Anti-CD3 antibodies modulate anti–factor VIII immune responses in hemophilia A mice after factor VIII plasmid-mediated gene therapy

Abstract

One major obstacle in gene therapy is the generation of immune responses directed against transgene product. Five consecutive anti-CD3 treatments concomitant with factor VIII (FVIII) plasmid injection prevented the formation of inhibitory antibodies against FVIII and achieved persistent, therapeutic levels of FVIII gene expression in treated hemophilia A mice. Repeated plasmid gene transfer is applicable in tolerized mice without eliciting immune responses. Anti-CD3 treatment significantly depleted both CD4+ and CD8+ T cells, whereas increased transforming growth factor-β levels in plasma and the frequency of both CD4+CD25+FoxP3+ and CD4+CD25−Foxp3+ regulatory T cells in the initial few weeks after treatment. Although prior depletion of CD4+CD25+ cells did not abrogate tolerance induction, adoptive transfer of CD4+ cells from tolerized mice at 6 weeks after treatment protected recipient mice from anti-FVIII immune responses. Anti-CD3–treated mice mounted immune responses against both T-dependent and T-independent neo-antigens, indicating that anti-CD3 did not hamper the immune systems in the long term. Concomitant FVIII plasmid + anti-CD3 treatment induced long-term tolerance specific to FVIII via a mechanism involving the increase in transforming growth factor-β levels and the generation of adaptive FVIII-specific CD4+Foxp3+ regulatory T cells at the periphery. Furthermore, anti-CD3 can reduce the titers of preexisting anti-FVIII inhibitory antibodies in hemophilia A mice.

Eradication of neutralizing antibodies to factor VIII in canine hemophilia A after liver gene therapy

“…Data on tolerance induction by gene therapy and/or immune modulatory strategies in preexisting immune responses has been limited to murine models. [46][47][48] Considering the limited numbers of hemophilia A dogs in this study and the modest inhibitor titers at the time of vector administration, these findings have to be considered a proof-of-principle that immune tolerance induction is feasible in the setting of preexisting immunity in a large animal model for an unmet medical need. These data may have relevance not only for hemophilia, but also for a variety of diseases in which antibody formation to the therapeutic protein or enzymes could prevent optimal clinical responses.…”

Synergistic Efficacy from Gene Therapy with Coreceptor Blockade and a β2-Agonist in Murine Pompe Disease

“…Multiple approaches for the induction of immune tolerance to a therapeutic protein (human factor IX) have been demonstrated in models for hemophilia, each of which might be adapted to the treatment of Pompe disease, including (1) liverspecific expression of therapeutic genes, 29,30 (2) neonatal exposure to the protein, 31,32 (3) expression of the therapeutic gene in precursor forms of immunologic cells 33 or in tolerogenic B cells, 34 or (4) blockade of coreceptors. 35 Coreceptor blockade has advantages over transgene-mediated approaches, at least regarding lack of toxicity from chromosomal integration or vector-directed immune responses. 36 Furthermore, coreceptor blockade by treatment with a nondepleting anti-CD4 mAb has achieved efficacy from low dosages of vector, 8 which could avoid T cell responses directed toward AAV capsid proteins.…”

Gene therapy for hemophilia

“…In vivo hydrodynamic injection of F.VIII-expressing plasmid can induce transgene expression; however, unlike with F.IX, this approach is limited by the development of anti-F.VIII inhibitors (254). Subsequent studies with the addition of immunomodulatory therapies have prevented inhibitor formation and induced F.VIII-specific tolerance mediated by Tregs (255, 330, 331). Hydrodynamic injection in conjunction with RNA trans-splicing (splicing therapeutic RNA into abundant albumin mRNA) has also been explored in the treatment of hemophilia A (332, 333).…”