Could a common vitamin a drug tame a deadly immune storm?

This study tests a drug called all-trans retinoic acid (ATRA) as a first treatment for hemophagocytic lymphohistiocytosis (HLH), a rare but life-threatening condition where the immune system goes into overdrive. ATRA is an oral medication already used for other blood diseases and may calm the immune response with fewer side effects than current harsh treatments. About 30 adults with newly diagnosed or untreated active HLH will receive ATRA, and researchers will check if it improves symptoms and blood markers at 4 and 8 weeks.