Inhibition by Retinoic Acid of Myeloid Progenitors in Chronic Myeloid Leukemia and Myeloproliferative Disease: Increased Sensitivity in Blastic Phase of Chronic Myeloid Leukemia

The effects of all-trans retinoic acid (RA) were tested on the growth in vitro of myeloid progenitors from peripheral blood or bone marrow, in 25 patients with chronic myeloid leukemia (CML), ten of whom were either in accelerated or blastic phase, and in nine patients with myeloproliferative disease (MPD). The responses were compared with 12 normal bone marrow controls obtained from patients with lymphoma. Clonal growth in CML blastic and accelerated phase was inhibited to the greatest degree (mean 49±9% (SEM) of control at 0.3 µM RA). The responses in CML chronic phase and MPD were more heterogeneous, but significant inhibition was seen at higher concentrations of RA (50 ± 12% CML chronic phase, 58 ± 26% MPD at 3.0 µM RA). At 0.3 µM and 1.0 µM RA there were significant differences between the CML chronic phase and the CML blastic phase patients (p < 0.02 and p < 0.05 respectively). At these concentrations there was no significant inhibition on normal bone marrow myeloid progonitors. Inhibition was indep...