Therapeutic monoclonal antibodies (mAbs) are effective treatments for a range of cancers and other serious diseases, however mAb treatments cost on average ~$100,000 per year per patient, limiting their use....
Monoclonal antibodies (mAbs) are used extensively as
biotherapeutics
for chronic and acute conditions. Production of mAbs is lengthy and
expensive, with protein A affinity capture the most costly step, due
both to the nature of the resin and its marked reduction in binding
capacity with repeated use. Our previous studies using in situ ATR-FTIR
spectroscopy indicated that loss in protein A binding capacity is
not the result of leaching or degradation of protein A ligand, suggesting
fouling is the principal cause. Here we explore binding behavior and
resin capacity loss using Raman spectroscopy. Our data reveal a distinct
Raman spectral fingerprint for mAb bound to the protein A ligand of
MabSelect SuRe. The results show that the drop in static binding capacity
(SBC) previously observed for used protein A resin is discernible
by Raman spectroscopy in combination with partial least-squares regression.
The SBC is lowest (35.76 mg mL–1) for used inlet
resin compared to used outlet (40.17 mg mL–1) and
unused resin samples (70.35 mg mL–1). Depth profiling
by Raman spectroscopy indicates that at below saturating concentrations
(∼18 mg mL–1), binding of mAb is not homogeneous
through used resin beads with protein binding preferentially to the
outer regions of the bead, in contrast to fully homogeneous distribution
through unused control MabSelect SuRe resin beads. Analysis of the
Raman spectra indicates that one foulant is irreversibly bound mAb.
The presence of irreversibly bound mAb and host cell proteins was
confirmed by mass spectrometric analysis of used resin beads.
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