Evidence for Long-term Efficacy and Safety of Gene Therapy for Wiskott–Aldrich Syndrome in Preclinical Models

Abstract

Wiskott-Aldrich Syndrome (WAS) is a life-threatening X-linked disease characterized by immunodeficiency, thrombocytopenia, autoimmunity, and malignancies. Gene therapy could represent a therapeutic option for patients lacking a suitable bone marrow (BM) donor. In this study, we analyzed the long-term outcome of WAS gene therapy mediated by a clinically compatible lentiviral vector (LV) in a large cohort of was(null) mice. We demonstrated stable and full donor engraftment and Wiskott-Aldrich Syndrome protein (WASP) expression in various hematopoietic lineages, up to 12 months after gene therapy. Importantly, we observed a selective advantage for T and B lymphocytes expressing transgenic WASP. T-cell receptor (TCR)-driven T-cell activation, as well as B-cell's ability to migrate in response to CXCL13, was fully restored. Safety was evaluated throughout the long-term follow-up of primary and secondary recipients of WAS gene therapy. WAS gene therapy did not affect the lifespan of treated animals. Both hematopoietic and nonhematopoietic tumors arose, but we excluded the association with gene therapy in all cases. Demonstration of long-term efficacy and safety of WAS gene therapy mediated by a clinically applicable LV is a key step toward the implementation of a gene therapy clinical trial for WAS.

Validation of a mutated PRE sequence allowing high and sustained transgene expression while abrogating WHV-X protein synthesis: application to the gene therapy of WAS

“…In long-term observation or secondary transplant models in mice, the WAS LV bearing the mut6 WPRE caused no observable hematopoietic toxicity. 27 This strongly supports the development of this LV toward clinical application. The presence of the mut6 WPRE in addition to the WAS promoter in such a vector constitutes two important safety feature for this objective.…”

Wiskott-Aldrich syndrome protein-deficient hematopoietic cells can be efficiently mobilized by granulocyte colony-stimulating factor

“…21,22 In the absence of WASp, hematopoietic bone marrow cells also respond poorly to CXCL12-induced chemotaxis and cdc42 activation and this hampers the migration of early HSC and progenitor cells from the liver to bone marrow during development. 23 Thus, by affecting chemokine responses, WASp-deficiency may interfere with HSC mobilization.…”

Lentiviral vectors and cardiovascular diseases: a genetic tool for manipulating cardiomyocyte differentiation and function

“…In fact, LLVs are being increasingly tested for applications in preclinical studies. [34][35][36][37]39,[64][65][66] LVVs have also been used successfully for reprogramming strategies that generate iPS cells and for the transdifferentiation of somatic cells. However, safety issue concerns are still restraining their use in the clinical setting: indeed, LVVs do have the potential drawback of causing insertional mutagenesis through the random integration of DNA into the host genome, leading to the aberrant expression of important genes and to tumorigenesis.…”