Figure 2.

(A) Concentration response curves of cell lines (n = 3–4) and patient-derived primary tumor cells (n = 6) to increasing concentrations of cisplatin (red line) with the addition of 0.4 (black line), 1.5 (green line), 3 (purple line) or 6 μM (grey line) quinacrine. Vertical lines highlight IC₅₀ values color matched; responses fitted to a five-parameter logistic equation. (B) Fraction affected vs Combination Index (Fa-CI) plot for each cell line, produced using CompuSyn. Concentrations range from 1/32x – 2x IC₅₀ for quinacrine (Q), and from 1/8x – 8x IC₅₀ for cisplatin (C), maintaining a ratio of 1:4 Q:C. Data points below 1 (dotted line) represent synergy (n = 3). (C) Dose reduction index (DRI) table for CAL27, SCC040 and SCC47 cell lines (n = 3). Green indicates DRI values > 1 (favorable reduction); orange indicates DRI values <1 (less favorable reduction).