Frequently Asked Questions
Bioanalytical Testing of Biosimilars
Initially, appropriate bioassays should be performed that demonstrate the molecule’s ability to bind to its intended target and possess the same primary mechanism of action (MOA) as the reference product. For example, the primary MOA of Humira is neutralization of TNF-alpha (TNFa), so a Humira biosimilar should fundamentally be able to first bind soluble TNFa, then subsequently neutralize TNFa’s cytotoxic effects on target cells. In this case, a Fab (antigen binding fragment) binding assay to measuring antigen binding would be recommended, followed by a neutralization assay, such as the L929 Cell Death Assay which measures the ability to neutralize TNFa’s cytotoxic effect on target L929 cells. Rituxan’s MOA is thought to be ADCC, so a Rituxan biosimilar should be able to bind CD20 at the surface of a target cell (such as Jeko-1 or Raji, both CD20+), and subsequently induce an ADCC reaction by an effector cell.
Once a biosimilar clone has been evaluated and confirmed for target binding and MOA, other follow-on Fab/Fc binding and functional assays can be employed to gain a better understanding of the other critical quality attributes (CQAs) of the biosimilar.
Relevant physicochemical analyses should also be performed in the early development stages of a biosimilar. Examples include size exclusion chromatography (SEC), isoelectric focusing (IEX), intact mass analysis, sequence analysis and several other tests which BioOutsource are currently adding the capability to support. In general, the client should eventually plan to analyse as many CQAs as possible, both structural and functional, in order to get the full picture of biosimilarity to the innovator. In general, though, this is a challenging question to answer in full and should be discussed with the client early on. Topics to address would include in-house analytical capabilities, the client’s approach to biosimilar development and characterization, the development stage of their molecule, budgetary considerations, etc.
In principle, BioOutsource should not offer an opinion on “when is enough” as it’s the primary responsibility of the sponsor to understand how to demonstrate when their biosimilar is highly comparable to the reference material. The decision on determining biosimilarity lies with the client.
Please consider the following;
- Regulatory guidelines on demonstrating biosimilarity are specifically vague; a biosimilar should be highly similar to the reference material in physicochemical and biological/functional terms. Any observed differences have to be duly justified with regard to their potential impact on safety and efficacy. A stepwise approach is normally recommended throughout the development programme, starting with comprehensive physicochemical and biological c The extent and nature of the nonclinical in vivo and clinical studies to be performed depend on the level of evidence obtained in the previous step(s) including the robustness of the physicochemical, biological and non-clinical data.
- See the following for more information; 22 May 2014 EMA/CHMP/BWP/247713/2012 Committee for Medicinal Products for Human Use (CHMP) Guideline on similar biological medicinal products containing biotechnology-derived proteins as active substance: quality issues (revision 1) http://www.ema.europa.eu/docs/en_GB/document_library/Scientific_guideline/2014/06/WC500167838.pdf
Perhaps the biggest miscalculation for the biosimilar sponsor is not doing enough analytical (physicochemical, binding and bioassays) work early on in the development programme. It’s much more difficult to get rid of a difficult or intractable problem than to replace an underperforming clone or optimise a cell line development process.
The underlying objective of a biosimilar development programme is to establish similarity with a regulatory approved reference product (or innovator), whilst also ensuring that the safety and efficacy of the biosimilar match that of the innovator. A stepwise approach following the principles established using quality by design (QbD) principles is recommended throughout the development programme using a combination of sensitive and orthogonal methods to determine not only similarities but also to identify differences in quality attributes. The primary amino acid sequence of the biosimilar should be confirmed and is expected to be identical to the innovator. Further studies must be performed to confirm physiochemical properties, purity, biological activity, immunological properties, impurity profiles and stability. The above represents considerable effort, is capital intensive and does not include clinical studies (Phase I/III), which also must be performed. It is, therefore, essential that a focused risk-based development plan be applied early in biosimilar development with key decision points identified.
It should also be noted that it is highly recommended and beneficial to fully characterize the CQAs of the innovator material, including stability, as early as possible, using material from as many distinct production batches and locales as possible.
The typical cost to develop a biosimilar is subjective and chiefly depends upon the molecule and scope of analytical testing requirements needed to show similarity. There is also a dependence upon the numbers of innovator batches required for comparative studies and commercial availability. Moreover, the complexity of monoclonal antibodies makes their development and manufacturing costs higher than for the non-monoclonal antibody biosimilars.
In general, the capital costs required to develop and bring a biosimilar to market is considerably higher than the $1 million to $4 million required in the small molecule generics market. It is estimated to take approximately 7 to 8 years to develop and commercialise a biosimilar, with cost projections in the range $100 million to $250 million.
Are your assays qualified and/or validated? What is the difference between qualification and validation?
In general, BioOutsource performs qualification studies for clients to describe a given assay’s performance metrics, such as accuracy, intermediate precision, relative potency, dilutional linearity, specificity, etc., using innovator material, while validation studies are typically specific to the client’s material, and likely of wider analytical scope. To be clear, validation is only required for those assays which will be used for Drug Substance (DS) or Drug Product (DP) lot release testing. In other words, assays only need to be validated to GMP when specified as part of the lot release package.
Yes, BioOutsource can procure innovator material, however, procurement timelines may vary depending on our supplier’s stock, and specific batch Reference Material may be harder to acquire. It’s preferred to use the client material. It’s appropriate to note that the cost of procuring innovator material is passed onto the client
Ideally, each client should have its own development and characterization approach to bioanalytical comparative studies. In general, though, more analytical testing is typically better; the more comparisons performed, the more comprehensive the data package, and the more certain the developer will likely be that any differences found will not be clinically relevant, or that any identified differences are true differences.
The BioOutsource R&D team is currently working on future molecules, such as Prolia, Simponi and Stelara, in line with market demands. However, if a client has a requirement for an assay not currently in the portfolio then we would be open to further discussions. Furthermore, we continue to support bioanalytical assay development for all of our biosimilar cell line engineering programmes.