Dynamic measurements of dual targets following the administration of a bi-specific NANOBODY® molecule in cynomolgus monkey

A bioanalytical evaluation of a bi-specific NANOBODY® molecule was performed to assess toxicokinetics, immunogenicity and a dual pharmacodynamic response in a repeated dose toxicity study in cynomolgus monkeys using subcutaneous administration.


For toxicokinetic evaluation, a method detecting bi-specific active exposure of the molecule in serum was validated on the MSD (Mesoscale Discovery) platform within a range of 2.9 - 1760 ng/mL.
Immunogenicity was assessed by measuring anti-drug antibodies (ADA) in serum samples using a validated precipitation and acid dissociation (PandA) method on the MSD platform with a sensitivity of 100.0 ng/mL using an affinity purified rabbit polyclonal antibody.
For the pharmacodynamic evaluation four ligand binding methods were required for both Target 1 and Target 2, because drug tolerance and sensitivity requirements could not be met in a single method for each target. The MSD and Singulex Erenna platforms were used. For Target 1 and Target 2 the sensitive, non-drug tolerant assay displayed a sensitivity of 4 and 2 pg/mL respectively, while the less sensitive, drug tolerant assay obtained a sensitivity of 200 pg/mL for both targets.


A dose dependent exposure was observed, except in two animals in the lowest dose group where a higher ADA response was observed with a concomitant drop in exposure, and this could also be correlated to an impact on both total target concentrations. In all other monkeys, the observed immunogenicity response did not impact TK/PD.
Baseline levels of Target 2 could be measured in most of the animals while Target 1 baseline levels were below the limit of quantification (BLQ). A significant increase in concentration for both targets was observed after NANOBODY® molecule administration, providing evidence for dual target engagement. No dose dependency was observed for either target, putatively because the lowest dose of drug achieved maximum target accumulation.


Overall, the results demonstrated ""bi-active"" exposure and clear pharmacology: the bispecific NANOBODY® molecule bound to both targets thus increasing their total concentration and half-life and confirming target engagement and target occupancy. A clear correlation was observed in the results obtained for drug concentration, immunogenicity and pharmacodynamics.


Sofie Poelmans, Muriel Smet, Thomas Antoine, Abdelhak Danoun, Valentine Allemon, Bram Callens, Samuel Pine


Ablynx, a Sanofi company

Presenting author

Bram Callens, Associate Scientist, Ablynx, a Sanofi company
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