Background: Infliximab (IFX) is a chimeric therapeutic monoclonal antibody targeting tumor
necrosis factor alpha (TNFα)-mediated inflammatory immune diseases. However, despite of an
initial good clinical response, decrease in response to long-term treatment is a common observation.
Objective: Recent studies suggest that IFX level in circulation has a correlation with clinical bioavailability.
Therefore, the management of IFX dosage for individual manifestation by IFX monitoring may
be valuable for the improvement of therapeutic response and outcomes.
Method: In order to develop a broad IFX therapeutic monitoring in human serum, we have developed
the validated IFX bioanalysis for RemicadeTM and its biosimilar product using our nano-surface and
molecular-orientation limited proteolysis (nSMOL) technology coupled with liquid chromatographytandem
mass spectrometry (LC-MS/MS). The nSMOL chemistry has a unique property of Fabselective
proteolysis, and makes it possible a global bioanalysis for many monoclonal antibodies.
Results: The quantitation range of IFX in serum was from 0.293 to 300 μg/ml with good linearity.
Quantitation verification at the concentrations of 0.293, 0.879, 14.1 and 240 µg/ml was within 1.56-
7.53% of precision and 98.9-111% of accuracy using H-chain signature peptide SINSATHYAESVK.
Moreover, cross-verified bioanalysis of Remicade quantitation using biosimilar standard, and its opposite
combination, obtained an identical and inter-comparative results.
Conclusion: The nSMOL strategy has the potential as a practical therapeutic monitoring technology in
IFX therapeutic applications.