Assessing the binding properties of the anti-PD-1 antibody landscape using label-free biosensors

Abstract

Here we describe an industry-wide collaboration aimed at assessing the binding properties of a comprehensive panel of monoclonal antibodies (mAbs) against programmed cell death protein 1 (PD-1), an important checkpoint protein in cancer immunotherapy and validated therapeutic target, with well over thirty unique mAbs either in clinical development or market-approved in the United States, the European Union or China. The binding kinetics of the PD-1/mAb interactions were measured by surface plasmon resonance (SPR) using a Carterra LSA instrument and the results were compared to data collected on a Biacore 8K. The effect of chip type on the SPR-derived binding rate constants and affinities were explored and the results compared with solution affinities from Meso Scale Discovery (MSD) and Kinetic Exclusion Assay (KinExA) experiments. When using flat chip types, the LSA and 8K platforms yielded near-identical kinetic rate and affinity constants that matched solution phase values more closely than those produced on 3D-hydrogels. Of the anti-PD-1 mAbs tested, which included a portion of those known to be in clinical development or approved, the affinities spanned from single digit picomolar to nearly 425 nM, challenging the dynamic range of our methods. The LSA instrument was also used to perform epitope binning and ligand competition studies which revealed over ten unique competitive binding profiles within this group of mAbs.

Differential Binding Kinetics for Evaluating Immune Checkpoint Inhibitors in Serum

“…Care is needed in making comparisons especially given the considerable discrepancies in the literature for the anti-PD-1 antibody binding constants, as indicated in Table 2 . 15–17 In general, it is best to compare drug-target interactions within the same platform using consistent experimental conditions.…”

Direct Comparison of Label-Free Biosensor Binding Kinetics Obtained on the Biacore 8K and the Carterra LSA

“…A recent study reported that 3D hydrogels systematically produce slower apparent on-rates ( k a values) than those on planar chips. 5 HC-30M is nearly planar as it is composed of short-hair (30 nm) unbranched polycarboxylate, compared with the Biacore CM5 chip, which is a complex branched carboxymethyl 3D hydrogel with a height of approximately 200 nm. Any differences between the two chip types were likely minimal in this study because the on-rates of the FAb interactions were relatively slow (<1 × 10 5 M −1 s −1 ), as chip type becomes more of a differentiator for binding interactions with fast on-rates that approach mass transport limitation.…”

“…6 That study (and others) also aimed to compare affinity determinations produced by solution and surface methods. 7 Other benchmark studies engaged many participants using various SPR biosensor platforms without mandating experimental protocols 8–12 to assess overall the performance of the scientific community to produce reliable affinity measurements with minimal experimental guidance.…”

Current Landscape of Immunotherapy Trials Involving the Programmed Cell Death Protein 1/Programmed Death-Ligand 1 Axis in Intrathoracic Tumors

“…Although a few drugs have novel mechanisms of action (e.g., dual targeting of PD-1/TIM-3, PD-L1/CTLA-4), these drugs largely target the same pathway. Although the unique binding properties of PD-(L)1 antibodies have been reported, 6 it is unknown whether the subtle differences in binding profiles translate into clinically meaningful differences in patient outcomes. Some studies suggest that the differences in clinical outcomes in clinical trial results between anti–PD-(L)1 agents are more likely because of trial design–related factors than differences in the mechanism of action or pharmacodynamics of the drugs.…”