficacy without the peak and trough pharmacokinetics associated with repeat recombinant mAb administration. 45 There is strong evidence of the prophylactic efficacy of AAV6.2FF-mAb therapies, [26][27][28] allowing for post-exposure use to extend the potential applications of this therapy. Potential exposures to EBOV in a lab accident or health-care setting are realistic possibilities.…”

“…25 This capsid elicits long-term systemic expression of mAbs, which conferred protection in multiple infectious disease models, including at mucosal surfaces. [26][27][28] Here, we further explore the immunity mediated by this AAV6.2FF-mAb approach at reduced vector doses, and we use human IgG1 (hIgG1) filovirus mAbs in immunocompetent mice to expand the utility of our AAV6.2FF-mAb expression platform. In dose reduction experiments, we demonstrate AAV6.2FF vectors expressing murine IgG2a, and later hIgG1 mAbs, have the ability to prevent morbidity and mortality in the mouse-adapted EBOV challenge model, even with low level mAb expression.…”

Single-shot AAV-vectored vaccine against SARS-CoV-2 with fast and long-lasting immunity

“…At last but not least, a recent study demonstrated that AAV6-based mutant could steadily express transgene at a high level in sheep by intramuscular injection 56 . Another research showed that AAV6 can efficiently infect the muscle tissue adjacent to the injection site through subcutaneous injection and induce detectable T cell responses against transgene 57 .…”

AAV-Vectored Expression of the Vascular Normalizing Agents 3TSR and Fc3TSR, and the Anti-Angiogenic Bevacizumab Extends Survival in a Murine Model of End-Stage Epithelial Ovarian Carcinoma

“…Although numerous AAV serotypes with variable tropism exist [ 33 ], the novel triple-mutant AAV6.2FF capsid, which possesses an amino acid substitution (F129L) that facilitates heparin binding (AAV6.2) at the cell surface [ 50 ], and two mutations (Y445F, Y731F) that abrogate ubiquitin-mediated degradation [ 51 ], represents and ideal candidate for in vivo expression of antiangiogenic compounds due to its ability to mediate rapid and sustained transgene expression following intramuscular administration [ 52 , 53 ]. In a head to head comparison, AAV6.2FF outperformed other commonly used AAV capsids including AAV6, AAV8, AAV9, and DJ, by expressing significantly more luciferase in the first 14 days post-administration [ 54 ].…”