A Study of XTMAB-16 in Patients With Pulmonary Sarcoidosis

Inclusion Criteria:

1. Participant between 18 to 80 years (inclusive) of age.

2. Weighs between 45 kg and 160 kg (99 to 353 lbs) at Screening.

3. Diagnosis of pulmonary sarcoidosis (at least 6 months before Screening) using the 2020 American Thoracic Society (ATS) Clinical Practice Guideline (Crouser et al, 2020), the European Respiratory Society (ERS) or the WASOG criteria including acompatible clinical and radiologic presentation with other causes of granulomatousdisease ruled out (cutaneous and ocular involvement permitted).

4. Modified Medical Research Conference (mMRC) Dyspnea Scale of ≥ 1.

5. Receiving treatment of 7.5 to 25 mg/day of oral prednisone, or equivalent, duringthe screening period and, at the determination of the investigator, is capable ofundergoing the protocol specific corticosteroid taper regimen.

6. Receiving treatment with methotrexate, azathioprine, mycophenolate, leflunomide,chloroquine, or hydroxychloroquine for at least 3 months before Screening that hasbeen at a stable dose for 4 weeks before Screening. All efforts should be made tomaintain stable background therapy at the Screening dose through the interventionperiod at the Investigator's discretion.

7. PART A only: Willing to refrain from consumption of grapefruit or grapefruit juice [pomelos, exotic citrus fruits, or grapefruit hybrids] from screening visit untilafter the final dose.

8. Polymerase chain reaction (PCR) test or rapid antigen test negative for severe acuterespiratory syndrome coronavirus 2 (SARS-CoV-2) at Screening.

9. Able to provide written informed consent.

10. In the opinion of the Investigator, the participant is capable of understanding andcomplying with protocol requirements

Exclusion Criteria:

1. Pregnant or breastfeeding women or women who are planning to become pregnant duringthe study.

2. PART A ONLY: Participants > 65 years of age. (This exclusion criterion is onlyapplicable for EU).

3. PART A ONLY: Known potentially significant fibrotic disease and/or activeinflammation contained solely in the hilar region as shown by high-resolutioncomputed tomography (HRCT), confirmed by a central reader. Participants with currentactive inflammation in the hilar region with concurrent inflammation outside thehilar region may be included. A historical HRCT performed within 6 months of screening may be submitted fordiagnostic confirmation by central review. If a subject's last HRCT was from > 6months of screening, an HRCT should be performed during screening for diagnosticconfirmation by central review.

4. PART A ONLY: Any prior TNFα inhibitor therapy.

5. Clinically significant extra-pulmonary sarcoidosis requiring systemic therapy asdetermined by the investigator.

6. PART B ONLY: Any therapy with an anti-TNFα monoclonal antibody (e.g., infliximab,adalimumab, golimumab and their biosimilars) within 6 months.

7. Baseline percent predicted forced vital capacity (FVC) of < 50%.

8. Prior treatment with rituximab or repository corticotropin injection within theprevious 12 months.

9. Clinically significant Central Nervous System (CNS) sarcoidosis requiring therapy,except history of isolated seventh cranial nerve palsy or evidence of demyelinatingneurologic disease.

10. Advanced congestive heart failure (New York Heart Association [NYHA] 3 or 4).

11. Current disease presentation consistent with Lofgren's syndrome (i.e., presence ofthe triad of erythema nodosum, bilateral hilar lymphadenopathy on chest X-ray, andjoint pain).

12. Clinically significant pulmonary hypertension requiring treatment. Note: Clinicallysignificant pulmonary hypertension requiring treatment would be defined as treatmentwith, i.e., prostacyclins, phosphodiesterase 5 inhibitors, and endothelin receptorantagonists.

13. Known hypersensitivity to any component of the formulation of XTMAB-16.

14. Live or messenger ribonucleic acid (mRNA) vaccination within 2 weeks before Day 1 orinoculation with a live or mRNA vaccine is planned during study participation.

15. Evidence of active or latent TB by interferon-gamma release assay (IGRA) or invasivefungal infections at Screening.

16. Known positive history of malignancy other than non-melanomatous skin cancer in thelast 2 years, including in-situ carcinoma of the uterine cervix completely cured byradical surgery.

17. Positive test result for hepatitis B surface antigen (HBsAg), hepatitis C virus (HCV) antibody, coronavirus disease (COVID-19), TB, or a known history of humanimmunodeficiency virus (HIV) infection at Screening.

18. Women of childbearing potential who are sexually active with a non-sterilized malepartner and are not willing to adhere to highly effective birth control measuresfrom the time of signing the informed consent, throughout the duration of the study,and for 90 days after 5 half-lives have elapsed since the last dose of study drug.

19. Male participants who are non-sterilized and sexually active with a female partnerof childbearing potential and are not willing to use highly effective contraceptionfrom the time of signing the informed consent throughout the duration of the study,and for 90 days after 5 half-lives have elapsed since last dose of study drug.

20. Clinically significant hepatic or renal disease, including uncontrolled diabetes atthe discretion of the investigator.

21. Any severe prior reaction to any type of biologics or human blood product such asalbumin, IgG, etc.

22. Concurrent emphysema.

23. Known hypercalcemia due to non-sarcoidosis conditions such as untreatedhyperparathyroidism, at the discretion of the investigator.

24. Abnormal ECG: ventricular arrhythmias (non-sustained ventricular tachycardia (VT),multifocal or frequent premature ventricular contractions, bundle branch block, axisdeviation, or abnormal Q waves). In the case of a QTcF (corrected QT interval byFredericia) interval > 450 ms (men) or > 480 ms (women; participants with bundlebranch block) or PR interval outside the range of 120 to 220 ms, the assessment maybe repeated once for eligibility determination at Screening or Baseline.

25. Donation or loss of 450 mL or more of his or her blood volume (includingplasmapheresis) or transfusion of any blood product within 90 days prior to dosing.

26. Known uncontrolled hypertension. Note: Uncontrolled hypertension is noted as bloodpressure ≥ 160/100 mmHg despite antihypertensive therapy within 3 months ofrandomization.

27. Clinical signs and symptoms consistent with COVID-19, e.g., fever, dry cough,dyspnea, sore throat, fatigue, new smell or taste disorder or confirmed infection byappropriate laboratory test within the last 4 weeks prior to Screening.

28. In the opinion of the investigator, inability to tolerate corticosteroid taper.

29. Concurrent systemic steroid use for non-sarcoidosis conditions.

30. Concurrent known auto-immune disease requiring treatment.

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

32. Any condition that required hospitalization within the 3 months prior to Day 1 or islikely to require so during the study.

33. Clinically significant abnormalities in the Screening physical exam, medicalhistory, vital signs, ECG, or clinical laboratory tests that are not known to be dueto concurrent sarcoidosis, and in the opinion of the Investigator and MedicalMonitor should preclude the participant's participation in the clinical study.