Rapid Affinity Maturation of Novel Anti-PD-L1 Antibodies by a Fast Drop of the Antigen Concentration and FACS Selection of Yeast Libraries

Figure 4

SPR binding analyses of mono- and bivalent complexes between rhPD-L1 and anti-PD-L1 IgGs. (a–g) Monovalent complexes: sensorgrams of multicycle kinetics, representative of monomeric rhPD-L1-his monovalent binding to anti-PD-L1 IgGs (colored curves), are superimposed on the calculated curves (black), fitted to the 1 : 1 Langmuir binding model. IgGs were captured (about 200 RU) onto the CM5-protein A chip, and binding of monomeric rhPD-L1-his to IgGs was analyzed by twofold serial dilution injections of rhPD-L1-his as follows: 500–15.62 nM (a) and 250–7.81 nM (b–g). (h–n) Bivalent complexes: sensorgrams of multicycle kinetics, representative of anti-PD-L1 IgGs binding to dimeric rhPD-L1-Fc (colored curves), are superimposed on the calculated curves (black), fitted to the 1 : 1 Langmuir binding model. Dimeric rhPD-L1-Fc was immobilized onto the CM5 chip by amine coupling chemistry, and binding of IgGs to rhPD-L1-Fc was analyzed by twofold serial dilution injections of IgGs as follows: 12.5–0.39 nM (h) and 6.25–0.39 nM (i–n).

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