Abstract Number: PB0578
Meeting: ISTH 2021 Congress
Theme: Hemophilia and Rare Bleeding Disorders » Hemophilia - Clinical
Background: The Phase 3 A-LONG/Kids A-LONG and ASPIRE extension studies evaluated efficacy and safety of extended half-life recombinant factor VIII Fc fusion protein (rFVIIIFc). No patients in Japan were enrolled in Kids A-LONG or previously untreated patients (PUPs) A-LONG studies. The prospective, multicenter, observational FACTs study is designed to evaluate effectiveness of rFVIIIFc in adolescents and children with hemophilia A (Part 1) and summarize the experience of immune tolerance induction (ITI; Part 2) in Japan.
Aims: Present results from the second interim analysis of FACTs Part 1.
Methods: Data from patients <18 years of age with hemophilia A treated with rFVIIIFc were collected at baseline (including retrospective pre-study data) and every 6 months for up to 2 years. The regimen was at the investigator’s discretion. Study participants provided written informed consent and local research ethics committees approved the study.
Results: As of July 4, 2020, 91/100 enrolled patients (from 62 centers) were included in this interim analysis; 16 (18%) were PUPs, 81 had >6 months’ follow-up, and 35 completed 2 years’ follow-up (Table 1). Prior to the study, 5/10 patients with a history of inhibitors underwent ITI with factor VIII (FVIII). Sixty-five (71%) patients had received prophylactic treatment with FVIII; of those, 29 (45%) received FVIII treatment at least 3 times/week. During the study, 49 patients on prophylaxis received rFVIIIFc 2 times/week. Overall, injection frequency was maintained or lower on study with rFVIIIFc compared with pre-study (Table 2). Median spontaneous annualized bleed rate (ABR) on study was 0 (interquartile range: 0–0). Three patients developed inhibitors (PUPs, n=2; minimally treated patient, n=1) with titers of 3.0, 0.8, and 5.2 BU/mL, respectively, and started ITI with rFVIIIFc.
Conclusions: In FACTs Part 1, rFVIIIFc prophylaxis was associated with reduced infusion frequency and low ABR in young Japanese patients, consistent with findings with rFVIIIFc in previous global studies.
All patients (N=91) | |
Median (range) age at rFVIIIFc start, years | 6.7 (0‒17.2) |
Hemophilia severity, n (%) Severe (<1 IU/dL FVIII) Moderate (1–5 IU/dL FVIII) Mild (5–40 IU/dL FVIII) Unknown |
61 (67.0) 22 (24.2) 6 (6.6) 2 (2.2) |
FVIII exposure prior to rFVIIIFc treatment (ED), n (%) 0 1–3 4–20 21–100 101–150 ≥151 Not available |
16 (17.6) 6 (6.6) 6 (6.6) 7 (7.7) 8 (8.8) 47 (51.6) 1 (1.1) |
Family history of inhibitor, n (%) | 8 (8.8) |
ED, exposure day; FVIII, factor VIII; rFVIIIFc, recombinant factor VIII Fc fusion protein. |
On study rFVIIIFc | |||||||||
Every other day (n=2) |
3 times weekly (n=10) |
2 times weekly (n=42) |
Every 3 days (n=2) |
Every 4 days (n=0) |
Every 5 days (n=0) |
Weekly (n=1) | Not available (n=1) | ||
Pre-study FVIII |
Every other day (n=5) | 1 | 0 | 4 | 0 | 0 | 0 | 0 | 0 |
3 times weekly (n=24) | 0 | 8 | 15 | 1 | 0 | 0 | 0 | 0 | |
2 times weekly (n=19) | 0 | 1 | 17 | 1 | 0 | 0 | 0 | 0 | |
Every 3 days (n=2) | 0 | 0 | 1 | 0 | 0 | 0 | 0 | 1 | |
Every 4 days (n=0) | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | |
Every 5 days (n=0) | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | |
Weekly (n=7) |
1 | 0 | 5 | 0 | 0 | 0 | 1 | 0 | |
Not available (n=1) | 0 | 1 | 0 | 0 | 0 | 0 | 0 | 0 | |
*Includes patients with data available pre- and post-baseline (n=58). FVIII, factor VIII; rFVIIIFc, recombinant factor VIII Fc fusion protein. |
To cite this abstract in AMA style:
Kobayashi M, Nogami K, Park Y-, Shiraishi M, Takatoku M, Matsushita T. Evaluating the Effectiveness of Recombinant Factor VIII Fc Fusion Protein (rFVIIIFc) in Adolescents and Children with Hemophilia A in the Real World in Japan: Interim Analysis of the Multicenter, Observational Fc Adolescent and Children Treatment Study (FACTs) [abstract]. Res Pract Thromb Haemost. 2021; 5 (Suppl 2). https://abstracts.isth.org/abstract/evaluating-the-effectiveness-of-recombinant-factor-viii-fc-fusion-protein-rfviiifc-in-adolescents-and-children-with-hemophilia-a-in-the-real-world-in-japan-interim-analysis-of-the-multicenter-obse/. Accessed March 22, 2024.« Back to ISTH 2021 Congress
ISTH Congress Abstracts - https://abstracts.isth.org/abstract/evaluating-the-effectiveness-of-recombinant-factor-viii-fc-fusion-protein-rfviiifc-in-adolescents-and-children-with-hemophilia-a-in-the-real-world-in-japan-interim-analysis-of-the-multicenter-obse/