Testing the Effectiveness of the Anti-cancer Drug, Mirdametinib, in Treating Relapsed, Refractory Chronic Lymphocytic Leukemia

This study tests a drug called mirdametinib — which blocks a specific cancer growth signal — in people with chronic lymphocytic leukemia (CLL) or small lymphocytic lymphoma (SLL) whose cancer came back or stopped responding to previous treatments. **You may be eligible if...** - You have been diagnosed with CLL or SLL confirmed by blood or tissue testing - Your cancer has relapsed (come back) or is no longer responding to treatment - Your cancer shows signs that require treatment, such as enlarged spleen, rapidly increasing blood cell counts, significant fatigue, or other symptoms - You are in reasonably good health overall **You may NOT be eligible if...** - Your cancer is well controlled and does not yet require treatment - You have not previously tried standard CLL therapies - You have significant other health conditions that could interfere with treatment Talk to your doctor to see if this trial is right for you.