Arthex and the EIC Accelerator: A DM1 Drug Still in Phase I

Arthex Biotech, a clinical-stage company in Valencia, is developing ATX-01, an RNA drug for myotonic dystrophy type 1 (DM1), an inherited disease that wastes muscles and has no approved disease-modifying treatment. Its EIC project promised that ATX-01 "will be validated through a Phase I/IIa clinical trial and chronic preclinical studies", according to CORDIS.

The European Innovation Council granted €2,500,000 towards a €20.07 million project from January 2023 to June 2025, so Arthex paid 88% itself. The EIC also invested in Arthex's €42 million Series B in May 2023, which was led by Columbus Venture Partners, according to Columbus. At the time Arthex said it would start its trial "in the second half of 2023". The trial, ArthemiR, started on 15 October 2024 and is still recruiting, with completion expected in July 2027, according to ClinicalTrials.gov. The report on CORDIS for the period to June 2025 describes study start-up activities and says the first US site would be ready "by Q2 24"; it reports no trial results.

Where Arthex Stands Now

In May 2026 Arthex presented its first human data at the International Myotonic Dystrophy Consortium meeting. It said ATX-01 "at single doses is safe and well tolerated, at the first 2 dose levels tested", with no dose-limiting toxicities so far at the third, according to its release. Muscle biopsy analyses of MBNL and DMPK levels will be reported at the end of the single-dose part. In March 2026 the FDA granted ATX-01 Fast Track designation.

The Technology: Blocking a MicroRNA

In DM1, a protein called MBNL is trapped by toxic RNA and also held down by a microRNA, miR-23b. ATX-01 is an oligonucleotide attached to oleic acid to help it reach muscle and brain, designed to block miR-23b. Arthex says this raises MBNL and reduces the toxic RNA, correcting faulty splicing in cells and mice. It also presented data in 2026 on the related type 2 disease.

What the EIC Project Promised, and What CORDIS Shows

The project promised clinical validation in a Phase I/IIa trial plus chronic preclinical studies. The trial received clearance from the FDA and Health Canada, orphan status was granted and a trial drug batch was made. But the trial started more than a year after Arthex's own target and was still in its single-dose stage a year after the project ended, so it did not validate the drug within the project. CORDIS lists the project as closed.

1. Trial authorisationDeliveredFDA and Health Canada.
2. Trial drug supplyDeliveredGMP batch made.
3. Phase I/IIa validationOngoingEnds July 2027.
4. Chronic preclinical studiesUnverifiedNo results published.

The Money

In September 2025 Bpifrance led an extension that took the Series B to $87 million, joined by all existing shareholders including the EIC, according to Arthex's release. The money is for the ArthemiR study and an open-label extension towards a registrational study. As a clinical-stage company, Arthex has no product revenue.

What Cannot Be Checked

Why Europe Should Care

DM1 affects at least 70,000 people in Europe by Arthex's estimate, with no approved disease-modifying drug. The EIC's grant and equity helped a Spanish company attract Bpifrance and other investors to fund a trial across Europe and North America. Whether ATX-01 works is still unknown.

The Verdict

Arthex and the EIC have not been asked for comment for this article. It is based entirely on public records and published statements, linked throughout.