Study of Intravenous ATYR1923 for Pulmonary Sarcoidosis

Key Inclusion Criteria:

- Diagnosis of pulmonary sarcoidosis for ≥1 year (cutaneous and ocular involvement
allowed), defined as:

- Histologically proven diagnosis of sarcoidosis by biopsy or bronchioalveolar
lavage

- Parenchymal lung involvement by historical radiological evidence

- Must have symptomatic and/or active pulmonary sarcoidosis as evidence by:

- Modified Medical Research Council Dyspnea Scale grade of >= 1; and

- Forced vital capacity ≥50 and ≤90 percent predicted; and

- Positive 18F-fluorodeoxyglucose positron-emission tomography/computed tomography
(18F-FDG-PET/CT) scan showing increased metabolic activity in lung parenchyma
within 4 weeks prior to Day 1.

- Receiving treatment with 10 to 25 mg/day of oral prednisone (or equivalent), at a
stable dose for ≥4 weeks prior to Day 1, and capable of undergoing the
protocol-specified steroid taper regimen.

- Body weight ≥55 kg and <140 kg.

Key Exclusion Criteria:

- Current disease presentation consistent with Lofgren's syndrome.

- History of severe allergic or anaphylactic reactions to therapeutic proteins.

- Treatment with biological immunomodulators such as tumor necrosis factor-alpha
inhibitors.

- Current evidence of clinically significant cardiovascular, hepatic, renal,
hematological, metabolic, or gastrointestinal disease, or has a condition that
requires other treatment.

- Clinically significant pulmonary hypertension requiring vasodilator treatment.

- History or evidence of active or latent systemic fungal or mycobacterial infection.

- History of clinically significant cardiac, neurological, gastrointestinal, and/or
renal manifestations of their sarcoidosis.

- Any condition that necessitated hospitalization within the 3 months prior to Day 1 or
is likely to require so during the study.

- Participation in another clinical study of an investigational agent or device within 3
months (small molecules) / 6 months (biologics) or 5 half-lives (if known) of the
agent, whichever is longer.

- History of or positive results of screening for hepatitis B, hepatitis C or human
immunodeficiency virus.

- Has smoked or inhaled (including e-cigarettes or e-vaporizers) any nicotine containing
product within 6 months prior to Screening.

- Active substance abuse or history of substance abuse within the 12 months prior to
Screening.

- Patient has received a live vaccination within 8 weeks before Day 1 or inoculation
with a live vaccine is planned during study participation.

- Positive for Jo-1 antibodies (Ab) at Screening, or past history of Jo-1 Ab positivity.

- Significant and/or acute illness within 5 days prior to drug administration that may
impact safety assessments, in the opinion of the Investigator.