Applications of a planar electrochemiluminescence platform to support regulated studies of macromolecules: benefits and limitations in assay range.

Development and validation of ligand binding methods that can measure therapeutic antibodies (TA) accurately and precisely are essential for bioanalysis that supports regulated pharmacokinetic (PK) and toxicokinetic (TK) studies. Non-bead (planar) electrochemiluminescence (ECL) methods are known to have high sensitivity and a wide assay range and are therefore potentially useful in supporting research studies in the early phases of development as well as for diagnostic fields and multiplex biomarker applications. Here, we demonstrate the applications for using ECL for regulated studies associated with protein drug development. Three planar ECL methods were developed, validated, and implemented to quantify three different TAs to support PK/TK studies. An automated liquid handler was used for the preparation of standards, quality controls, and validation samples to minimize assay variability. Robustness and ruggedness were tested during pre-study validations. During method optimization, the potential assay ranges were 3 log orders. To improve assay accuracy and precision, assay ranges in all 3 methods were truncated by at least 50% at the upper end before proceeding to pre-study validations. All 3 methods had assay ranges of about 2 logs during pre-study validations. The inter-assay accuracy and precision during pre-study validations were <6% and 8%, respectively. The total error of the assays was <15% for both in-study and pre-study validations in all 3 methods. With the incorporation of a robotic workstation we concluded that performance in all 3 planar ECL methods was extremely precise and accurate during pre-study and in-study validations, enabling >90% assay success during sample analyses. Although there were limitations in the assay ranges, the strength of this technology in assay accuracy, precision, and reproducibility can be beneficial for macromolecule analyses in support of PK and TK studies in a regulated environment.