Fig. 4: Synergistic antitumor efficacy of sacituzumab govitecan in combination with decitabine.

A–C Effect of combination of SG and decitabine on cell survival. BCX-010CL, BCX-011CL, and SUM159 cells were treated with decitabine, SG or their combination at concentrations in serial dilutions for 3 days. After viability measurement, dose-response curves of cell inhibition were calculated. IC50s of drugs in single or combination groups and combination index (CI) were calculated using CalcuSyn. CI < 1.0 (curve left-shift): synergistic; CI = 1.0, additive; CI > 1.0 (curve right-shift): antagonistic). D–F Effect of combination on cell colony formation. BCX-010CL, BCX-011CL, and SUM159 cells were treated with decitabine, SG, or their combination at the indicated concentrations for 2-3 weeks. Crystal violet stained cell colonies were imaged. G–I Effect of combination on cell apoptosis. BCX-010CL, BCX-011CL, and SUM159 cells were treated with decitabine at 1 µM, SG at 0.1 µM, or their combination for 3 days. Annexin V staining positive cells were sorted by flow cytometry. Percentage of apoptotic cells was calculated by Annexin V positive cells over total cell populations. J–M Effect of ZEB1 knockdown on SG efficacy. In cell survival assay, shRNA control and ZEB1 shRNA cell lines were treated with decitabine, SG or their combination at concentrations in serial dilutions for 3 days. Drug IC50s and CI were calculated as described in Fig. 4A–F (J). In cell colony formation assay, the control and knockdown cells were treated with decitabine, SG, or their combination at the indicated concentrations for 3 weeks (K, L). In apoptosis assay, cells were treated with decitabine at 1 µM, SG at 0.1 µM, or their combination for 3 days. Annexin V positive apoptotic cells were measured by flow cytometry. Percentage of apoptotic cells over total cell populations was calculated (M). N, O Effect of TROP2 overexpression on SG. BCX-010CL cells were transfected with TROP2 expression plasmid. After G-418 selection, immunoblotting was performed to detect TROP2 expression (N). TROP2-overexpressing cells and control cells were treated with SG at concentrations in serial dilutions for 3 days. SG IC50 was calculated (O). Data in A, B, C, G, H, I, J, M, and O was presented by means ± SEM).