JCR Pharmaceuticals Co., Ltd. announced that the first patient in the Phase I/II clinical trial with Mucopolysaccharidosis Type IIIA (MPS IIIA; Sanfilippo Syndrome Type A) has been dosed with JR-441, a blood-brain barrier (BBB) penetrating form of heparan N-sulfatase that was developed using JCR's proprietary J-Brain Cargo® BBB-penetrating technology. JR-441 is a recombinant fusion protein of antibody fragment against the human transferrin receptor and heparan N-sulfatase, the enzyme missing or malfunctioning in subjects with MPS IIIA. MPS IIIA is a lysosomal storage disorder (LSD) characterized by multiple somatic and neurological signs and symptoms with no established standard of care.

While MPS III is a heterogeneous disease, type IIIA is typically characterized by an earlier onset than other forms of MPS III. While less prevalent in Japan, MPS IIIA is considered to be the most prevalent form of MPS III globally. Preclinical evidence indicated that JR-441 may address the somatic as well as neurological sequalae of MPS IIIA in individuals affected with the disease.

JR-441 was received orphan drug designation by the European Commission (EC) in January 2022. The main objectives of the phase I/II clinical study which is conducted at the International Center for Lysosomal Disorders (ICLD) of the University Hospital of Hamburg Eppendorf (UKE) is to establish the safety of chronic dosing of JR-441 in individuals with MPS IIIA, the pharmacokinetics of JR-441 and to explore early signs of efficacy. The trial is an open-label study comparing two different doses of JR-441 over a treatment period of 52 weeks.

Patients participating in the trial will be offered to enter an extension study upon completion of the treatment period. The trial is a single-center study in Germany and intends to enroll a total of twelve patients, age one to 18 years at various stages of disease progression. Further information can be found at clinicaltrials.gov under the NCT identifier NCT06095388.