2.3. MTT cell viability assays

1 × 10⁴ Molm14, THP‐1 and OCI‐AML3 cells or 15 × 10⁴ fresh primary cells suspended in RPMI 1640 culture medium with 10% FBS were seeded in 96‐well plates. Cells were treated with either drug in single agent or combined mode under ambient air (21% O₂, normoxia) or hypoxic conditions (1% O₂) for 48 hours as outlined for each experiment. Cell viability was assessed using MTT (3‐(4,5‐dimethylthiazol‐2‐yl)‐2,5‐diphenyltetrazolium bromide; Roche) in accordance with the manufacturer's recommended protocols. Briefly, 20 µL MTT solution was added into each well and incubated at 37°C for 2 hours. Plates were read on at 490 nm with a plate reader. Growth inhibition percentage was calculated from the optical density ratio of treatment to DMSO control after subtraction of background under 21% O₂ and 1% O₂, respectively. All assays were performed in triplicate, and the results were obtained in at least three independent experiments as outlined for each experiment. Combination indexes (CIs) were determined using CompuSyn software.