Need to screen or characterize an antibody? Get 1 mg of recombinant antibody in 4 weeks to use in antibody screening, characterization, preclinical studies, and any other small-scale applications. Our proprietary mammalian expression system – XtenCHO™ – is the market’s leader in transient monoclonal antibody production. With proven ability to perform proper antibody folding and glycosylation, XtenCHO™ outperforms even the most competitive commercial solutions like ExpiCHO™. Partner with us to improve your production yields and access our wide range of lead optimization and production scale up services.

Our process of recombinant
antibody production

Monoclonal antibody sequencing

  • Full-length or variable region sequencing

Hybridoma sequencing

  • RNA isolation
  • cDNA synthesis
  • Amplification of antibody genes

De novo antibody protein sequencing

  • Enzymatic digestion
  • LC-MS/MS separation
  • De novo peptide sequencing

Monoclonal antibody sequencing

  • Full-length or variable region sequencing

Gene synthesis and cloning

  • Gene synthesis with codon optimization for the selected expression system
  • Subcloning into a high expression vector


  • Plasmid amplification an preparation
  • Co-transfection of target cells

Transient expression

  • Small-scale expression of the antibody
  • Antibody purification and QC analysis

Advanced services


Affinity (KD)


Stable Production
proprietary GS-…

Step Content Timeline Deliverables
Monoclonal antibody sequencing From hybridoma cell lines:
  • Hybridoma cell line provided by customer
  • RNA extraction and purification
  • Reverse transcription
  • cDNA amplification
  • Sequencing analysis
From purified antibody samples:
  • Antibody sample provided by customer
  • Enzymatic digestion of the antibody
  • LC-MS/MS separation
  • De novo peptide sequencing
  • Assembly of overlapping peptides
  • Data analysis
2 to 3 weeks for variable region & leader sequence
3 to 4 weeks for full length antibody
  • Detailed report
  • Antibody sequence
Gene synthesis and cloning
  • Gene synthesis
  • Codons optimization for Mammalian expression system
  • Subcloning into an expression vector
  • Test of two expression systems
  • Antigen production
2 to 3 weeks
  • Synthetic genes cloned into pUC57 plasmid
  • Certificate of analysis (CoA)
Monoclonal antibody production +purification
  • Plasmid amplification and preparation
  • Co-Transfection of target cells
  • Transient expression and purification
  • QC analysis (SDS-PAGE / UV280)
  • Antigen production
Starting from 3 to 4 weeks
  • Detailed report
  • Purified antibody

Options available (non exhaustive list):

  • Expression in alternative recombinant systems (bacterial, yeast, insect cells…)
  • Additional purification steps (IEX, SEC…)
  • Endotoxin assay and removal
  • Aggregate analysis : SEC-HPLC
  • KD determination : SPR (Biacore), SPRi (XelPlex), Octet Red96
  • Stability analysis : differential scanning calorimetry, IR

XtenCHO™: The gold standard expression system for transient monoclonal antibody production

Fast antibody production at competitive prices? XtenCHO™ makes it possible.

Thanks to our in-house Xten transfection protocol, proprietary cell line XtenCHO™, 28+ years of experience in recombinant production, and over 500 successful antibody production projects, we have the market’s most competitive solution.

With production yields consistently exceeding even those of ExpiCHO™, we are equipped to overcome your unique antibody expression challenges while keeping production costs low.

Here are some examples of the incredible results obtained in the transient expression of biosimilars.

For more detailed results about the use of XtenCHO™ for recombinant antibody production, discover other unbelievable results by downloading our poster or watching Dr. Marcelo Viegas presentation made at the Festival of Biologics (2020).

Case study: Pembrolizumab recombinant antibody production

Aim Of The Study

Here, we showcase the recombinant antibody production of Pembrolizumab using our proprietary Xten expression system.

Genes And Expression Vectors

The genes coding for the Heavy chain (HC) and the light chain (LC) of the therapeutic antibody Pembrolizumab were chemically synthesized with optimizations for expression in CHO cells. The genes were cloned in ProteoGenix’s proprietary mammalian cells expression vector pTXs1. The vector map is provided in the PDF report.

Small-scale Monoclonal Antibody Production And Purification Tests

An endotoxin-free DNA preparation was done for the pTXs1 expression constructions. By using the proprietary Xten transfection protocol, the plasmids were then transiently transfected in the proprietary XtenCHOTM cells.

Culture medium was collected and production yield was determined by Octet Red analysis. The recombinant antibody was then purified by affinity vs. protein G.

Recombinant antibody production QC

QC of the purified Pembrolizumab. Coomassie blue staining.
A. Non-reduced SDS-PAGE. B. Reduced SDS-PAGE.

Antibody Production Yield Purity
Pembrolizumab 235mg/L >95%

What are the benefits of
recombinant antibody production?

Recombinant antibody production has been a major breakthrough in the therapeutic antibody development context as it leads to several advantages over “traditional” antibody production in hybridoma cell lines.

1. Optimal reproducibility, control and security

Monoclonal antibody production for therapeutic applications requires high control and reproducibility. Because crucial parameters such as DNA and protein sequence are chemically defined, recombinant antibody production allows creating a standardized process for monoclonal antibody production with very low batch-to-batch variations. As recombinant antibody production starts from a known antibody or DNA sequence, mutations or cell-line drift that can occur in hybridoma cell lines are also obviated.

2. High purity

Recombinant antibody production leads to high purity grade due to the absence of serum contaminants.

3. Ease of engineering and reformatting

Recombinant monoclonal antibody production allows getting access to the control of the antibody structure at the genetic level. This is particularly important when it comes to therapeutic antibody development as it permits to modulate the pharmacological properties of an antibody.

The possibility to modify the gene that will further be expressed by a selected expression system gives also access to an infinite range of solutions in terms of:

  1. Reformatting: species, isotype or subtype switching
  2. Antibody engineering: monoclonal antibody humanization, affinity maturation, bispecific antibody, antibody drug conjugates (ADC), antibody fragments (Fab, Fab2, scFv).

4. No animal use

Today, more and more attention is dedicated to ethics and animal welfare. Thanks to recombinant production technology, the antibodies can be quickly produced without relying on animal use in any step of the process.

Transient or stable? Which recombinant antibody
production service should you choose?

Choosing the most appropriate solution for your monoclonal antibody production can have a major impact on your project, for instance in terms of time. For this reason, we put at your disposal this short section explaining how to decide between transient or stable antibody expression.

Recombinant antibody production offers a main advantage: it allows rapid production of a relatively large amount of antibody. However, in transient transfection, the transfected gene does not integrate the host genome and can be lost in several days (over a short time period, several days). Thus, it can be the perfect solution for short-term applications such as small-scale protein expression.

Stable cell line generation is related to the integration of a synthetic gene into the host genome of the expression system. As it can be a long and complicated development process (>3 months), stable cell lines are privileged for long-term applications such as therapeutic antibody production. For large scale bioproduction, stable cell line allows to construct a standardized process which guarantees higher yield and quality control.

For any additional question, please feel free to contact our PhD account manager who will be glad to guide you toward the most suitable antibody production solution.

What are the applications of transient antibody expression?

Transient antibody expression in mammalian systems is useful for many applications. These systems combine proper protein folding and post-translational modification with short lead times making them invaluable for:

  • Screening of drug candidates: transient expression allows the production of defined quantities of antibodies in systems very similar to those used for commercial biopharmaceutical production. In this way, transient production allows a preliminary characterization of these molecules as well as the detection of potential production hurdles exponentially increasing antibody developability.
  • Antibody variant screening: antibody variants are frequently produced in an attempt to improve certain biophysical properties of antibodies including affinity and stability. Variants are also produced during the process of antibody humanization. In this case, the small scale production of several variants helps selecting the best candidates for further development.
  • Small scale production for analytical applications: these systems allow the quick production of antibodies or fragments thereof in many different formats. Given that mammalian systems efficiently secrete these molecules to the culture media, they can be purified using inexpensive methods such as protein A/G purification. These highly pure antibody batches can be easily conjugated with enzymatic or fluorescent tags for research or diagnostic applications.

Recombinant antibody production: cells and approaches

Mammalian expression systems based on Chinese hamster ovary (CHO) or Human embryonic kidney (HEK) cells are the industry’s most robust solutions for recombinant antibody expression.

Their ability to perform human-like glycosylation (crucial to reduce immunogenicity of antibodies), proper protein folding and their efficient secretory pathways, makes the process ideal for therapeutic applications. Cell used for antibody production must be able to maintain a high productivity and batch-to-batch consistency. All these criteria are met by our proprietary cell line XtenCHO™.

Our vast expertise in producing antibodies in CHO and HEK systems is also complemented by our 28+ years of experience in protein production in a number of systems including bacterial, yeast, and insect cells.

The use of these systems for recombinant antibody expression continues to grow in popularity due to the growing demand for solutions with lower costs and shorter lead times. Although XtenCHO™ remains our gold standard for antibody production, we are also able to produce full-length or antibody fragments in all these alternative systems.

What are the advantages and limitations of these alternatives in comparison to mammalian production systems?

Mammalian systems Bacterial systems Yeast systems
  • Proper protein folding
  • Human-like glycosylation
  • Extracellular production – easier purification
  • High batch-to-batch consistency
  • High purity
  • High production yields meeting important quality standards
  • Adapted to any antibody format including full-length, antibody fragments, or antibody conjugates…
  • High production yields
  • Shorter lead times (in comparison to mammalian cells)
  • Advantageous for antibody fragment production (scFv, Fab, VHH)
  • Ease of genetic manipulation
  • No stable integration required for large-scale production
  • Ease of scaling up production
  • Extracellular production – easier purification
  • Ease of genetic manipulation
  • High production yield
  • Shorter lead times (in comparison to mammalian cells)
  • Post-translational modifications (but not human-like glycosylation)
  • No stable integration required for large-scale production
  • Ease of scaling up production
  • Longer lead times
  • Time-consuming and laborious when creating stable cell lines
  • Cell lines harder to engineer
  • No post-translational modifications
  • Intracellular production – harsher purification methods required
  • Risks of forming inclusion bodies
  • Contamination with endotoxins
  • Moderate risk of plasmid loss even in selective conditions
  • Inability to perform human-like glycosylation without extensive engineering

    Which system should you choose for the recombinant expression of your antibody?

    Each project is evaluated on a case by case basis thus we are always able to propose the best solution according to the structure of your antibody, intended application, available budget and timeline, and scale of production.

    Learn more about our protein expression services in:


    Discover our protein expression service in Escherichia coli or Bacillus subtilis and benefit from short lead time and high productivity


    Learn more about our protein production protocols in Saccharomyces cerevisiae or Pichia pastoris for optimal production and process scalability

    Insect cells

    Produce your protein leads in baculovirus/insect cells for improved protein folding and accurate post-translational modifications

    Monoclonal antibody production
    from gene to bioproduction

    The successful production of recombinant antibodies starts with a careful optimization of genes, vectors, and transfection protocols. These apparently inconsequential details represent one of the most important antibody production steps of the process. All these parameters must be compatible with the requirements of the cells used for antibody production.

    Access our page dedicated to the most frequently asked questions (FAQs) about recombinant antibodies, to learn more about all stages of the production process as well as ProteoGenix’s recommendations to help you achieve high and consistent levels of production in your project.

    ProteoGenix has guided thousands of researchers throughout their monoclonal antibody production projects since 2003. As a one-stop solution provider, we master the whole antibody development process from antibody generation by hybridoma development or antibody phage display to recombinant antibody production in XtenCHOTM and stable cell line generation. Trusting ProteoGenix, a monoclonal antibody production leader, is a guarantee to take your project to next level!