Acquired factor VIII inhibitors in non-haemophilic patients: clinical experience of 15 cases

We retrospectively analysed 15 non-haemophilic patients with acquired factor VIII inhibitors seen in our regional haemophilia centre. The median age was 55 years (range: 21-80). About 70% of patients older than 50 were male, while all five patients younger than 50 were female. The most common underlying condition was pregnancy or postpartum status (20%). About 27% of cases had no identifiable underlying condition. About 27% of patients had medical conditions that were unlikely to be related to acquired inhibitors. The most frequent presenting symptom was spontaneous haemorrhage of soft tissues, skin or joints. Twelve of 13 (92.3%) evaluable patients achieved complete remission (CR) with prednisone alone and/or combined prednisone and cyclophosphamide, but their clinical courses were highly variable. The median time to response was 21.5 weeks (range: 2-176) and the median treatment duration was 9 months (range: 1.25-66). All six patients treated with prednisone initially, and then combined prednisone/cyclophosphamide if no response (NR) to prednisone within 3-4 months (three patients), achieved CR; while four of five patients treated initially with combined prednisone/cyclophosphamide had CR. Patients older than 50 years had a similar response rate, median time to response and median treatment duration as did patients younger than 50 years (83% vs. 100%; 21.5 vs. 32 weeks, and 8 vs 16.5 months, respectively). Furthermore, the differences in the median time to response and treatment duration for patients with high or low baseline or peak inhibitor titres were negligible. Only one patient died of a treatment-related pulmonary aspergillosis 18 months after an acquired inhibitor was diagnosed. None of these patients died of bleeding complications. In conclusion, our patients with acquired FVIII inhibitor had highly variable clinical courses and responses to steroid or immunosuppressive therapy. The inhibitors in the majority of patients resolved in less than 6 months although in two cases it persisted for longer than 1 year before resolving. Treatment with prednisone alone as first line, then combined prednisone with cyclophosphamide if NR to prednisone seemed equally effective when compared with using combined prednisone and cyclophosphamide initially. Further studies of newer therapeutic agents such as 2-chlorodeoxyadenosine (2-CDA) and rituximab are warranted for patients refractory to conventional immunosupressive therapy.