Pfenex Expression Technology® (Pfenex) is Primrose Bio’s scalable microbial expression platform designed to deliver high-yield protein production with rapid, data-driven development cycles. Powered by Pseudomonas fluorescens, Pfenex helps teams move efficiently from construct to correctly folded protein, with expression and secretion strategies that support protein quality, productivity, and manufacturability. Six biologics using Pfenex have already received regulatory approval (FDA, WHO, EMA) and are on the market today.

Pfenex has achieved up to 20x higher yields relative to commonly used protein production systems. The platform supports a broad range of protein modalities, including VHHs, Fabs, scFvs and other antibody derivatives, peptides, enzymes, cytokines, and antigens. Pfenex is particularly well suited for antibody fragments, particularly VHHs and Fabs, where rapid iteration, high yield, efficient secretion, and early scalability are critical to advancing competitive antibody discovery and development programs.

At the core of Pfenex is a comprehensive expression toolbox shaped by more than 25 years of engineering. This includes highly efficient secretion leaders, plasmids, promoters, ribosome binding sites, and chaperones. The platform also supports site-specific incorporation of non-canonical amino acids for precise bioconjugation in novel antibodies and other proteins. Compatible with automated, high-throughput workflows, Pfenex supports efficient construction and screening of thousands of gene–vector–strain combinations.

Pfenex has delivered high titers and consistent product quality, including proteins with complex structures. In select programs, titers exceeding 30 g/L have been achieved. High-yielding strains with periplasmic release have supported cleaner downstream processing and higher purity, reducing process complexity and overall cost.

Designed with manufacturing in mind, Pfenex provides a continuous path from expression into scale-up and commercial manufacturing. For teams seeking an early read on platform fit, the Pfast™ feasibility program delivers rapid, cost-effective insights to guide development decisions before committing to full-scale process development. Together, Pfenex and Pfast support efficient, data-driven progress from expression to scale.