title: Deletions within the HSV-tk transgene in long-lasting circulating gene-modified T cells infused with a hematopoietic graft.
abstract: In our previous phase 1/2 study aimed at controlling graft-versus-host disease, 12 patients received Herpes simplex virus thymidine kinase (HSV-tk(+))/neomycin phosphotransferase (NeoR(+))-expressing donor gene-modified T cells (GMCs) and underwent an HLA-identical sibling T-cell-depleted bone marrow transplantation (BMT). This study's objective was to follow up, to quantify, and to characterize persistently circulating GMCs more than 10 years after BMT. Circulating GMCs remain detectable in all 4 evaluable patients. However, NeoR- and HSV-tk-polymerase chain reaction (PCR) differently quantified in vivo counts, suggesting deletions within the HSV-tk gene. Further experiments, including a novel "transgene walking" PCR method, confirmed the presence of deletions. The deletions were unique, patient-specific, present in most circulating GMCs expressing NeoR, and shown to occur at time of GMC production. Unique patient-specific retroviral insertion sites (ISs) were found in all GMCs capable of in vitro expansion/cloning as well. These findings suggest a rare initial gene deletion event and an in vivo survival advantage of rare GMC clones resulting from an anti-HSV-tk immune response and/or ganciclovir treatment. In conclusion, we show that donor mature T cells infused with a T-cell-depleted graft persist in vivo for more than a decade. These cells, containing transgene deletions and subjected to significant in vivo selection, represent a small fraction of T cells infused at transplantation.
authors: Institut National de la Santé et de la Recherche Médicale, U645, Besançon, France.
authors: Marina
authors: M
authors: Deschamps
authors: Patricia
authors: P
authors: Mercier-Lethondal
authors: Jean Marie
authors: JM
authors: Certoux
authors: Carole
authors: C
authors: Henry
authors: Bruno
authors: B
authors: Lioure
authors: Céline
authors: C
authors: Pagneux
authors: Jean Yves
authors: JY
authors: Cahn
authors: Eric
authors: E
authors: Deconinck
authors: Eric
authors: E
authors: Robinet
authors: Pierre
authors: P
authors: Tiberghien
authors: Christophe
authors: C
authors: Ferrand
mesh_terms: D001483:Base Sequence / Q000235:genetics*; D016026:Bone Marrow Transplantation; D017321:Clinical Trials, Phase I as Topic; D017322:Clinical Trials, Phase II as Topic; D005260:Female; D005500:Follow-Up Studies; D015316:Genetic Therapy; D006086:Graft vs Host Disease / Q000235:genetics / Q000276:immunology / Q000517:prevention & control; D019337:Hematologic Neoplasms / Q000201:enzymology / Q000235:genetics / Q000628:therapy; D006801:Humans; D019868:Kanamycin Kinase / Q000235:genetics / Q000276:immunology; D008212:Lymphocyte Depletion; D017710:Lymphocyte Transfusion; D008214:Lymphocytes / Q000276:immunology; D008297:Male; D008875:Middle Aged; D016133:Polymerase Chain Reaction; D017384:Sequence Deletion / Q000276:immunology; D018139:Simplexvirus / Q000201:enzymology / Q000235:genetics / Q000276:immunology; D013937:Thymidine Kinase / Q000235:genetics* / Q000276:immunology; D019076:Transgenes; D014184:Transplantation, Homologous; D014764:Viral Proteins / Q000235:genetics* / Q000276:immunology
chemical_list: D014764:Viral Proteins; D013937:Thymidine Kinase; D019868:Kanamycin Kinase