Primrose Bio home

Pfast™ Lead Identification and Optimization Supporting Computational Drug Discovery Technology 

Aug 24, 2026 | Case Studies

Challenge

  • AI-generated, humanized Fab from partner required production and binding assessment
  • A platform approach was requested by partner for evaluating this and future programs using this new workflow

Expression Strategy

  • Design coding sequences for diverse Fab designs to identify orientation, secretion leaders, and RBS combinations to work for three similar Fab variants
  • Workflow developed to optimize expression and purification of produced proteins in an automated 96-well scale format
  • Soluble lysate fractions analyzed by SDS-CGE (non-reduced) to verify Fab assembly
Expression strategy: 2 operon designs, 3 representative Fab sequences and 40 toolbox vectors give 288 unique expression strains in one host
Expression strategy screen: soluble Fab titer for HC-LC and LC-HC orientations of Fabv1, Fabv2 and Fabv3
Fab variant screen: ELISA fold change and Fab titer across three host strains with RBS and secretion leader combinations

Results & Takeaways

  • Soluble expression >1,000 mcg/mL for multiple Fab variants achieved.
  • 24 high-expressing Fabv1 strains (>350 mcg/mL soluble titer) enabled identification of Fab expression strategies.
  • Selected expression strategies used to screen Fab variants with soluble expression ranging to >1,000 mcg/mL.
  • Antigen binding of 48 Fab constructs confirmed by ELISA.
  • This simplified method accelerates drug discovery pipelines’ generation of humanized Fab molecules with improved antigen binding.
Discuss Your Project
#

Return to Resources