Barriers to the Use of Recombinant Bacterial Endotoxins Test Methods in Parenteral Drug, Vaccine and Device Safety Testing

Abstract

The Bacterial Endotoxins Test (BET) is a critical safety test that is used to detect bacterial endotoxins, which are the major contributor to fever-inducing contamination risks known as pyrogens. All parenteral therapies, including every lot of injected drugs, vaccines, medical devices, must be tested for pyrogens to ensure patient safety. Bacterial endotoxins test methods were developed as a highly sensitive detection method for bacterial endotoxins, after the discovery of a clotting cascade in horseshoe crab blood. However, horseshoe crab species are limited to some inshore coastal habitats along the Atlantic coast of the USA and others throughout Asia. Fully functional horseshoe crab clotting factors can be manufactured via recombinant protein production, and several BET methods featuring recombinant horseshoe crab proteins have now been developed for commercial use. Recombinant Bacterial Endotoxins Test (rBET) methods based on the use of recombinant Factor C (rFC) were established in the European Pharmacopoeia — however, these methods have not yet been granted compendial status in the United States Pharmacopoeia (USP). In order to facilitate dialogue between stakeholders, the Physicians Committee for Responsible Medicine hosted two virtual roundtable discussions on the perceived barriers to the use of rBET methods for US FDA requirements. Stakeholders agreed that multiple rFC-based methods have been demonstrated to have suitable analytical performance, as described in ICH Q2 on the Validation of Analytical Procedures and USP <1225> on the Validation of Compendial Procedures. United States Pharmacopoeia compendial inclusion of the rFC-based and other rBET methods was favoured, in order to reduce the additional burdens created by a lack of global harmonisation on BET testing requirements.

Research progress of limulus coagulation mechanism and limulus reagents

“…In the limulus enzyme-linked immunosorbent assay (ELISA), the endotoxin-activated pathway can be inhibited differently-by two methods. The reactivity of LAL to 10 different endotoxin preparations can be suppressed hundredfold by the former method, either by combining DSO with polymyxin B or by monoclonal antibodies against limulus factor C. And can be almost completely blocked by the latter method, regardless of the source of the endotoxin [8] .…”

Editorial

“…Baker et al provide a report on two roundtable discussions, organised by the Physician’s Committee for Responsible Medicine, to address the urgent need to replace the unsustainable practice of using clotting factors from horseshoe crabs. 1 This species is listed as endangered and vulnerable to extinction, with limited habitats on the Atlantic coast of the USA and others in Asia. All parenteral therapies, such as vaccines, must be safety tested for pyrogens by using a Bacterial Endotoxins Test (BET).…”