Transfusion independence and HMGA2 activation after gene therapy of human beta-thalassaemia. Nature

Clinical Investigation Center in Biotherapy, Groupe Hospitalier Universitaire Ouest, Inserm/Assistance Publique-Hôpitaux de Paris, Paris 75015, France.
Nature (Impact Factor: 42.35). 09/2010; 467(7313):318-22. DOI: 10.1038/nature09328
Source: PubMed

ABSTRACT The β-haemoglobinopathies are the most prevalent inherited disorders worldwide. Gene therapy of β-thalassaemia is particularly challenging given the requirement for massive haemoglobin production in a lineage-specific manner and the lack of selective advantage for corrected haematopoietic stem cells. Compound β(E)/β(0)-thalassaemia is the most common form of severe thalassaemia in southeast Asian countries and their diasporas. The β(E)-globin allele bears a point mutation that causes alternative splicing. The abnormally spliced form is non-coding, whereas the correctly spliced messenger RNA expresses a mutated β(E)-globin with partial instability. When this is compounded with a non-functional β(0) allele, a profound decrease in β-globin synthesis results, and approximately half of β(E)/β(0)-thalassaemia patients are transfusion-dependent. The only available curative therapy is allogeneic haematopoietic stem cell transplantation, although most patients do not have a human-leukocyte-antigen-matched, geno-identical donor, and those who do still risk rejection or graft-versus-host disease. Here we show that, 33 months after lentiviral β-globin gene transfer, an adult patient with severe β(E)/β(0)-thalassaemia dependent on monthly transfusions since early childhood has become transfusion independent for the past 21 months. Blood haemoglobin is maintained between 9 and 10 g dl(-1), of which one-third contains vector-encoded β-globin. Most of the therapeutic benefit results from a dominant, myeloid-biased cell clone, in which the integrated vector causes transcriptional activation of HMGA2 in erythroid cells with further increased expression of a truncated HMGA2 mRNA insensitive to degradation by let-7 microRNAs. The clonal dominance that accompanies therapeutic efficacy may be coincidental and stochastic or result from a hitherto benign cell expansion caused by dysregulation of the HMGA2 gene in stem/progenitor cells.

Download full-text


Available from: Axel Polack, Aug 20, 2015
  • Source
    • "As seen in previous gene-therapy clinical studies using murine leukemia virus (MLV) vectors, insertional mutagenesis may cause aberrant clonal proliferation or skewed differentiation. While low genotoxic effects of lentivirus vectors have been demonstrated in recent studies by VIS analysis for up to 2 years in humans (Aiuti et al., 2013; Biffi et al., 2013; Cartier et al., 2009; Cavazzana-Calvo et al., 2010), careful monitoring of the longterm effects by lentivirus vectors is required because genemodified HSCs will be maintained for a lifetime. Genomic VIS patterns of repopulating cells in our test animals largely reflect those of freshly transduced CD34+ HSPCs (acute infection) (Figure S7A). "
    [Show abstract] [Hide abstract]
    ABSTRACT: In mice, clonal tracking of hematopoietic stem cells (HSCs) has revealed variations in repopulation characteristics. However, it is unclear whether similar properties apply in primates. Here, we examined this issue through tracking of thousands of hematopoietic stem and progenitor cells (HSPCs) in rhesus macaques for up to 12 years. Approximately half of the clones analyzed contributed to long-term repopulation (over 3-10 years), arising in sequential groups and likely representing self-renewing HSCs. The remainder contributed primarily for the first year. The long-lived clones could be further subdivided into functional groups contributing primarily to myeloid, lymphoid, or both myeloid and lymphoid lineages. Over time, the 4%-10% of clones with robust dual lineage contribution predominated in repopulation. HSPCs expressing a CCR5 shRNA transgene behaved similarly to controls. Our study therefore documents HSPC behavior in a clinically relevant model over a long time frame and provides a substantial system-level data set that is a reference point for future work.
    Cell stem cell 04/2014; 14(4):473-85. DOI:10.1016/j.stem.2013.12.012 · 22.15 Impact Factor
  • Source
    • "The first clinically successful gene therapy (GT) trial for primary immunodeficiency was reported in 2000 (Cavazzana- Calvo et al., 2000). Since then, the list of indications for which GT treatment led to permanent or temporary benefit for treated patients has been continuously growing (Aiuti et al., 2002; Mavilio et al., 2006; Morgan et al., 2006; Ott et al., 2006; Kaplitt et al., 2007; Bainbridge et al., 2008; Cartier et al., 2009; Boztug et al., 2010; Cavazzana-Calvo et al., 2010; Porter et al., 2011). For CGD, the first clinically successful X-CGD GT trial with proven restoration of ROS production and resolution of treatment refractory Aspergillus infections was initiated in 2004 in Frankfurt and Zü rich. "
    [Show abstract] [Hide abstract]
    ABSTRACT: Targeting transgene expression to specific hematopoietic cell lineages could contribute to the safety of retroviral vectors in gene therapeutic applications. Chronic Granulomatous Disease (CGD), a defect of phagocytic cells, may be manageable by gene therapy using retroviral vectors with targeted expression to myeloid cells. In this context, we analyzed the myelospecificity of the human micro-RNA 223 promoter, which is known to be strongly upregulated during myeloid differentiation, to drive myeloid-restricted expression of p47phox and gp91phox in mouse models of CGD and in primary patient derived cells. The miR223 promoter restricted the expression of p47phox, gp91phox and GFP within self-inactivating gamma- and lentiviral vectors to granulocytes and macrophages with only marginal expression in lymphocytes or hematopoietic stem and progenitor cells. Furthermore, gene transfer into primary CD34+ cells derived from a p47phox patient followed by ex vivo differentiation to neutrophils resulted in restoration of E.coli killing activity by miR223 promoter mediated p47phox expression. These results indicate that the miR223 promoter as internal promoter within self-inactivating gene therapy vectors is able to efficiently correct the CGD phenotype with negligible activity in hematopoietic progenitors thereby limiting the risk of insertional oncogenesis and development of clonal dominance.
    Human Gene Therapy Methods 03/2013; 24. DOI:10.1089/hgtb.2012.157 · 1.64 Impact Factor
  • Source
    • "This allows concentration to higher titers by ultracentrifugation and confers broad tropism, as VSV.G binds to a still unknown ubiquitous membrane component (Cronin, Zhang et al. 2005). This superior transduction efficiency comes in handy for the treatment of genetic disorders such as β-thalassemia and X-linked adenoleukodystrophy (Cartier, Hacein-Bey-Abina et al. 2009; Cavazzana-Calvo, Payen et al. 2010). Nonetheless, VSV.G pseudotyped LVs also present several downsides. "
    Gene Therapy - Tools and Potential Applications, 03/2013; IntechOpen.
Show more