Authors
Gang Wu, Gangling Xu, Yue Zhao, Tie Gao, Yongbo Ni, Xiaolei Lv, Hongxu Chen, Meng Li, Jialiang Du, Chuanfei Yu
Published in
Applied biochemistry and biotechnology. Jul 21, 2026. Epub Jul 21, 2026.
Abstract
Loncastuximab tesirine is a cysteine-linked antibody-drug conjugate composed of an anti-CD19 monoclonal antibody linked to the PBD dimer payload SG3249 via a protease-cleavable linker, enabling targeted release of a highly cytotoxic DNA cross-linking agent. NAC-SG3249, a thiol adduct formed with N-acetylcysteine, serves as an important indicator of payload release and ADC stability. In this study, mass spectrometry techniques were employed to systematically investigate the stability and related small-molecule impurities of this ADC. Quantitative analysis of the free payload showed good linearity over 0.05-100 ng/mL (R² ≥ 0.991), with an LLOQ of 0.05 ng/mL, accuracy of 80%-120%, and precision below 5%, and the results were consistent between HRMS and TQMS, both methods can achieve effective quantification. Potential payload-related impurities were further characterized based on predicted hydrolysis pathways using targeted MRM analysis. Forced degradation studies under acidic, alkaline, photolytic, and thermal conditions revealed multiple degradation products using a highly sensitive nanoLC-HRMS method, with alkaline conditions producing the greatest number of impurities. Clinical trial number: not applicable.
PMID:
42479388
Bibliographic data and abstract were imported from PubMed on 21 Jul 2026.
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