title: O6-methylguanine-DNA-methyltransferase (MGMT) gene therapy targeting haematopoietic stem cells: studies addressing safety issues.
abstract: As haematopoietic stem cell gene therapy utilizing O(6)-methylguanine-DNA-methyltransferase has reached the clinical stage, safety-related questions become increasingly important. These issues concern insertional mutagenesis of viral vectors, the acute toxicity of pre-transplant conditioning protocols and in vivo selection regimens as well as potential genotoxic side effects of the alkylating drugs administered in this context. To address these questions, we have investigated toxicity-reduced conditioning regimens combining low-dose alkylator application with sublethal irradiation and have analysed their influence on engraftment and subsequent selectability of transduced haematopoietic stem cells. In addition, a strategy to monitor the acute and long-term genotoxic effects of drugs with high guanine-O(6) alkylating potential, such as chloroethylnitrosoureas or temozolomide is introduced. For this purpose, assays were implemented which allow an assessment of the generation and fate of primary drug-induced adducts as well as their long-term effect on chromosomal integrity at the single cell level.
authors.affiliation: Department of Internal Medicine (Cancer Research), West German Cancer Center, University of Duisburg-Essen Medical School, Hufelandstr. 55, 45122 Essen, Germany. ursula.sorg@uk-essen.de
authors.forename: Ursula R
authors.initials: UR
authors.lastname: Sorg
authors.forename: Veronika
authors.initials: V
authors.lastname: Kleff
authors.forename: Sepideh
authors.initials: S
authors.lastname: Fanaei
authors.forename: Alexandra
authors.initials: A
authors.lastname: Schumann
authors.forename: Michael
authors.initials: M
authors.lastname: Moellmann
authors.forename: Bertram
authors.initials: B
authors.lastname: Opalka
authors.forename: Jürgen
authors.initials: J
authors.lastname: Thomale
authors.forename: Thomas
authors.initials: T
authors.lastname: Moritz
mesh_terms: D019943:Amino Acid Substitution; D000818:Animals; D018906:Antineoplastic Agents, Alkylating / Q000009:adverse effects; D004249:DNA Damage; D015254:DNA Modification Methylases / Q000235:genetics; D004260:DNA Repair; D045643:DNA Repair Enzymes / Q000235:genetics; D019008:Drug Resistance, Neoplasm / Q000235:genetics; D005260:Female; D015316:Genetic Therapy / Q000009:adverse effects* / Q000379:methods*; D018380:Hematopoietic Stem Cell Transplantation; D006412:Hematopoietic Stem Cells / Q000201:enzymology*; D006801:Humans; D051379:Mice; D008810:Mice, Inbred C57BL; D016297:Mutagenesis, Site-Directed; D009369:Neoplasms / Q000628:therapy; D019853:O(6)-Methylguanine-DNA Methyltransferase / Q000235:genetics*; D011994:Recombinant Proteins / Q000235:genetics; D012449:Safety; D019172:Transplantation Conditioning; D025521:Tumor Suppressor Proteins / Q000235:genetics
chemical_list: D018906:Antineoplastic Agents, Alkylating; D011994:Recombinant Proteins; D025521:Tumor Suppressor Proteins; D015254:DNA Modification Methylases; C515491:MGMT protein, human; D019853:O(6)-Methylguanine-DNA Methyltransferase; D045643:DNA Repair Enzymes