Table 5

Comparison of the cytotoxic activity of MR1(Fv)-PE38 with two mutants with increased affinity for EGFRvIII

IC50s are calculated from assays using different amounts of immunotoxins. The values are the means ± SD. Ps are <0.01 when comparing MR1(Fv)-PE38 with MR1-1(Fv)-PE38 and MR1(Fv)(VH S98P-T99Y)-PE38 with MR1-1(Fv)-PE38 in experiment 1 and when comparing MR1(Fv)-PE38 with MR1(Fv)(VHS98P-T99Y)-PE38 and MR1(Fv)(VH S98P-T99Y)-PE38 with MR1-1(Fv)-PE38 in experiment 2.

ImmunotoxinExperiment 1 IC50Experiment 2 IC50
MR1(Fv)-PE389.2 ± 2.16.6 ± .2
MR1(Fv)(VHS98P-T99Y)-PE386.0 ± .394.6 ± .7
MR1-1(Fv)-PE382.6 ± 6.22.0 ± 1