Biomarker Qualification for Neurofilament Light Chain in ALS: Theory and Practice.

The increasing incorporation of NfL into ALS therapy development provides evidence that its utility-as a prognostic, response, risk/susceptibility, and/or safety biomarker-is already widely accepted by the community. The willingness of the FDA to base regulatory decisions on rigorous peer-reviewed data absent formal qualification, led us to conclude that formal qualification, despite some benefits, is not essential for ongoing and future use of NfL as a tool to aid ALS therapy development. While the balance of considerations for and against seeking NfL biomarker qualification will undoubtedly vary across different diseases and contexts-of-use, the robustness of the published data and careful deliberations of the ALS community may offer valuable insights for other disease communities grappling with the same issues. This article is protected by copyright. All rights reserved.