TABLE 1.

Combination index at IC₅₀ in malignant glioma cells

Six established human glioma cell lines were exposed to varying concentrations of SAHA and vandetanib at a fixed molar ratio (1:10) for 3 days. Live cell numbers at the end of treatment were quantified with MTS reagents. The data were then used to calculate the combination index (CI) by use of commercially available software (Calcusyn; Biosoft), which provides a semiquantitative assessment of the presence of additive, synergistic, or antagonistic interactions at different effect levels. The CI is substantially less than 1 for the combination of SAHA and vandetanib, indicating synergistic interactions. Data are the average of three independent experiments with triplicate samples.

Cell Line	CI
U87	0.465 ± 0.039
T98G	0.614 ± 0.041
A172	0.621 ± 0.028
U373	0.407 ± 0.011
LNZ308	0.421 ± 0.031
LNZ428	0.443 ± 0.024