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

Petr O Ilyinskii,Alicia M Michaud,Gina L Rizzo,Christopher J Roy,Sheldon S Leung,Stephanie L Elkins,Teresa Capela,Aparajita Chowdhury,Lina Li,Randy J Chandler,Irini Manoli,Eva Andres-Mateos,Lloyd P.M Johnston,Luk H Vandenberghe,Charles P Venditti,Takashi Kei Kishimoto

doi:10.1016/j.omtm.2021.06.015

Abstract

A major barrier to adeno-associated virus (AAV) gene therapy is the inability to re-dose patients due to formation of vector-induced 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 ImmTOR 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.

Highlights

Isolated methylmalonic acidemia (IMMA) is a rare and heterogeneous autosomal recessive metabolic disorder affecting the metabolism of branched-chain amino acids, odd-chain fatty acids, and cholesterol
Animals treated with Anc80-methylmalonyl-coenzyme A (CoA) mutase (MMUT) alone showed more rapid weight gain than did groups treated with Anc80-MMUT + ImmTOR; the differences became insignificant by the third week after treatment (Figure 1A)
The plasma methylmalonic acid (pMMA) levels in mice receiving Anc80-MMUT combined with ImmTOR were 3-fold lower than in mice treated with same low-dose Anc80MMUT alone, with the latter essentially being non-therapeutic (Figure S2)

Summary

Introduction

Isolated methylmalonic acidemia (IMMA) is a rare and heterogeneous autosomal recessive metabolic disorder affecting the metabolism of branched-chain amino acids, odd-chain fatty acids, and cholesterol. Patients with IMMA massively accrete “toxic” metabolites, and they share a common clinical phenotype characterized by metabolic decompensations and early mortality.[1,2,3,4,5] IMMA is most frequently caused by mutations in the gene encoding the mitochondrial localized enzyme, methylmalonyl-coenzyme A (CoA) mutase (MMUT). This enzyme catalyzes the isomerization of L-methylmalonyl-CoA into succinyl-CoA. Clinical observations have been supported by both transgenic animal modeling[21] and proof-of-concept gene therapy studies in IMMA mice[9,22] that unequivocally demonstrate the requirement to augment hepatic MMUT activity for therapeutic benefit in IMMA

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Results

Conclusion