4D-710 for cystic fibrosis

Last updated March 9, 2023, by Marisa Wexler, MS

✅ Fact-checked by Patrícia Silva, PhD

What is 4D-710 for cystic fibrosis?

4D-710 is an experimental aerosol gene therapy for cystic fibrosis (CF) that is being developed by 4D Molecular Therapeutics (4DMT).

How does 4D-710 work in cystic fibrosis?

CF is caused by mutations in the CFTR gene, which provides instructions to cells for making the CFTR protein. CF-causing mutations result in the production of a protein that doesn’t work properly, or they prevent any protein from being made at all.

The result is that the CFTR protein is not able to do its normal job of regulating the flow of water and salts in and out of cells, leading to the production of the thick, sticky mucus that causes CF symptoms.

4D-710 is designed to deliver an artificial version of the CFTR gene, called a transgene, that provides instructions for making a working version of the CFTR protein. By delivering this gene to lung cells, the therapy aims to increase CFTR protein function, normalizing mucus production and easing CF symptoms.

4D-710 delivers its genetic cargo using a harmless viral vector called A101, which was created by engineering an adeno-associated virus (AAV) using 4D’s proprietary technology. The vector was engineered to get through the thick mucus that characterizes CF and to avoid problems caused by patients having antibodies against the AAV virus, which can reduce the therapy’s effectiveness.

How will 4D-710 be administered in cystic fibrosis?

In clinical trials, 4D-710 is being administered as an aerosol — a spray of gas with a suspension of fine particles — that is delivered by inhalation directly into the lungs.

4D-710 in cystic fibrosis clinical trials

4DMT is conducting a Phase 1/2 clinical trial (NCT05248230) to test 4D-710 in about 21 adults with CF. All study participants will receive one of two doses of the gene therapy, given via a single inhaled administration, and will be monitored for at least 24 months (two years).

The study is specifically enrolling patients who are not eligible for treatment with CFTR modulators (medications that can boost the function of CFTR protein in people with certain mutations), or who have stopped taking modulators due to side effects. Recruitment is ongoing at about a dozen sites across the U.S.

The study’s main goal is to assess safety outcomes following the gene therapy’s use, including the incidence and severity of adverse events.

Data from the first three treated patients suggested that 4D-710 was well tolerated. One side effect, reported in one patient, was mild dry throat and fatigue during the therapy’s administration.

Findings in lung biopsies, conducted in these patients at four weeks after treatment, suggested that the gene therapy appears to be working as intended, with the CFTR transgene delivered by 4D-710 detectable in all analyzed lung tissue samples.

Common side effects of 4D-710

Early data covering the first three patients given 4D-710 in the ongoing Phase 1/2 clinical trial reported the only side effect of 4D-710 to be mild fatigue and dry throat at the time the inhaled therapy was administered. The trial, evaluating the safety of 4D-710, is ongoing.


Cystic Fibrosis News Today is strictly a news and information website about the disease. It does not provide medical advice, diagnosis, or treatment. This content is not intended to be a substitute for professional medical advice, diagnosis, or treatment. Always seek the advice of your physician or other qualified health provider with any questions you may have regarding a medical condition. Never disregard professional medical advice or delay in seeking it because of something you have read on this website.

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