Extended half-life factor VIII concentrates in adults with hemophilia A: Comparative pharmacokinetics of two products

A French Real-World Evidence Study Evaluating the Efficacy, Safety, and Pharmacokinetic Parameters of rVIII-SingleChain in Patients with Hemophilia A Receiving Prophylaxis

BACKGROUND

 rVIII-SingleChain is a recombinant factor VIII (FVIII) with increased binding affinity to von Willebrand factor compared with other FVIII products. rVIII-SingleChain is indicated for the treatment and prevention of bleeding episodes in patients with hemophilia A.

OBJECTIVES

 To collect real-world evidence data from patients treated with rVIII-SingleChain to confirm the efficacy and safety established in the clinical trial program and carry out a population pharmacokinetic (PK) analysis.

PATIENTS/METHODS

 This interim analysis includes data, collected between January 2018 - September 2021, from patients treated with rVIII-SingleChain prophylaxis at French Hemophilia Treatment centers. Data on annualized bleeding rates, dosing frequency, and consumption before and after switching to rVIII-SingleChain were recorded. A population PK analysis was also conducted to estimate PK parameters.

RESULTS

 Overall, 43 patients switched to prophylaxis with rVIII-SingleChain either from a previous prophylaxis regimen or from on-demand treatment. Following the switch to rVIII-SingleChain, patients maintained excellent bleed control. After switching to rVIII-SingleChain, most patients maintained or reduced their regimen. Interestingly, a majority of patients treated >2 ×/weekly with a standard half-life FVIII reduced both injection frequency and FVIII consumption with rVIII-SingleChain. A PK analysis revealed a lower clearance of rVIII-SingleChain (1.9 vs. 2.1 dL/h) and a longer half-life both in adolescents/adults (n = 28) and pediatric (n = 6) patients (15.5 and 11.9 hours, respectively vs. 14.5 and 10.3 hours) than previously reported.

CONCLUSIONS

 Patients who switched to rVIII-SingleChain prophylaxis demonstrated excellent bleed control and a reduction in infusion frequency. A population PK analysis revealed improved PK parameters compared with those reported in the clinical trial.

Healthcare costs among hemophilia A patients in the United States treated with rurioctocog alfa pegol (FVIII-PEG) or antihemophilic factor (recombinant), FC fusion protein (rFVIIIFc) using real-world data

AIMS

To compare healthcare costs in patients with non-inhibitor hemophilia A treated with Rurioctocog Alfa Pegol (FVIII-PEG) versus Antihemophilic Factor (Recombinant), FC Fusion Protein (rFVIIIFc).

MATERIALS AND METHODS

Administrative claims data from the Merative MarketScan Commercial (Commerical) and Medicaid (Medicaid) databases were used for these analyses. Males with non-inhibitor hemophilia A treated with FVIII-PEG or rFVIIIFc from 1 January 2016 to 31 March 2021 were identified (earliest treatment = index). Patients were required to have continuous database enrollment for six months before and after the index date. Follow-up was variable in length until disenrollment or study end. All-cause and hemophilia-related healthcare costs were reported per-patient per month [PPPM] and the average weekly dose during follow-up was compared between treatment groups. Generalized linear regressions were used to estimate multivariable-adjusted differences in total costs and weekly dosage in the two treatment groups.

RESULTS

A total of 131 FVIII-PEG (66 Commercial; 65 Medicaid) and 204 rFVIIIFc (111 Commercial; 93 Medicaid) patients were eligible. Mean age was 20.5 and 24.4 for FVIII-PEG and rFVIIIFc in Commercial and 14.9 and 17.5 for FVIII-PEG and rFVIIIFc in Medicaid. PPPM mean (standard deviations [SD]) total healthcare costs in Commercially insured patients were $35,868 [$21,717] for FVIII-PEG vs $40,424 [$25,882] for rFVIIIFc. Costs in Medicaid were $27,495 [$23,243] for FVIII-PEG vs $30,237 [$28,430] for rFVIIIFc. After adjusting for baseline characteristics, the costs for rFVIIIFc (vs FVIII-PEG) were higher by $5,215 in Commercial and $3,895 in Medicaid, but the differences were not statistically significant (p > 0.05). Similar findings were observed for hemophilia-specific healthcare costs. The adjusted mean weekly dose was 6,047 vs 4,892 IU, p = 0.21 for FVIII-PEG vs rFVIIIFc in Commercial and 5,549 vs 7,228 IU, p = 0.07 for FVIII-PEG vs rFVIIIFc in Medicaid.

CONCLUSIONS

Healthcare costs and treatment dosing were similar (p > 0.05) for non-inhibitor hemophilia A patients treated with FVIII-PEG and rFVIIIFc.

Current Understanding of Inherited Modifiers of FVIII Pharmacokinetic Variation

The inherited bleeding disorder hemophilia A involves the quantitative deficiency of the coagulation cofactor factor VIII (FVIII). Prophylactic treatment of severe hemophilia A patients with FVIII concentrates aims to reduce the frequency of spontaneous joint bleeding and requires personalized tailoring of dosing regimens to account for the substantial inter-individual variability of FVIII pharmacokinetics. The strong reproducibility of FVIII pharmacokinetic (PK) metrics between repeat analyses in the same individual suggests this trait is genetically regulated. While the influence of plasma von Willebrand factor antigen (VWF:Ag) levels, ABO blood group, and patient age on FVIII PK is well established, estimates suggest these factors account for less than 35% of the overall variability in FVIII PK. More recent studies have identified genetic determinants that modify FVIII clearance or half-life including VWF gene variants that impair VWF-FVIII binding resulting in the accelerated clearance of VWF-free FVIII. Additionally, variants in receptors that regulate the clearance of FVIII or the VWF-FVIII complex have been associated with FVIII PK. The characterization of genetic modifiers of FVIII PK will provide mechanistic insight into a subject of clinical significance and support the development of personalized treatment plans for patients with hemophilia A.

Comparison of Real-World Dose and Consumption for Two Extended Half-Life Recombinant Factor VIII Products for the Treatment of Hemophilia A in the United States

Background

US patients with hemophilia A can receive prophylaxis with extended half-life recombinant factor VIII (rFVIII) products, including efmoroctocog alfa (fragment crystallizable fusion protein) and rurioctocog alfa pegol (antihemophilic factor [recombinant], PEGylated).

Objective

To evaluate dosing patterns and weekly consumption of extended half-life rFVIII products in the United States.

Methods

We performed a retrospective analysis using the US Specialty Pharmacy Database (2015–2018). Included patients had a diagnosis of hemophilia A, ≥2 consecutive monthly claims for efmoroctocog alfa or rurioctocog alfa pegol for prophylaxis, and weight data. Outcome measures included weekly dosing frequency and dispensed weekly dose.

Results

The analysis included 774 patients (efmoroctocog alfa, 506; rurioctocog alfa pegol, 268). Mean (SD) age was 24.2 (15.8) and 26.3 (14.9) years for patients receiving efmoroctocog alfa and rurioctocog alfa pegol, respectively; mean (SD) weight was 68.4 (36.8) and 79.8 (37.7) kg, respectively. The most frequent efmoroctocog alfa regimen was twice weekly (45.7%), followed by every 4 days (20.6%), every 3 days (9.1%), and 3 times per week (7.5%). The most frequent rurioctocog alfa pegol regimen was twice weekly (72.4%), followed by 3 times per week (8.7%), every 4 days (7.6%), and every 3 days (5.5%). The proportion of efmoroctocog alfa twice-weekly dispensing records increased from 31.5% to 50.9%, and every 4 days dispensing records decreased from 31.3% to 14.5% (2015–2018). The proportion of rurioctocog alfa pegol dispensing records remained broadly stable (2016–2018). Overall, mean (SD; median) weekly prophylactic dose was 105.4 (77.9; 92.6) IU/kg with efmoroctocog alfa, and 96.8 (41.9; 90.9) IU/kg with rurioctocog alfa pegol.

Conclusion

In this database study, the most frequently observed dosing frequency was twice weekly for patients receiving efmoroctocog alfa or rurioctocog alfa pegol. The observed mean weekly consumption was slightly higher, and variation was greater, in patients receiving efmoroctocog alfa versus rurioctocog alfa pegol.