Compositions and methods for the treatment of hemoglobinopathies

Abstract

Provided are compositions and methods for the treatment of hemoglobinopathies such as thalassemias and sickle cell disease. Compositions and methods include one or more endonuclease(s) or endonuclease fusion protein(s), including one or more homing endonuclease(s) and / or homing endonuclease fusion protein(s) and / or CRISPR endonuclease(s) ad / or CRISPR endonuclease fusion protein(s): (a) to disrupt a Bcl11a coding region; (b) to disrupt a Bcl11a gene regulatory region; (c) to modify an adult human β-globin locus; (d) to disrupt a HbP silencing DNA regulatory element or pathway, such as a Bcl11a-regulated HbP silencing region; (e) to mutate one or more γ-globin gene promoter(s) to achieve increased expression of a γ-globin gene; (f) to mutate one or more δ-globin gene promoter(s) to achieve increased expression of a δ-globin gene; and / or (g) to correct one or more β-globin gene mutation(s).

Description

CROSS REFERENCE TO RELATED APPLICATIONS[0001]This application is being filed on 22 Feb. 2013, as a PCT International patent application, and claims priority to U.S. Provisional Patent Application No. 61 / 603,231, filed Feb. 24, 2012, the disclosure of which is hereby incorporated by reference herein in its entirety.SEQUENCE LISTING[0002]The present application includes a Sequence Listing in electronic format as a txt file entitled “sequence listing 54428.0006WOUI_ST25” and crested on Feb. 22, 2013 and which has a size of 174 kilobytes (KB). The contents of the txt file “sequence listing 54428.0006WOUI_ST25” are incorporated by reference herein.BACKGROUND OF THE DISCLOSURE[0003]1. Technical Field of the Disclosure[0004]The present disclosure relates, generally, to the treatment of genetic diseases. More specifically, the present disclosure provides endonuclease-based compositions and methods, including homing endonuclease- and Cas9 endonuclease-based compositions and methods, for alte...

AI Technical Summary

Benefits of technology

[0024]Within a second embodiment, the present disclosure provides compositions and methods that comprise a polynucleotide that encodes one or more endonuclease(s), such as a homing endonuclease (HE) or a CRISPR endonucleases (i.e. Cas9 endonucleases in combination with one or more RNA guide strands) to achieve the targeted disruption of a key regulatory sequence within a β-globin gene locus, thereby increasing to therapeutic levels the expression of an endogenous gene such, as a γ- or δ-globin gene. Within related aspects, the compositions of these embodiments comprise a polynucleotide that encodes one or more TALEN, one or more TALE-HE fusion protein, and / or one or more TREX2 protein.

[0026]The homing endonucleases and CRISPR endonucleases described herein exhibit unique advantages over conventional gene targeting nucleases. Because they are broadly efficacious regardless of genotype, the homing and Cas9 endonucleases in combination with one or more RNA guide strands described herein are not patient specific, they provide clinical benefit in the heterozygotic state, and avoid the insertion of vector sequences.

[0033]Within a fifth embodiment, the present disclosure provides compositions and methods comprising ex-vivo expanded modified hematopoietic stem cells (HSCs), which allow for efficient engraftment of corrected cells and the use of induced pluripotent stem cells (iPSCs) for screening and clinical application. Within certain aspects of these embodiments are provided compositions and methods for the efficient expansion of autologous HSCs, autologous gene-modified HSCs, iPSC-derived HSCs, and ES cells. Cord blood expansion methodology may be employed, which methodology utilizes Delta1 in serum free media supplemented with hematopoietic growth factors using mobilized peripheral blood CD34+ cells obtained from normal donors. These compositions and methods may be used in combination with one or more additional reagent to enhance the survival and proliferation of hematopoietic stem / progenitor cells. Within other aspects, these compositions and methods may employ endothelial cell co-cultures for the enhanced expansion of long-term repopulating cells, including corrected iPSC-derived HSCs.

Problems solved by technology

Hemoglobinopathies, such as thalassemias and sickle cell disease, are highly prevalent genetic red blood sell disorders that cause a significant health burden worldwide.

Thus α abnormalities manifest in utero, potentially with devastating consequences (e.g. hydrops fetalis).

β-thalassemia is caused by an abnormality in the adult β-globin locus, which results in an abnormal stoichiometry of β-like globin chains to α-like chains, resulting in the precipitation of the unpaired α-like chains.

The ensuing damage meditated through several pathways including oxidation of cellular and membrane proteins culminates in ineffective erythropoiesis, apoptosis, and decreased red cell survival.

The hydrophobic valine at position 6 of the hemoglobin β-chain forms a hydrophobic patch which can associate with the hydrophobic patch of other hemoglobin S molecules causing hemoglobin S molecules to aggregate and form fibrous precipitates which, in turn, cause the red blood cells to adopt a sickle-shape and leads to alterations in numerous pathways that result in tissue damage via vaso-occlusion and hemolyis.

Severe forms of thalassemia require chronic transfusions, resulting in iron overload.

Survival directly correlates with the efficacy of chelation, though cost, side effects, and compliance severely limit efficacy.

This treatment, however, is under-prescribed, compliance is poor, and it does not adequately protect health.

Allogeneic hematopoietic cell transplantation (HCT) from HLA-matched sibling or unrelated donors offers a cure for patients with hemoglobinopathies, but is limited by the need for a suitably matched related or unrelated donor and is complicated by graft versus host disease (GVHD) and infections.

In addition, a major barrier is a high rate of graft failures, which is higher than observed for HCT for malignancies.

Unfortunately, several factors, including the low cell dose available in many cord blood units lead to slow engraftment and an increase in transplant related mortality in adults and larger children.

Similarly, these low cell numbers correlate with higher rates of graft failure, thus a particular concern in hemoglobinopathies where there is already high risk of graft failure.

The majority of the NRM occurs within the first 100 days post transplant with infection being the most common cause of death.

Thus, the significant delay in myeloid recovery that is observed in CBT recipients remains a critical barrier to successful outcomes in the CBT setting.

Despite tremendous investment of resources by many laboratories for over 30 years, there has been little progress in the development of therapeutic regimens for hemoglobinopathies, in large part due to the lack of identified drugable targets and the requirement for gene therapy vectors to persistently express at extremely high levels, while not leading to insertional mutagenesis.

While increased expression of fetal hemoglobin (HbF) ameliorates both hemoglobinopathies, extensive research has not yielded viable new agents based on that observation.

HSC gene therapy, however, requires high-level persistent expression and carries a substantial / risk of insertional mutagenesis and leukemia.

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