BioPharm International - July 2021

BioPharm - July 2021 - Biopharmaceutical Analysis

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Page 24 of 38

24 BioPharm International eBook July 2021 The concept (Figure 4) comprises the following steps: • identification of key HCPs using mass spectrometry • in-silico screening of protein sequences to identify immuno- genic peptide regions • chemical synthesis of peptides (up to 20 amino acids) and coupling to a strong carrier antigen, keyhole limpet hemocyanin (KLH) • fast-track immunization using the peptide-KLH complex • affinity purification of anti-pep- tide antibodies from the above step • pooling of anti-peptide antibod- ies with the existing polyclonal antibodies to close the HCP detection gaps. This targeted approach leverages the power of MS to improve the existing immunoassays used for HCP quantitation. This concept is applicable for the improvement of ELISA kits, project-specif ic and platform assays, and also may be used to develop assays for single specific impurities. T he cha l lenges associated w ith HCP impurity testing of gene therapy products requires a holistic approach, taking advantage of both optimized immunoassays and mass spectrometry. T h e l a c k o f w e l l - e s t a b l i s h e d purification steps for AAV proven to be as powerful as Protein A for mAbs for example, emphasizes the need for stronger control strategies to monitor complex process related impurities. The following points should be con- sidered for a risk mitigation strategy: • Don´t trust generic ELISA kit results blindly. Remember that no single commercial ELISA is fully capable of detecting such a hetero- geneous mixture. • Verif y resu lts from immuno- assays by mass spectrometry at least on drug substance sample and ideally from process inter- mediates to define the efficacy of HCP removal. • Check the coverage of kit antibod- ies (at least "linear" coverage by 2D SDS-PAGE/Western Blot). • Check the immunoassay for detec- tion gaps. While immunoassays provide an aggregate measure- ment of dozens of proteins, these measurements can be misleading due to multiple factors. Mass spec- trometry will significantly help alleviate this problem. • If required, close the detection gaps by using a combination approach of in-silico immunoge- nicity prediction, peptide synthe- sis, and fast-track immunization. Pooling of antibodies from dif- ferent immunizations is feasi- ble and very helpful to improve existing assays. • Consider developing a project- specif ic assay early in the pro- cess. If a gene therapy product is delayed in get ting reg u la- tory approval, the setback could hold up drug development long enough for a competitor to get their product to market first. • Leverage MS-based proteom- ics analytical results from early pha se s i nto projec t- or pl at- for m-sp ec i f ic EL ISA de vel- o p m e n t , r e m e m b e r i n g t h a t d if ferent cel l l ines show d if- ferent and complex proteomes and secretomes. A holistic approach employing immu- noassays and MS will produce results that matter. Combining forces can help ensure f indings are accurate, which w ill help strengthen a dr ug product's profile. BP Biopharmaceutical Analysis Impurity Analysis The Cell and Gene Therapy Catapult (CGT Catapult) has formed a consortium of more than 20 organizations aimed at advancing the technology development and lowering costs of cell and gene therapy manufacturing by process analytical technologies that are either new or routinely used in other industries. The collaboration will help accel- erate the development of knowledge and understanding at reduced cost and investment risk to each organization. Consortium members are ABER Instruments, Anthony Nolan, BD, Bio-Techne, Cambridge Consultants, Cell and Gene Therapy Catapult, ChemoMetec, C-CIT Sensors, Cytiva, Eppendorf, GlaxoSmithKline, HORIBA, IMSPEX Diagnostics Ltd, Kaiser Optical Systems, Ocean Insight, Ori Biotech, Oxford Nanoimaging, Quantex, See-Through, TeloNostiX, Terumo Blood and Cell Technologies, and Univercells Technologies. "The industry needs to make a giant leap in terms of analytical capability and the dynamic use of information to control and improve processes, product, and costs," said Matthew Durdy, CEO at CGT Catapult, in a press statement. "The coming together of these leaders in the field is a very important first step towards achieving this." "By sharing knowledge and data, the consortium members will be able to reap potentially huge benefits that could lead to more efficient processes in this vital field," added Nicholas Medcalf, deputy challenge director, Medicines Manufacturing for Innovate UK, in the statement (1). Reference 1. Cell and Gene Therapy Catapult, "Cell and Gene Therapy Catapult Brings Together Over 20 Organisations with the Aim to Accelerate Technology Development and Potentially Lower Cost in Cell and Gene Therapy Manufacturing," Press Release, June 8, 2021. —The editors of BioPharm International Consortium to Accelerate Manufacturing Technology Development

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