Table 2.

Isobolographic interactions between CDDP and CAM at the fixed-ratio combination of 1:1 in four cancer cell lines (MCF7, T47D, MDA-MB-231, and MDA-MB-468) measured in vitro by the MTT assay. Results are presented as median inhibitory concentrations (IC₅₀ values in μg/mL ± S.E.M.) for two-drug mixtures, determined either experimentally (IC_{50 mix}) or theoretically calculated (IC_{50 add}) from the equations of additivity [32,33], blocking proliferation in 50% of tested cells in four cancer cell lines (MCF7, T47D, MDA-MB-231, and MDA-MB-468) measured in vitro by the MTT assay.

Cell Line	IC50 mix (μg/mL)	n mix	L IC50 add (μg/mL)	n add	U IC50 add (μg/mL)	n add	p-Value	Type of Interaction
MCF7	32.483 ± 1.508	90	4.314 ± 3.781	140	17.573 ± 4.743	140	0.0032 **	antagonism
T47D	19.112 ± 3.055	90	3.478 ± 2.515	140	14.158 ± 3.404	140	0.2799	tendency towards antagonism
MDA-MB-231	21.352 ± 1.980	72	3.638 ± 2.840	158	11.304 ± 3.813	158	0.0203 *	antagonism
MDA-MB-468	15.713 ± 1.513	90	3.671 ± 2.391	158	12.927 ± 3.155	158	0.4268	tendency towards antagonism

n_mix—total number of items used at those concentrations whose expected anti-proliferative effects ranged between 16% and 84% (i.e., 4 and 6 probits) for the experimental mixture; n _add—total number of items calculated for the additive mixture of the drugs examined; ^L—IC_{50 add} value calculated from the equation for the lower line of additivity; ^U—IC_{50 add} value calculated from the equation for the upper line of additivity. Statistical evaluation of data was performed with unpaired t-test with Welch’s correction. * p < 0.05 and ** p < 0.01 vs. the respective IC_{50 mix} value.