SEATTLE, Wash. — September 15, 2026
Curi Bio announced that the U.S. Food and Drug Administration’s Center for Drug Evaluation and Research (FDA CDER) has accepted the company’s Letter of Intent into the Innovative Science and Technology Approaches for New Drugs (ISTAND) Program. The regulatory milestone advances Curi Bio’s human iPSC-derived 3D neuromuscular junction (NMJ) assay toward qualification as a formally recognized Drug Development Tool (DDT) based on a non-animal method. The assay is being developed as an alternative to the traditional mouse bioassay used for botulinum neurotoxin (BoNT) potency testing. Following an initial question-and-answer exchange with the FDA, Curi Bio will now advance into the Qualification Plan phase, where the company will work with regulators to establish the technical and regulatory framework for qualification.
Human 3D NMJ Platform Targets BoNT Potency Testing
Curi Bio’s platform is designed to measure neuromuscular contractility directly in response to botulinum toxin activity using human iPSC-derived tissues. Traditional BoNT potency and lot-release testing has historically relied on the Mouse Lethality Bioassay, creating an opportunity for human-relevant non-animal methods. Curi Bio’s 3D NMJ system recreates functional neuromuscular activity through neuronal stimulation and measures resulting muscle contractility, providing a functional readout aligned with the mechanism of action of BoNT rather than relying solely on proxy measurements. The company says the platform is highly reproducible and can support routine potency assessment, batch-release testing and drug-development activities. Its development also aligns with broader regulatory momentum around new approach methodologies (NAMs) and the reduction or replacement of animal testing in pharmaceutical development.
FDA Qualification Plan Defines Next Regulatory Steps
The next stage of the ISTAND process will focus on establishing the Qualification Plan for Curi Bio’s 3D NMJ assay, including experimental protocols, cross-laboratory validation and defined context-of-use parameters. The company is targeting formal recognition of the assay as a Drug Development Tool for BoNT potency and safety assessment. Curi Bio said the platform is already commercially available and is being used by biopharmaceutical developers for development and testing activities. Formal qualification through the FDA framework could provide developers with a regulatory-supported pathway for incorporating the assay into development and regulatory submissions. The program also advances the broader principles of the 3Rs—Replacement, Reduction and Refinement—by targeting routine animal-based potency testing with a human-derived functional assay.
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Curi Bio Expands Human-Relevant Drug Testing Platform
The ISTAND milestone strengthens Curi Bio’s broader strategy to commercialize human-relevant functional testing technologies for pharmaceutical research and quality control. The company’s Curiverse™ ecosystem integrates iPSC-derived cells, automated biosystems and cloud-based analytics across cardiac, skeletal muscle and neuromuscular research. The platform includes the Mantarray™ and Nautilai Plus™ biosystems and Pulse™ analytics technology, supporting functional measurements at scale. For BoNT developers, qualification of the 3D NMJ assay could potentially provide a standardized alternative for potency and batch-release testing while reducing dependence on animal models. By entering the FDA ISTAND qualification pathway, Curi Bio is seeking to establish a regulatory-supported framework for human iPSC-derived neuromuscular testing and advance non-animal methods from commercial research applications toward broader regulatory use.
Source: Curi Bio, press release
