ImmTOR nanoparticles enhance AAV transgene expression after initial and repeat dosing in a mouse model of methylmalonic acidemia

Abstract

A major barrier to adeno-associated virus (AAV) gene therapy is the inability to re-dose patients due to formation of vectorinduced neutralizing antibodies (Nabs). Tolerogenic nanoparticles encapsulating rapamycin (ImmTOR) provide long-term and specific suppression of adaptive immune responses, allowing for vector re-dosing. Moreover, co-administration of hepatotropic AAV vectors and ImmTOR leads to an increase of transgene expression even after the first dose. ImmTOR and AAV Anc80 encoding the methylmalonyl-coenzyme A (CoA) mutase (MMUT) combination was tested in a mouse model of methylmalonic acidemia, a disease caused by mutations in the MMUT gene. Repeated co-administration of Anc80 and ImmTOR was well tolerated and led to nearly complete inhibition of immunoglobulin (Ig)G antibodies to the Anc80 capsid. A more profound decrease of plasma levels of the key toxic metabolite, plasma methylmalonic acid (pMMA), and disease biomarker, fibroblast growth factor 21 (FGF21), was observed after treatment with the ImmTOR and Anc80-MMUT combination. In addition, there were higher numbers of viral genomes per cell (vg/cell) and increased transgene expression when ImmTOR was co-administered with Anc80-MMUT. These effects were dose-dependent, with the higher doses of Im-mTOR providing higher vg/cell and mRNA levels, and an improved biomarker response. Combining of ImmTOR and AAV can not only block the IgG response against capsid, but it also appears to potentiate transduction and enhance therapeutic transgene expression in the mouse model.

Treatment of metabolic disorders using genomic technologies: Lessons from methylmalonic acidemia

“…Selecta Biosciences has developed a tolerogenic nanoparticle that encapsulates rapamycin known as ImmTOR (Figure 2A), 79–82 which causes long‐term suppression of humoral and T cell responses when co‐administered with an AAV therapy 80,96 . When combining ImmTOR with an MMUT rAAV in the Mmut −/− ; Tg INS − MCK − Mmut mouse model, we observed rapid weight gain, reduced plasma methylmalonic acid, and lowering of Fgf21 levels 79 . In mice treated only with the MMUT rAAV, high levels of IgG antibodies against the viral capsid (Anc80L65 in these experiments) were detected up to 300 days post treatment.…”

“…However, for mice treated with the combined ImmTOR and MMUT rAAV therapy, IgG antibodies were dramatically reduced in an ImmTOR dose-dependent fashion. 79 Hence, combining ImmTOR with rAAV therapy to induce a state of immune tolerance in the animals might allow for the redosing of patients with the same AAV vector in the future if needed.…”

“…ImmTOR is a tolerogenic nanoparticle encapsulating rapamycin. [79][80][81][82] (B) A human, codon-optimized hMMUT mRNA encapsulated in a lipid nanoparticle. (C) The schematic of an AAV-mediated, nuclease-free genome editing vector and the integration and subsequent expression.…”

Modern therapeutic approaches to liver-related disorders

“…64 One approach to overcome episome dilution involves an integrative strategy, 29 as used in the clinical trial for methylmalonic acidaemia (NCT04581785), or a gene editing strategy (described below). Strategies to prevent the formation of NAbs after rAAV infusion via the use of mTOR inhibitors encapsulated in LNPs co-administered with the vector, [65][66][67] or by removing extant NAb via immunoadsorption 68 or systemic administration of IgG-cleaving endopeptidase 69 have enabled successful readministration of the vector in pre-clinical models. However, their utility in clinical settings remains to be demonstrated.…”

Gene Therapy: Recent Advancement and Challenges

“…Another solution may emerge through gene delivery by non-viral nanoparticles. Aside from the advantage nanoparticles may have in evading the immune system, which restricts viral vector delivery, they may also be uniquely suitable for tissue targeting for in vivo gene transfer [27][28][29]. Liposomemediated gene transfer, for example, shows promise in targeting specific cells, principally in oncology [30,31].…”