A Study of ARRY-371797 in Patients With Symptomatic Dilated Cardiomyopathy Due to a Lamin A/C Gene Mutation

Selected Key Inclusion Criteria:

- Patients with symptomatic lamin A/C protein (LMNA)-related cardiomyopathy Class
II/III/ or Class IV defined as:

- Gene positive for a deleterious mutation in the LMNA gene as determined by the
study central laboratory or by initial laboratory testing (central confirmation
of initial laboratory results is required prior to randomization and study
treatment).

- Evidence of cardiac impairment in EF

- Patient will have an implantable cardioverter defibrillator/cardiac resynchronization
therapy defibrillator (ICD/CRT-D). ICD implanted at least 4 weeks prior to initiation
of study treatment or CRT-D initiated at least 6 months prior to initiation of study
treatment

- Class II/III patients must have objective functional impairment evidenced by a
reduction in 6-minute walk test (6MWT);

- Stable medical and/or device therapy consistent with American Heart Association (AHA)
/ American College of Cardiology (ACC) or European Society of Cardiology (ESC)
guidelines

- Patients must meet acceptable hematology, hepatic and renal laboratory values as
specified

Selected Key Exclusion Criteria:

- Presence of other form(s) of cardiomyopathy contributing to HF (e.g., inflammatory or
infiltrative cardiomyopathy) or clinically significant cardiac anatomic abnormality
(e.g., LV aneurysm).

- Clinically significant coronary artery disease (e.g., coronary revascularization,
exercise-induced angina) per Investigator judgment.

- Uncorrected, hemodynamically significant (i.e., moderate-severe) primary structural
valvular disease not due to HF.

- Currently receiving or deemed at high risk of requiring chronic renal replacement
therapy (e.g., hemodialysis or peritoneal dialysis) within 6 months.

- Treatment with any investigational agent(s) for HF within 28 days prior to Day 1. Any
treatment with an investigational agent(s) requires approval from the Medical Monitor.

- Malignancy that is active or has been diagnosed within 3 years prior to screening,
except surgically curatively resected in situ malignancies or surgically cured early
breast cancer, prostate cancer, skin cancer (basal cell carcinoma, squamous cell
carcinoma) or cervical cancer.

- Non-cardiac condition that limits lifespan to < 1 year.

- Serum positive for hepatitis B surface antigen, viremic hepatitis C, or human
immunodeficiency virus (HIV) at screening.