8.1. Inclusion Criteria
1. Provide a signed informed consent form (ICF, and assent form, if applicable) prior to the
initiation of any study-related procedures, as described in Appendix 1, Section 13.1.3.
Participants under guardianship or partial guardianship will be eligible unless prohibited
by local laws or by local/central ethics committees. For participants pediatric participants), written informed consent by parent(s)/legal guardian(s) must be
obtained before any study-specific assessments are performed. Consent or assent may also
be required for some participants, depending on their age and local requirements.
2. Male or female, aged ≥6 years at the time of signing the ICF (and assent form, if
applicable).
3. Diagnosis of FA, based on clinical phenotype and genotype (GAA expansion on both
alleles) performed at College of American Pathologists (CAP)/Clinical Laboratory
Improvement Amendments (CLIA) or equivalent laboratory, with onset of FA occurring
at ≤25 years of age.
4. Confirmed LVH by cMRI as per imaging charter definition based on age and sex (LVMi
>2 SD above normal for age and sex in adults and above >2 Z-scores above normal for
age and sex in pediatric participants).
5. Left ventricular ejection fraction ≥40% as measured by cMRI.
6. No documented history of a clinical illness or condition other than FXN variant that is
associated with CM or, in the judgment of the investigator, would make the participant
inappropriate for study participation.
7. Stable medical and/or device therapy for HF consistent with regional (eg, American Heart
Association, American College of Cardiology, or the European Society of Cardiology)
guidelines at the investigator’s discretion, without change in HF drug(s) dose in the past
1 month prior to Baseline Visit.
8. Stable medical and/or device therapy for FA consistent with regional guidelines at the
investigator’s discretion, without change in medication and dosing for FA in the past
12 weeks prior to Baseline Visit.
9. Acceptable hematology laboratory values prior to Day 1:
a. Hemoglobin >9.0 g/dL
b. White blood cells count >4000 cells/μL
c. Platelet count >150,000 platelets/μL
10. Acceptable hepatic and renal function laboratory values prior to Day 1:
a. Aspartate aminotransferase (AST) and/or alanine aminotransferase (ALT) ≤2.0 × the
upper limit of normal (ULN)
b. Total bilirubin c. Estimated glomerular filtration rate (eGFR) >30 mL/min/1.73 m2 (using the
simplified Modification of Diet in Renal Disease formula in adults). For participants
(Schwartz et al. 2009).
11. Willingness and ability to comply with scheduled visits, laboratory tests, and other study
procedures.
 

Exclusion Criteria
1. Presence of other form(s) of CM contributing to HF (eg, inflammatory or infiltrative
CM), clinically significant cardiac anatomic abnormality or congenital cardiac
malformation, clinically significant coronary artery disease (eg, coronary
revascularization, exercise-induced angina), uncorrected, hemodynamically significant
(ie, moderate-severe) primary structural valvular disease not due to CM, per investigator
judgment.
2. Currently receiving intermittent or continuous intravenous (IV) inotrope infusion,
presence of a ventricular assist device, or history of prior heart transplantation.
Participants listed for cardiac transplantation may be enrolled, provided transplantation is
not likely to occur in the next 12 months.
3. Contraindication to cMRI (eg, non-magnetic resonance imaging [MRI]-conditional
pacemaker/defibrillator/cardiac resynchronization therapy [CRT]) or hypersensitivity
(known or suspected) to MRI contrast not amenable to prophylaxis per the investigator’s
discretion.
4. Nonelective hospitalization within the 30 days prior to enrollment.
5. Prior organ transplantation (eg, heart, lung, liver, kidney, or bone marrow). Tissue
transplantation that does not require systemic immune suppression (eg, corneal
transplantation) is not exclusionary.
6. A significant disorder of coagulation and clotting, including but not limited to arterial or
venous thrombosis or thromboembolism within 90 days prior to enrollment; prothrombin
time/international normalized ratio ≥1.2 × ULN; in the absence of anticoagulation; or
contraindication to anticoagulation.
7. Currently receiving or deemed at high risk of requiring chronic renal replacement therapy
(eg, hemodialysis or peritoneal dialysis) within 6 months prior to Baseline Visit.
8. Initiation of CRT within 6 months prior to screening.
9. History of prior gene transfer or cell therapy.
10. Participation in a concurrent interventional study.
11. Active and/or uncontrolled infection per the discretion of the investigator requiring or
which may require systemic treatment within 4 weeks of starting the study, including but
not limited to the following:
a. Hepatitis B or C infection (including participants with positive hepatitis B surface
antigen, hepatitis B antigen, history of hepatitis B virus [HBV] or hepatitis C virus
[HCV] infection, positive HBV core antibody, or any HCV antibody, or detectable
HBV or HCV viral load).
b. History of active or latent tuberculosis.
c. Positive human immunodeficiency virus (HIV) serological test at screening, not
controlled with antiviral therapy as shown by CD4+ counts ≤200/μL or by a viral load
of >200 copies/mL.
d. Other viral (excluding herpes simplex virus or human papillomavirus), bacterial, or
fungal infection.
12. Poorly controlled diabetes (hemoglobin A1c ≥8%).
13. Active hematologic or solid organ malignancy, not including nonmelanoma skin cancer or
another carcinoma in situ. Participants with previously resected solid organ malignancies
or definitively treated hematologic malignancies may be eligible if there has been no
evidence of active malignancy during the prior 5 years.
14. Pregnant or nursing.
15. Any concomitant medical or psychiatric diagnosis or social status that, at the investigator's
discretion, renders the patient unfit for study participation or risk of nonadherence.