Affinity measurements of the CD19xCD3 BiTE molecule and the CD19xCD3 DART molecule
| Protein . | CD3 interaction . | CD19 interaction . | ||||
|---|---|---|---|---|---|---|
| ka, 1/Ms . | kd, 1/s . | Kd, nM . | ka, 1/Ms . | kd, 1/s . | Kd, nM . | |
| CD19xCD3DART molecule | 3.2 × 106 | 0.4 | 125 | 1.2 × 106 | 0.8 × 10−3 | 0.7 |
| CD19xCD3BiTE molecule | 1.9 × 106 | 0.5 | 263 | 1.2 × 106 | 1.5 × 10−3 | 1.3 |
| Protein . | CD3 interaction . | CD19 interaction . | ||||
|---|---|---|---|---|---|---|
| ka, 1/Ms . | kd, 1/s . | Kd, nM . | ka, 1/Ms . | kd, 1/s . | Kd, nM . | |
| CD19xCD3DART molecule | 3.2 × 106 | 0.4 | 125 | 1.2 × 106 | 0.8 × 10−3 | 0.7 |
| CD19xCD3BiTE molecule | 1.9 × 106 | 0.5 | 263 | 1.2 × 106 | 1.5 × 10−3 | 1.3 |
Bispecific proteins at concentrations of 0, 12.5, 25, 50, 100, and 200nM were injected over immobilized antigens. Binding curves were analyzed using BIAevaluation 4.1 software. The association rate constant (ka) and the dissociation rate constant (kd) were estimated by global fitting analysis of the association/dissociation curves to the 1:1 Langmuir interaction model. Kd was calculated as Kd = kd/ka. Data are representative of at least 2 independent experiments.