A Phase 2 Study of Mavacamten in Adults With Symptomatic Non-Obstructive Hypertrophic Cardiomyopathy (nHCM)

Key Inclusion Criteria:

- Diagnosed with nHCM (hypertrophied and non-dilated left ventricle in absence of
systemic or other known cause), with LV wall thickness ≥ 15mm at Screening or ≥ 13mm
with a positive family history of HCM.

- Age 18 and greater, Body weight ≥ 45kg

- Documented LVEF ≥ 55% at the Screening as determined by echo central lab

- LVOT gradient < 30 mmHg at rest AND during Valsalva AND post-exercise

- NYHA functional class II or III

- Elevated NT-proBNP at rest

Key Exclusion Criteria:

- History of syncope, sustained ventricular tachyarrhythmia with exercise, obstructive
coronary artery disease or myocardial infarction within the past 6 months

- History of resuscitated sudden cardiac arrest at any time or known appropriate
implantable cardioverter defibrillator (ICD) discharge within 6 months prior to
Screening

- Current treatment with disopyramide or ranolazine (within 14 days prior to Screening)

- Current or planned treatment during the study with a combination of beta-blockers and
calcium channel blockers

- Has been treated with invasive septal reduction (surgical myectomy or percutaneous
alcohol septal ablation [ASA]) within 6 months prior to Screening

- History of resting or post-exercise LVOT >30 mmHg unless subsequently treated by
septal reduction

- Has QTc Fridericia (QTcF) >480 ms or any other ECG abnormality considered by the
investigator to pose a risk to participant safety (eg, second-degree atrioventricular
block type II)

- Has persistent or permanent atrial fibrillation not on anticoagulation for at least 4
weeks prior to Screening and/or not adequately rate-controlled within 1 year of
Screening

- History of clinically significant malignant disease within 10 years such as
non-metastatic cutaneous squamous cell or basal cell carcinoma

- History or evidence of any other clinically significant disorder, condition, or
disease that, in the opinion of the investigator or MyoKardia physician, would pose a
risk to subject safety or interfere with the study evaluation, procedures, or
completion.