TFRC and mucopolysaccharidosis type 2: Conventional intravenous ERT fails to address retinal complicationsin MPS II because of the BRB, which limits the transport of macromoleculesfrom the systemic circulation to the retina.37 Pabinafusp alfa, a fusion protein consisting of antihuman TfR antibodyand IDS, was designed to penetrate the BBB into the brain by targetingTfR.18 Because the structure and iron transportmechanism of the BRB closely resemble those of the BBB,27,30,31 we hypothesized that the TfR-targetingstrategy could also be applied to retinal drug delivery.