Maximizing In Vivo Target Clearance by Design of pH-dependent Target Binding Antibodies with Altered Affinity to FcR

Yang D, et al., 9(7):1105-1117, MAbs, 2017

Reported herein is the identification of a series of mouse-derived high affinity antibodies with pH-dependent target binding characteristics against two soluble antigens. Studies carried out in cynomolgus (cyno) monkeys demonstrate that the accumulation of total antigen in plasma can be reduced by increasing the affinity of antibodies to FcRn at neutral or acidic pH. Binding affinities of mAbs to FcRn (human and cyno) at pH 7.4 and pH 6.0 were analyzed by using Bio-Layer Interferometry (BLI). A Pall ForetBio Octet RED384 system equipped with Anti-Human Fab-CH1 Biosensor probes was used to perform all BLI experiments. Sensor tips were immobilized with mAbs. Subsequently, mAb loaded sensor tips were dipped into microplate wells containing human or cyno FcRn at pH 7.4 and pH 6.0. The sensor tips were regenerated with glycine (pH 1.5) after each binding cycle. Tighter binding interactions were fitted using a 1:1 Langmuir kinetic model, while Equilibrium binding analysis (steady-state analysis) was performed on the weaker interactions. The KD values were generated for each antibody Fc variant that represent binding affinities of the mAb and FcRn at pH 7.4 and pH 6.0. Overall results of this investigation provide guidance for optimal selection, design, and evaluation of sweeping antibodies.

Read More