JCR Pharmaceuticals’ Research Presentations at the 18th International Symposium on MPS and Related Lysosomal Diseases 2026 Showcase Data from Its Investigational Treatments for Lysosomal Storage Disorders
JCR Pharmaceuticals Co., Ltd. a global specialty biopharmaceutical company dedicated to developing therapies for rare and genetic diseases, announced that it presented new clinical data in a poster session at the 18th International Symposium on MPS and Related Lysosomal Diseases, which was held June 4-7, 2026, in Florence, Italy.
Due to the protective blood-brain barrier, lysosomal storage disorders historically have been challenging to treat due to the inability to deliver a therapy into the central nervous system. With our J-Brain Cargo® platform technology, we have the potential to address the progressive neurological symptoms associated with these rare and life-limiting diseases, many of which have inadequate treatment options or no approved therapies available,” said Hiroyuki Sonoda, Ph.D., President and Chief Scientific Officer of JCR Pharmaceuticals.
The data presented at this symposium demonstrate the safety and efficacy evidence of JR-171 (lepunafusp alfa) in people with mucopolysaccharidosis type I (MPS I) and highlight its potential. We look forward to sharing additional data from our J-Brain Cargo® platform technology as they are available. We wish to thank all of the patients who have participated in our clinical programs and their families, clinical investigators, and other partners who continue to support our work.
New Clinical Data Presentation
Three-Year safety and pharmacodynamics of lepunafusp alfa (JR-171) in patients with mucopolysaccharidosis type I (MPS-I): Results from a phase I/II trial and extension study
(Presentation Number: 63)
Lead Author:Paul Harmatz, M.D. (UCSF Benioff Children’s Hospital, Oakland, CA)
Researchers reported on three years of data describing safety and pharmacodynamics of lepunafusp alfa (JR-171) in patients with mucopolysaccharidosis type I (MPS I) who were treated in a Phase I/II trial plus a three-year extension study (NCT04227600 and NCT04453085). Patients with MPS I were randomized to weekly intravenous lepunafusp alfa at a “Low” (2.0 mg/kg; n=6) or a “High” (4.0 mg/kg; n=8) dose and followed for three years. Enrollment was open to all MPS I phenotypes (Hurler [n=7], Hurler-Scheie [n=5], Scheie [n=2]); one Low-dose Hurler patient did not continue in the extension study.
Both the High‑ and Low‑dose cohorts demonstrated a favorable safety and tolerability profile, with compliance exceeding 90% in both groups. Overall, six patients experienced serious adverse events (SAEs) [5/8 in the High dose group, 1/5 in the Low dose group]. Of the 8 serious treatment-emergent adverse events (TEAEs), none were attributed to lepunafusp alfa. Adverse events of special interest — specifically anaphylaxis or infusion‑associated reactions — were uncommon, occurring in fewer than 5% of participants across both dose groups.
By Week 12, cerebrospinal fluid-heparan sulfate (CSF-HS) decreased in all patients. In the High dose group, CSF-HS decreases remained stable during the three-year study period in most patients; partial rebound was observed in one patient. In the Low dose group, two patients, both with Hurler syndrome, had a subsequent rebound in HS levels. Rebound did not correlate with presence/absence of antibodies.
The somatic symptoms (including serum HS levels, and liver and spleen volume) remained stable, or improved, in patients in both doses who received previous laronidase and decreased in the treatment-naïve patient.
With three years of follow-up, researchers concluded that weekly lepunafusp alfa is safe and well tolerated in a broad spectrum of patients with MPS I, with no serious TEAEs attributable to the study drug. Pharmacodynamic response of CSF-HS demonstrates that lepunafusp alfa crosses the blood-brain barrier (BBB), with a trend toward greater reduction in CSF-HS in the High dose cohort (4mg/kg). The long-term safety and clinical efficacy warrants evaluation in a larger clinical trial.
Encore Clinical Data Presentations
The following encore presentations provide additional evidence and context for the use of JR-141 (pabinafusp alfa) in the treatment of MPS II and were shared at the 22nd Annual WORLDSymposium™ 2026 (February 2-6, 2026).
Sustained cognitive and adaptive behavior outcomes of long-term treatment with pabinafusp alfa in patients with severe or attenuated mucopolysaccharidosis type II
(Presentation Number: 61)
Lead Author:Roberto Giugliani, M.D., Ph.D. (Federal University of Rio Grande do Sul, Brazil)
In a longitudinal, pooled, post hoc analysis of patients with MPS II receiving pabinafusp alfa across five open-label trials with up to five years of follow-up, researchers reported on sustained cognitive and adaptive behavior outcomes of long-term treatment with pabinafusp alfa in patients with severe or attenuated MPS II.Researchers concluded that long-term treatment with pabinafusp alfa was well tolerated and associated with stabilization or continued skill acquisition in many patients with severe or attenuated MPS II, suggesting that, with timely initiation prior to the onset of irreversible neurodegeneration, treatment with pabinafusp alfa may provide a benefit to patients with MPS II.
Long-term somatic efficacy of pabinafusp alfa across a broad spectrum of age groups and phenotypes in patients with mucopolysaccharidosis type II
(Presentation Number: 62)
Lead Author:Ana Maria Martins, M.D., Ph.D. (Federal University of São Paulo)
In a longitudinal, pooled, post hoc analysis of patients with MPS II receiving pabinafusp alfa in open-label trials with up to five years of follow-up, researchers reported on the somatic effects of pabinafusp alfa in a heterogenous population of patients with MPS II who initiated treatment at different ages. Researchers concluded that long-term treatment with pabinafusp alfa was well tolerated and provided positive somatic effects to a broad spectrum of severe and attenuated patients with MPS II.
About the International Symposium on MPS and Related Lysosomal Diseases
The International Symposium on MPS and Related Lysosomal Diseases brings together healthcare professionals, researchers, and industry leaders to accelerate progress in mucopolysaccharidoses (MPS) and related lysosomal storage disorders through collaborative innovation. We unite diverse perspectives to advance early diagnosis through cutting-edge technologies, develop revolutionary therapies, and ensure equitable global access to care. Our mission is to foster the next generation of rare disease advocates and professionals while creating sustainable partnerships that transform scientific breakthroughs into real-world improvements in patient outcomes worldwide.
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