SIMILAR Trial: Fostamatinib for Lung Transplant Patients with Donor-Specific Antibodies
This study, called SIMILAR, is testing a drug called fostamatinib in adults who have received a lung transplant and have developed donor-specific antibodies (DSA). DSA are proteins that can cause the body to reject the new lung. Fostamatinib is given by mouth. The main goal is to see how safe fostamatinib is and how well people tolerate it compared to a placebo (an inactive pill). Researchers will also look for potential benefits of fostamatinib in preventing rejection. You may be eligible if you are an adult (18-99 years old) who has had your first lung transplant and developed DSA. The study aims to enroll 30 participants.
- Study design
- This is an interventional study where participants will be randomly assigned to receive either fostamatinib or a placebo, and neither you nor your doctors will know which you are receiving (blinded).
- What's involved
- You will take fostamatinib or placebo orally, starting at 100 mg daily, increasing to 100 mg twice daily, then 150 mg twice daily over 8 weeks.
- Compensation
- Not stated in the trial record.
- Follow-up
- You will be monitored for 28 additional days after the 8-week treatment period, with the primary outcome measured at 12 weeks.
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NCT06948097
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
Recruiting
PHASE1Ages 18–99InterventionalTreatmentNational Heart, Lung, and Blood Institute (NHLBI)Government-funded
~30 participants
Updated 2026-08-28 on ClinicalTrials.gov
What's tested:fostamatinibPlacebo
At a glance
Recruiting sites
4 of 4 listed sites are recruiting right now
RecruitingSuspended, closed, or not yet open
What they're measuring
Study Drug Discontinuation Rate.
Measured over 12 weeks
Conditions
Where it's being run
4 sites across 4 statesCalifornia1
Maryland1
Utah1
Virginia1
Study leadership
- Sean T Agbor-Enoh, M.D. · PRINCIPAL_INVESTIGATOR · National Heart, Lung, and Blood Institute (NHLBI)
Who to contact
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Do you actually qualify for this trial?
Add a private profile and we'll compare every criterion below against your situation — and tell you which ones are met, uncertain, or excluding.
Eligibility criteria
Inclusion
First time LT recipients
Have provided signed written informed consent, prior to performing any study procedure, including screening procedures.
Age greater than or equal to 18 years
Patients who are positive for de novo DSA that is first reported on or after day 21 post-transplantation in a recipient with no prior history of the same DSA specificity, and who sign informed consent within 30 days of positive test results.
No prior demonstration of DSA specificity at any time point preceding the qualifying positive test (including pre-transplant and post-transplant testing).
Demonstrate no clinical or spirometry signs of allograft dysfunction at the time of enrollment.
Have adequate liver function, as defined by:
Serum aspartate aminotransferase (AST) \<=1.5 x Upper Limit of Normal (ULN) (unless the increased AST is assessed by the Investigator as due to hemolysis) and alanine aminotransferase (ALT) \<=1.5 x ULN.
Absolute neutrophil count \>=1.0 x 10\^9/L.
Hemoglobin \>= 9 g/dL
For women of reproductive potential, have a negative serum pregnancy test during the screening period. Women of reproductive potential are defined as sexually mature women who have not undergone a hysterectomy, bilateral oophorectomy, or tubal occlusion; or who have not been naturally postmenopausal (i.e., who have not menstruated at all for at least the preceding 1 year prior to signing informed consent unrelated to hormonal contraception).
For women of reproductive potential, be abstinent as part of their usual lifestyle, or agree to use 2 effective forms of contraception from the time of giving informed consent, during the study, and for 28 days following the last dose of study treatment. An effective form of contraception is defined as hormonal oral contraceptives, injectables, patches, intrauterine or subdermal contraceptive implants, and barrier methods.
Be willing to comply with all study procedures for the duration of the study.
Exclusion
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,
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.
What this trial measures
- Study Drug Discontinuation Rate.12 weeks
The primary outcome is the number of participants who discontinue the study drug due to adverse events, intolerance, or other reasons during the treatment period.