Preliminary report on prophylaxis with emicizumab in Polish infants with hemophilia A

Introduction: ICH and early-life bleeding remain major threats in infants with severe HA. In infancy, intravenous FVIII prophylaxis may be delayed because of difficult venous access and the potential need for central venous access devices. Subcutaneous emicizumab enables prophylaxis independent of venous access. To describe early Polish multicentre real-world experience with emicizumab prophylaxis in infants with severe HA following its introduction into the national treatment programme. Material and methods: This retrospective national multicentre questionnaire-based survey was conducted among Polish paediatric hemophilia care centres. Severe HA was defined as FVIII activity <1 IU/dL or <1% of normal activity. Infants who started emicizumab prophylaxis by the predefined data cut-off and had available pre- and post-emicizumab follow-up data were included. Reported treated bleeding episodes before and after emicizumab initiation were described using individual patient data and cABR (treated bleeds/observation months × 12). Paired before-after binary outcomes were explored using McNemar's exact test, and paired cABR values were compared using the Wilcoxon signed-rank test. p values were interpreted as exploratory. Results: Six centres reported 13 infants considered for emicizumab prophylaxis; 11 infants were included in the analysis because they had started emicizumab by the data cut-off and had follow-up data. The remaining two infants were excluded because treatment had not yet started. All analysed infants were FVIII inhibitor negative. Emicizumab was initiated at 2–10 months of age (median 7 months). Before emicizumab, 10/11 infants had reported treated bleeds over 66 infant-months, including one ICH. During 105 infant-months of emicizumab follow-up (5–12 months per patient), 2/11 infants had reported treated soft-tissue bleeds; no ICH and no adverse events were reported. In exploratory paired analyses, the proportion of infants with reported treated bleeds decreased according to McNemar's exact test ( p = 0.0078), and individual cABR decreased according to the Wilcoxon signed-rank test ( p = 0.002). No AE/SAE were reported. Conclusions: In this small national multicentre questionnaire-based survey, emicizumab prophylaxis in infants with severe HA was associated with fewer reported treated bleeding episodes during short follow-up. No ICH or adverse events were reported during emicizumab exposure, but the study was not powered to assess rare outcomes or long-term safety.