Emicizumab therapy leading to resolution of a massive iliopsoas haematoma and allowing removal of port-a-cath in an adolescent with severe haemophilia A, chronic high titre FVIII inhibitor and previous pulmonary embolism

Abstract

Introduction: Inhibitor formation in children with severe haemophilia A remains the most significant complication of FVIII therapy. Treatment of bleeding episodes in individuals with a FVIII inhibitor utilises by-passing agents (BPA) such as recombinant activated factor VII and activated prothrombin complex concentrates. Recent studies have reported prevention of bleeds in patients with inhibitors using a novel monoclonal antibody, Emicizumab. We report a case where Emicizumab therapy lead to the resolution of a massive retroperitoneal haematoma originating from the iliopsoas muscle, and allowed removal of a port-a- cath. Methods: Case report. Results: A 15-year- old male, who had failed immune tolerisation, and had a chronic high titre FVIII inhibitor (maximum 3328 BU/mL) presented in haemodynamic shock with a massive retroperitoneal bleed (estimated 2L, nadir Hb 64 g/L) despite daily BPA prophylaxis. He had a history of recurrent musculoskeletal bleeds (ABR >30), chronic arthropathy (HJHS 25) with subsequent mobility issues, regularly missed school due to bleeds, and previously suffered a pulmonary embolus (PE) during BPA therapy. The acute iliopsoas bleed was controlled with BPA therapy, and a port-a- cath was re-inserted (complicated by a large wound haematoma) to facilitate intensified haemostatic therapy. An application for compassionate use Emicizumab was lodged a month before the bleed. Emicizumab therapy (3 mg/kg weekly sc injections for 4 weeks and 1.5 mg/kg weekly injections thereafter) was approved and commenced 14 weeks after the initial bleed. On Emicizumab the TEG normalised, the haematoma (pre-Emicizumab size 6 x 4 x 5 cm) fully resolved over 19 months, the ABR was 0, school attendance increased and the port-a- cath was removed without BPA therapy. No complications or adverse events were encountered on Emicizumab. Discussion/Conclusion: Emicizumab is a novel monoclonal antibody that bridges FIXa with FX, activating FX and thereby bypassing FVIII. This case demonstrates the safe and effective use of Emicizumab for over 20 months in an individual with a prior history of PE complicating his severe haemophilia A with a chronic high titre FVIII inhibitor.L6264148342019-02-22 <br />