What Are Research Biosimilars? Applications in Preclinical and Functional Studies

If you work in biopharmaceutical development, bioanalytical method development, or preclinical immunology research, you have likely encountered the term "research biosimilar" or "research-grade biosimilar." These are recombinant antibodies that replicate the amino acid sequence and binding specificity of approved therapeutic monoclonal antibodies, produced specifically for laboratory research use.

This guide explains what research biosimilars are, how they differ from clinical biosimilars, and the key applications where they provide essential value in drug development and translational research workflows.

1. What Is a Research Biosimilar?

A research biosimilar (also called a "research-grade therapeutic antibody" or "reference antibody") is a recombinant monoclonal antibody that shares the same amino acid sequence as an approved or clinical-stage therapeutic antibody, but is manufactured for research use only (RUO) — not for administration to patients.

These antibodies are expressed in mammalian cell systems (typically HEK293 or CHO), purified, and quality-tested for identity, purity, and functional activity. They provide researchers with an affordable, readily available alternative to purchasing the actual clinical drug product — which is often prohibitively expensive, difficult to obtain, or restricted in supply for laboratory research purposes.

2. Research Biosimilar vs. Clinical Biosimilar vs. Originator

For a detailed side-by-side comparison of research biosimilars and originator drugs across key parameters including purity, glycosylation, and functional equivalence, see our Research Biosimilar vs. Originator Drug guide.

3. Key Applications

3.1 PK (Pharmacokinetic) Bioanalytical Assays

In pharmacokinetic studies, researchers need to measure drug concentrations in biological samples (serum, plasma) over time. Sandwich ELISA is the standard method: the therapeutic antibody (the "drug") is captured by an anti-drug antibody and detected with a labeled secondary. Research biosimilars serve as calibration standards and quality control (QC) samples in these assays — spiked at known concentrations to build the standard curve. Using the actual clinical drug product as a standard would be cost-prohibitive for routine assay runs. For a comprehensive walkthrough of PK/ADA assay setup using research biosimilar reference standards, see our PK/ADA Bioanalytical Assay Development guide.

3.2 ADA (Anti-Drug Antibody) Assays

When patients receive therapeutic antibodies, they may develop anti-drug antibodies (ADAs) that neutralize or clear the drug. ADA assays detect and quantify these immune responses. Research biosimilars are used as positive controls to validate assay sensitivity — for example, to confirm that the bridging ELISA can detect ADAs that bind the drug molecule. They are also used to generate anti-idiotype antibodies for ADA assay development.

3.3 Functional and Preclinical Studies

Research biosimilars are used in cell-based functional assays (receptor-ligand blocking, ADCC, CDC, cell proliferation), in vivo efficacy studies in animal models, and competitive binding experiments. They provide a cost-effective way to include known-mechanism reference antibodies in head-to-head comparisons with novel candidates during drug discovery. For more on functional blocking assay design, see our Neutralization Assay Guide.

3.4 Flow Cytometry and Target Validation

Research biosimilars can serve as positive-control reagents for confirming target expression by flow cytometry. Since they replicate the binding specificity of the therapeutic antibody, they can be conjugated to fluorophores and used to verify that the target antigen (e.g., PD-L1, HER2, CD20) is expressed on the cell population of interest before proceeding with novel antibody testing. For practical guidance on flow cytometry staining protocols, see our Flow Cytometry Antibody Staining Guide.

4. Target Coverage

Research biosimilars are available for a wide range of therapeutic targets across oncology, immunology, ophthalmology, and infectious disease:

5. Practical Considerations

6. Frequently Asked Questions

Q: Is a research biosimilar the same antibody as the approved drug?

It has the same amino acid sequence (variable and constant regions) as the approved therapeutic antibody, so it binds the same target epitope with the same specificity. However, it is produced in a different manufacturing facility under non-GMP conditions, so post-translational modifications (especially glycosylation) may differ. For binding specificity, target validation, and most bioanalytical applications, it functions equivalently. For applications where exact glycosylation patterns affect function (e.g., ADCC potency), consider side-by-side comparison with the originator.

Q: Can I use a research biosimilar as a positive control in a clinical ADA assay?

Research biosimilars are commonly used as positive controls during assay development and validation phases. They can serve as the "drug" component in bridging ELISA ADA assays to verify that the assay detects ADAs that bind the therapeutic molecule. However, for formal GLP-compliant bioanalytical studies intended for regulatory submission, the positive control should be traceable to a qualified reference standard. Consult your regulatory team for guidance specific to your submission pathway.

Q: Why are research biosimilars so much cheaper than the clinical drug?

The cost difference reflects manufacturing and regulatory overhead. Clinical drugs are produced under GMP with extensive process validation, quality testing (stability, sterility, particulate), regulatory filing costs, and clinical trial expenses. Research biosimilars are produced in standard research-grade cell culture, with QC focused on identity (SDS-PAGE, SEC-HPLC), purity (> 90%), and basic functional validation. This eliminates the regulatory compliance burden that drives clinical drug pricing.

Q: Can I use a research biosimilar for in vivo animal studies?

Yes, this is one of the most common applications. Research biosimilars are routinely used in preclinical mouse models (xenograft, syngeneic tumor models) to evaluate target engagement, anti-tumor efficacy, immune modulation, or dose-response relationships. Verify endotoxin levels before injection (target < 1 EU/µg), use carrier-free formulations, and reconstitute in sterile, endotoxin-free saline or PBS. For animal welfare compliance, confirm the product is produced from an animal-origin-free process if required by your institution. For guidance on selecting isotype-matched controls for in vivo studies, see our Isotype Control Antibodies for In Vivo Research guide.

Q: How do I cite a research biosimilar in a publication?

In the Materials and Methods section, describe the research biosimilar by its functional name (e.g., "a research-grade version of pembrolizumab"), the supplier (e.g., "abinScience, catalog no. XXX"), the format (e.g., "recombinant human IgG4, HEK293-expressed"), and the lot number. State explicitly that this is a research-grade product, not the clinical drug product. This transparency helps reviewers assess the experimental context.

References

1. US FDA. Biosimilar and interchangeable biologics: more treatment choices. FDA.gov. 2024. https://www.fda.gov/consumers/consumer-updates/biosimilar-and-interchangeable-biologics-more-treatment-choices

2. Shankar G, Arkin S, Cocea L, et al. Assessment and reporting of the clinical immunogenicity of therapeutic proteins and peptides — harmonized terminology and tactical recommendations. AAPS J. 2014;16(4):658-673. doi: 10.1208/s12248-014-9599-2

3. Gorovits B, Baltrukonis DJ, Bhattacharya I, et al. Immunoassay methods used in clinical studies for the detection of anti-drug antibodies to adalimumab and infliximab. Clin Exp Immunol. 2018;192(3):348-365. doi: 10.1111/cei.13112

Research biosimilar antibodies are for research use only (RUO). Not for diagnostic or therapeutic use. For technical support, contact order@abinscience.com.