By Aaron Martin, Analytical Development Senior Scientist, Cytovance Biologics
Titer methods are useful at many stages during biopharmaceutical development from cell-line development to in-process control testing. Antibody-based titer methods can have the added benefit of recognizing properly folded and active forms of the biomolecule thus monitoring a critical quality attribute from bioreactor to drug substance. In this case study the Analytical Development group at Cytovance Biologics was provided an ELISA titer method and the method was redeveloped to operate by biolayer interferometry (BLI) using the ForteBio Octet RED96. The biomolecule of interest was a viral surface trimeric glycoprotein (Protein X) with a commercially available monoclonal antibody. Method development experiments involved testing antibody immobilization techniques, antibody loading conditions, standard curve and sample detection conditions. The developed BLI method was fully automated after plate preparation and approximately two times faster than the original ELISA method. The simplicity of experiment setup and analysis allowed bioreactor titer sampling to be performed by members of the upstream process development group. The method was qualified using guidance from ICH Q2R1 and has been transferred to the Quality Control group for titer testing of GMP samples.