Continuous cell flocculation for recombinant antibody harvesting

BACKGROUND: Integrated continuous production technology is of great interest in biopharmaceutical industry. Efficient, flexible and cost effective methods for continuous cell removal have to be developed, before a fully continuous and integrated product train can be realized. The paper describes the development and testing of such an integrated continuous and disposable set‐up for cell separation by flocculation combined with depth filtration. RESULTS: Screening of multiple flocculation agents, depth filters, and conditions demonstrated that the best performance was obtained with 0.0375% polydiallyldimethylammonium chloride (pDADMAC; a polycationic flocculation agent) in combination with Clarisolve® depth filters. Using this set‐up, a 4‐fold decrease of filtration area was achieved relative to standard filtration without flocculation, with yields of ≥97% and DNA depletion of up to 99%. Continuous operation was accomplished using a simple tubular reactor design with parallelization of the filtration. The reactor length was selected to allow a 13.2‐min residence time, which was sufficient to complete flocculation in batch experiments. Continuous flocculation performance was monitored on‐line using focused beam reflectance measurement. Filter switch cycles based on upstream pressure were controlled by in‐line pressure sensors, and were stable from one filter to the next. CONCLUSION: It was demonstrated that stable and efficient continuous flocculation associated with depth filtration can be easily accomplished using tubular reactors and parallelization. Continuous cell separation is essential for the development of fully continuous integrated process trains. This cost‐efficient disposable design run in continuous mode significantly reduces facility foot print, process costs and enables great flexbility. © 2017 The Authors. Journal of Chemical Technology & Biotechnology published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.