Characterisation of Membrane Processes in the Manufacture of Vectors for Cell and Gene Therapies

The number of clinical trials for Advanced Therapeutic Medicinal Products in the UK is increasing and with many of these advancing past Phase I/II, there is a need for scalable and robust manufacturing process [1]. A key component in the delivery of many of these therapies is the vector capable of carrying the therapeutic genetic material to the host's cells. More recently, the use of vectors in fighting infectious diseases has put a spotlight on the ability to manufacture such critical components for advanced therapies.

The manufacturing of these vectors is broadly subdivided into upstream processing (generation of the vector,) and downstream processing (harvest, clarification and purification steps). A large proportion of loses occurs during the purification and formulation steps [2]. Membrane processing are commonly employed in the preparation and manufacture of vectors for cell and gene therapies: from dead-end filtration during clarification to tangential flow filtration during vector concentration/formulation in ultrafiltration/diafiltration and finally, sterile filtration to produce the final vector. The systematic study of these membrane operations on the functional loss of vectors is yet to be investigated.

Currently, no scale-down model exists to investigate these loses and develop an optimised membrane processing system. A recent study has developed an ultra-scale down model to investigate the optimal parameters required for membrane processing for antibody therapeutics [3]. A similar ultra scale-down approach will be applied to gain understanding of the processing of vectors using membranes filters.

The overall aim of this PhD project to investigate the effect of the types of membrane materials, cell culture media or buffers on these membrane operations and explore the experimental design space for the robust and effective processing of vectors. Examples of vectors that will be studied are lentiviral vectors and extracellular vesicles, specifically exosomes.

The proposed project builds on the ultra-scale down model developed at UCL. This and other tools will be used to achieve the following objectives:

- Applying ultra-scale down methodology to vectors for cell and gene therapy.
- Characterising membrane and vector interaction during ultrafiltration (concentration)/diafiltration or sterile filtration.
- Using a multivariate data analysis approach to explore the design space required to manufacture high yield concentrated functional vector.
- Elucidate the effect of buffer choice on filtration and vector stability using physical and biological characterisation methods.

EPSRC Research Areas Classification: Process Systems: Components and Integration, Manufacturing Technologies, Healthcare Technologies, Biomaterials and Tissue Engineering

EPSRC Research Theme: Manufacturing the Future

[1] Cell and Gene Therapy Catapult Clinical Trials Database 2019. [online] Available at: https://ct.catapult.org.uk/sites/default/files/publication/Clinical%20Trials%20Commentary_for%20publication_150120.pdf
[2] Valkama, A. J. et al. (2020) 'Development of Large-Scale Downstream Processing for Lentiviral Vectors', Molecular Therapy - Methods and Clinical Development. Cell Press, 17, pp. 717-730. doi: 10.1016/j.omtm.2020.03.025.
[3] Fernandez-Cerezo, L. et al. (2019) 'An ultra scale-down method to investigate monoclonal antibody processing during tangential flow filtration using ultrafiltration membranes', Biotechnology and Bioengineering, 116(3), pp. 581-590. doi: 10.1002/bit.26859.