Study of Intravenous ATYR1923 (Efzofitimod) for Pulmonary Sarcoidosis

Key Inclusion Criteria: * Diagnosis of pulmonary sarcoidosis for ≥6 months (cutaneous and ocular involvement allowed), defined as: * Histologically proven diagnosis of sarcoidosis by bronchoscopy, biopsy (any organ) or bronchioalveolar lavage * Parenchymal lung involvement by historical radiological evidence * Must have symptomatic and/or active pulmonary sarcoidosis as evidenced by: * Modified Medical Research Council Dyspnea Scale grade of \>= 1; and * Forced vital capacity ≥50%; and * 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 ≥45 kg and \<160 kg. Key Exclusion Criteria: * Current disease presentation consistent with Lofgren's syndrome. * History of severe allergic or anaphylactic reactions to therapeutic proteins or known sensitivity to efzofitimod or to its inactive components (L-histidine, sodium chloride, sucrose, L-methionine, and polysorbate-20). * 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. * Any history of tuberculosis or evidence of active systemic non-tuberculosis fungal or mycobacterial infection within 1 year of Screening. * History of clinically significant cardiac, neurological, gastrointestinal, and/or renal manifestations of 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. * Is an active, heavy smoker of tobacco/nicotine-containing products (defined as \>20 cigarettes/day or e-cigarette equivalent). * Active substance abuse or history of substance abuse within the 12 months prior to Screening. * Participant 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.