Advances in Animal-Free Monoclonal Antibody Production

The Need for Animal-Free Antibodies

The global antibody production market size was valued at USD 16.4 billion in 2022 and is projected to reach USD 48.88 Billion by 2031, with a projected compound annual growth rate of 12.9% between 2024 to 2031. Despite their widespread use, animal-derived antibodies present challenges such as high costs, inconsistent specificity, and batch-to-batch variations (in the case of pAbs).

Ensuring antibody reproducibility when using animal antibody generation technologies is challenging due to immune response variability across different species. Using animals to make polyclonal antibodies, in particular, can produce antibodies with batch-to-batch variability, increasing the likelihood of unintended cross-reactivity. These issues can compromise the reliability and reproducibility of research findings, highlighting the need for more reliable antibody production methods.

The use of animals for antibody generation also raises ethical concerns for animal welfare. Although in vitro (animal technologies used for generating monoclonal antibodies represent a significant advancement in antibody production, it still remains underutilized in the antibody industry, with the vast majority of research and suppliers relying on animal-derived-antibody generation.

The lack of widespread adoption of animal-free antibodies can be attributed to a combination of factors, including limited awareness and understanding of non-animal techniques for antibody development and production, misconceptions regarding their quality, and limited commercial availability.

Methods of Antibody Generation: A Brief Overview

There are two types of animal-generated antibodies – polyclonal antibodies (pAb), which are extracted from the animal’s blood, and monoclonal antibodies (mAb), extracted from the animal’s spleen as B cells. Both have unique advantages and disadvantages to weigh for antibody selection.

Breakthroughs such as Behring’s antitoxins (polyclonal antibodies) and Milstein and Köhler’s hybridoma technology for monoclonal antibodies have significantly impacted various fields from medical to biomedical research. 

Hybridoma cell lines are produced by fusing antibody-producing B cells with an immortalized myeloma B cell line. Fusing these two cells together results in antibody-producing B cells that can grow in cell culture indefinitely. Although animal-derived monoclonal antibodies generally offer better batch-to-batch consistency than polyclonal antibodies, there could also be potential performance issues.

A 2018 study revealed that nearly one-third of tested hybridoma cell lines contained at least one additional heavy or light chain. This reduced the antibody’s specificity and binding specificity. Additionally, hybridoma cell lines may experience genetic drift over time, resulting in diminished antibody binding capacity or even complete loss of antibody expression.

Modern Animal-Free Alternatives: Can You Make Monoclonal Antibodies without Animals?

There are alternative methods for monoclonal antibody production that do not require animal immunization. Animal-free antibody technologies include:

•       In vitro-derived antibodies: These antibodies produced from pre-made naïve antibody phage display libraries or recombinant antibody technology avoid the need for animal immunization during their development or production.
•       Affinity reagents: Non-animal-derived antibody reagents are artificially synthesized polypeptides or oligonucleotides designed to bind to specific targets with high affinity, similar to animal-derived antibodies.

Antibody Display Libraries

Antibody display libraries allow scientists to isolate monoclonal antibodies from a library based on binding affinity and specificity to a target antigen. They are generated using alternative formats such as phage display or yeast display technologies. The isolated antibody is attached to a bacteriophage or yeast cell that contains the antibodies genetic code. That DNA code can be isolated and expressed in mammalian, yeast, or insect expression systems.

Phage display is the most mature and widely used technology to generate antibodies completely without immunization. In phage display, an antibody library is made by isolating B cells from the blood of an animal. Next, the conserved DNA segments of antibody encoding genes are amplified by PCR and cloned into the genome of a bacteria phage, bacteria viruses. 

These phages subsequently express antibodies (or antibody fragments) on the outer surface of the phage. Immobilizing the antigen of interest to a surface can capture bacteriophages that bind the target with precision and specificity. The antibody genes inside the phages that stick to the target are isolated and cloned into mammalian expression systems to validate antigen specificity.   

Numerous antibodies generated through phage display have gained regulatory approval, especially for antibody therapeutics, with many others currently undergoing clinical trials. Newer in vitro antibody selection techniques, such as yeast display or mammalian cell display, operate on a similar principle – clonal selection from extensive DNA repertoires, utilizing the antigen-binding capability of antibodies linked to the cells containing the respective encoding genes.

Recombinant Antibody Technology

The in vitro recombinant antibody generation method presents a solution for generating highly consistent antibodies across various formats, offering an unlimited supply of monoclonal antibodies. In recent years, significant progress has been made in recombinant technologies, enabling the engineering of antibodies without relying on animal immunization.

Animal-free recombinant antibodies mimic the natural immune system’s diversity by either extracting antibody genes from donor B cells or utilizing recombinant gene sequences. Subsequently, yeast or phage display techniques are used to select antibodies specific to the desired antigen, offering a more ethical and efficient alternative to traditional methods.

They produce recombinant antibodies in vitro with predetermined sequences, allowing for precise characterization and indefinite production using E. coli, insect cell lines, or mammalian expression cell lines. These expansive libraries encompass a vast antibody repertoire, enabling the generation of animal-free antibodies after the library is constructed.

In Silico Modeling: A Promising Alternative

In silicon structure-based antibody design refers to computational approaches that model most antibodies and antigens, and predict mAb properties, aiding in rational design and reducing the need for animal testing.

This animal-free antibody technology, coupled with the increasing availability of antibody sequences, paves the way for extensive in silico antibody screening. While significant progress has been made using in silico antibody design to build precision antibodies in a test tube, more technological advancement is required for future developments in this field.

Advantages of Transitioning to Animal-Free Antibody Production

Non-animal-derived antibodies offer several benefits over their animal-derived counterparts:

• Ethical: Animal-free methods eliminate the need for immunization of animals, reducing ethical concerns. In vitro methods also do not necessitate sophisticated animal housing facilities.
• Improved Affinity, Specificity, and Stability: Non-animal-derived antibodies typically exhibit high binding affinity and specificity. They can form strong bonds with their targets, making them effective in various applications.
• Faster Generation Time: Animal-free antibodies can be generated more efficiently and quickly using methods like phage display technology. This versatility allows for the production of a wide range of high-quality antibodies.
• Reduced Immunogenicity: Non-animal-derived antibodies [MM2] can be developed for therapeutic compatibility in humans, making them less likely to cause an adverse immune response (immunogenicity) when used clinically, which is crucial for safety and efficacy.
• Reproducibility: Unlike animal-derived polyclonal antibodies, non-animal-derived antibodies are highly reproducible. Their well-defined DNA sequences allow for exact replication, ensuring consistent performance in scientific experiments.
• Large-Scale Production: Unlike polyclonal antibodies, animal-free antibodies can be reliably produced in unlimited amounts, ensuring a lifetime supply with identical performance. This is essential for reproducibility in scientific research.

Challenges of Animal-Free Antibody Generation Methods

Animal-free antibodies offer a distinct advantage over their animal-derived counterparts in terms of reproducibility, owing to their precisely defined DNA sequences that enable exact replication. They exhibit more consistent binding properties compared to polyclonal antibodies and can be swiftly produced in substantial quantities within shorter timeframes. 

However, there are hurdles to overcome before scientists can unlock their widespread use.

•       Technological Hurdles: Adoption of these alternative methods may require new skills and infrastructure.
•       Availability of Alternatives: Despite the scientific merits, there’s a general lack of commercial sources and availability of non-animal-derived antibodies, so scarcity hinders their widespread adoption.
•       Cost Considerations: Initial setup costs for animal-free antibody production can be higher but are often offset by long-term benefits. Ensuring competitive pricing will encourage broader usage.

What Do the Regulators in the Antibody Production Field Say?

When it comes to the regulatory landscape, the EU has been at the forefront of promoting alternative methods to reduce and replace the use of animals in research, influencing global practices. A recent assessment conducted by the EU Reference Laboratory for alternatives to animal testing (EURL ECVAM) has recommended the use of non-animal-derived antibodies for upcoming antibody development endeavors.

The report highlights phage display technology as a legitimate approach for the animal-free creation of antibodies and outlines various strategies to facilitate the prompt transition away from animal-derived antibodies and to overcome resistance to adopting this shift, appealing to everyone from end-users and commercial providers to regulatory bodies and funding agencies.

Animal-derived-antibody generation might face strict reform in Europe in accordance with European Union policy on animal use. This directive prohibits the utilization of animals when alternative methods are available. Outside of Europe, in the United States, the National Institutes of Health (NIH) is already devising a strategy in response to the EU report and recommendation for antibody standards.

The Future of Animal-Free Antibody Generation

The shift towards animal-free monoclonal antibody production represents a transformative change in the field of antibody technology. While complete replacement of animal use still remains challenging, these advances in antibody engineering and animal-free antibody alternatives offer promising avenues to refine and reduce animal involvement in antibody production.

Researchers and antibody manufacturers around the world continue to explore innovative methods to meet ethical and scientific goals and harness the benefits of these innovative methods for both therapeutic and industrial applications. For anyone ready to join the animal-free antibody movement, ProteoGenix offers various animal-free solutions. 

From the XtenCHO ™ starter kit, which results in higher antibody production yields, better batch-to-batch consistency, and enhanced purity of custom antibody services with no animal use or species restriction, we’re paving the way for a more sustainable and effective future in antibody production.