The Impact of Disposables on Project Economics in a New Antibody Plant: A Case Study - A case study compares capital costs, operating expenses, and net present value for a new MAb plant. - BioPharm


The Impact of Disposables on Project Economics in a New Antibody Plant: A Case Study
A case study compares capital costs, operating expenses, and net present value for a new MAb plant.

BioPharm International
Volume 22, Issue 12


The basic production process used in the new plant is very similar to standard reported antibody production schemes. Cell culture and fermentation are carried out in a continuous perfusion mode that lasts for several months, with harvests being collected at regular intervals. The purification scheme starts with a capture step based on Protein A chromatography, followed by several chromatography steps for contaminant removal and product polishing. Adequate viral reduction is achieved by viral (nano) filtration as well as by viral inactivation steps along with the chromatographic operations.

Figure 1
The plant was designed with two segregated production trains, which each have 2,000 L of fermentation capacity. This setup allows two products to be manufactured simultaneously. The layout was organized to facilitate liquid handling in bags at large scale, based on experience with our current process. Cell culture medium and buffers are stored in a central service corridor, from where all the process rooms are fed through a closed liquid distribution system (Figure 1). This open space allows for flexible allocation of movable pallet tanks with bag containers up to 2,500 L. Larger bags are not available, however, so fixed stainless-steel tanks are used for volumes of 3,000 L and greater. A significant reduction of highly controlled cleanroom space was achieved with this approach.

Table 1. Vessel types used in the stainless steel (SS) and hybrid (HYB) models.
Liquid storage in bags accounts for the most extended use of disposable elements in the hybrid facility. Table 1 describes the level of substitution of stainless steel tanks by disposable containers in the various steps of the manufacturing process in this model. Disposable bags replaced 73% of the total liquid storage capacity of the plant, estimated at 117 m3 and distributed over more than a hundred process vessels. Other disposable elements were also introduced, such as chromatographic membranes and disposable viral filtration, but those had a limited effect on equipment cost savings.


Figure 2
Figure 2 shows the total capital costs for constructing a 100 kg antibody plant under each project alternative. This calculation started with a detailed estimate of equipment purchase costs (PC) based on recent price quotes. Prices were corrected for volume and currency depreciation where needed. To avoid significant distortions of the results because of land prices and construction costs in Cuba, the total capital costs were calculated using Lang coefficients, as updated by Petrides for the biotech sector.3,4 This method makes it possible to calculate the various items of the capital cost based on the equipment purchase cost using several multipliers (or coefficients). The use of these coefficients for disposable and stainless-steel technology has been discussed in the past by various authors.1,4

After making the calculations for our case study using the combination of the selected Lang coefficients, we found that direct fixed capital was seven times greater than the equipment purchase cost for the stainless steel project alternative, but only five times greater in the hybrid alternative, similar to the estimates obtained by Farid.1 These results correspond to our experience that a significant reduction in facility complexity is achieved when disposable technology is used extensively throughout the manufacturing process.

As can be seen in Figure 2, equipment purchase costs in the hybrid project were 34% lower than in the stainless steel project, which in turn reduced the total capital cost by 54% compared to the stainless steel alternative. This result demonstrates the significant capital savings that can be achieved through a broad integration of disposables in a medium-sized biopharmaceutical plant.

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