Illustration of eluforsen correcting genetic defects in cystic fibrosis.

Eluforsen Breakthrough: A Promising New Treatment for F508del Cystic Fibrosis

Nico Varela in Health & Wellness December 2025 • 5 min read.

"Groundbreaking research shows that eluforsen, an antisense oligonucleotide, significantly improves CFTR function in patients with F508del cystic fibrosis, paving the way for more effective therapies."

Cystic fibrosis (CF) is a genetic disorder caused by mutations in the CF transmembrane conductance regulator (CFTR) gene. These mutations lead to the production of a faulty CFTR protein, which disrupts the normal flow of salt and water across cell membranes. This disruption results in the buildup of thick mucus in the lungs, pancreas, and other organs, leading to chronic infections, inflammation, and impaired organ function. One of the most common and challenging mutations is the F508del mutation, present in nearly 90% of CF patients.

Traditionally, CF management has focused on treating the symptoms and complications of the disease. However, recent advances in molecular therapies aim to correct the underlying CFTR defect. Eluforsen, also known as QR-010, represents a novel approach to treating CF. It’s an antisense oligonucleotide designed to bind specifically to the mutated mRNA region around the F508del deletion. By doing so, it helps to restore CFTR protein function in the airway epithelium. This innovative RNA-based therapy offers the potential to address the root cause of the disease.

A new study published in the Journal of Cystic Fibrosis explores the efficacy of eluforsen in improving CFTR function. The study focuses on patients with the F508del mutation and assesses the impact of intranasal eluforsen administration on CFTR biological activity using Nasal Potential Difference (NPD) measurements. The findings provide encouraging insights into the potential of eluforsen as a disease-modifying therapy.

How Does Eluforsen Improve CFTR Function?

Illustration of eluforsen correcting genetic defects in cystic fibrosis.

The study was designed as a multi-center, exploratory, open-label trial. It included adult participants with CF who were either homozygous or compound heterozygous for the F508del-CFTR mutation. The participants received intranasal eluforsen three times weekly for four weeks. The primary endpoint was the change in total chloride transport (Cl-free+iso) from baseline, measured by NPD.

Nasal Potential Difference (NPD) is a technique used to measure the electrical properties of the nasal epithelium, which closely mirrors the respiratory epithelium. It assesses the function of CFTR by measuring chloride and sodium transport across the nasal lining. Here's how the NPD assessment works:

Baseline Measurement: The initial electrical potential difference is measured under normal conditions using Ringer's solution.
Amiloride Perfusion: Amiloride blocks epithelial sodium channels (ENaC), reducing sodium transport and allowing CFTR-mediated chloride transport to be more clearly assessed.
Chloride-Free Solution: Perfusing the nasal cavity with a chloride-free solution creates an electrochemical gradient, stimulating chloride efflux through CFTR channels.
Isoproterenol Infusion: Isoproterenol stimulates cyclic adenosine monophosphate (cAMP)-dependent chloride secretion, further activating CFTR.
ATP Stimulation: Adenosine triphosphate (ATP) is used as a positive control to verify the integrity of the epithelial membrane.

The study's central reader, blinded to the subject ID, genotype, and time point, randomized and batched the acquired data. Changes in these parameters indicate improvements or impairments in CFTR function. Positive changes reflect improved chloride transport, while negative changes may indicate impaired function. Sodium transport parameters, including average basal PD and maximum basal PD, were also assessed to provide a comprehensive view of ion transport.

What Does This Mean for Cystic Fibrosis Treatment?

The study provides encouraging evidence that eluforsen can improve CFTR function in patients with the F508del mutation. Specifically, homozygous subjects showed increased total chloride transport, supported by improved sodium transport. These findings suggest that eluforsen could potentially address the underlying defect in CF, rather than just managing the symptoms. This is particularly significant because the F508del mutation is highly prevalent, making eluforsen a potentially widely applicable therapy. While more research is needed to confirm these findings and assess long-term benefits, eluforsen represents a promising new avenue for cystic fibrosis treatment. Further studies using inhaled pulmonary delivery are warranted to confirm these findings, and ensure that those who are homozygous for the F508del-CFTR mutation benefit from therapeutic interventions.

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This article is based on research published under:

DOI-LINK: 10.1016/j.jcf.2018.10.015, Alternate LINK

Title: Antisense Oligonucleotide Eluforsen Improves Cftr Function In F508Del Cystic Fibrosis

Subject: Pulmonary and Respiratory Medicine

Journal: Journal of Cystic Fibrosis

Publisher: Elsevier BV

Authors: Isabelle Sermet-Gaudelus, John P. Clancy, David P. Nichols, Jerry A. Nick, Kris De Boeck, George M. Solomon, Marcus A. Mall, James Bolognese, Florilene Bouisset, Wilhelmina Den Hollander, Nicolas Paquette-Lamontagne, Nigel Tomkinson, Noreen Henig, J. Stuart Elborn, Steven M. Rowe

Published: 2019-07-01

Everything You Need To Know

What exactly is eluforsen, and how does it work to treat cystic fibrosis?

Eluforsen, also known as QR-010, is an antisense oligonucleotide. It is designed to bind to the mutated messenger RNA (mRNA) region around the F508del deletion in the CFTR gene. By binding to this region, eluforsen helps to restore the function of the CFTR protein in the airway epithelium, addressing the root cause of cystic fibrosis. This is crucial because the F508del mutation leads to a faulty CFTR protein, disrupting salt and water flow across cell membranes and causing mucus buildup in various organs.

Why is the F508del mutation so important in the context of cystic fibrosis?

The F508del mutation is significant because it is the most common mutation in cystic fibrosis patients, affecting nearly 90% of individuals with the disease. Addressing this mutation with therapies like eluforsen can potentially benefit a large proportion of the CF population, improving CFTR protein function and reducing the complications associated with mucus buildup in the lungs and other organs. This specificity allows for a more targeted approach to treating the underlying cause of the disease.

Can you explain what Nasal Potential Difference (NPD) is and how it's used to measure CFTR function?

Nasal Potential Difference (NPD) is a technique used to assess CFTR function by measuring electrical properties of the nasal epithelium, which mirrors the respiratory epithelium. The process involves baseline measurements, amiloride perfusion to block sodium channels, chloride-free solutions to stimulate chloride efflux, isoproterenol infusion to activate CFTR, and ATP stimulation as a positive control. Changes in these parameters indicate improvements or impairments in CFTR function, providing a comprehensive view of ion transport.

What were the main findings of the study on eluforsen and what do they suggest for treating cystic fibrosis?

The study showed that eluforsen can improve CFTR function, particularly in individuals homozygous for the F508del mutation. This means that eluforsen has the potential to address the underlying defect in CF, rather than merely managing the symptoms. The findings are encouraging because they suggest that eluforsen could become a widely applicable therapy, especially given the high prevalence of the F508del mutation. Additional studies are needed to confirm these results and assess the long-term benefits, potentially using inhaled pulmonary delivery to ensure therapeutic benefits for those with the F508del-CFTR mutation.

What is cystic fibrosis, and how does it affect the body?

Cystic Fibrosis (CF) is a genetic disorder caused by mutations in the CFTR gene, leading to the production of a faulty CFTR protein. This disrupts the normal flow of salt and water across cell membranes, resulting in the buildup of thick mucus in the lungs, pancreas, and other organs. This leads to chronic infections, inflammation, and impaired organ function. Addressing the CFTR defect with therapies like eluforsen aims to correct the underlying cause of the disease, rather than just managing the symptoms.