Purpose: Bispecific antibody formats recruiting T cells as effector cells (e.g. tetravalent bispecific antibodies) are in development as biotherapeutic drugs for a variety of indications, primarily in cancer therapy. Their excellent specificity and selectivity in combination with their ability to recruit immune-effector cells to tumor tissue makes them very attractive candidates in fighting cancer.
However, T cell-based therapies have been associated with TOX profiles (e.g. potential cytokine release syndrome) which need to be carefully managed and based on their high potency, initial dosing is very low in clinical trials. In consequence, the expected drug concentrations in PK profiling are well below the technical limitations of conventional ELISA-type ligand-binding assay (LBA) support. Thus, novel assays are required to overcome these limitations.
Methods: Immuno-PCR (IPCR) based LBA technology enables highly sensitive sample analysis and a broad dynamic range, both are important for PK studies of biomolecule drugs. The PK assay for tetravalent bispecific antibodies was developed on Chimera’s IPCR platform Imperacer®. Assay development and bioanalytical method validation were conducted in consent with clinical trial support.
Results: The PK assay for tetravalent bispecific antibodies developed on Chimera’s Immuno-PCR platform Imperacer® showed +4 log units assay range from 5 pg/ml – 75,000 pg/ml and was fully validated according to bioanalytical method validation guidance documents. A special focus was laid on matrix adaptation using Chimera’s AnySource® sample dilution technology. GCP bioanalytical analyses to support clinical studies are ongoing with excellent assay performance in different hematologic patient sub-populations.
In conclusion the provided combination of broad assay range and high sensitivity is a powerful tool in PK analysis of low dosed drug concentrations.
Conclusion: Here we present assay development and method validation for support of an ultra sensitive PK assay for GCP regulated bioanalytical sample testing support. The challenge to overcome was the extreme low dosing during first-in-human studies of a highly potent T cell recruiting bispecific tetravalent antibody for the treatment of hematological malignancies.