- SPM-2551 demonstrated robust and durable pharmacological activity following a single low-dose administration in preclinical Duchenne muscular dystrophy (DMD) models
- Data support Sapreme’s proprietary SPT platform, designed to overcome endosomal entrapment and enable intracellular delivery of RNA therapeutics
- “We believe these data are unprecedented in the field, showing superior efficacy after only a single, low dose, beyond any of the existing data of marketed therapies and programs currently in development.” Marco Timmers, Chief Executive Officer
Utrecht, Netherlands – 14 October 2026: Sapreme Therapeutics (“Sapreme” or the “Company”), a biotechnology company developing next-generation RNA therapeutics for patients with genetically driven diseases, today announces the oral presentation of new preclinical data from its lead Duchenne muscular dystrophy (DMD) programme, SPM-2551, at the 22nd Annual Meeting of the Oligonucleotide Therapeutics Society (OTS), taking place in Denver, Colorado, US. A selection of these data was also presented recently by Sapreme’s Scientific Advisory Board member, Professor Annemieke Aartsma-Rus, a leading international expert in DMD and oligonucleotide therapeutics, at the 31st Annual Congress of the World Muscle Society in Hiroshima, Japan.
SPM-2551 has been developed as a potential best-in-class treatment for patients with DMD. It is intended to restore dystrophin to more than 15% of normal levels – a level expected to be clinically meaningful on patients with DMD – while using lower doses and less frequent dosing than current therapies. SPM-2551 does this by combining a muscle-targeting transferrin receptor 1 (TfR1)-targeting antibody, an exon-skipping antisense oligonucleotide (ASO), and Sapreme’s proprietary endosomal escape enhancer, known as SPT.
Larger molecules, like oligonucleotide-based RNA therapeutics, face a significant delivery bottleneck. Even after successful cellular uptake, most of the oligonucleotide payload will typically remain trapped within endosomes – effectively sealing the drug off from the rest of the cell and preventing it from reaching its intracellular target. With up to 99% of the intended RNA payload remaining in endosomes, this significantly limits therapeutic potential. Sapreme’s proprietary endosomal escape enhancer, SPT, overcomes this challenge, allowing substantially more of the RNA therapeutic to escape endosomes and act on the target as intended.
“The data being presented at OTS today highlight the tremendous potential of Sapreme’s SPT platform to overcome intracellular delivery, one of the biggest challenges in RNA therapeutics,” said Marco Timmers, Chief Executive Officer of Sapreme Therapeutics. “These findings demonstrate that by combining targeted delivery with efficient endosomal escape, Sapreme can drive robust and durable pharmacological activity at exceptionally low tissue exposures. In terms of DMD, a truly devastating muscle-wasting disease, we believe these data are unprecedented in the field, showing superior efficacy after only a single, low dose, beyond any of the existing data of marketed therapies and programs currently in development. These data support the advancement of SPM-2551 toward the clinic for DMD, and the wider utility of our endosomal escape technology in turbo-charging the therapeutic impact of RNA medicines.”
The presentation, titled “Toward the Clinic: Targeted Oligonucleotide Conjugates with Built-in Endosomal Escape Enable Durable Pharmacology at Picomolar Tissue Exposure”, will be given by Miriam Bujny, Chief Development Officer at Sapreme, and highlight results from multiple preclinical species, including non-human primates, demonstrating robust target engagement and durable pharmacological activity despite requiring dramatically lower tissue exposure than unconjugated oligonucleotides or conventional antibody-oligonucleotide conjugates.
In a humanised DMD model developed in the laboratories of Professor Aartsma-Rus, SPM-2551 demonstrated 5-10-fold higher exon skipping than both naked and targeted comparator oligonucleotides at an order of magnitude lower ASO dose, leading to greater dystrophin restoration. Following the lowest single doses of 1 and 3 mg/kg, SPM-2551 restored dystrophin to more than 35% and 55% of wild-type levels after 56 days, respectively, demonstrating dose-dependent and sustained activity. These findings support the potential for best-in-class efficacy, achieved with low doses and extended dosing intervals.
Professor Annemieke Aartsma-Rus, Professor Human Genetics at Leiden University, said: “Four RNA therapies have been approved for different DMD subgroups, but there is definitely room for improvement. In our DMD mouse models, Sapreme’s lead candidate SPM-2551 restored dystrophin to very high levels after only a single low dose, substantially exceeding what we observed in comparators without targeting or without enhanced endosomal escape.”
The data further validate Sapreme’s endosomal escape platform and support the Company’s ongoing preparations for IND-enabling studies of its lead DMD programme in 2027.
Presentation details
Presentation title: Toward the Clinic: Targeted Oligonucleotide Conjugates with Built-in Endosomal Escape Enable Durable Pharmacology at Picomolar Tissue Exposure
Presenter: Miriam Bujny, Chief Development Officer, Sapreme Therapeutics
Conference: 22nd Annual Meeting of the Oligonucleotide Therapeutics Society (OTS)
Date and time: 14 October 2026, 9:55-10:10 MDT
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For more information contact:
Optimum Strategic Communications
Nick Bastin, Stephen Adams, Katie Flint, Ben Cowe
sapreme@optimumcomms.com
+44 20 3922 1906
About Sapreme Therapeutics
Sapreme Therapeutics is a preclinical-stage biotechnology company developing next-generation RNA therapeutics for patients with genetically driven diseases. The company’s proprietary endosomal escape technology enables targeted intracellular delivery of large molecules, including antisense oligonucleotides (ASOs) and small interfering RNAs (siRNAs), to both liver and extrahepatic tissues such as muscle, heart and brain.
Supported by successful proof-of-concept studies in rodents and non-human primates, Sapreme is advancing a pipeline of therapeutic candidates aimed at addressing significant unmet needs across neuromuscular, cardiometabolic and other serious diseases. Its lead programme is being developed as a potential best-in-class therapy for Duchenne muscular dystrophy, a severe and fatal paediatric genetic disorder. Sapreme is also pursuing strategic partnerships with pharmaceutical and biotechnology companies to co-develop novel RNA-based medicines.
About Duchenne muscular dystrophy (DMD)
Duchenne muscular dystrophy (DMD) is an incurable, fatal, X-linked genetic disorder that primarily affects boys and is among the most common severe genetic disorders of childhood, occurring in approximately 1 in every 3,500-5,000 live male births. Symptoms typically emerge in early childhood and lead to progressive muscle degeneration, loss of ambulation, and ultimately cardiac and respiratory failure. Exon-skipping therapies aim to address the underlying cause of the disease by restoring production of a shortened but functional form of dystrophin. However, clinical responses to currently approved therapies remain limited, highlighting the significant unmet need for treatments that can deliver meaningful and durable improvements in disease progression.