Table 1. Combinatorial use of trastuzumab and fulvestrant (CalcuSyn).
| Cell lines | ED50 | Treatment | Concentration ratio | DRI (ED50)c | CI (ED50)d | E | ||||
|---|---|---|---|---|---|---|---|---|---|---|
| Individual drugs | Combination | |||||||||
| Tras (mg/ml) | Ful (nmol/L) | Tras (mg/ml) | Ful (nmol/L) | Tras | Ful | |||||
| ZR-75-1 | 0.65 | 45.12 | 0.17 | 16.74 | Tras:Ful | 16480.71a | 3.9 | 2.7 | 0.629<1 | S |
| BT-474 | 0.13 | 34.27 | 0.03 | 8.54 | Tras:Ful | 6592.28b | 3.8 | 4.0 | 0.513<1 | S |
DRI values indicate that the doses of trastuzumab and fulvestrant required in the combination treatment groups are much lower than those used in the individually treated groups in both cell lines. Despite the use of lower concentrations in the combination treatment group, equal effects were observed over the same period as in individually treated groups. Thus, both drugs exhibited synergistic effects when used in combination as CI<1 for both drug combinations and cell lines.
a Tras:Ful concentration ratio = 0.1(g/L)/(606.77×10×10−9)(g/L) = 16480.71.
b Tras:Ful concectration ratio = 0.02(g/L)/(606.77×5×10−9)(g/L) = 6592.28. (606.77: MW of fulvestrant.
c DRI value at the ED50 level.
d CI value at the ED50 level. Tras: Trastuzumab; Ful: Fulvestrant; E: Effect; S: Synergism.