Lexeo Therapeutics is a genetic medicine company, developing treatments for a number of conditions including cardiomyopathy associated with Friedreich’s ataxia (FA). Cardiomyopathy is a heart condition involving stretching, thickening, or stiffening of the heart muscle, making it harder to pump blood around the body.
The article below starts with the first update in February 2022, with newer updates below
In February 2022, Lexeo announced that the US medicines regulators, the Food and Drug Administration (FDA), had cleared an Investigational New Drug (IND) application for their gene therapy product LX2006. This is a requirement before clinical trials can take place.
Frataxin is a protein that is deficient in people with FA. LX2006 is designed to transfer the FXN gene (which codes for the frataxin protein) to heart cells and increase frataxin protein levels in the energy centres of cells called mitochondria. The increase in frataxin levels in mitochondria restores energy production in heart cells. In preclinical studies, LX2006 reversed the cardiac symptoms of FA in animal models.
Lexeo is planning to start a Phase I/II clinical trial later this year (in 2022) in people with FA cardiomyopathy. This trial will be carried out on 10 people with FA in the US and will mainly evaluate the safety of LX2006. Once receiving LX2006, patients will be followed for safety and efficacy (initial 12-month observation followed by long-term follow-up for a total of 5 years). If this trial is successful, Lexeo hopes to conduct future trials in other regions.
Read the press release from 16th February 2022 here.
Update June 2023:
In June 2023, Lexeo announced the completion of the first cohort in its Phase I/II trial, called SUNRISE-FA, testing its gene therapy, LX2006. In the first cohort, LX2006 was well tolerated with no unexpected events observed. Based on this, Lexeo has begun dosing the second cohort of participants. This is a 52-week trial taking place in America. Results from this trial are expected in the first half of 2024.
Read the press release from 13th June 2023 here.
Read about the trial here.
Update March 2024:
On 11th March 2024, Lexeo announced preliminary data from a subset of their second dose cohort of the trial, showing an increase in frataxin levels in cardiac biopsies at 3 months following treatment with LX2006 compared to pre-treatment baseline levels. SUNRISE-FA is the first clinical trial to evaluate frataxin levels in the heart via cardiac biopsy, where heart tissue is taken from a person for examination before and after treatment. 3 participants in the trial showed an increase in frataxin 3 months after treatment with LX2006, as shown in cardiac biopsy data. Lexeo expects further data from the trial in mid-2024.
Read the press release from 11th March 2024 here.
Update April 2024:
On 16th April 2024, Lexeo announced that a fast-track designation was granted by the FDA for LX2006 for people with FA cardiomyopathy. Fast-track designations are designed to support the development and expedite the review of new drugs to treat serious conditions. In this case, the fast-track designation was granted based on preclinical data on LX2006 for FA cardiomyopathy.
Read the press release from 16th April 2024 here.
Update July 2024:
On 15th July 2024, Lexeo shared positive interim phase I/II data for LX2006 for FA cardiomyopathy. This new interim data showed clinically meaningful improvements across multiple cardiac markers of hypertrophy (thickening), which is a key hallmark of FA cardiomyopathy. Hypertrophy of the left ventricle of the heart has been shown to be elevated in a natural history study of adults with FA cardiomyopathy conducted by Lexeo. Interim data have been provided from 8 participants with 6 or more months of follow-up following treatment with LX2006. This data showed reduced thickening of the ventricular wall, as well as lower levels of heart disease markers after 12 months of taking LX2006.
As of July 15th 2024, 13 participants have been dosed across two trials (Lexeo SUNRISE-FA Phase 1/2 clinical trial (NCT05445323) and the Weill Cornell Medicine investigator-initiated Phase 1A trial). Lexeo expects to provide further details of these interim results in autumn of 2024.
Read the press release from July 15th 2024 here.
Update March 2025:
On March 24th 2025 Lexeo provided a number of updates on the investigational gene therapy drug LX2006 to treat cardiomyopathy in FA which they shared with the FA community here.
Key updates from the letter include:
- The FDA agreed with Lexeo’s plan to include paediatric patients (children and adolescents) in the pivotal study
- The FDA agreed that Lexeo will not need to have a placebo arm in the pivotal study. Instead, a separate natural history study (CLARITY-FA) will be used to compare against the pivotal study
- Lexeo plans to share new data from the Phase I/II trial for LX2006 in mid 2025
- Lexeo plans to start the CLARITY-FA natural history study in the US in April 2025. CLARITY-FA will study how heart disease develops in FA, providing valuable information about the condition, as well as supporting their gene therapy development.
Update July 2025:
In July 2025, Lexeo announced FDA Breakthrough Therapy designation for LX2006. Breakthrough Therapy designation is intended to accelerate the development and review of investigational therapies that aim to treat serious or life-threatening diseases.
Read the press release from 7th July 2025 here.
Update October 2025:
Lexeo has announced positive interim data for the investigational gene therapy LX2006 which is being studied in the Lexeo-sponsored SUNRISE-FA Phase 1/2 clinical trial and the Weill Cornell Medicine investigator-initiated Phase 1A trial for the treatment of Friedreich ataxia cardiomyopathy. This positive interim data includes findings in most participants of sustained or deepening improvements in cardiac measures, but also neurological measures with clinically meaningful improvement in the modified Friedreich Ataxia Rating Scale (mFARS), indicating slowed disease progression and improved function.
Following this, Lexeo is in discussions with the FDA about an accelerated approval pathway for LX2006. They plan to start a registrational trial in the first half of 2026 and are currently exploring UK sites.
Read Lexeo’s letter to the community here.
Read the press release from 7th October 2025 here.
Update March 2026:
On March 30th 2026, Lexeo shared an update on their investigational gene therapy LX2006 summarising highlights from the full-year and fourth quarter 2025 corporate update. The update includes a summary of the encouraging clinical results, encouraging safety data from ongoing trials, and an update on plans to initiate the SUNRISE-FA 2 pivotal trial in the first half of 2026.
Lexeo’s message to the Friedreich’s ataxia community including an update and highlights can be accessed here.
Read the press release here.
