EX-VIVO TREATMENT OF BONE-MARROW WITH PHOSPHOROTHIOATE OLIGONUCLEOTIDE OL(1)P53 FOR AUTOLOGOUS TRANSPLANTATION IN ACUTE MYELOGENOUS LEUKEMIA AND MYELODYSPLASTIC SYNDROME

Effective ex vivo purging techniques can decrease the likelihood of in fusing bone marrow contaminated with leukemic cells during autologous transplantation. In preliminary studies, OL(1)p53, a 20-mer phosphorot hioate oligonucleotide directed against p53 mRNA, decreased the number of acute myelogenous leukemia (AML) cells in vitro, suggesting a poss ible role for OL(1)p53 in purging bone marrow harvests of leukemia cel ls. To demonstrate that OL(1)p53 was nontoxic to hematopoietic progeni tor cells, normal bone marrow cells were incubated with 10 mu M OL(1)p 53 for 36 h, and hematopoietic progenitor cell survival was determined by in vitro colony assays. OL(1)p53 had no toxic effect on the growth of either myeloid (CFU-GM) or erythroid (BFU-E) progenitor cells. OL( 1)p53 was then used to ex vivo purge bone marrow harvests from nine pa tients with either AML or myelodysplastic syndrome (MDS). Bone marrow cells were incubated-with 10 mu M OL(1)p53 for 36 h before transplanta tion. The median times posttransplantation for the patient to recover an absolute neutrophil count greater than 0.5 x 10(9)/L and a platelet transfusion independence were 30 days and 56 days, respectively. Incu bation of bone marrow cells with OL(1)p53 had no detrimental effect on the growth of hematopoietic progenitor cells, and transplantation of autologous bone marrow cells treated with the phosphorothioate oligonu cleotide, OL(1)p53, resulted in successful recovery of circulating neu trophils following high-dose therapy in patients with AML or MDS. The data show that OL(1)p53 can be used safely to purge autologous bone ma rrow harvests from patients with leukemia.