A workflow for the development of template-assisted membrane crystallization downstream processing for monoclonal antibody purification

Monoclonal antibodies (mAbs) are commonly used biologic drugs for the treatment of diseases such as rheumatoid arthritis, multiple sclerosis, COVID-19 and various cancers. They are produced in Chinese hamster ovary cell lines and are purified via a number of complex and expensive chromatography-based steps, operated in batch mode, that rely heavily on protein A resin. The major drawback of conventional procedures is the high cost of the adsorption media and the extensive use of chemicals for the regeneration of the chromatographic columns, with an environmental cost. We have shown that conventional protein A chromatography can be replaced with a single crystallization step and gram-scale production can be achieved in continuous flow using the template-assisted membrane crystallization process. The templates are embedded in a membrane (e.g., porous polyvinylidene fluoride with a layer of polymerized polyvinyl alcohol) and serve as nucleants for crystallization. mAbs are flexible proteins that are difficult to crystallize, so it can be challenging to determine the optimal conditions for crystallization. The objective of this protocol is to establish a systematic and flexible approach for the design of a robust, economic and sustainable mAb purification platform to replace at least the protein A affinity stage in traditional chromatography-based purification platforms. The procedure provides details on how to establish the optimal parameters for separation (crystallization conditions, choice of templates, choice of membrane) and advice on analytical and characterization methods.

Limited hepatitis B immunoglobulin with potent nucleos(t)ide analogue is a cost-effective prophylaxis against hepatitis B virus after liver transplantation

BACKGROUND

Prophylaxis against hepatitis B virus (HBV) recurrence after orthotopic liver transplantation (OLT) includes lifelong hepatitis B immunoglobulin (HBIG) and oral antiviral agent(s). In the presence of high-genetic-barrier nucleos(t)ide analogues, the need for lifelong HBIG is questioned. We evaluated the safety and cost-effectiveness of a limited HBIG course.

METHODS

OLT from 2006 to 2013 were reviewed. Patients with pre-OLT hepatitis B virus surface antigen who received HBV prophylaxis with 2 HBIG doses (anhepatic and first post-operative day; 10,000 units/dose) and potent nucleos(t)ide analogues were included. The primary end point was HBV recurrence (HBV-DNA detection).

RESULTS

Thirteen patients (primary transplants) were included, median Model for End-Stage Liver Disease score was 18, and there was no fulminant failure; HBV-DNA was detected in 4 patients at OLT. After OLT, 10 patients received entecavir and/or tenofovir. Median follow-up was 23 months. One recurrence occurred (7.7%) at month 13 (HBV-DNA: 14 IU/mL); the graft maintained excellent function. This minimal viremic expression is related to hepatocellular carcinoma recurrence with neoplastic replication carrying integrated HBV-DNA; thus, there is no defined HBV viral recurrence. No graft loss or patient death was related to HBV recurrence. The 1-year patient and graft survival rate was 84.6%. Cost-savings in the first year was $178,100 per patient when compared with Food and Drug Administration-approved HBIG dosing.

CONCLUSIONS

In the era of potent oral nucleos(t)ide analogues, a limited HBIG course appears to be cost-effective in preventing HBV recurrence.