Vestronidase alfa, an enzyme replacement therapy, is an approved drug for the treatment of MPS VII. The approval of this drug has set a precedent for future drug development for the regulators and drug developers. First, the pivotal clinical trial was conducted to evaluate the totality of the clinical data for determining the efficacy of the treatment, therefore, no primary clinical endpoint was established. Second, the drug obtains approval positive outcome on the secondary endpoint; changes in the urinary glycosaminoglycan, from placebo control. The glycosaminoglycan is also the pharmacodynamic biomarker that reflected the efficacy of the drug. Third, the novel multi-domain clinical responder index was designed to evaluate the treatment outcomes and included six minutes walk test (6MWT), forced vital capacity (FVC), shoulder range motion, visual acuity, BOT-2 fine, and gross motor activity. While MRDI evaluation per subject suggested the stabilization of clinical condition if no...