O6-methylguanine-DNA-methyltransferase (MGMT) gene therapy targeting haematopoietic stem cells: studies addressing safety issues

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 protoco...

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Bibliographic Details
Published in:DNA repair 2007-08, Vol.6 (8), p.1197-1209
Main Authors: Sorg, Ursula R, Kleff, Veronika, Fanaei, Sepideh, Schumann, Alexandra, Moellmann, Michael, Opalka, Bertram, Thomale, Jürgen, Moritz, Thomas
Format: Article
Language:English
Subjects:
Amino Acid Substitution
Animals
Antineoplastic Agents, Alkylating - adverse effects
DNA Damage
DNA Modification Methylases - genetics
DNA Repair
DNA Repair Enzymes - genetics
Drug Resistance, Neoplasm - genetics
Female
Genetic Therapy - adverse effects
Genetic Therapy - methods
Hematopoietic Stem Cell Transplantation
Hematopoietic Stem Cells - enzymology
Humans
Mice
Mice, Inbred C57BL
Mutagenesis, Site-Directed
Neoplasms - therapy
O-Methylguanine-DNA Methyltransferase - genetics
Recombinant Proteins - genetics
Safety
Transplantation Conditioning
Tumor Suppressor Proteins - genetics
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Summary: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.
ISSN:1568-7864
DOI:10.1016/j.dnarep.2007.03.021