Elimination of clonogenic Philadelphia-positive cells using BCR-ABL antisense oligodeoxynucleotides.

Synthetic BCR-ABL antisense oligodeoxynucleotides are known to suppress in vitro clonogenic growth of primary cells from patients with CML. To evaluate the use of BCR-ABL antisense oligodeoxynucleotides as in vitro purging agents before autografting, we studied their effect on the clonogenic BV-173 cell line. At a concentration of 80 micrograms/ml, antisense oligodeoxynucleotides suppressed 85%, 95.5% and 95% of leukaemic cell growth after 24, 48 and 72 h of incubation, respectively. A correlation was observed between the concentration of oligomers and cell inhibition; however, concentrations higher than 80 micrograms/ml did not produce significant increase of BV-173 cell elimination. When the antisense treatment was performed on a wide range of target cell concentrations (from 1 x 10(5) to 5 x 10(6)/ml), the efficacy of purging was similar in all the groups. Addition of antisense oligodeoxynucleotides every 24 h produced, after 3 days, a cell growth inhibition superior to any single treatment; in particular, three treatments for 24 h at a concentration of 80 micrograms/ml were more effective than a single treatment at the same concentration or a single treatment at a concentration of 160 micrograms/ml. Incubation of normal human BM cells with the same doses which were very effective at inhibiting BV-173 cell proliferation, did not affect the growth of normal CFU-GM and of more immature progenitors.