Chinese researchers have reported early results from a six-patient trial of RAG-17, an experimental gene-silencing therapy for a genetic form of amyotrophic lateral sclerosis (ALS). The study was published this month in Nature Medicine.
RAG-17 uses small interfering RNA (siRNA) to suppress the SOD1 gene, whose mutations account for roughly 2% of ALS cases and can cause a hereditary form of the disease. The drug was jointly developed by a team led by Wang Yilong at Beijing Tiantan Hospital and researchers led by Li Longcheng at Ractigen Therapeutics.
In the trial, six patients with SOD1-related ALS received repeated intrathecal injections of the drug over several months. Researchers reported no serious adverse events; two participants experienced mild muscle tremors that later resolved.
The treatment produced substantial reductions in two disease-related biomarkers. SOD1 protein levels in cerebrospinal fluid fell by more than half, while plasma levels of neurofilament light chain, a marker of nerve-cell damage, also declined.
The biomarker changes indicate that RAG-17 reached its intended target in the central nervous system. Preclinical studies in rodent models had shown that the therapy delayed disease progression, preserved motor function, and extended survival. Tests in macaques also found sustained suppression of the SOD1 gene.
ALS is a progressive neurodegenerative disease that destroys motor neurons, gradually impairing movement, speech, swallowing, and breathing. It remains incurable. China has an estimated 60,000 to 100,000 people living with ALS, with about 23,000 new cases diagnosed each year.
The only approved targeted treatment for SOD1-related ALS is tofersen, which received U.S. approval in April 2023 and was approved in China in September 2024. The Chinese research team said a larger clinical trial of RAG-17 is now underway.
The current findings are limited to six patients and biomarker endpoints; clinical benefit such as slowed functional decline has not yet been demonstrated in humans.
China-Developed ALS Therapy Shows Early Trial Promise
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