Biologics and Drug‐Induced Immunogenicity: A Case Report of Acquired Hemophilia A Presenting After Immunotherapy

Acquired hemophilia A is a rare, potentially life-threatening bleeding disorder caused by autoantibody inhibitors to coagulation factor VIII. We report the case of an 87-year-old female who presented with symptomatic bleeding and was subsequently diagnosed with acquired hemophilia A. Her clinical course, treatment, and recovery are described. Notably, her recent medication history included ixekizumab, an immunotherapy agent used for an underlying autoimmune condition, and a course of antibiotics, complicating the identification of a definitive etiology. This case raises the possibility of ixekizumab as a potential novel pharmacologic trigger for AHA. We highlight challenges in establishing causality and review current literature on hematologic manifestations of drug-induced autoimmunity, with a focus on biologic immunotherapies.