Enzolytics Inc (ENZC)

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How humanizing mAbs has led to better drugs


Antibodies from human cells

Single B cell antibody technologies use the robust response of the human immune system to generate fully human mAbs. These methods only require a few cells, which can be rapidly and efficiently isolated from either peripheral blood mononuclear cells (PBMCs) or lymphoid tissues. Fluorescence-activated cell sorting is widely utilized to identify specific B cells based on their expression of cell surface markers, and a process called antigen baiting using antigen-coated magnetic beads and fluorescence-conjugated antigens is used to select antigen-specific cells.

After single B cells are isolated, expressed immunoglobulin transcripts are amplified using reverse transcription polymerase chain reaction (RT-PCR), and then cloned and expressed in mammalian cell lines.
Single B cell isolation and cloning can be used to rapidly develop immunotherapies for infectious diseases. Human mAbs have been generated by the single B cell method for bacterial, parasitic, viral, and autoimmune diseases.
Choice of cell line impacts transition from development to production


Therapeutic mAbs require a mammalian expression system that provides the cell machinery required to glycosylate, fold, orient, and covalently bind antibody peptide chains to produce the complete, biologically functional molecule. Lower organism expression platforms can be used if the product is a mAb fragment or where glycosylation is simpler, or not required.

Antibody genes of interest are introduced into a suitable expression vector and transfected into cell lines for antibody expression and secretion. Expression vectors are designed to maximize mAb expression and ensure cell line stabilization through host cell codon optimization and the addition of highly efficient transcription, secretion, selection, and integration elements.

Chinese hamster ovary (CHO) cells are a popular host for producing therapeutic mAbs as they are suited to high-yield production of recombinant proteins and are good at performing the post-translational modifications required to produce the correct high-level conformation of an active mAb.

Mammalian cell lines have been adapted to suspension culture and engineered for enhanced functions (e.g., introducing glycosylation pathways and resistance to apoptosis). These newer cell lines support high cell densities and product high mAb titers, so are suitable for production in large scale-fed batches, perfusion systems, or continuous culture techniques. Commercially developed CHO cell lines with enhanced stability are used in many current mAb therapeutic expression platforms.

The ability to produce transient CHO-derived mAbs early during biotherapeutic development is highly desirable, as products will closely mimic the final CQAs of the mAb when manufactured at bioproduction scales.

The future of therapeutic monoclonal antibodies
As our understanding of the molecular mechanisms underlying disease grows, opportunities for the development of new mAb-based drugs increase. In the last decade the focus has been on producing mAbs for cancer immunotherapy, inflammatory diseases, and autoimmune diseases, but they are becoming increasingly important in treatments and prophylaxis for infectious diseases such as fungal diseases, Ebola, and the novel coronavirus SARS-CoV-2. In the future, mAbs could be used to target multidrug-resistant pathogens and may help prevent the emergence of antimicrobial resistance.

The therapeutic antibody field is also exploring the use of new modality antibodies such as bispecific and trispecific antibodies that recognize multiple epitopes on the same antigen, single-domain antibodies that can more easily penetrate tissues, and antibody–drug conjugates for targeting chemotherapy agents to specific cell types. Some bispecific antibodies and antibody–drug conjugates are already on the market, with several more in development.
One thing is certain, therapeutic monoclonal antibodies are going to continue to increase in importance for many years to come.
https://www.thermofisher.com/us/en/home/biotech-lab-solutions/biotech-learning-center/monoclonal-antibodies-therapeutics.html