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A modified γ-retrovirus vector for X-linked severe combined immunodeficiency
Salima Hacein-Bey-Abina1, Sung-Yun Pai, H Bobby Gaspar
1From the Departments of Biotherapy (S.H.-B.-A., J. Blondeau, L.C., F.T., M.C.) and Immunology and Pediatric Hematology (S.B., G.C., D.M., B.N., C.P., F.T., A.F.) and the Centre d'Étude des Déficits Immunitaires (C.P.), Hôpital Necker-Enfants Malades, Assistance Publique-Hôpitaux de Paris (AP-HP), the Biotherapy Clinical Investigation Center, Groupe Hospitalier Universitaire Ouest, AP-HP, INSERM (S.H.-B.-A., J. Blondeau, L.C., F.T., M.C.), Unité de Technologies Chimiques et Biologiques pour la Santé, Centre National de la Recherche Scientifique, 8258-INSERM Unité 1022, Faculté des Sciences Pharmaceutiques et Biologiques, Université Paris Descartes (S.H.-B.-A.), Immunology Laboratory, Groupe Hospitalier Universitaire Paris-Sud, AP-HP, Le Kremlin-Bicêtre (S.H.-B.-A.), Imagine Institute, Paris Descartes-Sorbonne Paris Cité University (S.B., J. Blondeau, L.C., D.M., B.N., C.P., E.S., A.F., M.C.), INSERM Unités Mixtes de Recherche 1163, Laboratory of Human Lymphohematopoiesis (J. Blondeau, L.C., E.S., F.T., A.F., M.C.), Groupe Immunoscope, Immunology Department, Institut Pasteur (A.L.), and Collège de France (A.F.) - all in Paris; Division of Hematology-Oncology (S.-Y.P., H.B., D.G., C.E.H., G.H., L.E.L., W.B.L., D.A.W.) and Division of Immunology (L.D.N.), Boston Children's Hospital, Department of Pediatric Oncology, Dana-Farber Cancer Institute (S.-Y.P., D.G., L.E.L., W.B.L., D.A.W.), Harvard Medical School (S.-Y.P., M.A., L.E.L., W.B.L., J.R., L.E.S., A.T., L.D.N., D.A.W.), Center for Human Cell Therapy, Program in Cellular and Molecular Medicine, Boston Children's Hospital (M.A., J.R., L.E.S., A.T.), Division of Hematologic Malignancies, Dana-Farber Cancer Institute (J.R.), and the Manton Center for Orphan Disease Research (L.D.N.) - all in Boston; Great Ormond Street Hospital for Children NHS Foundation Trust (H.B.G., J.X.-B., A.J.T.) and Section of Molecular and Cellular Immunology, University College London Institute of Child Health (H.B.G., K.F.B., A.
A novel self-inactivating retrovirus vector effectively treated severe combined immunodeficiency X-linked (SCID-X1) in boys, restoring immune function with reduced oncogenic risk compared to previous therapies.
Area of Science:
- Immunology
- Gene Therapy
- Pediatric Hematology
Background:
- X-linked severe combined immunodeficiency (SCID-X1) is a primary immunodeficiency disorder.
- Previous γ-retrovirus vector gene therapy for SCID-X1 showed efficacy but carried a risk of leukemia due to enhancer-mediated mutagenesis.
- A need exists for safer gene therapy vectors for SCID-X1.
Purpose of the Study:
- To assess the efficacy and safety of a self-inactivating (SIN) γ-retrovirus vector for treating SCID-X1.
- To evaluate immune reconstitution and potential oncogenic risks associated with the SIN-γc vector.
Main Methods:
- Nine boys with SCID-X1 were treated with autologous CD34+ cells transduced with a SIN-γc retrovirus vector.
- Patients did not receive preparative conditioning before cell infusion.
- Follow-up included monitoring for immune recovery, clinical outcomes, and vector insertion sites.
Main Results:
- Seven of eight surviving patients achieved functional T-cell recovery and resolution of infections.
- Vector insertion site analysis showed significantly less clustering in proto-oncogenes compared to previous trials.
- No new cases of vector-induced leukemia were observed during the follow-up period.
Conclusions:
- The modified SIN-γc retrovirus vector is effective in treating SCID-X1, restoring immunity.
- This vector demonstrates a potentially improved safety profile regarding leukemogenesis.
- Long-term monitoring is necessary to fully ascertain the risk of leukemogenesis.
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