Key Inclusion Criteria:

   - Patients with idiopathic dilated cardiomyopathy and stable New York Heart Association
   (NYHA) Class II - IIIa congestive heart failure (CHF).

   - Stable, guidelines-based medical and device therapy, without any CHF hospitalizations
   or change in heart failure drug dose with ≥ 50% reduction in dose or ≥ 100% increase
   in dose in the past 3 months.

   - Left ventricular (LV) end diastolic diameter by trans-thoracic echocardiography of >
   3.3 cm/m2 (for females) or 3.4 cm/m2 (for males) and/or LV ejection fraction ≤ 45%.

   - Gene positive for a pathogenic mutation in the LMNA gene, as determined by a
   CLIA-certified clinical laboratory (mutations including but not limited to:
   splice-site, non-sense, deletion mutations, a mis-sense mutation in a highly conserved
   codon, a mis-sense mutation involving a major charge change, a mis-sense mutation
   previously associated with genetic dilated cardiomyopathy).

   - Within 3 weeks prior to first dose of study drug, completed distance during six minute
   walk test of ≥ 100 m and ≤ 350 m AND/OR ≥ 100 m and ≤ 450 m AND ≤ 60% predicted
   distance AND patient is symptomatic for dilated cardiomyopathy per Investigator
   judgment.

   - On the day before and day of first dose of study drug, completed distance during six
   minute walk test of ≥ 100 m and ≤ 400 m (with the greater value within 10% of the
   lesser value) AND/OR ≥ 100 m and ≤ 475 m (with the greater value within 10% of the
   lesser value) AND patient is symptomatic for dilated cardiomyopathy per Investigator
   judgment.

   - Acceptable hematology, hepatic and renal function laboratory values within 3 weeks
   prior to first dose of study drug.

   - Additional criteria exist.

Key Exclusion Criteria:

   - Unstable clinical cardiac symptoms requiring unscheduled hospitalization within 60
   days prior to study start.

   - Clinically significant coronary artery disease, as per Investigator judgment.

   - Currently receiving continuous intravenous (IV) inotrope infusion, or presence of a
   ventricular assist device, or history of prior heart transplantation.

   - Any of the following within 60 days prior to study start: Myocardial infarction,
   cardiac surgical procedures, acute coronary syndrome, hemodynamically destabilizing
   cardiac arrhythmia, serious systemic infection with evidence of septicemia, any major
   surgical procedure requiring general anesthesia.

   - Uncorrected, hemodynamically significant primary valvular disease.

   - Initiation of cardiac resynchronization therapy within 180 days prior to study start.

   - Likelihood, in the Investigator's opinion, of undergoing cardiac transplantation, left
   ventricular assist device or other device implantation, or other cardiac surgery
   within the next 6 months; or of requiring continuous IV inotropic treatment, or
   referral for hospice or end-of-life treatment.

   - Active malignancy (except surgically-curative basal cell carcinoma, squamous cell
   carcinoma, or cervical carcinoma).

   - Receiving chronic immunosuppressant therapy.

   - Known positive serology for the human immunodeficiency virus (HIV), active hepatitis B
   and/or hepatitis C.

   - Participation in any other investigational study of drugs or devices within 30 days
   prior to study start.

   - Additional criteria exist.