BTD-backed gene therapy for a fatal heart complication of Friedreich ataxia heads to a 26-patient pivotal trial — approvability on a single-arm-adjacent external-control design is the deciding question

Lexeo Therapeutics is a clinical-stage gene therapy company developing a treatment for the heart damage caused by Friedreich ataxia, a rare inherited neurological disease; the therapy is not yet approved.

LX2006 is an AAV gene therapy restoring frataxin in cardiac tissue to prevent the progressive cardiomyopathy that kills most Friedreich ataxia patients, backed by Breakthrough Therapy designation on Phase I/II data showing 18-23% LVMI improvement exceeding the FDA-aligned threshold. The thesis resolves on whether SUNRISE-FA 2 meets its primary endpoint and FDA accepts a 13-vs-13 external-control BLA under accelerated approval. The principal risk is regulatory: a small external-control study with no randomization faces meaningful approvability uncertainty, and Rocket Pharmaceuticals' RP-A601 competes directly in the PKP2 arrhythmogenic cardiomyopathy program, LX2020, which is secondary but real.