FDA Clears IND for Phase 1/2a ArthemiR Trial of ATX-01 in Myotonic Dystrophy Type 1


The first patient enrolled into the phase 1/2a ArthemiR trial assessing ATX-01 myotonic dystrophy type 1 is expected in the second quarter of 2024.

Judith Walker, MD, chief medical officer at Arthex

Judith Walker, MD

Credit: Myotonic Dystrophy Foundation

According to a recent announcement, the FDA has cleared ARTHEx Biotech’s investigational new drug application (IND) to assess ATX-01, an antimiR designed to target microRNA 23b (miR-23b), in the phase 1/2a ArthemiR trial (NCT06300307) of patients with myotonic dystrophy type 1 (DM1).1 ATX-01 is the first microRNA therapeutic to be explored for patients living with DM1 and is the first therapeutic from the company’s pipeline to enter the clinic.

Research shows that miR-23b is associated with regulating the expression of MBNL proteins involved in the pathogenesis of DM1. In human DM1 myoblast cell lines, findings show that ATX-01 has a unique, dual mechanism of action that can potentially reduce toxic DMPK mRNA and increase MBNL protein levels, which have both been identified as molecular underpinnings of DM1.

Top Clinical Takeaways

  • ATX-01 represents a promising advancement as the first microRNA therapeutic explored for myotonic dystrophy type 1 (DM1), potentially addressing both DMPK mRNA toxicity and reduced MBNL protein levels.
  • The FDA clearance for the ArthemiR trial signifies a significant milestone for both ARTHEx Biotech and patients with DM1, offering hope for improved therapeutic options.
  • The ArthemiR study's design, including its focus on safety, target engagement, and clinical endpoints, highlights a comprehensive approach to evaluating ATX-01's potential effectiveness in treating DM1.

“Receiving FDA clearance to initiate our first-in-human study, ArthemiR, for ATX-01 in DM1 is a major milestone for ARTHEX and for patients with DM1 and their families who are in need of an approved therapeutic option,” Judith Walker, MD, chief medical officer at Arthex, said in a statement. “ATX-01 holds significant potential to deliver therapeutic benefit to DM1 patients, based on its dual mechanism of action that targets both the toxic DMPK mRNA and the reduced active MBNL levels. We plan to launch the ArthemiR study first in the US, followed by Canada and Europe.”

READ MORE: First Patient Dosed With PGN-EDODM1 in Phase 1 FREEDOM-DM1 Trial for Myotonic Dystrophy Type 1

The ArthemiR study is a phase 1/2a double-blind, placebo-controlled, dose escalation trial anticipated to enroll patients with congenital DM1. The primary objective of the study is to assess the safety and tolerability of single and multiple ascending doses of ATX-01 in participants with DM1. In the single-ascending dose part, patients will receive 1 dose of ATX-01 or placebo and participants will receive 3 doses of ATX-01 or placebo in the multiple-ascending dose part. The company will also explore target engagement at the muscle level in participants through biomarkers such as MBNL levels and splicing index. Additionally, clinical end points from the trial will include measures associated with muscle function, patient-reported outcomes, and quality of life measures.

Nicholas E. Johnson, MD, MSc, FAAN, associate professor and vice chair of research in the department of neurology at Virginia Commonwealth University

Nicholas E. Johnson, MD, MSc, FAAN

Credit: Virginia Commonwealth University

“It is exciting to see new agents coming to clinical trials, especially compounds with different mechanisms of action. This increases our hope of one day having effective and safe, disease modifying treatments for this multisystemic condition. Patients are eager for new trials, and we are delighted to start enrollment in the coming months,” lead investigator Nicholas E. Johnson, MD, MSc, FAAN, associate professor and vice chair of research in the department of neurology at Virginia Commonwealth University, said in a statement.1

In July 2022, the FDA granted orphan drug designation for ATX-01 in DM1.2 The treatment was discovered through the company’s in-house discovery engine, which is developed to recognize and optimize novel microRNA modulators and ensure preferential delivery to target tissues, for the treatment of diseases in which microRNAs are involved in the disease pathogenesis such as DM1.

“ATX-01 has the potential to be a viable treatment that may slow or halt the progression of DM1, relieve symptoms, and provide some relief to persons with this devastating condition. The FDA’s orphan drug designation further underscores the potential for ATX-01 to offer hope to the DM1 patient population currently faced with limited options” Beatriz Llamusí, PhD, founder and CEO at ARTHEx Biotech, said in a statement at the time.2

1. ARTHEx Biotech Receives IND Clearance from FDA to Initiate the Phase I-IIa ArthemiR™ Trial of ATX-01 for Myotonic Dystrophy Type 1 (DM1). News Release. ARTHEx Biotech. Published February 28, 2024. Accessed April 8, 2024. https://www.arthexbiotech.com/post/arthex-biotech-receives-ind-clearance-from-fda-to-initiate-the-phase-i-iia-arthemir-tm-trial-of-atx-01-for-myotonic-dystrophy-type-1-dm1#:~:text=Valencia%2C%20Spain%2C%20February%2028th%2C,of%20ATX%2D01%20for%20the
2. ARTHEx Biotech announces ATX-01 has been granted Orphan Drug Designation by the FDA. ARTHEx Biotech. Published July 20, 2022. Accessed April 8, 2024. https://www.arthexbiotech.com/post/arthex-biotech-announces-atx-01-has-been-granted-orphan-drug-designation-by-the-fda
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