Table 1.
Characteristics of bsAbs used in this study
| Description | Ab code | Clone CD3-arm | Clone HER2-arm | kD CD3 (nM)* | Apparent affinity EC50 HER2 (nM)** | kD HER2 (nM)*** |
|---|---|---|---|---|---|---|
| bsAb CD3wt × HER2Herceptin | BisG1-huCACAO-FEAL/Herceptin-FEAR | huCACAO | Herceptin | 15 | 5.7 | 0.1 |
| bsAb CD3wt × HER2LbD2 | BisG1-huCACAO-FEAL/Herceptin-FEAR LbD2 | huCACAO | LbD2 | 15 | 100 | |
| bsAb CD3wt × HER2153 | BisG1-huCACAO-FEAL/153-FEAR | huCACAO | 153 | 15 | 4.2 | |
| bsAb CD3wt × HER2169 | BisG1-huCACAO-FEAL/169-FEAR | huCACAO | 169 | 15 | 6.1 | |
| bsAb CD3wt × ctrl | BisG1-huCACAO-FEAL/b12-FEAR | huCACAO | b12 | 15 | N.A. | |
| bsAb CD3Low × HER2Herceptin | BisG1-huCACAO-H101G-FEAL/Herceptin-FEAR | huCACAO-H101G | Herceptin | 310 | 5.7 | 0.1 |
| bsAb CD3Low × HER2LbD2 | BisG1-huCACAO-H101G-FEAL/Herceptin-FEAR LbD2 | huCACAO-H101G | LbD2 | 310 | 100 | |
| bsAb CD3Low × HER2153 | BisG1-huCACAO-H101G-FEAL/153-FEAR | huCACAO-H101G | 153 | 310 | 4.2 | |
| bsAb CD3Low × HER2169 | BisG1-huCACAO-H101G-FEAL/169-FEAR | huCACAO-H101G | 169 | 310 | 6.1 | |
| bsAb CD3Low × ctrl | BisG1-huCACAO-H101G-FEAL/b12-FEAR | huCACAO-H101G | b12 | 310 | N.A. | |
| bsAb ctrl × HER2Herceptin | BisG1-b12-FEAL/Herceptin-FEAR | b12 | Herceptin | N.A. | 5.7 | 0.1 |
| bsAb ctrl × HER2LbD2 | BisG1-b12-FEAL/Herceptin-FEAR LbD2 | b12 | LbD2 | N.A. | 100 | |
| bsAb ctrl × HER2153 | BisG1-b12-FEAL/153-FEAR | b12 | 153 | N.A. | 4.2 | |
| bsAb ctrl × HER2169 | BisG1-b12-FEAL/169-FEAR | b12 | 169 | N.A. | 6.1 |
Wt high affinity binding to CD3, low low affinity binding to CD3, ctrl non-binding arm using HIV-1 gp120-specific mAb IgG1-b12, Herceptin interaction with HER2 at Herceptin epitope, LbD2 low affinity interaction with HER2 at Herceptin epitope due to light chain bD2 mutation, 153 high affinity interaction with membrane distal HER2 epitope “153”, 169 high affinity interaction with membrane proximal HER2 epitope “169”, N.A. not applicable, FEAL L234F, L235E, D265A Fc-inert with F405L mutations, FEAR L234F, L235E, D265A Fc-inert with K409R mutations.
*kD values for WT CD3 arm described in patent WO-2017/009442 and for H101G mutant in ref. 59.
**kD values for Herceptin and LbD2 mutant arms determined in ref. 60.
***Apparent affinities determined in house.