STEP® technology

Maximizing protein expression

To enable the rapid generation of stable protein or antibody expressing CHO cell lines, we have developed an affordable and complete package of services and technologies.

Our approach provides significant more product per cell compared to commercially available benchmarks.

Over the last decades, advances in cell culture technologies, media developments and expression plasmid technology have resulted in significant improvements in protein yields from mammalian cells. However, for many therapeutic proteins, the yield requires improvement and thus cell lines that are stable and have high protein expression are in demand. We deploy our STEP® technology for the rapid generation of recombinant protein expressing CHO cell lines (hormones, clotting factors, enzymes, etc) and our STEP®-mAb technology for high antibody expressing cell lines.

STEP®-mAb for monoclonal antibodies

For monoclonal antibodies, we offer a full services package including cell line generation, process development and manufacturing, marketed as STEP®-mAb. For cell line generation we use the CHO-GS expression system developed by Horizon Discovery. CHO-GS expression systems are the industry’s standard to optimize costs and accelerate production processes. They enable rapid identification of clones expressing high levels of monoclonal antibody during development of a stable cell line. The affordable and flexible licensing terms of the technology from Horizon Discovery facilitate access to this high-performance cell line to meet client demands.

A comprehensive cell line history and a clear intellectual property (IP) position ensure freedom of operation in biotherapeutic production. Over 50 commercial licenses (and many more pending) prove the success and wide acceptance of this offering. At least five successful Investigational New Drug (IND) filings have enabled clients to progress to clinical trial demonstrating regulatory compliance.

We are in the unique position to combine this proven technology with extensive experience in cell line generation and development of robust production and purification processes. Therefore, you can rely on us to take on any challenge associated with monoclonal antibody production on CHO cells.

STEP® for recombinant proteins

For recombinant proteins, we have developed a plasmid–based expression technology that allows high product yield in CHO cells. Our STEP® plasmid contains a CMV promotor that drives the transcription of a single mRNA molecule from which two proteins are translated via an internal ribosomal entry site:

  1. The protein of interest
  2. A mutated, less potent selection marker protein (Zeocin)

The Zeocin marker mutant is combined with variable sizes of upstream open reading frames that variably hamper translation resulting in an adaptably stringent cell selection system. Because a cell needs to express high amounts of zeoR in order to survive selection, that cell, by default, will also produce high amounts of the protein of interest, as the gene of interest and the zeoR gene are expressed together on the single mRNA molecule. Three different zeoR mutants allow for different levels of stringency, depending on what is optimal for the protein of interest.

To further enhance expression, two enhancer elements are cloned upstream and downstream of the expression cassette of the STEP® plasmid. The final STEP® plasmid, with minimum size enhancer elements and convenient multiple cloning sites for insertion of the gene of interest was completely synthesized under strict regulatory conditions to ensure suitability for developing pharmaceutical-grade cell lines.

STEP® technology has consistently proven to increase protein expression in CHO cells by generally more than 10-fold and taking about 12 weeks to generate stable cell clones. A highly stringent selection ensures our platform achieves extremely high protein expression levels in CHO cells without the need for gene amplification or time-consuming rounds of cell subcloning.

Process development
Preclinical manufacturing
Clinical manufacturing

Talk to our experts

Remco Spanjaard - Bioprocess expert
Remco Spanjaard

Technical Lead
+31 (0) 88 9950600

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