Table 2

A mixture of three anti-Her-2 F(ab′)2 fragments induces similar growth inhibition and apoptosis as the mixture of three anti-Her-2 IgGs in vitro

AntibodyIC50 × 10−8 (m)a% Annexin-V+ cellsb% PI+ cellsb,c% Total dead cells
F(ab′)2
 Mixture0.43 ± 0.32d28.0 ± 0.0331.6 ± 14.559.6 ± 7.3
 Herceptin1.3 ± 0.015.9 ± 2.912.1 ± 3.128 ± 3.0
 RFT5 (control)582.5 ± 428.32.3 ± 1.61.8 ± 1.74.1 ± 1.7
IgG1
 Mixture0.1 ± 0.0428.4 ± 0.738.2 ± 5.966.6 ± 3.3
 Herceptin0.3 ± 0.136.4 ± 2.210.0 ± 8.546.4 ± 4.3
 RFT5 (control)233.8 ± 167.80.7 ± 0.20.7 ± 0.31.4 ± 0.3
Other
 NoneNA0.6 ± 0.20.64 ± 0.121.24 ± 0.2
 NaN3e0.004 ± 0.00343.8 ± 9.049.2 ± 11.993 ± 5.3
  • a Cells (2.5 × 105 cells/ml) were incubated for 72 h at 37°C with different concentrations of anti-Her-2 monoclonal antibodies or F(ab′)2s and then pulsed with [3H]thymidine for 6 h. IC50 values represent the concentration of monoclonal antibodies required to kill 50% of cells. The difference between the IC50in each treatment group versus untreated control is statistically significant, with Ps < 0.01.

  • b Cells (2.5 × 105 cells/ml) were incubated for 4 h at 37°C with 300 μg/ml anti-Her-2 monoclonal antibodies or F(ab′)2s and then stained with annexin-V FITC plus propidium iodide (50 μg/ml) and analyzed by FACScan. The percentage of total dead cells is the sum of the percentage of annexin-V-FITC-positive plus propidium iodide-positive cells. The difference between the percentage of annexin-V-positive cells in each treatment group versus untreated control is statistically significant, with Pvalues < 0.04. The difference between the percentage of propidium iodide-positive cells in each treatment group versus untreated control is statistically significant, with Pvalues < 0.01.

  • c PI, propidium iodide; NA, not applicable (because the untreated control values were taken as 100%).

  • d SD are based on at least three experiments.

  • e Positive control.