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

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.

Currently Available Recombinant Alternatives to Horseshoe Crab Blood Lysates: Are They Comparable for the Detection of Environmental Bacterial Endotoxins? A Review

Endotoxin testing by recombinant factor C (rFC) is increasing with the addition of new suppliers of reagents. By use of a recombinantly produced factor C , based on the sequence of a coagulation enzyme present in horseshoe crab amebocyte lysates, the rFC tests are designed as substitutes for the traditional Limulus amebocyte lysate (LAL)/Tachypleus amebocyte lysate tests based on horseshoe crab blood. Comparative testing of samples with both the LAL and recombinant reagents has shown a high degree of correlation, suggesting that use of rFC is comparable to the more traditional LAL tests and may be technologically superior. Recombinant factor C does not recognize the factor G pathway, the alternate coagulation pathway that the lysate reagents detect. This feature allows rFC to detect endotoxin more selectively. As a recombinantly produced material, it avoids the use of the horseshoe crabs required for lysate production, thereby protecting this species, which is at risk in some parts of the world. Recombinant factor C is expected to further benefit from a more sustainable supply chain based upon a robust biotechnological production process. We summarize here the results of many studies that evaluated the use of recombinant technology for the detection of environmental endotoxin. Additionally, we include a review of the current compendia and regulatory status of the recombinant technologies for use in the quality control of pharmaceutical manufacturing. Our analysis confirms that the recombinant technologies are comparable in protecting patient safety.

Application of Recombinant Factor C Reagent for the Detection of Bacterial Endotoxins in Pharmaceutical Products

Recombinant Factor C (rFC) is non-animal-derived reagent used to detect bacterial endotoxins in pharmaceutical products. Despite the fact that the reagent was first commercially available nearly 15 years ago, the broad use of rFC in pharmaceutical industry has long been lagging, presumably due to historical single-source supplier concerns and the lack of inclusion in worldwide pharmacopeias. Commercial rFC reagents are now available from multiple manufacturers, thus single sourcing is no longer an issue. We report here the successful validation of several pharmaceutical products by an end-point florescence-based endotoxin method using the rFC reagent. The method is equivalent or superior to the compendia bacterial endotoxins test method. Based on the comparability data and extenuating circumstances, the incorporation of the end point fluorescence technique and rFC reagent in global compendia bacterial endotoxins test chapters is desired and warranted.LAY ABSTRACT: Public health has been protected for over 30 years with the use of a purified blood product of the horseshoe crab, limulus amebocyte lysate. More recently, this blood product can be produced in biotech manufacturing processes, which reduces potential impacts to the horseshoe crab and related species dependent upon the crab, for example, migrating shorebirds. The pharmaceutical industry has been slow to adopt the use of this reagent, Recombinant Factor C (rFC), for various reasons. We evaluated the use of rFC across many pharmaceutical products, and in other feasibility demonstration experiments, and found rFC to be a suitable alternative to the animal-derived limulus amebocyte lysate. Incorporation of rFC and its analytical method into national testing standards would provide an equivalent or better test while continuing to maintain patient safety for those who depend on medicines and while securing pharmaceutical supply chains. In addition, widespread use of this method would benefit existing animal conservation efforts.

Results of a harmonized endotoxin recovery study protocol evaluation by 14 BioPhorum Operations Group (BPOG) member companies

Significant regulatory and biopharmaceutical manufacturing attention has been recently generated regarding the inability to recover purified lipopolysaccharide in certain biopharmaceutical products, specifically those containing a chelator and surfactant. Disparate data has been generated and submitted during regulatory review. Study design is thought to significantly impact, and cause the confounding data. The BioPhorum Operations Group (BPOG) is an industry consortium of biopharmaceutical manufacturers. A BPOG team developed a collaborative experiment to determine if multiple laboratories could execute a harmonized protocol and reach equivalent conclusions. Twenty-one laboratories across fourteen different companies participated, yielding a robust study and large dataset. The experiment was successful as nearly all of the laboratories reached the same conclusions despite allowable variation in methods, suppliers, reagents, locations and analysts. The results of the study indicate a naturally occurring endotoxin analyte activity was recovered in a chelating buffer containing surfactant (citrate and polysorbate), and a buffer without surfactant (phosphate), while the purified lipopolysaccharide analyte activity was not recovered in the chelating buffer containing surfactant, but was recovered in the buffer without surfactant. Because the harmonized protocol yields consistent results across many different laboratories, the BPOG LER team recommends adoption of this protocol for use in endotoxin recovery studies.