Table 3.

Cytotoxicity profile of MAC-321 versus standard chemotherapeutics in PTX- and Epo-resistant cell lines that contain mutations in the taxane-binding site of β-tubulin^a

Compound	IC₅₀ (nm)*							Relative Resistance^b
Compound		1A9	1A9 PTX10	1A9 PTX22	1A9 EpoA8	1A9 PTX10	1A9 PTX22	EpoA8
MAC -321	1.6 ± 0.6	5.4 ± 2.7	8 ± 1.4	2.6 ± 1.6	3.4	5.0	1.6
PTX	5.1 ± 1.0	26.6 ± 16.3	89.2 ± 55.6	20.9 ± 10.8	5.2	17.5	4.1
DTX	1.8 ± 0.6	7.5 ± 0.3	7.9 ± 0.2	2.2 ± 1.2	4.2	4.4	1.2
EpoA	1.8 ± 0.5	16.0 ± 49.0	4.1 ± 3.3	31.8 ± 14.0	8.9	2.3	17.7

Compound	IC₅₀ (nm)**			Relative Resistance^b
Compound		A549	A549.EpoB40	A549.EpoB40
MAC-321	1.1 ± 0.6	11.3 ± 1.2	10.7
PTX	7.5 ± 1.3	156.9 ± 16.9	20.8
DTX	1.9 ± 0.7	31.8 ± 1.6	16.6
EpoB	1.0 ± 0.1	91.5 ± 3.9	95.3

↵a Parental cells and their resistant cell counterpart were grown in the presence of the indicated agents for 3 days and growth assessed by SRB staining (*) or ATP-binding (**) as described in “Materials and Methods.” Data are reported as average IC₅₀ ± SD.
↵b Average relative resistance is defined as the ratio of the IC₅₀ of the resistant cell model to that of the respective sensitive/parental cell counterpart.