What ARTHEx Biotech does

ARTHEx Biotech S.L. is a clinical-stage biotechnology company founded in 2019 as a spin-out of the University of Valencia, Spain, developing RNA-based therapeutics for rare neuromuscular and related disorders. Its lead investigational product, ATX-01, is an antimiR oligonucleotide designed to inhibit microRNA-23b (miR-23b) for the treatment of Myotonic Dystrophy Type 1 (DM1), a rare genetic disease affecting more than one million people worldwide with no approved disease-modifying therapy. ATX-01 is described as the first anti-miR to enter clinical investigation for DM1 and employs a dual mechanism of action that reduces toxic DMPK mRNA and increases MBNL protein levels, conjugated to a fatty acid via the proprietary ENTRY™ platform to enable preferential skeletal muscle and CNS delivery.

The company's core scientific and operational focus is the ArthemiR Phase I/IIa randomized, placebo-controlled, double-blind, single- and multiple-ascending-dose trial of ATX-01, which is running across specialist DM1 centers in the United States, Canada, and Europe, with first patient dosed in October 2024. ARTHEx has accumulated a stacked regulatory moat around ATX-01: FDA Orphan Drug Designation (July 2022), EMA Orphan Drug Designation (December 2022), FDA Rare Pediatric Designation (November 2024), and FDA Fast Track Designation (March 2026). Capital has scaled accordingly, from a €4.25M seed (2020) to an EIC Accelerator award of up to €14M (2022), a €42M Series B led by Columbus Venture Partners (May 2023), and an upsized $87M Series B led by Bpifrance (September 2025), with additional CDTI/Invivo/Columbus follow-on capital in October 2025. Leadership combines scientific founder Dr. Beatriz Llamusí (CSO) with operator-CEO Frédéric Legros (formerly COO of Dynacure, VP BD at Valneva SE), CMO Dr. Judith Walker, and Chief Medical Advisor Dr. Nicholas Johnson of VCU.

ARTHEx is pre-revenue and does not yet commercialize any product. Its business model is the standard clinical-stage biotech playbook: raise dilutive and non-dilutive capital, advance ATX-01 through clinical and regulatory milestones, and either license, partner, or directly commercialize the asset post-approval via specialty rare-disease channels in the US and EU. Patient-advocacy partnerships (MDF, Euro-Dyma, ASEM, BENE, AFM-Téléthon, Cure DM, MD Nederland) and scientific-conference presence (TIDES, OTS, Chardan, Needham, Jefferies) supplement a relatively lean 1–10 person operating team. The September 2025 Series B upsizing explicitly signals pipeline expansion beyond DM1 into additional muscular, CNS, and cardiac indications.

Name

ARTHEx Biotech

Legal name

Arthex Biotech S.L.

Website

https://arthexbiotech.com

Company type

Private

Founded year

2019

Operating status

Operating

Headcount range

1–10 employees

Short description

ARTHEx Biotech is a clinical-stage Spanish biotech developing ATX-01, a first-in-class anti-miR-23b oligonucleotide using its proprietary ENTRY™ fatty-acid delivery platform to treat Myotonic Dystrophy Type 1 (DM1), a rare neuromuscular disease with no approved disease-modifying therapy.

Ownership category

akta.pro rank

Product category

Antisense Oligonucleotide Therapeutics

NAICS

Research and Development in Biotechnology (except Nanobiotechnology) (541714), Biological Product (except Diagnostic) Manufacturing (325414)

SIC

Pharmaceutical Preparations (2834)

akta.pro primary industry

siRNA Therapeutics (gene silencing) (HLAAADAB)

Keywords

• Antisense oligonucleotide therapeutics
• MicroRNA modulating drugs
• Rare disease therapeutics
• RNA-based medicines
• Neuromuscular disease treatment

Headquarters

HQ city

Valencia

HQ country

Spain

HQ region

Europe

Offices1 record

Markets served

GTM type

B2B

Offering type

Hardware or Manufacturing

Cost components

Personnel, Technology or R&D, Operations, Marketing or Sales, Infrastructure

Revenue model

1. Drug Development and Commercialization: ARTHEx Biotech is a clinical-stage biotechnology company focused on developing RNA-based therapeutics. The company does not yet have commercial products and is in the research and development phase, advancing ATX-01 through clinical trials for potential future commercialization.

Go-to-market motion2 records

Distribution channels1 record

Marketing channels6 records

Core offering

ARTHEx Biotech develops investigational antisense oligonucleotide therapeutics (antimiRs) for rare genetic diseases, with lead candidate ATX-01 targeting microRNA-23b (miR-23b) for the treatment of Myotonic Dystrophy Type 1 (DM1). The company leverages its proprietary ENTRY™ drug delivery platform, which conjugates antimiR oligonucleotides to fatty acids for enhanced delivery to skeletal muscle and central nervous system tissues. ATX-01 employs a dual mechanism of action that reduces toxic DMPK mRNA foci and restores MBNL protein function, and is currently being evaluated in the Phase I/IIa ArthemiR trial across specialist DM1 centers in the USA, Canada, and Europe.

Product overview

ARTHEx Biotech is a clinical-stage biotechnology company developing RNA-based therapeutics for rare neuromuscular disorders. The company's lead product is ATX-01, an antimiR oligonucleotide targeting microRNA 23b for Myotonic Dystrophy Type 1, currently being evaluated in the Phase I/IIa ArthemiR™ clinical trial. ARTHEx leverages its proprietary ENTRY™ drug delivery platform, which conjugates oligonucleotides to fatty acids for enhanced skeletal muscle and tissue delivery. The company is also advancing pipeline programs targeting muscular, CNS, and cardiac conditions.

Differentiator

Problem solved

Functional benefit

Products and services

• ATX-01 ATX-01 is an investigational anti-miR oligonucleotide drug candidate targeting microRNA 23b (miR-23b) for the treatment of Myotonic Dystrophy Type 1 (DM1). It employs a dual mechanism of action that reduces toxic DMPK mRNA foci and increases MBNL protein levels, addressing the underlying genetic pathology of DM1. ATX-01 is conjugated with oleic acid (fatty acid) for enhanced skeletal muscle delivery via the ENTRY™ platform. It has received FDA Orphan Drug Designation, EMA Orphan Drug Designation, FDA Rare Pediatric Designation, and FDA Fast Track Designation.
• ENTRY™ Drug Delivery Platform The ENTRY™ platform is ARTHEx Biotech's proprietary drug delivery technology that links antisense oligonucleotides (antimiRs) to fatty acids for improved tissue selectivity and preferential delivery to skeletal muscle and CNS tissues. The platform enables the use of very low active doses and underpins the development of antimiR therapeutics for diseases with unmet medical need.
• ArthemiR™ Phase I/IIa Clinical Trial The ArthemiR™ trial is a Phase I/IIa randomized, double-blind, placebo-controlled, single and multiple ascending dose clinical study evaluating the safety, tolerability, pharmacokinetics, pharmacodynamics, and preliminary clinical efficacy of ATX-01 in adult participants with Myotonic Dystrophy Type 1. The trial is being conducted at specialist DM1 centers in the USA, Canada, and Europe (ClinicalTrials.gov NCT06300307).

Quantifiable outcome

• ATX-01 has shown safety and tolerability at first three dose levels with no dose-limiting toxicities observed in Phase I/IIa ArthemiR trial
• +2 more outcomes

Named customers2 records

Segments1 record

Ideal customer profiles2 records

Technology focussed Yes

API detail

Has API

No

API docs

API detail

Core technology

AI maturity

App detail

Feature3 records

Partnerships

Ten partnerships are on record, tiered core and minor.

• University of ValenciacoreStrategic or Co-development PartnerARTHEx Biotech is a spin-off of the University of Valencia. The foundational technology was discovered and developed at the university over decades.
• IIS La Fe (Hospital La Fe)minorStrategic or Co-development PartnerARTHEx and IIS La Fe co-organized the Spanish Meeting on Oligonucleotide Therapeutics (SMOT III) in October 2023.
• Myotonic Dystrophy Foundation (MDF)coreStrategic or Co-development PartnerPatient advocacy organization collaborating with ARTHEx for patient engagement, surveys, and community outreach. MDF organizes Meet the DM drug developers program.
• Euro-DymaminorStrategic or Co-development PartnerEuropean patient advocacy organization for myotonic dystrophy. ARTHEx collaborates with Euro-Dyma for patient engagement in Europe.
• ASEMminorStrategic or Co-development PartnerSpanish patient association for neuromuscular diseases. ARTHEx collaborates with ASEM for patient engagement in Spain.
• BENEminorStrategic or Co-development PartnerSpanish patient advocacy organization. ARTHEx collaborates with BENE for patient engagement and awareness activities.
• AFM TelethonminorStrategic or Co-development PartnerFrench patient organization for neuromuscular diseases listed as advocacy partner on patient page.
• Cure DMminorStrategic or Co-development PartnerPatient advocacy organization focused on congenital myotonic dystrophy, listed as advocacy partner on patient page.
• MD NederlandminorStrategic or Co-development PartnerDutch patient organization for myotonic dystrophy, listed as advocacy partner on patient page.
• Virginia Commonwealth UniversityminorStrategic or Co-development PartnerDr. Nicholas Johnson, Professor and Vice Chair of Research in Neurology at VCU, serves as lead investigator for the ArthemiR Phase I/IIa clinical trial.

Scale indicators11 records

Recent moves7 records

Expansion highlights5 records

Direct peers

• Dyne Therapeutics: Clinical-stage company developing oligonucleotide therapeutics for serious muscle diseases including Myotonic Dystrophy Type 1 (DYNE-101). Directly comparable as a DM1-focused oligonucleotide developer with muscle-targeted delivery technology.
• Avidity Biosciences: Develops antibody-oligonucleotide conjugates (AOCs) with an active DM1 program. Directly comparable in targeting DM1 with RNA-based therapeutics and shares the rare neuromuscular disease focus.
• PepGen: Clinical-stage company developing peptide-conjugated oligonucleotides for neuromuscular diseases including DM1. Directly comparable as a conjugate-delivered RNA therapeutics developer targeting DM1.
• Expansion Therapeutics: Develops small molecules and RNA-targeted therapies for repeat expansion diseases including myotonic dystrophy. Directly comparable in targeting DM1 with novel RNA-modulating approaches.

Emerging players

• Locanabio: Emerging RNA-targeted therapeutics company with programs in neuromuscular and rare diseases. Comparable as a developer of RNA-modulating therapeutics for genetic neuromuscular disorders.

Broad incumbents

• Ionis Pharmaceuticals: Established leader in antisense oligonucleotide (ASO) technology with a broad pipeline across rare and severe diseases. Comparable as the foundational ASO platform company whose chemistry and delivery approaches inform oligonucleotide therapeutic development including antimiRs.
• Alnylam Pharmaceuticals: Leading RNAi therapeutics company with siRNA platform technology and rare disease focus. Comparable as an established RNA-silencing therapeutics developer whose delivery platforms (e.g., GalNAc) compete with ENTRY™ for tissue targeting.
• Wave Life Sciences: Clinical-stage oligonucleotide therapeutics company with programs in neurological and muscular diseases. Comparable as a developer of stereopure oligonucleotides for rare genetic disorders including DM1-adjacent indications.
• Sarepta Therapeutics: Commercial-stage company specializing in genetic medicines for neuromuscular diseases (Duchenne muscular dystrophy and related disorders). Comparable as a specialized neuromuscular disease therapeutics developer with rare disease regulatory and commercial expertise.
• Arrowhead Pharmaceuticals: Clinical-stage RNAi therapeutics company with broad pipeline in rare and liver diseases. Comparable as an RNA-silencing platform developer with delivery technologies relevant to oligonucleotide therapeutic development.

Market position

Strengths4 records

Weaknesses4 records

Competitive moat4 records

Key risks6 records

Key highlights6 records

Customer concentration

• Xx.com/Arthexbiotech
• LinkedInlinkedin.com/company/arthex-pharma

Compliance5 records

Revenue estimate

Valuation estimate

Number of profiles

Profiles6 records

Funding overview

Funding rounds7 records

Investors9 records

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M&A

Investments

M&A and investment is available on the Subscription and Enterprise plan.Contact sales →

Frequently asked questions about ARTHEx Biotech