What are Biosimilar Antibodies?

To support research on existing therapeutic antibodies, investigators benefit from having an accessible and cost-effective alternative to using prescription drugs for their basic research.  Biosimilar antibodies have identical variable sequences to FDA-approved therapeutic antibodies and can thus be used as convenient surrogates in basic research settings

How are Biosimilar Antibodies Used in Research?

Research-grade biosimilar antibodies are used to understand how therapeutic antibodies work, with the goal of designing the next generation of antibody-based biologics. Functional studies probe mechanism(s) of action of a therapeutic antibody and require a biosimilar with wildtype Fc sequence for intact effector functions. Alternatively, biosimilars can be optimized for flow cytometry by mutating the Fc region to reduce background Fc receptor binding and support investigations that examine target location and modulation. BD Biosciences offers both biosimilar versions to support these distinct avenues of investigation.

Biosimilars for Functional Studies

Some examples of functional studies using biosimilars include: 

• Mechanism-of-action (MOA) studies  
• Target cell depletion 
• Target downregulation, when used with a non-competing conjugated antibody
• Target agonistic/antagonistic signaling studies
• Combination treatment modeling
• Antigens for anti-drug antibody research or anti-idiotype antibody development 

Our wildtype biosimilar products feature:
 

• Low endotoxin levels: ≤0.01 EU/µg (≤0.001 ng/µg)
• Sodium azide-free formulation
• Specificity validation
• In vitro functional validation 

Induction of Cellular Cytotoxicity

Research-grade biosimilars enable investigators to explore various cellular processes that a given therapeutic antibody relies upon. For example, the following experiment demonstrates that Rituximab primarily uses complement-mediated cytotoxicity (CDC), while Obinutuzumab elicits direct cell death (DCD) and/or antibody-dependent cellular toxicity (ADCC).

Blockade of Key Cell Functions

A variety of therapeutic antibody effects can be modeled with sodium-azide-free, low endotoxin (NA/LE) biosimilars. Trastuzumab inhibition of breast cancer cell (SK-BR-3) growth was assessed as decrease in MTT colorimetric reading. Vedolizumab blockade of LPAM-1 integrin was determined by decrease of HUT-78 cell adhesion to MAdCAM-1. Adalimumab or infliximab blockade of TNF-α-induced cell death was demonstrated by restoration of L929 cell growth by MTT assay.  

Target Identification and Modulation

Therapeutic antibody treatment can result in downregulation of cell surface targets through various endocytic pathways. In this context, monitoring the expression of the target protein becomes critical to ensure therapeutic success. This task is challenging when using the same antibody clone for analysis as the therapeutic, or a clone that competes for binding to the same epitope. To avoid this problem, non-competing fluorochrome-conjugated antibodies have emerged as a solution to accurately measure the expression of such targets, whether in the presence or absence of a therapeutic antibody or equivalent biosimilar.

Flow Cytometry Optimized Biosimilar Antibodies

The Value of Fc-Mutated Biosimilar Antibodies in Flow Cytometry-Based Assays

Flow cytometry optimized BD Biosciences biosimilar antibodies have a point mutation (N279A) in the Fc region to prevent Fc gamma receptor binding, thereby reducing non-specific background signals and unwanted Fc-mediated effector functions.

The combination of low background staining and availability in a wide range of fluorochrome options allows BD biosimilars to be used in a diverse array of applications such as:

• Deeper phenotyping of target cell population
• FACS-based target cell sorting

• Receptor-occupancy assays
• Subcellular target localization

Reduced Background Staining in Flow Cytometry with Optimized Fc-mutated Biosimilars

Fc receptor interference can obscure the study of therapeutic antibody target specificity. Using Fc-mutated biosimilars reduces the impact of background signals, offering cleaner data on cell staining applications.

Target Identification and Subcellular Localization

Soluble proteins such as cytokines (e.g., TNF, IL-12/23, IL-1, VEGF) can also be detected intracellularly, or in membrane-bound states in some cases. Identifying membrane-bound states is critical for the success of target therapies, in which both soluble and transmembrane proteins (through cell-cell interactions) can equally trigger cellular processes. Determining which cells express membrane-bound targets is also important for predicting specific cytotoxicity.

BD Biosimilar Antibodies

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