A Study of MK-2225 / ACE-1334 in Participants With Systemic Sclerosis With and Without Interstitial Lung Disease (MK-2225-002)

The main inclusion and exclusion criteria include but are not limited to the following:

Inclusion Criteria:

Participants must have SSc, as defined using the 2013 American College of Rheumatology/European League Against Rheumatism criteria
If participant is on a non-excluded immunosuppressive therapy (e.g. mycophenolate, methotrexate, azathioprine, etc.) the dose should be stable for > 2 months at the time of screening

Women of childbearing potential must:

If sexually active, have used, and agree to use, highly effective contraception without interruption, for at least 28 days prior to starting investigational product, during the study (including dose interruptions), and for 17 weeks (119 days) after discontinuation of study treatment
Refrain from breastfeeding a child or donating blood, eggs, or ovum for the duration of the study and for at least 17 weeks (119 days) after the last dose of study treatment

Male participants must:

Agree to use a condom, defined as a male latex condom or nonlatex condom NOT made out of natural (animal) membrane (e.g., polyurethane), during sexual contact with a pregnant female or a female of childbearing potential while participating in the study, during dose interruptions, and for at least 17 weeks (119 days) following investigational product discontinuation, even if he has undergone a successful vasectomy
Refrain from donating blood or sperm for the duration of the study and for 17 weeks (119 days) after the last dose of study treatment
Must agree to not participate in any other study of investigational drugs/devices while enrolled in this study

Exclusion Criteria:

Participant with SSc-pulmonary arterial hypertension (PAH) (except those participants with mild PAH on up to 2 oral drugs and mean pulmonary arterial pressure < 30 mmHg or low risk by risk calculator)
In the opinion of the investigator, other clinically significant pulmonary abnormalities (such as obstructive lung disease, asthma, etc.)
Other investigational therapy received within 1 month or 6 half-lives (whichever is greater) prior to the Screening Visit
Prior exposure to MK-2225 or other TGF-β antibodies or any TGF-β family targeted biologic or hypersensitivity to the components of MK-2225
Hypersensitivity to placebo or any of its components
Previous hematopoietic stem cell transplantation (HSCT) or HSCT planned within the next year
Major surgical procedures planned during the study period
Oral prednisone or equivalent > 10 mg/day
Participant with history of gastric antral vascular ectasia or gastrointestinal bleed
On anticoagulation therapy (such as prophylaxis anticoagulation, warfarin, direct thrombin inhibitors or other including low molecular weight subcutaneous or intravenous therapeutic heparin), or antiplatelet therapy including aspirin. Use of fish oil supplements within 2 weeks prior to randomization and throughout study is not permitted.
History of any other medical condition that might interfere with a participant's ability to participate in the study
Active clinically significant viral, bacterial, or fungal infection, or any episode of infection requiring hospitalization within 4 weeks prior to screening
Use of cyclophosphamide ≤ 6 months from screening
Use of nintedanib or pirfenidone ≤ 28 days from screening
Recent scleroderma renal crisis < 6 months before screening
Use of tocilizumab ≤ 2 months from screening
Has received any nonlive vaccine starting from 14 days prior to study intervention or is scheduled to receive any nonlive vaccine through 30 days following study intervention. Exception: COVID-19 vaccine may be administered.