RAPID COMMUNICATION Gene Therapy for Chronic Myelogenous Leukemia (CML): A Retroviral Vector That Renders Hematopoietic Progenitors Methotrexate-Resistant and CML Progenitors Functionally Normal and Nontumorigenic In Vivo

Chronic myelogenous leukemia (CML) is a malignant disease BCR/ABL mRNA and p210 protein levels by 6to 10fold in most cells. This subsequently led to the restoration of the human hematopoietic stem cell caused by the BCR/ ABL gene rearrangement. The only curative therapy is alloof normal function of BCR/ABL cDNA cells: they grew significantly slower in the presence of interleukin-3 (IL-3); they geneic transplantation. Although autologous transplants may prolong survival, most patients relapse because of disunderwent apoptotic cell death when cultured without IL-3; and they had restored expression and function of adhesion ease persisting in the host and in the graft. Continued administration of chemotherapy after transplant could reduce the receptors. These effects were specific, because LasBD-containing AS sequences directed at the b3a2 BCR/ABL incidence of relapse provided that the autograft can be protected by transfer of a drug-resistance gene. However, CML breakpoint did not affect p190-containing cells. LasBD also rendered 20% to 30% of primary Ph and Ph CD34 autografts will almost certainly contain malignant stem cells that will also be rendered drug-resistant. The presence of cells MTX-resistant and decreased BCR/ABL mRNA levels in MTX resistant Ph CD34 cells by 10-fold. Expression of the the BCR/ABL oncoprotein is necessary and sufficient for malignant transformation seen in CML. We thus hypothesized MTX-resistant DHFR gene and the AS sequences has been stable for at least 1 year in vitro and for more than 70 days that transfer of a vector that combines a drug-resistance gene with anti-BCR/ABL antisense (AS) sequences may in vivo. Finally, LasBD decreased tumorigenicity of 32D cells in vivo by 3 to 4 logs. In conclusion, the allow for posttransplant chemotherapy to decrease persistent disease while rendering inadvertently transduced CML tyr22-DHFR gene in the LasBD vector can protect normal hematopoietic cells from MTX-mediated toxicity, whereas stem and progenitor cells functionally normal. We constructed a retroviral vector, LasBD, that combines the meththe AS sequences in LasBD can suppress expression of the BCR/ABL gene and restore normal function of BCR/ABL otrexate (MTX)-resistant tyrosine-22 dihydrofolate-reductase (tyr22-DHFR) gene and AS sequences directed at the cDNA-containing cells. The LasBD vector may therefore prove to be an extremely useful adjunct in autologous transb3a2 BCR/ABL breakpoint. b3a2 BCR/ABL containing 32D and MO7e cells were transduced with LasBD and selected plantation for CML. q 1997 by The American Society of Hematology. in MTX for 14 days. Expression of the AS sequences reduced