Implementation and validation of dosage of a monoclonal antibody by QC-Prep®: Example of Avelumab (BAVENCIO®)
Avelumab is a human antibody specific for a protein called PD-L1, or programmed death ligand-1. This drug obtains its Marketing Authorization (MA) in metastatic Merkel cell carcinoma in the first line therapy and its preparation in the Chemotherapy Preparation Unit (CPU) may be more frequent. To ensure this procedure, an analytical control of Avelumab is implemented by using QC-Prep®.
Material and methods
QC-Prep® allows dosing and identifying the active substance, using UV spectrophotometry and Raman spectroscopy. Avelumab is packaged in a 20 mg.mL-1 concentrate vial as a ready-to-use solution. The solution is then diluted in 250 mL of 0,9 % sodium chloride infusion bag.
An automatic programmed dilution by QC-Prep® allows us to obtain a calibration curve determined by 7 concentrations in the range of 0.8 to 8 mg.mL-1. These spectrums are integrated into the specific spectral antibody libraries. Repeatability and accuracy are assessed by using 9 determinations (3 concentrations/3 replicates each). The limits of acceptability are a coefficient of variation (CV) <5%, a bias ± 10% and a recovery rate in the confidence interval.
The optimal wavelength in UV for quantification was determined at 223 nm for Avelumab by QC-Prep®. The linearity of the calibration curves in the desired concentration range is acceptable (correlation coefficient R² > 0.997). The method is reproducible and accurate, with CV <5%, biases ±10% and recovery rate in the range of 97 to 103% at the 3 desired concentrations.
The antibody library does not identify correctly Avelumab because of resemblance with the Nivolumab (in the UV and Raman spectrum). Then, the creation of specific Nivolumab and Avelumab library based on 3 "discriminant" spectral bands (in the Raman spectrum) does not improve their identification.
The dosing method is linear, reproducible, accurate and it routinely allows to quantify Avelumab. However, QC-Prep® is not specific enough to separate Avelumab from other antibodies because of their spectral resemblance (UV or Raman).
A double visual control in preparation of these drugs is however required to complete the analytical control. The arrival of numerous macromolecules with a potential spectral similarity (anti PD1 and anti PD-L1) leads us to think of ways of improvement for specific identification of these molecules.