Phase I/II Open Label Study of Belumosudil Mesylate Alone, and in Combination With Dexamethasone, in Patients With Relapsed/Refractory Multiple Myeloma

This Phase I/II trial is testing belumosudil mesylate — alone or combined with dexamethasone (a steroid) — in patients with multiple myeloma that has returned or stopped responding to prior treatments. Belumosudil is normally used for graft-versus-host disease and is being explored here as a new option for myeloma. **You may be eligible if...** - You have been diagnosed with multiple myeloma and the disease has relapsed or is no longer responding to treatment - You have had prior treatment including a proteasome inhibitor, an immunomodulatory drug, and an anti-CD38 antibody - You have measurable disease (detectable myeloma in blood or urine) - Your organ function (heart, kidneys, liver, blood counts) meets minimum thresholds - Your overall health is adequate for treatment **You may NOT be eligible if...** - You have active cancer spreading to the brain or spinal fluid - You have active or uncontrolled infection (including hepatitis B, C, or HIV) - You have received an allogeneic (donor) stem cell transplant - You have severe lung disease or other serious heart/organ conditions - You are pregnant or breastfeeding Talk to your doctor to see if this trial is right for you.