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Extension Study With rVIII-SingleChain in Previously Untreated Patients (PUPs) With Severe Haemophilia A

Mahlangu J, Mancuso ME, Fischer K, Djambas Khayat C, Carvalho M, Karim FA, Jobe S, Lucas S et al.

Haemophilia : the official journal of the World Federation of Hemophilia, 2025

2 citations

Abstract

Introduction: Clinical trials and real-world evidence have demonstrated the efficacy and safety of rVIII-SingleChain in previously treated patients with haemophilia A.

Aim: To investigate the safety and efficacy of rVIII-SingleChain in previously untreated patients (PUPs).

Methods: In an open-label, phase 3, extension study, PUPs with severe haemophilia A (FVIII <1%) received rVIII-SingleChain prophylactically or on-demand. The primary endpoints were incidence of high-titre (HT) inhibitor formation to FVIII, treatment success for major bleeding episodes and annualised spontaneous bleeding rate (AsBR).

Results: Twenty-four PUPs (median age 1 year [range 0-5]) were treated with rVIII-SingleChain; median time on study was 35.0 months (range 2.4-54.0). Overall, six PUPs developed a HT inhibitor (>5 BU/mL) and six developed a low-titre (LT) inhibitor (≤5 BU/mL). The median number of exposure days at inhibitor development was 10 (interquartile range [IQR] 5.0-14.0). Of 11 inhibitor-positive PUPs (five HT, six LT) who continued rVIII-SingleChain therapy, nine (81.8%; three HT, six LT) achieved inhibitor eradication (<0.6 BU/mL). Median time to eradication was 14.3 weeks (IQR 9.8-53.8). Seventeen treatment-emergent adverse events in 12 PUPs (50.0%) were related to rVIII-SingleChain, mainly inhibitor development (14/17 events). Treatment was successful (haemostatic efficacy rated excellent or good) for 290/315 bleeding events (92.1%). During prophylactic therapy, inhibitor-negative…

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Evidence Hub reads this as a clinical trial, done in people. Its evidence level is 3 of 5 (Moderate · trial / cohort / secondary analysis). Trials without a large randomized design, cohorts and secondary analyses give moderate evidence.

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