Abstract Number: PB0500
Meeting: ISTH 2021 Congress
Background: In 2016, the SIPPET study reported that in previously untreated patients (PUPs) with severe haemophilia A (HA) the choice of plasma-derived FVIII (pdFVIII) products in the first 50 exposure days (EDs) is associated with a significantly lower incidence of inhibitors compared to recombinant FVIII (rFVIII) products.1 However, the choice of FVIII product class after this high‐risk period has been subject of debate. It has been established that switching products in multi-transfused patients (> 150 EDs) does not affect the risk of inhibitor development which becomes approximately 100 times lower in these previously treated patients (PTPs).
Aims: To investigate whether a switch from pdFVIII to rFVIII in PUPs after the early high‐risk period would follow the expected low-risk pattern of inhibitor incidence as previously reported in PTPs, or a novel peak of inhibitors would appear.
Methods: We designed a survey on the ISTH REDCap platform2 to investigate the rate of novel inhibitors after the switching of PUPs from pdFVIII to rFVIII between 50 and 150 EDs (Figure 1.A). Centres who did the switch after the SIPPET publication were identified and invited to participate in this observational cohort study on PUPs under 6 years old with severe HA, who have been switched according to this strategy.
Results: To date, 11 Turkish centres, 1 Iranian centre, and 1 German centre have participated in this study. Fourty-seven surveys were analysed, among which 39 patients satisfied all eligibility criteria (Figure 1.B). Patients were switched at a median of 60 (54 – 71) EDs and received a median of 111 (84 – 222) EDs with rFVIII after the switch. None of these 39 patients developed an inhibitor after the switch (Table 1).
|Eligible patients||ED of switch||EDs with rFVIII after switch||Total EDs with rFVIII at survey retrieval||Inhibitor after switch|
|39||60||54 – 71||111||84 – 222||178||144 – 279||0|
Conclusions: Preliminary results from the first 39 patients enrolled in the PUP-SWITCH study did not show an additional risk of inhibitor incidence upon switch from pdFVIII to rFVIII.
To cite this abstract in AMA style:Miri S, Kavakli RK, Halimeh S, Nicolò G, Gürlek Gökçebay D, Özbek NY, Celkan T, Karimi M, Shahsavani A, Gunes BT, Atabay B, Kaya Z, Ay Y, Oymak Y, Akbayram S, Yılmaz B, Kazanci E, Mannucci PM, Rosendaal FR, Peyvandi F, PUP-SWITCH Study Group . Inhibitor Development upon Switch from Plasma-derived to Recombinant FVIII in PUPs with Severe Haemophilia A: Preliminary Analysis from the PUP-SWITCH Study [abstract]. Res Pract Thromb Haemost. 2021; 5 (Suppl 1). https://abstracts.isth.org/abstract/inhibitor-development-upon-switch-from-plasma-derived-to-recombinant-fviii-in-pups-with-severe-haemophilia-a-preliminary-analysis-from-the-pup-switch-study/. Accessed September 16, 2021.
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