It is prudent to adopt a stepwise approach, starting with an evaluation of publicly available information pertaining to the reference product which, together with prior knowledge, is used to establish a preliminary Quality Target Product Profile (QTPP) and define the expected Critical Quality Attributes (CQAs). Early stage formats of analytical methodologies can then be employed to characterise a small range of relevant reference product lots and define the anticipated target range for the CQAs which will guide the development of the manufacturing process. Comparative head-to-head analytical similarity studies of increasing complexity are conducted as the program progress, employing more comprehensive, robust and qualified methods. The capacity and sensitivity of these methods to identify potential differences between the biosimilar candidate and reference product is critical and must be formally demonstrated. 

Your goal is to demonstrate no clinically meaningful differences between your biosimilar candidate and its reference product. Some differences are to be expected, and when these are unrelated to the clinically inactive components, the potential impact to safety, purity and potency must be investigated through additional characterisation studies.

Our experience in biosimilars

A successful biosimilar development program requires key decisions to be made at the right time. You need a partner with experience and knowledge of biosimilar assay design and effective study approaches who has contributed to successful biosimilar programmes to help you navigate the requirements of the regulatory authorities. We can help you plan your studies in an efficient, cost-effective manner, pre-empting regulatory questions, and establishing and running fit for purpose assay solutions. 

With a global biosimilar customer base, we support the overarching analytical similarity design and practical delivery of data, providing industry leading expertise in the functional characterisation of biosimilar antibodies. We aid definition of anticipated CQAs, selection of appropriate and relevant methods at the right time to support the definition of reference product characteristics and analytical similarity studies alike. We offer a range of advanced off-the-shelf methods, generic platform approaches with custom development capabilities that employ advanced instrumentation. Our portfolio includes solutions to support developers to determine the clinical significance of any observed differences between their candidates and the reference product with a range of investigatory approaches. 

We have extensive experience in characterising biosimilar antibodies, with biosimilar packages and the continual expansion of our method portfolio through internal investment in research and development of new approaches. 

Our current characterisation packages include:

Get in touch with us to discuss how we can accelerate your biosimilar program. 

Our tools and approaches to guarantee success 

Enabled by our significant investment in Research & Development, we have created unique, innovative solutions for biosimilar antibody characterisation. Our laboratory services are underpinned by years of experience of running complex, multicellular assays to facilitate early discovery through to the development of regulatory potency assays, with everything in between. 

Engineered cells:We have leveraged our comprehensive cell line development capabilities to create a range of proprietary cell lines that form the basis of our off-the-shelf platform methodologies. Antibody effector function studies benefit from our range of target cell lines over-expressing the antigen (target) of interest together with a control antigen; confirming the mechanism under test by demonstrating cell line susceptibility. We can couple this with our CD16a or CD32a-expressing reporter cell lines, which can be used as an alternative effector cell preparation to primary cells when needed. 

Primary effector cells:We have invested heavily to establish processes that deliver reliable human donor material to ensure consistency in performance across all of our assay formats employing primary cells, particularly effector function assessments. We stock thousands of donor vials, including CD16a/CD32a genotyped donors. We can provide access to recallable donors and can reserve significant quantities of the donors that perform best in your studies, allowing consistency of performance over many years. 

Expert bioassay design:Our experience of developing potency assays for product release allows us to develop bioassays with an understanding of the levels of control that are required for high-performing, reliable, consistent assays that will be employed for late phase characterisation studies. Assays can be conducted in 384-well formats allowing complex plate maps with high levels of replication to be employed that minimise and manage assay bias and random variability to deliver exceptional assay performance. Stage appropriate qualification studies can be conducted which focus both upon standard method attributes as well as factors known to influence biological activity. Studies are conducted under defined protocols with specific analytical procedures that are prepared for individual methods. Results are summarised in comprehensive Study reports.

Functional characterisation approaches

Analytical similarity requirements are now comprehensively defined by both the EMA and FDA together with many publicly available case studies that exist in the form of approved biosimilar drugs. From these, the complexity of conducting functional characterisation for biosimilar antibodies is evident. A risk assessment should be conducted that evaluates each of the potential multiple mechanisms of action (MMOAs) to determine which are the most likely to have a clinical effect. From this an appropriate testing strategy can be devised, specific to the biosimilar molecule in question. The strategy will be updated once structural information is available regarding potential differences between the biosimilar candidate and the reference product. Critical to method selection is the application of orthogonal methods and knowledge of method sensitivity to specific structural attributes, such as Fc glycans or aggregation. 

Our portfolio of assays can be considered from the perspectives of target binding, standard bioassays, complex bioassays, Fc binding assays and effector function assays.

Biosimilar assay portfolio 

1. Target binding 

We have established a range of platform methods, together with off-the-shelf solutions to evaluate binding to recombinant proteins and cells. Kinetic assessments that deliver affinity measurements using the Biacore 8K+ is our approach of choice for characterisation of target binding and can be supplemented using flow cytometry or plate-based assessments using target-expressing cell lines, where scientifically relevant. 

2. Standard bioassays 

These employ the use of continuous or engineered continuous cell lines and are generally applied to evaluate the primary mechanism of action of an antibody. As such, they can play the most important role of all functionality assessments, providing a direct measure of biological activity, and frequently form the basis of the lot release method. Due to the importance of these methods, it is essential that high quality assay formats are developed in which critical materials are controlled; robust system suitability controls are implemented, and comprehensive qualification studies undertaken. Standard bioassays may also function as specificity assessments, confirming binding where the target antigen exists within different molecules or showing a lack of binding to related proteins. 

Our range of standard bioassays are conducted using plate-based endpoints, xCELLigence, flow cytometry or multiplex cytokine systems. 

3. Complex bioassays 

The need for the application of complex bioassays is increasing, particularly as attention turns towards checkpoint inhibitors and other immune system modulators. We have established a range of primary immune cell platform approaches underpinned by our fundamental understanding of immunology, bioanalytical method design and our control of primary cell sources. These assay formats model specific aspects of immune system biology and can employ a combination of multiple primary immune cell types, including PBMCs, T cells, regulatory T cells, monocytes, dendritic cells, NK cells and polarised macrophages (M0, M1, M2a, M2b, M2c, M2d, TAMs). Optimum performance that delivers consistent assays with appropriate response levels is delivered by our donor screening programmes. Assay examples include one-way and two-way MLRs, defined T cell activation formats, suppression assays and antigen recall assays. 

4. Fcγ Receptor, FcRn and C1q target binding

We offer an advanced solution to characterising Fc-Fcγ receptor (FcγR) interactions which delivers exceptional assay performance for the full panel of human Fcγ receptors and FcRn in a high throughput manner. Assay performance is delivered using high quality FcγRs and FcRn, produced in house, in quantities that allow our unique inverse orientation assay design, capturing test antibodies in the first step of the assay. This approach improves assay performance, acting as a sample clean-up step. This eliminates any issues associated with formulation differences between the proposed biosimilar and reference product.

5. Effector function bioassays 

We have invested significantly in establishing a comprehensive portfolio of approaches to characterise the presence or absence of effector function activity across different biosimilar molecules. We have conducted analytical similarity studies to assess ADCC activity, CDC activity, ADCP activity and trogocytosis. All available in formats that deliver differing levels of sensitivity, applying a variety of effector cell preparations that differ in their ability to yield biological relevance or sensitivity to the method. 

We conduct ADCC assessments using proprietary target cell lines, engineered to contain an endogenous reporter. Specific measurement of this reporter facilitates the use of frozen effector cells, as interference from cell death signals from the effector preparation is eliminated. The same target cell lines can be used for CDC, ADCP and trogocytosis assessments. In each of the formats, we use characterised and genotyped effector preparations with the potential to test hundreds of samples using cells from the same donor. ADCC assays can be conducted using PBMCs, enriched NK cells, whole blood or CD16a/CD32a reporter systems. ADCP and trogocytosis assays can employ monocytes or a range of polarised macrophages, depending upon the specific requirements of an individual project.