title: Cytoreductive conditioning intensity predicts clonal diversity in ADA-SCID retroviral gene therapy patients.
abstract: Retroviral gene therapy has proved efficacious for multiple genetic diseases of the hematopoietic system, but roughly half of clinical gene therapy trial protocols using gammaretroviral vectors have reported leukemias in some of the patients treated. In dramatic contrast, 39 adenosine deaminase-deficient severe combined immunodeficiency (ADA-SCID) patients have been treated with 4 distinct gammaretroviral vectors without oncogenic consequence. We investigated clonal dynamics and diversity in a cohort of 15 ADA-SCID children treated with gammaretroviral vectors and found clear evidence of genotoxicity, indicated by numerous common integration sites near proto-oncogenes and by increased abundance of clones with integrations nearMECOMandLMO2These clones showed stable behavior over multiple years and never expanded to the point of dominance or dysplasia. One patient developed a benign clonal dominance that could not be attributed to insertional mutagenesis and instead likely resulted from expansion of a transduced natural killer clone in response to chronic Epstein-Barr virus viremia. Clonal diversity and T-cell repertoire, measured by vector integration site sequencing and T-cell receptor β-chain rearrangement sequencing, correlated significantly with the amount of busulfan preconditioning delivered to patients and to CD34+cell dose. These data, in combination with results of other ADA-SCID gene therapy trials, suggest that disease background may be a crucial factor in leukemogenic potential of retroviral gene therapy and underscore the importance of cytoreductive conditioning in this type of gene therapy approach.
authors.affiliation: Department of Microbiology, Immunology and Molecular Genetics and.|Molecular Biology Interdepartmental PhD Program, University of California, Los Angeles, Los Angeles, CA.
authors.forename: Aaron R
authors.identifier: 0000-0003-4588-2513
authors.initials: AR
authors.lastname: Cooper
authors.affiliation: Department of Microbiology, Immunology and Molecular Genetics and.
authors.forename: Georgia R
authors.initials: GR
authors.lastname: Lill
authors.affiliation: Department of Microbiology, Immunology and Molecular Genetics and.
authors.forename: Kit
authors.initials: K
authors.lastname: Shaw
authors.affiliation: Department of Microbiology, Immunology and Molecular Genetics and.
authors.forename: Denise A
authors.initials: DA
authors.lastname: Carbonaro-Sarracino
authors.affiliation: Department of Microbiology, Immunology and Molecular Genetics and.
authors.forename: Alejandra
authors.initials: A
authors.lastname: Davila
authors.affiliation: Genetics and Molecular Biology Branch, National Human Genome Research Institute, National Institutes of Health, Bethesda, MD; and.
authors.forename: Robert
authors.initials: R
authors.lastname: Sokolic
authors.affiliation: Genetics and Molecular Biology Branch, National Human Genome Research Institute, National Institutes of Health, Bethesda, MD; and.
authors.forename: Fabio
authors.initials: F
authors.lastname: Candotti
authors.affiliation: Department of Molecular, Cellular and Developmental Biology.
authors.forename: Matteo
authors.initials: M
authors.lastname: Pellegrini
authors.affiliation: Department of Microbiology, Immunology and Molecular Genetics and.|Molecular Biology Institute, and.|Eli & Edythe Broad Center of Regenerative Medicine & Stem Cell Research, University of California, Los Angeles, Los Angeles, CA.
authors.forename: Donald B
authors.initials: DB
authors.lastname: Kohn
mesh_terms: D048868:Adaptor Proteins, Signal Transducing / Q000235:genetics; D000243:Adenosine Deaminase / Q000172:deficiency* / Q000235:genetics; D000361:Agammaglobulinemia / Q000235:genetics* / Q000473:pathology / Q000628:therapy*; D018906:Antineoplastic Agents, Alkylating / Q000627:therapeutic use*; D002066:Busulfan / Q000627:therapeutic use*; D002648:Child; D004268:DNA-Binding Proteins / Q000235:genetics; D017988:Gammaretrovirus / Q000235:genetics*; D015316:Genetic Therapy / Q000379:methods*; D005822:Genetic Vectors / Q000235:genetics / Q000627:therapeutic use*; D006801:Humans; D060588:LIM Domain Proteins / Q000235:genetics; D000074008:MDS1 and EVI1 Complex Locus Protein; D011518:Proto-Oncogene Proteins / Q000235:genetics; D011519:Proto-Oncogenes / Q000235:genetics; D016511:Severe Combined Immunodeficiency / Q000235:genetics* / Q000473:pathology / Q000628:therapy*; D013601:T-Lymphocytes / Q000166:cytology / Q000187:drug effects / Q000378:metabolism / Q000473:pathology; D014157:Transcription Factors / Q000235:genetics
chemical_list: D048868:Adaptor Proteins, Signal Transducing; D018906:Antineoplastic Agents, Alkylating; D004268:DNA-Binding Proteins; D060588:LIM Domain Proteins; C085117:LMO2 protein, human; D000074008:MDS1 and EVI1 Complex Locus Protein; C063575:MECOM protein, human; D011518:Proto-Oncogene Proteins; D014157:Transcription Factors; D000243:Adenosine Deaminase; D002066:Busulfan