Elaprase (idursulfase) / Samaritan Pharma, Takeda - LARVOL DELTA

Effectiveness of idursulfase therapy in young children with mucopolysaccharidosis II: an international retrospective chart review (SSIEM 2026) - "This study supports real-world effectiveness of idursulfase in young patients and the benefit of treatment initiation at an earlier age."

Retrospective data • Review • Alzheimer's Disease • Cognitive Disorders • Hunter Syndrome • Musculoskeletal Diseases • Otorhinolaryngology • Rare Diseases

Real-world safety and effectiveness of idursulfase treatment in patients with mucopolysaccharidosis II aged <16 months (SSIEM 2026) - P | "These findings support the long-term effectiveness of idursulfase in patients with MPS II who initiate treatment aged <16 months."

Clinical • Real-world • Real-world evidence • Hunter Syndrome • Infectious Disease • Rare Diseases

Treatment outcomes maintained in Hunter syndrome patients: a case series on switching from idursulfase to idursulfase beta in Belarus. (PubMed, Ther Adv Rare Dis) - "This retrospective case series describes clinical and biochemical outcomes in seven patients with Hunter syndrome in Belarus who were switched from idursulfase (Elaprase®) to idursulfase beta (Hunterase®). No new safety concerns were identified. These findings suggest that switching to idursulfase beta may preserve therapeutic benefits and support treatment continuity in real-world settings."

Journal • Hunter Syndrome • Lysosomal Storage Diseases • Metabolic Disorders • Rare Diseases

An international observational study on transition of care from paediatric to adult services for patients with mucopolysaccharidosis II. (PubMed, BMC Health Serv Res) - "Our study highlights the need for the establishment of common standards for the transition of care from paediatric to adult services for patients with MPS II. Based on the interview responses, we have proposed additional considerations for patients with neuronopathic MPS II. The findings may inform the development of effective transition practices for MPS II and other rare diseases, to optimize the transition of care experience for patients, caregivers and healthcare professionals."

Journal • Observational data • Genetic Disorders • Hunter Syndrome • Metabolic Disorders • Pediatrics • Rare Diseases

Intrathecal idursulfase-IT in children younger than 3 years with neuronopathic mucopolysaccharidosis II in a single-arm, open-label, phase 2/3 substudy and extension. (PubMed, JIMD Rep) - P2/3 | "Cerebrospinal fluid concentrations of total glycosaminoglycans were markedly reduced from baseline levels (mean [range] 1278 [429-2660] ng/mL) by week 16 and remained low thereafter. Data suggest early enzyme replacement therapy may stabilize cognitive development or slow the progression of cognitive impairment in young patients with neuronopathic MPS II."

Journal • P2/3 data • Alzheimer's Disease • Cognitive Disorders • Hunter Syndrome

Safety profile of idursulfase administered at home in patients with mucopolysaccharidosis II enrolled in the Hunter Outcome Survey. (PubMed, Mol Genet Metab) - "The rate of missed infusions was 0.52/year during the home therapy period compared with 1.42/year during the in-clinic period for the same patients and 0.57/year for patients who never received home therapy. Our data indicate a similar safety/tolerability profile for intravenous idursulfase administered at home and in clinic in patients with mucopolysaccharidosis II."

Journal • Hunter Syndrome

A Study of ELAPRASE in Treatment-naïve Participants With Hunter Syndrome (Mucopolysaccharidosis [MPS] II) (clinicaltrials.gov) - P4 | N=0 | Withdrawn | Sponsor: Takeda | Trial completion date: Jul 2028 ➔ Aug 2025 | Recruiting ➔ Withdrawn | Trial primary completion date: Jul 2028 ➔ Aug 2025

Trial completion date • Trial primary completion date • Trial withdrawal • Hunter Syndrome

Female Patients With Mucopolysaccharidosis II (MPS II): Insights From the Hunter Outcome Survey. (PubMed, JIMD Rep) - P | "Most patients (11/15, 73.3%) had received at least one dose of idursulfase, which was generally well tolerated; no serious adverse events during follow-up were considered treatment-related...Notably, only the female siblings displayed cognitive impairment. This report illustrates the disease burden in female patients with MPS II, helping to inform clinicians about the likely prognosis for this extremely rare subgroup of patients."

Journal • Alzheimer's Disease • Cognitive Disorders • Hunter Syndrome • Musculoskeletal Diseases • Pulmonary Disease • Respiratory Diseases

Clinical characteristics and real-world outcomes in patients with mucopolysaccharidosis II over 18 years: final report of the Hunter Outcome Survey. (PubMed, Mol Genet Metab) - P | "Data from HOS, collected for over 18 years, represent the largest dataset of patients with MPS II to date. The effectiveness and safety profile of idursulfase support its use for the long-term treatment of patients with MPS II."

Journal • Real-world evidence • Bone Marrow Transplantation • Hunter Syndrome • Lysosomal Storage Diseases • Metabolic Disorders • Rare Diseases • Transplantation

Long-term Evaluation on Height and Weight in Patients With MPS II Who Started Treatment at < 6 Years of Age (clinicaltrials.gov) - P4 | N=21 | Completed | Sponsor: Shire | Active, not recruiting ➔ Completed

Trial completion • Hunter Syndrome

An Extension Study of HGT-HIT-045 Evaluating Long-Term Safety and Clinical Outcomes of Idursulfase-IT in Conjunction With Elaprase in Pediatric Participants With Hunter Syndrome and Cognitive Impairment (clinicaltrials.gov) - P1/2 | N=15 | Completed | Sponsor: Takeda | N=25 ➔ 15

Enrollment change • Cognitive Disorders • Hunter Syndrome • Pediatrics

Extension Study of Idursulfase-IT Along With Elaprase in Children and Adults With Hunter Syndrome and Cognitive Impairment (clinicaltrials.gov) - P2/3 | N=6 | Active, not recruiting | Sponsor: Takeda | Recruiting ➔ Active, not recruiting | Trial completion date: Jun 2034 ➔ Jan 2029 | Trial primary completion date: Jan 2034 ➔ Jan 2029

Enrollment closed • Trial completion date • Trial primary completion date • Cognitive Disorders • Hunter Syndrome

Hypersensitivity Reaction and a Single-Bag Rapid Desensitization to Idursulfase. (PubMed, Am J Med Genet A) - "Therefore, it is critical to evaluate for hypersensitivity reactions and desensitize patients to idursulfase. We report a fourteen-year-old male who was evaluated using a nonirritating skin test concentration and underwent a novel desensitization protocol for Lysosomal Storage Disease ERT."

Journal • Cardiomyopathy • Cardiovascular • Hunter Syndrome • Immunology • Lysosomal Storage Diseases • Metabolic Disorders • Rare Diseases

A link between baseline neurofilament light chain and primary substrate accumulation in cerebrospinal fluid, and clinical outcomes in patients with MPS II from a phase 2/3 clinical trial and extension study of intrathecal idursulfase. (PubMed, Mol Genet Metab) - "TAK-609 is an intrathecal formulation of idursulfase (idursulfase-IT) that is delivered directly to the cerebrospinal fluid (CSF) of patients with neuronopathic MPS II to attenuate the neurocognitive decline. Taken together, this study establishes a clear link between genetic status, accumulation of primary substrate and circulating CSF NfL levels, allowing for bioanalytical stratification of patient outcomes in MPS II. TAKE-HOME MESSAGE: Baseline cerebrospinal neurofilament light chain levels correspond to the severity of iduronate-2-sulfatase gene (IDS) genotype, the degree of primary substrate burden and subsequent clinical outcomes in patients with neuronopathic mucopolysaccharidosis II, and can complement clinical assessments of disease heterogeneity."

Clinical data • Journal • P2/3 data • Alzheimer's Disease • CNS Disorders • Cognitive Disorders • Hunter Syndrome • Lysosomal Storage Diseases • Metabolic Disorders • Rare Diseases • CSF NfL • NEFL

A Study of ELAPRASE in Treatment-naïve Participants With Hunter Syndrome (Mucopolysaccharidosis [MPS] II) (clinicaltrials.gov) - P4 | N=5 | Recruiting | Sponsor: Takeda | Trial completion date: Jun 2027 ➔ Jul 2028 | Trial primary completion date: Jun 2027 ➔ Jul 2028

Trial completion date • Trial primary completion date • Hunter Syndrome

A Study of Elaprase in Children and Adults With Hunter Syndrome (Mucopolysaccharidosis II) in India (clinicaltrialsregister.eu) - P4 | N=5 | Sponsor: Takeda Biopharmaceuticals India Pvt. Ltd.

New P4 trial • Genetic Disorders • Hunter Syndrome • Pediatrics