PB1194 - Daratumumab as a Well-Tolerated and Effective Treatment Option for Acquired Hemophilia A in a Frail Elderly Patient

Background: Acquired hemophilia A (AHA) is a rare serious bleeding disorder caused by autoantibodies inhibiting coagulation factor VIII (FVIII). The one-year survival rate is approximately 68%, and worse if the inhibitor cannot be eliminated. Complications primarily arise from the immunosuppressive therapy. AHA mainly affects elderly patients. Due to their increased susceptibility to complications there is a need to find a treatment suitable for frail elderly patients.

Aims: We here present a case of a 83-year-old female patient with multiple health conditions with AHA and high levels of FVIII inhibitor, who received daratumumab to treat AHA.

Methods: Recombinant coagulation factor VIIa (rFVIIa) was used for initial hemostatic therapy, followed by emicizumab to maintain hemostasis. However, the patient's frailty limited the immunosuppressive therapy. It was therefore decided to treat the AHA off-label with subcutaneous daratumumab on an outpatient basis.

Results: The patient presented with spontaneous subcutaneous bleeds. Bleeding was
controlled with rFVIIa and emicizumab. Maximum inhibitor titer was 2653 Bethesda Units (BU)/ml after starting treatment with prednisolone and rituximab. As intensive outpatient immunosuppressive therapy was not feasible, rituximab and additional cyclophosphamide were discontinued. Instead, the patient received daratumumab weekly initially, followed by every 2nd week and finally every 4th week. Prednisolone was tapered off during weekly treatment with daratumumab. After six months the inhibitor was eliminated, emicizumab was discontinued and after seven months the patient‘s FVIII activity was fully restored at 104%. No infusion-related reaction and no infection was observed.

Conclusion(s): The inhibitor was eliminated effectively using daratumumab as an off-label treatment approach, which led to a complete recovery of the patient's physiological hemostasis. The treatment with daratumumab and emicizumab was well-tolerated by this frail elderly patient However, clinical studies are needed to establish safe and effective treatment regimens using daratumumab for vulnerable patients with AHA.