CB1093, a novel vitamin D analog; effects on differentiation and clonal growth on HL-60 and de novo leukemia cells.

We studied the effects of a novel vitamin D analog CB1093, EB1089 (one of the most antileukemic analogs yet) and 1 alpha,25(OH)2D3 both on HL-60 cells and cells from 13 AML patients. Differentiation was measured both by induction of superoxide production and non-specific esterase. Cell proliferation was assessed by colony assay and 3H-thymidine incorporation. The effect on serum calcium was measured in rats. The CB1093 proved to be the most efficient of the analogs tested so far, both in inducing differentiation and in inhibiting proliferation. This, combined with its low hypercalcemic effect shown here, makes it a promising candidate for preclinical animal studies.