Botulinum neurotoxin serotype A specific cell-based potency assay to replace the mouse bioassay

Area of Science:

• Neuroscience
• Biochemistry
• Pharmacology

Background:

• Botulinum neurotoxin serotype A (BoNT/A) is a potent therapeutic that inhibits neurotransmitter release by cleaving SNAP25.
• Developing cell-based potency assays (CBPAs) for BoNT/A is challenging due to its high potency.
• Current mouse bioassays for BoNT/A potency are being replaced by more sensitive and validated methods.

Purpose of the Study:

• To develop and validate a robust cell-based potency assay (CBPA) for Botulinum neurotoxin serotype A (BoNT/A).
• To establish a CBPA that can replace the traditional mouse bioassay for BoNT/A potency testing.
• To create a screening assay for discovering novel BoNT/A inhibitors.

Main Methods:

• Utilized differentiated human neuroblastoma SiMa cells for the CBPA.
• Employed a sandwich ELISA to quantify BoNT/A-induced intracellular cleavage of SNAP25.
• Validated the CBPA in a Quality Control laboratory setting.

Main Results:

• The developed CBPA demonstrates sensitivity comparable to the mouse bioassay.
• The assay accurately measures the biological activity of BoNT/A in bulk drug substance and commercial products like BOTOX®.
• A version of the CBPA received regulatory approval from the FDA, Health Canada, and the European Union for potency testing.

Conclusions:

• The developed CBPA is a reliable and validated method for assessing BoNT/A biological activity.
• This assay facilitates regulatory approval for BoNT/A containing products.
• The optimized CBPA screening assay supports the discovery of new therapeutic agents targeting BoNT/A.