The oncolytic properties of measles viruses make them highly interesting as anti-cancer drug candidates. One therapeutic dose for cancer treatment must contain 108 to 1011 infectious virus particles (TCID50). This shows the importance of a high titer virus production and the relevance of its downstream processing (DSP), as in DSP, the full recovery of oncolytic measles virus (OMV) infectivity is targeted. Furthermore, the depletion of impurities, such as host cell proteins (HCP) and host cell DNA (hcDNA), have to meet the appropriate limits set by regulatory authorities. We established a high titer bioreactor process, achieving OMV titers of 1010 TCID50 mL-1 and then focused on the DSP of OMV. For this purpose, we characterized size, surface charge and pI of OMV as well as its stability concerning temperature, salt, pH and other important DSP parameters. The DSP procedure combined membrane-based and chromatographic methods. The clarification was carried out with depth filters, followed by a tangential flow filtration. For the OMV purification/concentration, various membrane materials and filtration modes were investigated. In the concentration mode, we were able to recover the infectious virus and reduced the impurities by ~70% for hcDNA as well as by ~80% for protein content. A subsequent diafiltration depleted the impurities by ~95% in total. In order to meet the required low levels for HCP and hcDNA, we tested chromatographic materials in a knowledge-based approach. In the bind-and-elute mode, the potential of ion-exchange chromatography was evaluated for the purification and concentration of OMV. We further investigated the flow-through mode for polishing. Our work showed that the combination of membrane filtration and chromatography is a versatile option to reach the highest OMV yields with regard to purity and potency.

Combination of membrane-based and chromatographic methods to achieve pure and concentrated oncolytic measles viruses

2019 Spring National Meeting

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