Rituximab in the Treatment of Acquired Hemophilia a (AHA): A Novel Eradicating Therapy?

Abstract

Background: Acquired inhibitors against factor VIII (FVIII), also termed Acquired Hemophilia A (AHA), occur rarely in the nonhemophilic population. Its incidence is approximately 1 to 4 per million/year. The incidence of AHA increases with age and a major peak is seeing in patients aged 68 to 80 years. These autoantibodies are associated with high rate of morbidity (90% of severe bleeding in affected patients) and mortality (8–22% of the cases). The diagnosis of AHA is based on the demonstration of an isolated prolongation of the activated partial thromboplastin time (APTT), not corrected by incubating the patient’s plasma with equal volumes of normal plasma (mixing study), associated with FVIII reduced levels and formal evidence of a FVIII inhibitor in a patient with no previous personal or family history of bleeding. In approximately half of affected patients there is no identification of relevant concomitant diseases. The bleeding pattern in AHA is characterized by hemorrhages into the skin, muscles or soft tissues, and mucous membranes. Rituximab (Mabthera®; Roche; Switzerland) is a chimeric monoclonal antibody against the pan B-cell antigen CD20 that induces a rapid in vivo depletion of normal B lymphocytes. Primarily developed to treat B-cell non Hodgkin Lymphomas, more recently, Rituximab has demonstrated effectiveness in a number of autoantibody-mediated diseases including AHA. Case Report: We treated a 69-year-old diabetic and hypertensive patient with AHA. In March 2007, the diagnosis was made by a prolonged APTT (ratio 2.74 sec), not corrected by the mixing study, and FVIII inhibitor 320 Bethesda units. The patient had no evidence of malignancy, autoimmune disease or use of drugs. His bleeding manifestations were large ecchymosis of upper and lower extremities for almost a year, and at admission to the hospital, a hematoma of left calf and gengival bleeding. First line therapy consisted of steroids and cyclophosphamide (CFM). The steroids had to be withdraw after one week of use, because of very difficult glycemic control. The CFM were use in the dose of 50mg/day adding an total accumulative dose of 3g. This protocol were used considering the incapacity of the patient to tolerate higher dose of CFM due to leukopenia. After treatment, the patient was evaluated and neither normalization of APTT nor improvement of clinical findings happened. Therefore, considering all the above, it was decided to use Rituximab 375mg/m2, weekly, for four weeks. In June 2007, the patient received and tolereted very well all the infusions. In August 2007, he had no bleeding symptoms and his APTT was normal. At his laterest visit to the clinic in July 2008, an year after finishing his treatment, he was still very well and his bleeding tests were normal. Conclusion: Rituximab should be considered a treatment option for AHA.