A four-year real-world study published in Molecular Genetics and Metabolism found arimoclomol (MIPLYFFA) maintained stable disease severity and demonstrated long-term safety in adults and children with Niemann-Pick disease type C enrolled in the U.S. Early Access Program.
Written By: Fariha Sameen, PharmD
Reviewed By: Pharmacally Editorial Team
Zevra Therapeutics has reported the first published real-world data evaluating arimoclomol in adults with Niemann-Pick disease type C (NPC), showing stable long-term clinical outcomes and a safety profile consistent with previous clinical studies. The findings, published in Molecular Genetics and Metabolism, provide up to four years of follow-up from routine clinical practice through the U.S. Early Access Program (EAP), expanding evidence beyond the pivotal Phase 3 trial.
Niemann-Pick disease type C (NPC) is a rare, inherited lysosomal storage disorder caused by mutations in the NPC1 or NPC2 genes, leading to the accumulation of cholesterol and other lipids inside cells. The progressive disease primarily affects the brain, causing worsening neurological symptoms such as impaired coordination, difficulty swallowing, abnormal eye movements, cognitive decline, and loss of motor function. Because NPC has limited treatment options and progressively reduces quality of life and survival, therapies that slow disease progression remain a major unmet medical need.
Long-Term Real-World Evidence Expands Understanding of NPC Treatment
The longitudinal analysis included 109 individuals with NPC enrolled across 14 U.S. treatment centers, representing one of the broadest real-world assessments of arimoclomol to date. Notably, 53 participants (48.6%) were adults, making this the first published real-world evaluation of arimoclomol in an adult NPC population, an age group that has historically been underrepresented in clinical research.
Participants received arimoclomol during the U.S. Early Access Program before commercial availability. The mean treatment duration reached 820 days, providing an opportunity to evaluate long-term effectiveness and safety under routine clinical care.
Disease progression was monitored using the 5-domain NPC Clinical Severity Scale (5DNPCCSS), with additional analyses performed using the rescored 4-domain NPC Clinical Severity Scale (R4DNPCCSS).
Disease Severity Remained Stable during Four Years of Follow-Up
Across the study population, mean disease severity scores remained relatively stable throughout follow-up. Similar longitudinal trends were observed among patients assessed at Years 1, 2, 3, and 4, suggesting sustained disease stabilization over prolonged treatment.
The R4DNPCCSS analyses produced findings consistent with the original clinical severity assessments, reinforcing the overall effectiveness observations across multiple evaluation methods.
Safety outcomes also aligned with the established tolerability profile of arimoclomol, with no new safety concerns identified during long-term real-world use.
Real-World Data Complement Clinical Trial Findings
Lead study author Elizabeth Berry-Kravis, MD, of Rush University Medical Center, said long-term observational studies provide valuable information that complements clinical trials, particularly in ultra-rare diseases such as NPC.
She noted that consistent longitudinal assessment helps improve understanding of disease progression, treatment outcomes, and the challenges clinicians face when managing NPC in routine practice. Continued follow-up also strengthens the evidence base for long-term therapeutic decision-making in this complex neurodegenerative disorder.
MIPLYFFA Is the First FDA-Approved Therapy for NPC
Arimoclomol is marketed in the United States as MIPLYFFA®, which received U.S. Food and Drug Administration approval on September 20, 2024, for the treatment of Niemann-Pick disease type C.
The therapy activates the transcription factors TFEB and TFE3, increasing expression of genes involved in lysosomal function through the coordinated lysosomal expression and regulation (CLEAR) pathway. It has also been shown to reduce unesterified cholesterol accumulation in lysosomes of human NPC fibroblasts, although the clinical significance of this cellular effect remains under investigation.
In the pivotal Phase 3 study, arimoclomol halted disease progression over one year compared with placebo using the validated NPC Clinical Severity Scale.
Regulatory Progress Continues Beyond the United States
Beyond its U.S. approval, arimoclomol has received Orphan Medicinal Product designation from the European Medicines Agency for NPC. Zevra Therapeutics has also submitted a Marketing Authorization Application (MAA) to the EMA, where the therapy is currently under regulatory review.
The company’s clinical development program now includes data from more than 270 patients worldwide across the pivotal Phase 2/3 trial, open-label extension studies, expanded access programs, and a pediatric sub study, representing one of the largest evidence bases generated for a treatment in Niemann-Pick disease type C.
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About the Writer
Fariha Sameen, PharmD (LinkedIn), is a clinical pharmacy professional with hands-on experience in patient counselling, medication review, therapeutic monitoring, and clinical documentation across multiple departments. She has experience identifying and assessing drug-related problems and supporting medication safety practices. Her interests include pharmacovigilance, ADR reporting, clinical research, and medical writing focused on clear, evidence-based communication