Evaluate Safety and Biological Activity of ATYR1940 in Patients With Early Onset Facioscapulohumeral Muscular Dystrophy

A Phase 1b/2 open-label, intrapatient dose escalation study aiming to evaluate the safety,
tolerability, immunogenicity, biological and pharmacodynamic activity of intravenous
ATYR1940, administered once weekly for 12 weeks, in early onset FSHD patients with signs or
symptoms prior to 10 years of age. In Stage 1, up to 8 patients between the ages of 16 and
25 years will be enrolled. Stage 2 of enrollment will include patients with early onset FSHD
between the ages of 12 and 15 years.

Inclusion Criteria:

- Established, genetically confirmed diagnosis of FSHD.

- Onset of FSHD signs or symptoms prior to 10 years of age, as documented in the
patient's medical record or based on patient or family report.

- Provide written informed consent or assent

- In the Investigator's opinion, patient is willing and able to complete all study
procedures and comply with the weekly study visit schedule.

Exclusion Criteria:

- Currently receiving treatment with an immunomodulatory agent including targeted
biological therapies within the 3 months before baseline; corticosteroids within 3
months before baseline; or high-dose non-steroidal anti-inflammatory agents within 2
weeks before baseline.

- Currently receiving curcumin or albuterol; use of a product that putatively enhances
muscle growth or activity on a chronic basis within 4 weeks before baseline; statin
treatment initiation or significant adjustment to statin regimen within 3 months
before baseline (stable, chronic statin use is permissible).

- Use of an investigational product or device within 30 days before baseline.

- Evidence of an alternative diagnosis other than FSHD or a coexisting myopathy or
dystrophy, based on prior muscle biopsy or other available investigations.

- History of severe restrictive or obstructive lung disease, or evidence for
interstitial lung disease on screening chest radiograph.

- History of anti-synthetase syndrome, prior Jo-1 Ab-positivity, or a positive or
equivocally positive Jo-1 Ab test result during screening.

- Chronic infection, such as hepatitis B, hepatitis C, or human immunodeficiency virus
or a history of tuberculosis.

- Vaccination within 8 weeks before baseline or vaccination is planned during study
participation.

- Symptomatic cardiomyopathy or severe cardiac arrhythmia, that may, in the
Investigator's opinion, limit the patient's ability to complete the study protocol.

- Muscle biopsy within 30 days before baseline.