Downstream Processing

Investigating Flow Distribution and Its Effects on Scale-Up

Depth filtration is widely used in the biopharmaceutical industry to purify target proteins by removing whole cells, cellular debris, fines, aggregates, and colloidal particles from the fermentation broth (1,2). At large scale (>2,000 L), culture harvest from a bioreactor is typically processed with a disc-stack centrifuge to remove cells and cell debris. Although centrifugation is very effective for removing whole cells and larger debris, it cannot remove small-size particles, which remain suspended in the centrate. Depth filters are commonly used…

50 Years of Sephadex Media

It has been 50 years since the first Sephadex paper was published (1). Readers of BioProcess International work in a field that was fundamentally affected by what happened after that paper appeared in 1959. So this anniversary is certainly worthy of a party and a few speeches. But there are lessons to be learned, too. Here we take a look at threads connecting events before and after the discovery of gel filtration chromatography and introduction of the Sephadex product. Interdisciplinary…

A Presanitized, Purpose-Designed, Single-Use TFF Strategy

    For many years, biopharmaceutical manufacturers have worked to increase capacity, address upstream production issues, and improve product yields. Notable successes recently achieved in upstream technology have significantly increased expression rates and therefore, upstream production capacities. Successes in generating higher titers combined with increasingly stringent quality and regulatory requirements have led to a number of challenges in aligning the efficiency of downstream processing with upstream titers. It is generally recognized that downstream processing costs account for about 70% of…

The Road to a Fully Disposable Protein Purification Process

    What’s keeping senior biopharmaceutical executives awake late at night? According to BioPlan Associates, Inc., which publishes an annual comprehensive survey of the state of worldwide biopharmaceutical manufacturing, capacity constraints are among the key issues at hand (1). And one of the most important constraints is the lack of physical capacity in purification equipment. Bioreactors are producing a lot more protein than current downstream purification steps are designed for. Overcoming the resulting bottlenecks may require increasing the productivity of…

Single-Use, Continuous-Countercurrent, Multicolumn Chromatography

    Manufacturing processes for biopharmaceuticals have undergone significant changes over the past decade. One of the most striking results of improved process sciences is the dramatic rise in expression levels from animal cell cultures. Figure 1 shows how some monoclonal antibody titers have increased about 30-fold over the past 15 years. These increasing titers have allowed current biomanufacturing facilities to produce larger product quantities than anticipated at the time they were designed and built. Figure 1:   As a…

Hydrophobic-Interaction Membrane Chromatography for Large-Scale Purification of Biopharmaceuticals

    Biopharmaceutical manufacturing is divided into two areas: upstream fermentation or cell culture and downstream purification processes. Each area contains multiple unit operations. A unit operation is defined as a step in processing using a particular type of equipment. Here, we focus on downstream process development, which must reliably produce a highly purified drug substance (often >99%). Downstream processing includes recovery, capturing, and polishing steps. The primary downstream unit operation is chromatography because of its simplicity and high resolving…

Development of a Turn-Key Harvest Solution for Small-Volume Bioreactors

Over the past 10 years, disposable bioreactors have grown from a niche tool servicing small-scale projects to a common and essential component in the CGMP production of human therapeutics (1). Recent advances in filter integration, aseptic connectors, and disposable sensing allow entire cell culture processes to be performed using only single-use components. However, harvest and clarification operations remain largely dependent on centrifugation, cross-flow filtration, and depth filtration (2), which are all techniques that have not been widely adapted to single-use…

Setting the Stage

Much has already been written lately about addressing the so-called “downstream bottleneck(s).” A number of companies are leading the way toward developing products and platforms for reducing both the costs and the time required for downstream processing. Our task with this special issue was to provide a state-of-the-art update on these activities — but as always, within a limited number of pages allotted. The primary issue behind this bottleneck debacle is to address purification challenges posed by aggregation in cell…

Development of a High-Capacity MAb Capture Step Based on Cation-Exchange Chromatography

Protein A affinity chromatography is traditionally used as the capture step for monoclonal antibodies (MAbs) (1,2,3). It yields high purity because only the fragment-crystallizable (Fc) region of an antibody (IgG1 or IgG2) or Fc-containing fusion protein can bind to the protein A ligand. The resulting specificity provides substantial reduction in impurities such as host cell proteins (HCPs) and DNA (4,5,6,7,8). The dynamic binding capacity of protein A chromatography resins is generally ≤40 g/L and depends highly on residence time because…

Increasing MAb Capture Productivity

Continually increasing bioreactor titers is placing pressure on downstream processing, especially chromatography steps, to process the greater mass of protein produced. Whereas an order of magnitude increase has been seen in titers over the last few years, no similar increase has yet been achieved in the capacity of chromatography resins. Meanwhile, the industry is coming under rising pressure to reduce manufacturing costs and the resulting cost per gram of monoclonal antibodies (MAbs) produced. Because of the specificity it offers, protein…