Evaluation of One‐Stage Assays for the Monitoring of Recombinant Human Factor IX Padua Activity After Etranacogene Dezaparvovec Gene Therapy

FIX activity differences between central and local OSAs were modest; similar differences were observed in vitro with rhFIX-wt versus rhFIX-Padua. Commonly available OSAs can be used to monitor patients post-etranacogene dezaparvovec administration; we recommend using the same assay platform throughout the post-treatment period.