Exhibit 99.1

Lexeo Therapeutics Reports Third Quarter 2025 Financial Results and Operational Highlights
FDA open to pooling data from ongoing Phase I/II studies of LX2006 with data from pivotal trial, and to earlier
co-primary endpoint assessment, to support a Biologics License Application
FDA approved comparability report between LX2006 HEK and Sf9 manufacturing processes in November 2025, endorsing use of Sf9 final commercial manufacturing process to begin dosing patients in upcoming pivotal study
LX2006 interim clinical data show clinically meaningful improvements across cardiac and neurologic measures of Friedreich ataxia, including left ventricular mass index and the modified Friedreich Ataxia Rating Scale
Completed enrollment of LX2020 HEROIC-PKP2 Phase I/II trial with ten participants dosed; interim data from low-dose cohort reported and additional clinical data from high-dose cohorts on track for January 2026
$154 million equity financing in October to support LX2006 registrational activities and further development of cardiac pipeline; in addition to Q3-25 end cash, cash equivalents and investments, expected to fund operations into 2028
NEW YORK – November 5, 2025 (GLOBE NEWSWIRE) – Lexeo Therapeutics, Inc. (Nasdaq: LXEO), a clinical stage genetic medicine company dedicated to pioneering novel treatments for cardiovascular diseases, today provided business updates across its portfolio and reported third quarter 2025 financial results.
“We continue to build significant momentum across our cardiac pipeline, and the recent financing strengthens our ability to execute on essential manufacturing and commercial activities for LX2006 as we look towards registrational readiness,” said R. Nolan Townsend, Chief Executive Officer of Lexeo Therapeutics. “Interim clinical data for LX2006 demonstrate meaningful benefit across measures of cardiac health and neurologic function, including improvements in the modified Friedreich Ataxia Rating Scale (mFARS), and we believe this therapy could represent a transformational step forward in the standard of care for FA. Furthermore with enrollment complete in the HEROIC-PKP2 Phase I/II trial, we look forward to sharing new clinical data for LX2020 in January.”
Business and Program Updates
•LX2006 in Friedreich Ataxia (FA):
oRegulatory Progress: In response to questions regarding the possibility of a faster path to a Biologics License Application (BLA), the FDA has indicated openness to a BLA submission for accelerated approval that includes clinical data from the ongoing Phase I/II studies of LX2006 pooled with new clinical data to be generated in the planned pivotal study. To enable pooling of these data to support licensure, Lexeo plans to submit enhanced manufacturing comparability data and additional nonclinical data. The FDA also previously agreed to evaluate the co-primary endpoint of left ventricular mass index (LVMI) at a time point earlier than 12 months. Lexeo continues to engage with the FDA on the pivotal trial protocol and enhanced comparability. There have been no changes to the previously disclosed alignment with FDA on key parameters related to the LX2006 planned registrational study to date.
oInterim Clinical Data: In October 2025, Lexeo shared interim clinical data from both ongoing Phase I/II studies of LX2006, which continue to show encouraging safety and efficacy:
•18% mean improvement in LVMI at 6 months and 23% mean improvement at 12 months in participants with abnormal baseline LVMI (n=6), exceeding the 10% FDA-aligned efficacy threshold for the planned pivotal study
▪Improvement or stabilization in secondary cardiac biomarkers high-sensitivity troponin I and lateral wall thickness in 14 of 16 participants (n=16)
▪2.0-point mean improvement in mFARS from baseline at latest visit across all participants with >6-months of follow-up (n=16)