Lexeo Therapeutics publishes LX2006 Phase I/II data in JAMA Cardiology
Lexeo Therapeutics has announced the publication of Phase I/II clinical data for its LX2006 gene therapy in JAMA Cardiology, with results drawn from 17 patients enrolled across two independent studies. The findings, which cover both safety and exploratory efficacy, support the company's progression into a pivotal trial it says is on track to begin by the end of June 2026.
The combined dataset brings together nine participants from a Weill Cornell Medicine study funded by the National Heart, Lung, and Blood Institute and eight from Lexeo's own SUNRISE-FA trial. Patients spanned a range of cardiac disease severity and received a single intravenous infusion of LX2006. Follow-up ran from six to 36 months across three dose cohorts.
Key clinical findings
Cardiac outcomes were the primary focus of the publication. Among participants with abnormal baseline left ventricular mass index (LVMI) in the mid- and high-dose cohorts, the data showed a mean 28% improvement at six months and 33% at 12 months, with some patients maintaining gains out to three years. Secondary cardiac biomarkers, including high-sensitivity troponin I and lateral wall thickness, also improved or stabilised in most patients regardless of their starting LVMI, a finding the company says supports LX2006's potential across different stages of Friedreich ataxia cardiomyopathy.
Cardiac biopsy data from the SUNRISE-FA cohort showed that all eight participants achieved increases in frataxin protein expression from baseline at three months. The company describes this as the first evidence of meaningful frataxin expression in disease-relevant cardiac tissue. Neurological outcomes, measured by the modified Friedreich Ataxia Rating Scale, also showed stabilisation over time.
On safety, LX2006 was generally well tolerated across the 17 dosed participants. There were no Grade 3 or above serious adverse events, no clinically significant complement activation, and only minimal, transient liver function test elevations. One patient experienced a possibly treatment-related Grade 2 asymptomatic myocarditis event, observed a year after dosing.
Narinder Bhalla, Chief Medical Officer of Lexeo Therapeutics, said the Phase I/II data "demonstrate clinically meaningful improvements across both cardiac and neurologic measures of Friedreich ataxia" and underscored the potential of the therapy for a condition he described as devastating.
Market context and competitive landscape
Friedreich ataxia is a rare, progressive inherited disease affecting roughly one in 50,000 people. The cardiomyopathy it causes remains the leading cause of death in patients, and no cardiac-specific treatments have yet received regulatory approval. That unmet need has drawn increasing gene therapy interest, with Lexeo among a small number of companies pursuing adeno-associated virus based approaches targeting frataxin restoration.
The broader cardiac gene therapy sector has faced headwinds in recent years, particularly around durability of expression and immune responses to AAV vectors. Lexeo's safety profile to date, notably the absence of serious complement events, may address some investor concerns in this regard, though the pivotal SUNRISE-FA 2 study will need to replicate these results at scale before regulatory submissions become viable. Topline data from that pivotal study are expected in the second half of 2027, putting a potential BLA filing on a timeline that extends into 2028 at the earliest.
The publication in JAMA Cardiology, a high-impact peer-reviewed journal, lends independent validation to the dataset beyond the press release context, though the Phase I/II sample size of 17 patients remains small and the pivotal study will be the decisive evidentiary moment for the programme.