Retroviral Transfer of Human Mutated Thymidylate Synthase Gene into Hematopoietic Stem Cells for Protection from High-Dose Fluoropyrimidine Toxicity.

摘要

In the field of breast cancer, the significant cytoreduction followed by consolidation chemotherapy has been accepted to reduce disease relapse in breast cancer. However, myelosuppression still impose restrictions on the optimization of this treatment modality. Insertion of drug resistance genes into hematopoietic progenitor cells offers an additional approach to allow further dose intensification and treatment post transplant. We have generated and characterized human thymidylate synthase (TS) mutants, one of which resulted in a 15 fold increase Ki for 5-fluoro2-deoxyuridylate (FdUMP) compared to the wild type TS. This mutant TSG52S transfectant confers a 97 fold resistance to fluorodeoxyuridine (FdUrd) in TS negative mouse cell lines. 5-fluorouracil (5- FU), is a commonly used drug in breast cancer treatment with significant myelosuppressive effects. We hypothesize that after administration of high dose chemotherapy, transplanted progenitor cells transduced with the fluoropyrimidine drug resistance gene, TSG52S, will allow for higher doses of 5-FU to be given during maintenance therapy without significant myelosuppression possibly leading to improved cure rates Therefore, the overall objective is to develop retroviral vectors and efficient viral transduction methods for introducing TSGE2S into mouse and human hematopoietic progenitor cells and then to evaluate the level of resistance to myelosuippression from 5-FU this method produces.