11/06/2025

Challenges in the determination of a peptibody at low pg/mL concentrations

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The therapeutic use of biologically active peptides linked to the Fc domain of an IgG, also known as peptibodies, is an innovative and promising field, as the chimeric protein boosts the half-life and stability of the peptide whilst keeping their biological properties. However, peptibodies present several concerns, such as predicting their stability which depends, within others, on the production method and truncation, which makes ligand binding bioanalysis particularly challenging. For this reason, the detection of these molecules requires greater sensitivity, together with good accuracy and precision results, and good selectivity and specificity performance.

The poster we presented at the 11th EBF Young Scientist Symposium (please see below for your reference) highlights the main challenges encountered during the development and validation of an analytical method for the determination of a peptibody by electrochemiluminescence immunoassay (ECLIA, required sensitivity 15 - 20 pg/mL), and describes the approaches implemented to overcome them.

The presence of non-specific interactions resulting in a variable background signal between individual matrices, a low recovery in quality controls at CMAX when diluted in matrix and a high variability in accuracy of quality controls at low pg/mL concentrations were some of the challenges tackled within the development of the assay. After testing several assay buffer compositions, changing the biological matrix, using low-bind material for handling and storage the samples and performing some method re-adjustments, these issues were overcome and the method was validated successfully.

Get in touch with our team to discuss your upcoming bioanalytical requirements — we will be happy to support you in moving your project forward.