Table 2.
Binding characteristics of IPI anti-integrin antibodies.
| Antibody (Motif in CDR3) |
Antigen | IgG cell surface immunostaining EC50 (nM)a | IgG ectodomain SPR KD (nM)b |
IgG competition of ectodomain binding to RGD mimetic KD (nM)c |
IgG binding to ligand binding site on cell surface KD (nM) |
Fab binding to ligand binding site on cell surface KD (nM)f |
IgG inhibition of cell adhesion IC50 (nM)g |
|---|---|---|---|---|---|---|---|
| IPI-αVβ3.7 (RGD) | αVβ3 | 3.7 ± 0.1 | 0.39 ± 0.08 | 0.76 ± 0.02 | 1.09 ± 0.46d | 12.0 ± 1.8 | 42.6 ± 9.1 |
| αVβ8 | – | – | 2200 ± 800 | – | n.d. | – | |
| IPI-αVβ3.13 (RLD) | αVβ3 | 2.3 ± 0.4 | 1.2 ± 0.1 | 2.6 ± 0.9 | 1.35 ± 0.36d | 38.8 ± 5.9 | 26.6 ± 4.9 |
| IPI-αVβ5.9 (RGD) | αVβ5 | 0.76 ± 0.13 | 4.8 ± 0.4 | 2.4 ± 0.7 | 0.74 ± 0.28d | 41.9 ± 6.3 | 5.0 ± 0.1 |
| αVβ3 | – | 490.5 ± 17.2 | 1700 ± 400 | 1200 ± 400e | n.d. | – | |
| αVβ8 | – | – | – | 5200 ± 100e | n.d. | – | |
| IPI-αVβ6.3 (RGD) | αVβ6 | 5.0 ± 2.0 | 2.3 ± 0.6 | 5.5 ± 0.5 | 0.99 ± 0.20d | 50.8 ± 4.8 | 2100 ± 500 |
| αVβ8 | – | – | – | – | n.d. | – | |
| IPI-αVβ6.4 (RTD) | αVβ6 | 5.7 ± 2.9 | 10.4 ± 4.7 | 9.8 ± 2.3 | 0.73 ± 0.14d | 60.9 ± 5.8 | 7400 ± 2800 |
| αVβ8 | 7.2 ± 2.1 | 18.9 ± 7.1 | 11.3 ± 2.2 | 2.66 ± 0.41d | 131.2 ± 11.2 | 5.1 ± 1.1 | |
| αVβ1 | – | - | 2400 ± 700 | – | n.d. | – | |
| IPI-αVβ6.12 (RGD) | αVβ6 | 3.4 ± 1.6 | 2.2 ± 0.2 | 2.3 ± 0.3 | 1.08 ± 0.21d | 24.0 ± 2.3 | 1900 ± 400 |
| αVβ8 | – | 386.9 ± 34.6 | 630 ± 140 | – | n.d. | – | |
| αVβ1 | – | n.r.f. | 2800 ± 800 | – | n.d. | - | |
| αVβ3 | – | – | 2300 ± 600 | – | n.d. | – | |
| IPI-αVβ6.2 | αVβ6 | 3.4 ± 1.2 | 11.3 ± 0.5 | n.a. | n.a. | n.a. | 3700 ± 700 |
| αVβ8 | – | 172 ± 36 | n.a. | n.a. | n.a. | ||
| αVβ1 | – | n.r.f. | n.a. | n.a. | n.a. | – | |
| IPI-αVβ8.1 | αVβ8 | 2.6 ± 0.6 | 0.27 ± 0.16 | n.a. | n.a. | n.a. | – |
| IPI-αVβ8.8 | αVβ8 | 0.69 ± 0.20 | 1.6 ± 0.7 | n.a. | n.a. | n.a. | – |
| IPI-α5β1.2 | α5β1 | 0.22 ± 0.05 | 1.9 ± 0.2 | n.a. | n.a. | n.a. | - |
| IPI-α5β1.4 | α5β1 | 0.17 ± 0.06 | 4.3 ± 0.1 | n.a. | n.a. | n.a. | – |
| αVβ6 | – | n.r.f. | n.a. | n.a. | n.a. | – |
aValues are fitting value ± s.e. in Figure 2.
bValues are average ± s.d. from three independent measurements in Figure 3 and supplementary Figure S1 – S4.
cValues are fitting value ± s.e. from Figure 4.
dValues are average ± s.d. from five measurements including duplicates in Figure 5 and triplicates in Figure 6.
eValues are average ± difference from the mean from duplicate measurements in Figure 5.
fValues are average ± s.d. from triplicate measurements in Figure 6.
gValues are average ± s.d. from triplicate measurements in Figure 7.
n.a.: not applicable.
n.d.: not done.
-: no binding/inhibition.
n.r.f.: no reliable fit.