Fig. 6: Cell death induced by fadraciclib and venetoclax was reversible.

A CLL cells were incubated with fadraciclib (0.8 μM) for 8, 12, and 24 h before they were washed and re-incubated with drug-free medium, and cell viability was measured at the indicated times up to 72 h. One representative graph from 2 samples is shown. B Representative immunoblot from 2 samples showing recovery of RNA Pol II phosphorylation, Mcl-1 level, and PARP cleavage after wash. C CLL cells were incubated with venetoclax (0.07 μM) for 4, 8, and 24 h before they were washed and re-incubated with drug-free medium, and cell viability was measured at the indicated times up to 72 h. One representative graph from 2 samples is shown. D Representative immunoblot of the samples collected in C from 2 samples. E Reversible cell death induced by the combination of fadraciclib and venetoclax. A representative time course of viability in CLL cells incubated with IC₅₀ concentrations of fadraciclib (0.87 μM), venetoclax (0.05 μM), and the combination for the indicated times; the combination sample (purple) was washed at 4 h before incubation in the drug-free medium. F Effects of tandem administration of fadraciclib and venetoclax on different schedules. CLL cells were incubated with IC₅₀ concentration of fadraciclib. After 8 h, the cells either continued in fadraciclib till 72 h (Fad continuous, dark blue) or received the addition of the IC₅₀ concentration of venetoclax (Fad-8h + Ven, red). The rest of the cells were washed at 8 h, then re-incubated in drug-free medium (Fad-8h wash, blue) or with venetoclax (Fad-8h wash + Ven, pink), or wait until 24 h before adding venetoclax (Fad-8h wash wait + Ven@24 h, green). Cell viability was measured at indicated times. The cells incubated in drug-free medium (control) or venetoclax (venetoclax continuous, maroon) served as controls. A representative plot from 3 samples is shown.