Combined use of UV and MS data for ICH Stability-Indication Method: Quantification and isoforms identification of intact nivolumab

Abstract

Nivolumab (Opdivo®) is a fully human immunoglobulin G4 isotype approved for the treatment of many cancers. It acts as an immune checkpoint inhibitor by blocking the interaction between PD-1 (Programmed Cell Death Protein 1) – an inhibitory receptor expressed on activated T cells- and its ligands, PD-L1 and PD-L2. The quantification of therapeutic proteins in their medicines and pharmaceutical preparations remains challenging because the protein content, a critical quality attribute, must be rigorously calculated using a validated stability-indicating method, such as that indicated by the International Conference on Harmonization (ICH) quality guidelines, and this requires the analysis of the drug in the presence of its degraded products. In this work, we present an strategy based on the combined use of the UV and MS data to full file the requirement of the ICH-Q2(R1) to develop and validated as stability indicated a (RP)UHPLC/UV-(HESI/Orbitrap™)MS method for the quantification of nivolumab in medicinal products. A comparative study of all figures of merit of the method using UV or MS data are shown and discussed. The results show that linearity was similar for the two detectors and was established over a range of 4–45 μg/mL and 1–45 μg/mL for the UV and (HESI/Orbitrap™)MS signals, respectively. The sensitivity of the method was higher when using the (HESI/Orbitrap™)MS signal (0.2 μg/mL) than with the UV(2.0 μg/mL). However, the UV signal provided better accuracy and precision than the (HESI/Orbitrap™)MS signal, which did not meet the criteria for method robustness and system suitability. In spite of this, the MS signal plays a crucial role in this methodology by obtaining the molecular weight profile of the nivolumab isoforms, so enabling us to propose the glycans profile and detect structural modification due to degradation. The specificity of the method was evaluated by conducting forced degradation tests on samples of nivolumab in medicine form. The aim was to find out whether nivolumab suffers structural modifications when subject to stress. Structural modifications were detected by analysing the MS isoform profile, as changes of this kind promote new isoforms that are not chromatographically separated or detected by the UV signal. In this way, we demonstrated that the (RP)UHPLC/UV-(HESI/Orbitrap™)MS method was capable of detecting nivolumab degradation, and was suitable for use in nivolumab stability studies. Thus, the protein content in the daily surplus of the Opdivo® medicine, stored either at room temperature (20 °C) or refrigerated at 4 °C, could be tracked for 15 days.