26th February 2019

Unlike chemically synthesised small molecule pharmaceuticals, biopharmaceuticals are a new generation of protein-based medicines. These biologics are usually protected by patents but as those patents expire the door is opened to biosimilar proteins which perform similarly to the original biologic. Small adjustments can affect the efficacy and stability of the biosimilar, so characterisation is important for safety and viability determination.

Laborious analytical methods exist for characterisation, as well as common antibody solutions, but these reagents are not always available or specific enough to detect small differences in modification between biosimilars and their original reference medicine. This study describes the development and characterisation of aptamers to rituximab, a monoclonal anti-CD20 antibody for cancer treatment.  Six DNA aptamers reactive with rituximab were identified with binding affinities in the nanomolar range. Robustness of the test assays was verified and specific binding mainly to the Fab fragment of rituximab was revealed. Selected aptamers were able to detect structural changes of thermally or ultraviolet light stressed rituximab. Analysis of different rituximab biosimilar candidates revealed a high similarity between the products, while one aptamer was able to reveal a structural difference between the originator and a proposed copy product.

Aptamers can be implemented as additional analytical methods for development and approval of biosimilars and follow on products. During de novo biologic development aptamers can also be used for analysing various complexes (drug conjugates), production methods and preclinical testing.


Aptamer Group is currently developing aptamers to a variety of protein, cell, and peptide targets, and can include negative similar targets for specificity.  If you would like more information on aptamers for your research contact us using the form below.


Wildner, S., Huber, S., Regl, C., Huber, C., Lohrig, U., Gadermaier, G. (2019).  Aptamers as quality control tool for production, storage and biosimilarity of the anti-CD20 biopharmaceutical rituximab. Scientific Reports. 2019; 9: 1111