How are antibody drug conjugates or biosimilars are analyzed

How are antibody drug conjugates or biosimilars are analyzed?

Similar to small molecules, recombinant peptides or proteins such as antibody drug conjugates (ADCs), recombinant interleukins, cytokinins, and insulins, as well as recombinant human growth hormone, can be well characterized using improved established analytical approaches. 

Biologics or biological molecules such as antibody drug conjugates (ADCs), interleukins, cytokinins, growth hormones or other protein or peptide based molecules are much more complex than small-molecules. In recent years, the clinical and commercial success of biologics, especially the recombinant versions of endogenous proteins, is transforming the pharmaceutical industry. Many new drugs waiting for approval will be biologics soon. Some forecasts expect that close to 70% of new drugs may be biologics by 2025. As the earlier drugs come of patent other companies can now make copies or “generic” versions of these drugs. Unfortunately, as the biologics become bigger and more complex these analytical approaches become more challenging and difficult. Sometimes it is very difficult to prove for certain that the same biologic product produced by two different companies is actually the same molecule. Biologics that come of patent and are now produced as generics by a different company are sometimes also called "follow-on biologics" or biosimilars. Biosimilars of therapeutic proteins such as monoclonal antibodies or antibody drug conjugates are manufactured protein drugs regulated by the FDA. Commonly used analytical methods for the characterization of proteins includes methods for structure elucidation, glycan characterization, biophysical characterization, potency measurement, purity and impurity analyses. Key elements in the analysis of biosimilars entail strategies and practices that allow for method validation and method transfer. Regulatory compliance is needed at different stages of product development, the application of design of experiments (DOE) and QbD.

The design of experiments (DOE) refers to a systematic and rigorous approach to engineering problem-solving that applies principles and techniques at the data collection stage so as to ensure the generation of valid, defensible, and supportable engineering conclusions which in the case of therapeutic proteins ensures the reproducible production of these biomolecules.

• A designed manufacturing process should follow basic regulatory standards and rules.

• The knowledge and application of basic protein chemistry, such as the knowledge of the  structure, post-translational modifications (PTMs) and degradation products, is needed.

• Various protein quantitation methods can be employed, e.g. absorbance measurements at 280 nm or the Bradford method, among others.

• Gel electrophoresis and Western Blotting are basic standard biochemical analysis methods.

• Capillary electrophoresis (cZE, cIEF, CGE, iCE280, Labchip).

• Chromatography methods (RP, IEX, SEC, UPLC).

• Mass spectrometry.

• Protein structure elucidation (MS/MS, peptide mapping, AAA, and terminal sequencing may be employed).

• Glycosylation and glycan characterization.

• Biophysical characterizations (CD, FT-IR, DSC, fluorescence).

• Protein aggregation and sub visible particles (SEC-MALS, AUC, FFF, LO, MFI).

• Host cell proteins assay and host cell DNA assay (immunoassay, threshold assay, qPCR).

• Bioassay (enzymatic activity, binding and cell-based assay).

• Method validation should be performed at different stages of product development.

• Common pitfalls need to be identified during method transfers and need to be avoided.

• The application of QbD and DOE is highly recommended.
  
  
  

  Please contact BSI if you need more information regarding these methods and for all your analytical needs.