(389b) Single-Pass Tangential Flow Filtration (SPTFF) of Nanoparticles: Achieving Sustainable Operation with Dilute Colloidal Suspensions for Gene Therapy Applications

Recent approval of several viral vector-based therapeutics has led to renewed interest in the development of more efficient bioprocessing strategies for gene therapy products. Single-Pass Tangential Flow Filtration (SPTFF) can potentially provide inline concentration and final formulation of viral vectors with enhanced product quality (due to the reduction in total shear exposure) and direct integration in continuous biomanufacturing. In this study, SPTFF performance was evaluated using a suspension of 100 nm nanoparticles that mimics a typical lentivirus system. Data were obtained with flat-sheet cassettes having membranes with a 300 kDa nominal molecular weight cutoff either in full recirculation or single-pass mode. Flux-stepping experiments identified two critical fluxes for this dilute colloidal system, one based on boundary-layer particle accumulation (J_bl) and one based on membrane fouling (J_foul). The critical fluxes were well-described using a modified concentration polarization model that captures the observed dependence on feed flow rate and feed concentration. Long-time filtration experiments were conducted under stable SPTFF conditions, with the results suggesting that sustainable performance could be achieved for as much as 6 weeks of continuous operation. Ongoing work is focused on improving the model framework to account for the significant variation in local flow rate, pressure, and nanoparticle concentration within the module during SPTFF. Additionally, data with the model nanoparticle suspension will be compared with results for an actual lentivirus suspension to validate the use of nanoparticles as an appropriate model system. These results provide important insights into the potential application of SPTFF for the continuous concentration of viral vectors in the downstream processing of gene therapy products.