— Single intrathecal dose of SCAD-siRNA therapeutic RAG-17 yields favorable safety profile and profound, durable biomarker reductions —
— Preliminary data from 180 mg cohort shows trends of clinical stabilization (ALSFRS-R) —
— Phase II trial is now actively dosing participants —
CHICAGO, April 22, 2026 /PRNewswire/ — Ractigen Therapeutics, a clinical-stage biopharmaceutical company focused on developing next-generation RNA-based medicines, today announced positive preliminary data from the single ascending dose (SAD) Phase I portion of its ongoing Phase I/II clinical trial of RAG-17. RAG-17 is a novel small interfering RNA (siRNA) therapeutic in development for the treatment of amyotrophic lateral sclerosis (ALS) patients with mutations in the superoxide dismutase 1 (SOD1) gene.
The data were presented on April 19, at the 2026 American Academy of Neurology (AAN) Annual Meeting in Chicago, Illinois. The presentation was delivered by Dr. Zhi-Ying Wu, Principal Investigator of the Second Affiliated Hospital Zhejiang University School of Medicine.
RAG-17 utilizes Ractigen’s proprietary Smart Chemistry-Aided Delivery (SCAD™) technology, which conjugates the siRNA duplex to an accessory oligonucleotide (ACO). This innovative architecture enables widespread central nervous system (CNS) distribution and exceptionally durable target engagement following a single intrathecal (IT) injection, potentially allowing for significantly extended dosing intervals compared to current therapies.
“The data presented at AAN this year represents a major milestone for Ractigen and, more importantly, for patients living with SOD1-ALS,” said Dr. Long-Cheng Li, CEO of Ractigen Therapeutics. “Achieving an 81% reduction in plasma NfL—a critical marker of neuroaxonal damage—alongside a highly favorable safety profile from a single administration is unprecedented. Furthermore, the early signals of clinical stabilization we are observing at the highest dose level strongly validate our SCAD platform. We are thrilled to have already initiated dosing in the Phase II portion of the study to further evaluate RAG-17’s transformative potential.”
“SOD1-ALS is a genetically defined disease with a clear biological target, yet patients still face a very limited treatment landscape,” commented Dr. Zhi-Ying Wu. “What we observed in this Phase I study—a substantial and durable reduction in CSF SOD1 protein after a single dose, accompanied by a profound decrease in plasma NfL and early stabilization of functional scores in the highest dose group—gives us strong reason for optimism. These data clearly suggest that RAG-17 is engaging its target in a highly meaningful way, and we look forward to generating further evidence in the ongoing Phase II study.”
Key Highlights from the AAN Presentation (NCT06556394):
The randomized, double-blind, placebo-controlled SAD phase evaluated 20 participants across five sequential dose cohorts (30, 90, 120, 150, and 180 mg). The participants received RAG-17 or placebo at 3:1 ratio. The study is still ongoing so the results were presented in a blinded way:
- Favorable Safety & Tolerability: RAG-17 was well-tolerated across all ascending dose cohorts. There were no serious adverse events (SAEs) or Grade3 treatment-emergent adverse events. Only three treatment-related adverse events were reported and all were mild ≥ 3 treatment-emergent adverse events. Only three treatment-related adverse events were reported and all were mild.
- Profound Target Engagement: A single IT dose yielded rapid and durable reductions in the disease-driving protein. In the 150 mg cohort, the maximum reduction in cerebrospinal fluid (CSF) SOD1 reached 58.1% (blinded analysis) by Day 90, maintaining a clinically meaningful reduction through Day 210.
- Deep Reductions in Neurodegeneration Biomarkers: RAG-17 induced a progressive and significant reduction in plasma neurofilament light chain (NfL). In the 180 mg cohort, plasma NfL levels dropped by 81.2% (blinded analysis) from baseline by Day 150.
- Encouraging Clinical Stabilization: Functional assessment was conducted with ALS Functional Rating Score-Revised (ALSFRS-R) in the 180mg cohort. In this cohort, blinded preliminary data indicated an attenuation of clinical decline:
- At Day 90, all the participants who had baseline and at least one assessment after dosing (n=3) exhibited zero functional decline (a 0-point change from baseline).
- At Day 150, decreases remained minimal (ranging from 0 to 4 points).
Phase II Trial Update
Ractigen Therapeutics also reports that a Phase II clinical trial for RAG-17 is now underway. This randomized, double-blind, placebo-controlled, multiple ascending dose (MAD) study is designed to evaluate the safety, tolerability, pharmacokinetics (PK), pharmacodynamics (PD), and preliminary efficacy of repeated intrathecal injections of RAG-17 in patients with SOD1 mutations. Since the first participant was successfully dosed on January 13, 2026, enrollment for two cohorts has been successfully completed. The trial is being conducted across multiple sites, led by investigators including Dr. Yilong Wang at Beijing Tiantan Hospital, Dr. Zhi-Ying Wu at the Second Affiliated Hospital of Zhejiang University School of Medicine; Capital Medical University; Dr. Hui-Fang Shang at West China Hospital of Sichuan University; Dr. Zhang-Yu Zou at Fujian Medical University Union Hospital; and Dr. Jing-Sheng Zeng at the First Affiliated Hospital of Sun Yat-sen University.
About RAG-17
RAG-17 is an investigational siRNA therapeutic candidate designed using Ractigen’s proprietary SCAD™ delivery platform technology to specifically target and silence the superoxide dismutase 1 (SOD1) gene mRNA. Mutations in the SOD1 gene cause a toxic gain-of-function and are a known cause of familial ALS. By reducing the production of the toxic mutant SOD1 protein, RAG-17 aims to slow or halt the progression of SOD1-ALS.
RAG-17 has obtained Orphan Drug Designation (ODD) from the U.S. Food and Drug Administration (FDA) and been selected for the CARE Program of the Center for Drug Evaluation (CDE), National Medical Products Administration (NMPA), which facilitates the accelerated development of rare disease therapies.
About ALS
Amyotrophic Lateral Sclerosis (ALS) is a progressive neurodegenerative disease affecting nerve cells in the brain and spinal cord, leading to muscle weakness, paralysis, and ultimately death, typically within three to five years of diagnosis. SOD1 gene mutations account for approximately 10-30% of familial ALS cases and about 1-2% of sporadic ALS cases. There remains a critical unmet medical need for effective treatments that can slow or stop disease progression.
About Ractigen Therapeutics
Ractigen Therapeutics is a clinical-stage biopharmaceutical company innovating next-generation RNA therapeutics, with a primary focus on small activating RNAs (saRNAs) developed through its clinically validated RNA activation (RNAa) technology. Leveraging proprietary delivery platforms such as SCAD™, LiCO™, and GLORY™, Ractigen is advancing a robust pipeline addressing unmet medical needs in oncology, neurological diseases, and genetic disorders. Its versatile technologies also enable the rapid development of RNA-based solutions, including siRNAs, where applicable, to target life-threatening, fast-progressing conditions such as those in the CNS. Committed to scientific excellence and patient-centered innovation, Ractigen strives to transform healthcare through the power of RNA therapeutics. For more information, visit www.ractigen.com.
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