Ruxolitinib in Treating Patients With Hypereosinophilic Syndrome or Primary Eosinophilic Disorders

This trial is testing whether ruxolitinib — a drug that blocks certain inflammatory signals — can effectively treat hypereosinophilic syndrome (HES) and related conditions, which are disorders where the body produces too many eosinophils (a type of white blood cell), causing damage to organs and tissues. **You may be eligible if...** - You have idiopathic hypereosinophilic syndrome with blood eosinophil counts above 1,500 per cubic millimeter on at least 2 occasions in the past 3 months - Your condition depends on steroids, you cannot tolerate them, or other treatments have not worked - You have a primary eosinophilic disorder that has not responded to standard therapies **You may NOT be eligible if...** - Your condition is well-controlled with current treatment without relapse - You have another cause of elevated eosinophils (such as parasites or certain cancers) - You have serious infections or organ problems that would make the drug unsafe Talk to your doctor to see if this trial is right for you.