In today’s mAb manufacturing the production via host cells can be done through different approaches, e.g. fed-batch, intensified fed-batch, or perfusion to just name a few. Depending on the cultivation method, the feed stream can be highly challenging for the following primary recovery and capture. Especially when the USP dictates a single harvest at very high cell mass. Typically, the steps of primary recovery have potentially high consumable costs, are time intensive, require pre-treatment and, importantly, lead to high host cell proteins (HCP) levels. To reduce the pressure on the downstream side, we propose a streamlined process where cell clarification and mAb capture from pilot-scale fed-batches and very high cell density intensified fed-batches are performed in a single step using magnetic beads coupled with protein A.
The study investigates the performance of magnetic bead-based mAb capture on non-clarified cell suspension from pilot scale fed-batch and intensified fed-batch cultures with cell densities higher than 100 x 10⁶ cells/mL. Here the magnetic bead-based separation is immediately performed on the harvest from the different cell cultures. The one-step integrated process was challenged with cell densities starting from ≈ 10 x 10⁶ cells/mL via ≈ 50 x 10⁶ cells/mL to very high cell density greater than 100 x 10⁶ cells/mL as well as different culture volumes. Here the process provides an overall mAb recovery of ≈ 90 %, while being mechanically gentle towards the cells with and HCP concentration in the eluate of below 10 ppm already complying with the regulatory acceptance range.
These results show that the proposed process of direct capture based on magnetic beads is possible without prior processing or pre-treatment and brings significant benefits. It is a powerful tool evade the challenge imposed by process intensification leading to higher cell concentrations.

Nils Brechmann

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