Examples of such brain shuttles currently in middle to late stage clinical trials include transferrin receptor (TfR) targeting antibodies such as Roche’s Trotinemab (NCT07169578) for the treatment of Alzheimer’s disease [5,6,7], Denali’s DNL310 (NCT05371613, NCT04251026, NCT06075537) [8,9,10] for the treatment of Mucopolysaccharidosis Type II (MPS-II), and JCR Pharmaceutical’s Pabinafusp alfa (JR-141) (NCT04573023, NCT05594992), which has been approved for patient use in Japan for the treatment of MPS-II [11,12]. The gene discussed is TFRC; the disease is early-onset autosomal dominant Alzheimer disease.