BackgroundImmune tolerance induction (ITI) therapy is currently unaffordable in China. Management of hemophilia A children with high‐titer inhibitor is therefore a challenge.AimTo describe the ITI strategy using plasma‐derived factor VIII/von Willebrand factor concentrate (pdFVIII/VWF) +/− immunosuppression and to report its efficacy in children with hemophilia A having poor‐risk status for ITI success.MethodsA prospective pilot study on children with hemophilia A having poor‐risk status (all with at least inhibitor titer > 10 BU pre‐ITI initiation). Patients received ~50 IU/kg FVIII every other day using domestic intermediate purity pdFVIII/VWF products, either alone or in combination with rituximab +/− prednisone.ResultsSixteen patients with median age 2.9 (range, 2.2‐13.2) years and median pre‐ITI inhibitor titer 30.7 (range, 10.4‐128) BU were enrolled. Analysis at median 14.7 (range, 12.4‐22.6) months’ follow‐up showed a total response rate of 87.5%. This included success (achieving inhibitor < 0.6 BU) in 13 patients (81.3%) in a median of 8.8 (range, 3.2‐11.8) months, and partial success (achieving inhibitor < 5 BU but > 0.6BU) in 1 (6.3%). Compared to the pre‐ITI period, the mean bleeds/month during ITI was 0.51 (64.0% reduction), and joint bleeds/month was 0.34 (64.3% reduction). This low‐dose ITI strategy cost less by 70% to 87% than that for the high‐dose FVIII regimen. No severe adverse events were observed.ConclusionThis low‐dose ITI strategy of pdFVIII/VWF +/− immunosuppression achieved relatively satisfactory outcomes in children with hemophilia A inhibitor having poor‐risk status. This low‐dose regimen showed economic advantages and is therefore suitable for using in China. However, further study in a larger cohort with a longer follow‐up time is needed.

Introduction: Development of haemophilia B inhibitors (HBI) results in the ineffectiveness of FIX replacement therapy. Inhibitor eradication by immune tolerance induction (ITI) is therefore necessary. In HBI, ITI even at high FIX dose is less effective and has a higher risk of severe complications. Aim: To characterize clinical features and outcome of ITI on HBI. Methods: This retrospective study was conducted in Haemophilia Paediatric Comprehensive Care Centre of China. We used low-dose ITI (25-50 FIX IU/kg/three-timesweekly to every-other-day) with domestic prothrombin complex concentrate (PCC), combined with two successive immunosuppressive (IS) regimens.Results: Sixteen HBI children, representing 5.7% of all and 14.4% of our severe registered HB patients, were enroled. Seven cases reported allergic reactions (ARs) proximal to inhibitor development. The historic peak inhibitor titre was median 54.2 (range 4.7-512) BU, and 15 (93.8%) had high-titre inhibitors. Twelve patients adherent to ITI were analysable. Of the nine ITI patients who received rituximab/prednisone (IS Regimen-1), four achieved tolerization in 1.4-43.3 months. Two subsequently relapsed but re-tolerized after a second course of IS Regimen-1. During ITI, the median treated bleed was .39/month (82.7% reduction from before ITI), and the incidence of AR and nephrotic syndrome (NS) complications was each at 22% (2/9). Three ITI patients