Extension financing led by new investor Bpifrance, with renewed participation from all existing shareholders, AdBio Partners, CDTI Innovación, Columbus Venture Partners, European Innovation Council (EIC), Hadean Ventures, Invivo Partners and Sound Bioventures
Proceeds to support further clinical development of lead program ATX-01 in Myotonic Dystrophy Type 1, a unique therapy currently in Phase I-IIa, targeting miR23b
Funding to also advance a broader pipeline of targeted RNA medicines across areas of high unmet need in muscular, CNS, cardiac conditions
ARTHEx Biotech S.L., a clinical-stage biotechnology company focused on developing targeted RNA medicines for rare genetic neuromuscular disorders, today announced the successful closing of its upsized Series B financing with new investor Bpifrance, bringing the total size of the funding round to $87 million.
The Series B extension financing was led by Bpifrance, as part of both Large Venture and InnoBio investment strategies, and joined by all existing shareholders, including AdBio Partners, CDTI Innovación (through its Innvierte program), Columbus Venture Partners, European Innovation Council (EIC), Hadean Ventures, Invivo Partners and Sound Bioventures.
Proceeds from the financing will be used to further advance the global clinical development of ARTHEx’s lead program, ATX-01 for Myotonic Dystrophy Type 1 (DM1), including the ongoing interventional Phase I/IIa ArthemiRTM study and the preparation for an open-label extension to support a registrational study.
ATX-01 is an anti-miR oligonucleotide designed to inhibit microRNA23b (miR-23b), which is a natural repressor of MBNL protein expression. In DM1 patients, loss of MBNL protein function is caused by (1), reduced expression of MBNL proteins due to miR-23b upregulation and (2) MBNL sequestration in toxic DMPK mRNA, which leads to a spliceopathy, and is the cause of symptomatology in DM1 patients.
By inhibiting miR-23b, ARTHEx has demonstrated that ATX-01 increases MBNL production and decreases foci formation and toxic DMPK mRNA. This highly differentiated dual mechanism of action leads to a significant increase of free MBNL, improving splicing abnormalities, and ultimately restoring function in animal models.
Laurent Higueret, Deputy Director at Bpifrance’s Large Venture Fund, stated: “We believe ATX-01 could be a game-changer for patients suffering from DM1 on the basis of novel science and impressive data generated so far. We are excited to partner with ARTHEx as the company reaches clinical proof-of-concept stage and look forward to supporting Frederic and team in their efforts to build a leading franchise of precision RNA medicines.”
Benoit Barteau, Investment Director at Bpifrance’s InnoBio funds, added: “The approach developed by ARTHEx for DM1 aiming at targeting miR-23b has demonstrated compelling in vitro and in vivo results. The dual mechanism of action of ATX-01 offers real potential to be the best-in-class treatment for DM1. In addition, the Company’s delivery platform enables uptake into multiple tissues affected by DM1, allowing ATX-01 to go beyond the muscle, treating the whole disease and not just the symptomatology. We are eager to see initial clinical data in 2026.”
Frédéric Legros, Chairman and CEO, commented, “This financing marks an important milestone for ARTHEx and underscores the strength of our approach in DM1 and our emerging delivery platform, with its potential to deliver nucleic acid-based therapies beyond muscle. We are well positioned to advance ATX-01 toward a registrational study for DM1, while continuing to expand our pipeline across areas of high unmet need in muscular, CNS, cardiac conditions.”
“Arthex has made significant progress over the past years, advancing both its science and its clinical program. All investors are very pleased to continue supporting the company, and we believe that reinforcing its position through this financing is an important step to enable the next phase of its development,” said Jose Mesa, Partner at Columbus Venture Partners, initial lead investor of the Series B.
