Endotoxin Detection: The Four Pillars of rFC Adoption in Lieu of LAL

Abstract

Endotoxin from Gram negative bacteria (GNB) interacts with cellular receptors to trigger strong systemic inflammatory responses including fever, septic shock and death. The threat of endotoxin to the pharmaceutical and healthcare industries cannot be overstated. Unless GNB and endotoxin contamination in parenteral drugs and implantable devices are rapidly and reliably detected to enable their elimination, peril lurks. The quality control (QC) of biomedical products begun in 1942 with the slow, laborious and costly rabbit pyrogen test (RPT). Then in 1977, the US FDA approved the Limulus amoebocyte lysate (LAL) test. However, the LAL test requires harvesting and bleeding of the endangered horseshoe crab, disrupting the ecosystem. The emerging acceptance of recombinant Factor C (rFC) in lieu of LAL rests upon specific pillars that include the advantages of rFC and also stands upon the original established utility of LAL as a replacement for RPT. The first pillar of rFC adoption is the established utility of LAL which first used the blood of an arthropod, Limulus polyphemus, in place of RPT. It was then necessary to establish the relevance of an arthropod immune system to the mammalian response as well as to demonstrate that endotoxin is the predominant biological pyrogenic contaminant of water-based drug manufacturing, rather than previous concerns of detecting all pyrogens. The second pillar of rFC includes 3-4 decades of biotechnology efforts to develop recombinant technologies that have allowed for the transformation of therapeutic capabilities, including recombinant drugs, monoclonal antibodies, gene therapy, and understanding disease causation at a molecular-genetics level. These efforts include developing an alternative, highly reproducible synthetic endotoxin-biosensor, rFC. The second pillar also rests on the fragility of harvesting and bleeding vulnerable endangered animals to manufacture LAL. The third pillar of rFC explores why rFC has not been more widely adopted to date; what have been the roadblocks? We review man-made reasons as there are no inadequacies associated with biotechnological production of synthetic rFC; furthermore the rFC single enzyme-based endotoxin detection technology is widely accepted and has provided a revolution in therapeutic safety and efficacy. The fourth pillar of rFC elaborates the way forward for rFC in terms of validation and compendial acceptance which is rapidly gaining recognition towards utility worldwide. This pillar rests upon the significant features of rFC, including standardized operating procedures and production, which will allow for its widespread adoption.