Table 1.

Reversal effects of osimertinib on ABCB1-mediated MDR in KB-3-1 and KB-C2 cell lines.

Treatment	KB-3-1		KB-C2
	IC50 ± SD a (nM)	RF b	IC50 ± SD (µM)	RF
Paclitaxel	3.58 ± 0.35	[1.0]	1.075 ± 0.299	[307.1]
+ Osimertinib (0.3 µM)	3.63 ± 0.49	[1.0]	0.603 ± 0.045 *	[172.3]
+ Osimertinib (0.5 µM)	3.57 ± 0.41	[1.0]	0.092 ± 0.008 *	[26.3]
+ Osimertinib (1.0 µM)	3.12 ± 0.47	[0.9]	0.017 ± 0.005 *	[4.9]
+ Verapamil (3.0 µM)	3.24 ± 0.44	[0.9]	0.056 ± 0.011 *	[16.0]
+ Zosuquidar (0.3 µM)	2.81 ± 0.36	[0.8]	0.013 ± 0.003 *	[3.7]
Colchicine	59.82 ± 8.57	[1.0]	15.528 ± 4.565	[259.6]
+ Osimertinib (0.3 µM)	56.60 ± 7.13	[0.9]	5.120 ± 0.982 *	[85.6]
+ Osimertinib (0.5 µM)	58.66 ± 5.20	[1.0]	1.279 ± 0.606 *	[21.4]
+ Osimertinib (1.0 µM)	52.53 ± 7.39	[0.9]	0.637 ± 0.071 *	[10.6]
+ Verapamil (3.0 µM)	58.87 ± 9.65	[1.0]	0.279 ± 0.015 *	[4.7]
+ Zosuquidar (0.3 µM)	52.54 ± 9.12	[0.9]	0.078 ± 0.020 *	[3.7]
Vincristine	5.05 ± 0.89	[1.0]	0.797 ± 0.019	[157.8]
+ Osimertinib (0.3 µM)	5.49 ± 0.54	[1.1]	0.789 ± 0.027	[156.3]
+ Osimertinib (0.5 µM)	5.26 ± 0.71	[1.0]	0.228 ± 0.037 *	[45.1]
+ Osimertinib (1.0 µM)	5.56 ± 0.96	[1.1]	0.027 ± 0.006 *	[5.2]
+ Verapamil (3.0 µM)	4.61 ± 0.86	[0.9]	0.062 ± 0.008 *	[12.3]
+ Zosuquidar (0.3 µM)	4.58 ± 0.65	[0.9]	0.013 ± 0.003 *	[2.6]
	IC50 ± SD (µM)	RF	IC50 ± SD (µM)	RF
Cisplatin	2.90 ± 0.27	[1.0]	3.12 ± 0.20	[1.1]
+ Osimertinib (1.0 µM)	2.78 ± 0.17	[1.0]	2.98 ± 0.22	[1.0]
+ Verapamil (3.0 µM)	2.61 ± 0.20	[0.9]	2.66 ± 0.31	[0.9]

^a IC₅₀ values are represented as mean ± SD of at least three independent experiments performed in triplicate; ^b Values represent the resistance fold (RF) obtained by dividing IC₅₀ value of anticancer drug in KB-3-1 and KB-C2 cells with or without reversal agent divided by the IC₅₀ value of the respective anticancer drug in KB-3-1 cells without reversal agent. * p < 0.01 versus the control group.