Syk Inhibition in MItigating Lung Allograft Rejection (SIMILAR): A Trial to Evaluate the Safety and Tolerability of Fostamatinib in Lung Transplant Patients With Donor-Specific Antibodies

Starting soon · Phase 1 · Has a placebo group

Conditions studied: Lung Transplantation

In brief

Background: People who have lung transplants often survive 6 or 7 years. But some people develop donor-specific antibodies (DSA) after their transplants; antibodies are proteins that attack foreign invaders in the body. Antibodies typically kill viruses and other agents that can cause disease. But when the antibodies attack a transplanted organ, they can cause the body to reject the new tissues. People who develop DSA after a transplant have a higher risk of death within 1 year. Objective: To test a drug called fostamatinib in people who develop DSA after a lung transplant. Eligibility: Adults aged 18 and older who developed DSA after a lung transplant. Design: Participants will continue with their standard care after a transplant. Fostamatinib is a pill taken by mouth. Some participants will take the study drug along with their standard care; others will take a placebo. A placebo is a pill that looks just like the real drug but contains no medicine. All participants will take 1 pill per day for 2 weeks. Then they will take 2 pills per day for the next 6 weeks. Participants will have clinic visits every 2 weeks while taking their pills. They will have a physical exam, with blood and urine tests, during each visit. If participants have fluid samples collected from their airways during their standard treatment, some extra fluid may be collected for this study. Participants will have a follow-up visit 4 weeks after they stop taking their pills.

Key facts

Study ID

NCT06948097

Run by

National Heart, Lung, and Blood Institute (NHLBI)

People needed

30

Starts

2026-08-13

Expected to finish

2028-07-14

Last updated by the study team

2026-08-10

Who can join

Age: 18 and older, up to 99. Sex: any. Healthy volunteers: not accepted.

You may not qualify if…

• An individual who meets any of the following criteria will be excluded from participation in this study:
• Have a significant medical condition that confers an unacceptable risk to participating in the study, and/or that could confound the interpretation of the study data. Such significant medical conditions include, but are not limited to the following:
• History of neutropenia (benign ethnic neutropenia and/or acquired neutropenia) within 90 days of screening.
• History of posterior reversible encephalopathy syndrome (PRES)
• History of poorly controlled hypertension or hypertensive crises (defined as systolic blood pressure >=180 mmHg or average diastolic blood pressure >=120 mmHg based on an average of 3 blood pressure readings despite adequate antihypertensive therapy) unless controlled for >90 days prior to enrollment
• History of positive post-transplant active hepatitis C and/or hepatitis B viral infection.
• History of drug-induced cholestatic hepatitis within 90 days of screening.
• History of any primary malignancy within the last 5 years, with the exception of: curatively treated non-melanomatous skin cancer; curatively treated cervical or breast carcinoma in situ; or other primary tumor treated with curative intent, no known active disease present, and no treatment administered during the last 5 years.
• Testing positive for human immunodeficiency virus 1 or 2 Ab with evidence for ongoing active infection (i.e., CD 4 count <400/microliter and viral load >100,000 copies/ml) on antiretroviral therapy.
• Current or recent history of psychiatric disorder within the last 90 days that, in the opinion of the Investigator or Medical Monitor, could compromise the ability of the subject to cooperate with study visits and procedures.
• Are currently enrolled in another therapeutic clinical trial involving ongoing therapy with any investigational or marketed product or placebo.
• Having had a prior lung or any organ transplant.
• Currently pregnant or lactating.
• Estimated glomerular filtration (eGFR) rate less than 30 mL/min.
• Any grade 3 diarrhea within 90 days of screening.
• Subjects on strong CYP3A4 inducers. Glucocorticoids are standard transplant therapies and are not excluded. Relevant strong inducers include apalutamide, carbamazepine, encorafenib, enzalutamide, fosphenytoin, lumacaftor, lumacaftor-ivacaftor, mitotane,
• phenytoin, rifampin (rifampicin) - (https://www.uptodate.com/contents/image?imageKey=CARD%2F76992)
• Subjects who have received prior treatment for DSA within 6 months of screening. Patients on an on-going therapy for first-time DSA are eligible, if screening is performed within 30 days of positive DSA results.

Where it is running

• Stanford University School of Medicine — Stanford, California, United States
• Johns Hopkins University School of Medicine — Baltimore, Maryland, United States
• National Heart, Lung and Blood Institute (NHLBI) — Bethesda, Maryland, United States
• University of Utah Health — Salt Lake City, Utah, United States
• Inova Health System Foundation — Falls Church, Virginia, United States

Full record on ClinicalTrials.gov

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