Provide evidence to demonstrate the biosimilar manufacturer has established an in-house primary reference standard comparable to the reference preparation in the comparability study.

Following any subsequent significant manufacturing process changes, the sponsor must provide evidence that the post variation product is comparable to both the in-house primary reference standard and the pre-variation product.

All comparability studies done to show similarity between the biosimilar and the reference product should be in accordance with the following three guidelines:

• EMEA/CHMP/BWP/49348/2005 Guideline on Similar Biological Medicinal Products containing Biotechnology-Derived Proteins as Active Substance: Quality Issues
• CPMP/ICH/5721/03 ICH Topic Q 5 E: Comparability of Biotechnological/Biological Products Note for Guidance on Biotechnological/Biological Products Subject to Changes in their Manufacturing Process
• CHMP/BMWP/101695/2006: Guideline on Comparability of Biotechnology-Derived Medicinal Products after a change in the Manufacturing Process - Non-Clinical and Clinical Issues.

The comparability study should directly compare the reference standard and the biosimilar, preferably drug substance manufactured by a single process used to make the biosimilar product for both clinical trials and commercial distribution.

It is undesirable to change the manufacturing process during later pharmaceutical development. However, if the biosimilar manufacturing process changes significantly between clinical trial and commercial stages:

• include the reference product in the second comparability study (according to ICH Q5E) to show the clinical trial and commercial products are similar
• clearly identify such second comparability studies in the application data submitted.

The use of more than two comparability studies is not acceptable as it is not possible to make robust comparison between the reference product and batches of biosimilar material made using different or evolving processes.

Where direct comparison is not possible (e.g. if the concentration of the active substance in the reference product is too low or there are interfering excipients such as human serum albumin) then extraction or concentration techniques may be used, but these must be:

• declared in the dossier
• described in full
• validated for use.

Analytical techniques used in comparability studies

The analytical techniques should be:

• carefully selected and optimised to maximise the potential for detecting relevant differences in quality attributes
• sufficiently broad in scope to capture the full range of quality attributes. Batch release testing or testing specified in a relevant monograph is insufficient, hence additional characterisation tests should also be utilised
• intensive enough to fully investigate each physicochemical property or biological activity. Apply more than one analytical procedure to evaluate the same quality attribute (e.g. molecular weight, impurities, secondary/tertiary structures). Each method should employ different physicochemical or biological principles (i.e. orthogonal approaches) to collect data for the same parameter to maximise the likelihood of detecting any differences between the biosimilar and the reference substance.

A list of suggested techniques which may be used in comparability studies is provided in Appendix 1.