This is a multicenter, randomized, double-blind, placebo-controlled, study comparing the efficacy and safety of intravenous (IV) efzofitimod 3 mg/kg and 5 mg/kg versus placebo after 48 weeks of treatment. This study will enroll adults with histologically confirmed pulmonary sarcoidosis receiving stable treatment with oral corticosteroid (OCS), with or without immunosuppressant therapy.

Inclusion Criteria:

• Documented history of pulmonary sarcoidosis for at least 6 months, supported by the following evidence: documented histologically proven diagnosis of sarcoidosis by tissue biopsy and documented evidence of parenchymal lung involvement by historical radiological evidence
• Evidence of symptomatic pulmonary sarcoidosis, as demonstrated by the following criteria: Modified Medical Research Council (MRC) dyspnea scale grade of at least 1 and KSQ-Lung score ≤70
• Patients must be receiving treatment with OCS of ≥ 3 months at Day 1 with a starting dose between ≥ 7.5 and ≤ 25 mg/day ≥ 4 weeks prior to Day 1.
• Body weight ≥ 40 kg and < 160 kg

Exclusion Criteria:

• Treatment with > 1 immunosuppressant therapy
• Treatment with biological immunomodulators, such as tumor necrosis factor-alpha (TNF-α) inhibitors or antifibrotics or interleukin inhibitors
• Likelihood of significant pulmonary fibrosis as shown by any 1 or more of the following: High resolution CT fibrosis > 20% within the last 12 months; FVC percent predicted (FVCPP) < 50% and KSQ-Lung score < 30
• In the opinion of the investigator, clinically significant pulmonary hypertension
• Patients with active cardiac, neuro, or renal sarcoidosis requiring organ-specific therapy in the past 2 years
• Patients with cutaneous or ocular sarcoidosis, which in the opinion of the Investigator, are at risk for exacerbation, necessitating OCS rescue or other systemic therapy
• History of Addisonian symptoms that precluded previous OCS taper attempts
• Is an active, heavy smoker of tobacco/nicotine-containing products
• History of anti-synthetase syndrome or Jo-1 positive at Screening
• Patients with active tuberculosis or those currently undergoing treatment for tuberculosis