Figure 6.

Gefitinib and crizotinib treatment promotes an additive effect for inhibiting canine OSA cell proliferation. OSA8 cells were plated in C1 RPMI media and treated for 72 h with gefitinib only, crizotinib only or a combination of gefitinib and crizotinib using concentrations ranging from 0.0625X to 4X their IC₅₀ concentrations. (A) Cell proliferation was assessed using a CyQuant assay, which was then used for CompuSyn analysis. (B) The combination of gefitinib and crizotinib promoted an additive effect on inhibition of cell proliferation. The resulting CI values are shown for ED₅₀ ≥ 50% (the point on the curve where the cell number is 50% of that in the untreated controls) (top table). The bottom table shows the data for ED₅₀. To achieve 50% killing of the cells, it would require approximately twice the dose of gefitinib and crizotinib used individually compared to these drugs used in combination. The CI value definitions are as follows: 1.45–1.2 is moderately antagonistic, 1.2–1.1 is slightly antagonistic, 1.1–0.9 is additive, 0.9–0.85 is slightly synergistic, 0.85–0.7 is moderately synergistic and 0.7–0.3 is synergistic.