[18F]PF-06445974 to Image PDE4B in Major Depressive Disorder Using PET

Background: Major depressive disorder (MDD) is a psychiatric condition. People with MDD have occasional bouts of depressive symptoms; these bouts are called major depressive episodes (MDEs). Researchers want to know if people having MDEs have lower levels of an enzyme called PDE4B in their brains. Primary Objective: To determine whether PDE4B is reduced in the brains of individuals with MDD experiencing a major depressive episode (MDE). Secondary Objectives: To determine the optimal length of scanning and the retest variability and reliability of \[18F\]PF-06445974, and whether PDE4B binding correlates with clinical rating scales. To measure if PDE4B radioligand binding can be blocked by taking apremilast. Eligibility: People aged 18-70 years with MDD. Healthy volunteers are also needed. Design: Participants will have up to 5 clinic visits. Participants will be screened. They will have a physical exam with blood tests. They will have a test of their heart function. Some participants may have a psychiatric assessment; they will answer questions about their state of mind and related topics. Participants will have magnetic resonance imaging (MRI) of the brain. They will lie on a table that slides into a metal cylinder. Participants will have a positron emission tomography (PET) scan. A needle will be used to guide a thin plastic tube (catheter) into a vein in one arm. An experimental substance called a radioactive tracer (\[18F\]PF-06445974) will be injected through the catheter. Participants will lie on a table that slides into a doughnut-shaped machine. The scan will last up to 4 hours with a 15-minute break. Participants blood pressure, heart rate, and breathing will be monitored before, during, and after the PET scan. A second catheter will be inserted in the artery of the wrist so blood can be drawn during the scan. Some participants may return for a second PET scan; have a lung scan or receive apremilast. https://nimhcontent.nimh.nih.gov/start/surveys/?s=KE88DXXPLDFHHTF8

NCT Number	NCT05703685
Lead Sponsor	National Institute of Mental Health (NIMH)
Conditions	Depression
Enrollment	108 participants
Start Date	2023-06-22
Primary Completion	2028-10-03 (estimated)
Study Completion	2029-04-11 (estimated)
Updated on ClinicalTrials.gov	2026-07-02