Recombinant FVIIIFc Versus BAY 94-9027 for Treatment of Patients with Haemophilia A: Comparative Efficacy Using a Matching Adjusted Indirect Comparison

Bioequivalence of recombinant factor VIII products: a position paper from the Italian Association of Hemophilia Centers

Over the last three decades, the continuous evolution of recombinant factor VIII (rFVIII) concentrates for replacement treatment of hemophilia A, including recent extended half-life products, implies that patients may switch from one product to another, technologically more advanced, with the aim of improving treatment efficacy, safety, management and, ultimately, quality of life. In this scenario, the issues of bioequivalence of rFVIII products and the clinical implications of their interchangeability are keenly debated, in particular when economic reasons or purchasing systems influence product availability and choices. Although sharing the same Anatomical Therapeutic Chemical (ATC) level, rFVIII concentrates, as other biological products, show relevant differences in terms of molecular structure, source and manufacturing process, which make them unique products, recognized as new active substances by regulatory agencies. Moreover, data from clinical trials with both standard and extended half-life products clearly document the large inter-patient variability of pharmacokinetic profiles after administering the same dose of the same product; in cross-over evaluations, even when mean values are comparable, some patients show better patterns with one product or with the comparator one. Pharmacokinetic assessment thus reflects the response to a specific product in the individual patient, with his genetic determinants, only partially identified, affecting the behavior of exogenous FVIII. These concepts, consistent with the currently recommended approach of personalization of prophylaxis, are discussed in this position paper endorsed by the Italian Association of Hemophilia Centers (AICE), highlighting that ATC or other available classifications do not completely consider differences between drugs and innovations and that substitutions of rFVIII products will not invariably ensure the previously achieved clinical outcomes or generate benefits for all patients.

Efficacy of rFIXFc versus N9-GP Prophylaxis in Patients with Hemophilia B: Matching-Adjusted Indirect Comparison of B-LONG and PARADIGM 2 Trials

Purpose

For patients with hemophilia B, extended half-life factor IX (FIX) products are available for prophylaxis and for treating bleeds. Different methods are used to extend the half-lives of recombinant FIX Fc fusion protein (rFIXFc) and nonacog beta pegol (N9-GP). This affects their biodistribution and plasma FIX levels, although differences do not always correlate with clinical outcomes. A matching-adjusted indirect comparison (MAIC) of prophylaxis with rFIXFc and N9-GP was performed, based on licensed dosing in the European Union.

Patients and Methods

Combined rFIXFc data from the weekly and individualized interval prophylaxis arms of the B-LONG clinical trial, and N9-GP data from the 40 IU/kg once-weekly prophylaxis arm of PARADIGM 2 were used in a MAIC. Individual patient data for rFIXFc (n=87) were matched to aggregated data for N9-GP (n=29). Estimated annualized bleeding rates (ABRs) for rFIXFc were recalculated using a Poisson regression model with adjustment for over-dispersion, and compared with ABRs reported for N9-GP, using incidence rate ratios (IRRs) with 95% confidence interval (CI).

Results

There was no evidence of significant differences in estimated ABRs between prophylaxis with rFIXFc and N9-GP. Analysis of pooled rFIXFc weekly and interval-adjusted dosing compared with N9-GP 40 IU/kg once weekly produced estimated ABRs of 2.59 versus 2.51 (IRR 1.03; 95% CI 0.56-1.89), as well as 1.34 versus 1.22 (IRR 1.10; 95% CI 0.42-2.91) and 1.13 versus 1.29 (IRR 0.88; 95% CI 0.47-1.63) for overall, spontaneous, and traumatic bleeding events, respectively.

Conclusion

The study did not reveal any significant differences in the efficacy of rFIXFc and N9-GP prophylaxis. Given differences in trough levels (rFIXFc dosing was targeted to achieve a trough 1-3 IU/dL above baseline versus a reported estimated N9-GP mean trough of 27.3 IU/dL), interpreting plasma FIX levels as potential surrogate efficacy markers requires consideration of compound-specific pharmacokinetic profiles.

Cost-minimization analysis of recombinant factor VIII Fc versus emicizumab for treating patients with hemophilia A without inhibitors in Europe

BACKGROUND AND OBJECTIVE

A cost-minimization model was developed to compare recombinant factor VIII Fc (rFVIIIFc) and emicizumab as prophylaxis for hemophilia A without inhibitors.

METHODS

The model was based on 100 patients from the healthcare payer perspective in the UK, France, Italy, Spain, and Germany (5-year time horizon). Costs included: drug acquisition; emicizumab wastage by bodyweight (manufacturer's dosing recommendations); and additional FVIII for breakthrough bleeds. Scenario analyses (UK only): reduced emicizumab dosing frequency; and emicizumab maximum wastage.

RESULTS

Total incremental 5-year savings for rFVIIIFc rather than emicizumab use range from €89,320,131 to €149,990,408 in adolescents/adults (≥12 years) and €173,417,486 to €253,240,465 in children (<12 years). Emicizumab wastage accounts for 6% of its total cost in adolescents/adults and 26% in children. Reducing the emicizumab dosing frequency reduces the incremental cost savings with rFVIIIFc, but these remain substantial (adolescents/adults, >€92 million; children >€32 million). Maximum emicizumab wastage increases by 86% and 106%, respectively, increasing the incremental cost savings with rFVIIIFc to €125,352,125 and €105,872,727, respectively.

CONCLUSION

Based on cost-minimization modeling, rFVIIIFc use for hemophilia A prophylaxis in patients without inhibitors is associated with substantial cost savings in Europe, reflecting not only higher acquisition costs of emicizumab, but also other costs including wastage related to available vial sizes.

Indirect Treatment Comparison of Damoctocog Alfa Pegol versus Turoctocog Alfa Pegol as Prophylactic Treatment in Patients with Hemophilia A

Purpose

To assess the efficacy and FVIII consumption of BAY 94-9027 versus N8-GP in prophylaxis in adolescent and adult patients with severe hemophilia A (HA).

Patients and Methods

A systematic literature review was conducted to identify studies on the efficacy of BAY-94-9027 and N8-GP for prophylaxis in patients with HA aged ≥12 years without a history of inhibitors. Eight studies met systematic literature review inclusion criteria, but only data from PROTECT VIII on BAY 94-9027 and PATHFINDER 2 on N8-GP could be used for an indirect comparison. Matching-adjusted indirect comparison (MAIC) and simulated treatment comparison were performed.

Results

No significant differences (unadjusted and adjusted) were observed in the mean annualized bleeding rate (ABR) for any bleed and proportion of patients with zero bleeds when comparing BAY 94-9027 to N8-GP. The adjusted treatment difference [incidence rate ratio (IRR)] in terms of ABR was 1.11 (95% CI, 0.85–1.44). The odds ratio (OR) of any bleed, measuring the relative effect of BAY 94-9027 versus N8-GP on the proportion of patients with zero bleeds, was 1.03 (95% CI, 0.60–1.77). FVIII consumption was significantly lower in BAY 94-9027 [mean adjusted difference=−1292.57 IU/kg/year (95% CI, ‒2152.44 to ‒432.70)]; a 26.7% reduction in consumption of BAY-94-9027. The results of the sensitivity analyses were similar to the main analysis for mean ABRs, percentages of patients with zero bleeds, and significant reduction in rFVIII consumption. For patients on BAY 94-9027 every-5-days and every-7-days, no differences versus every-4-days N8-GP were observed for the mean ABR for any bleed [IRR=0.90 (95% CI, 0.68‒1.20)] and proportion of patients with zero bleeds [OR=1.06 (95% CI, 0.56‒2.02)].

Conclusion

BAY 94-9027 prophylaxis demonstrated 26.7% lower annual consumption when compared to N8-GP with similar efficacy in terms of ABR and percentage of patients with zero bleeds.

Efmoroctocog Alfa: A Review in Haemophilia A

Efmoroctocog alfa (Elocta®, Eloctate®, Eloctate™), an extended half-life (EHL) recombinant factor VIII (rFVIII)-Fc fusion protein, is approved for the treatment and prophylaxis of bleeding in patients with haemophilia A. The efficacy of efmoroctocog alfa in the prevention and treatment of bleeding in previously treated patients (PTPs) and previously untreated patients (PUPs) with severe haemophilia A has been demonstrated in phase III studies; this includes its use in the perioperative setting (in PTPs). Furthermore, the effectiveness of efmoroctocog alfa in clinical practice has been confirmed in numerous real-world studies; compared with conventional, standard half-life (SHL) FVIII products, prophylaxis with this EHL FVIII product achieved similar or reduced bleeding rates with fewer injections. Efmoroctocog alfa was generally well tolerated; inhibitors occurred in approximately one-third of PUPs in a phase III study. Efmoroctocog alfa is an established and effective EHL FVIII replacement therapy for the management of haemophilia A. Compared with SHL FVIII products, EHL FVIII products such as efmoroctocog alfa have the potential to optimise prophylactic outcomes by decreasing the burden of treatment or increasing the level of bleed protection.

Efficacy, safety, and immunogenicity of rurioctocog alfa pegol for prophylactic treatment in previously treated patients with severe hemophilia A: a systematic review and meta-analysis of clinical trials

Background: Patients with severe hemophilia often present with painful joint and soft tissue bleeding which may restrict them from their daily activities. The current standard of care still relies on a regular prophylactic factor VIII (FVIII), which has a high daily treatment burden. Recently, rurioctocog alfa pegol, a third-generation recombinant FVIII with a modification in its polyethylene glycol (PEG) component, has been developed. Several trials have studied this synthetic drug as bleeding prophylaxis in severe hemophilia A. This study aims to evaluate the efficacy, safety, and immunogenicity of rurioctocog alfa pegol for previously treated patients with severe hemophilia A. Methods: This study was conducted in conformity with the PRISMA guidelines. Data were retrieved from PubMed, Scopus, Cochrane Library, Wiley Online Library, and CINAHL (via EBSCOhost). Study qualities were assessed using the Methodological Index for Non-Randomized Studies (MINORS) and Modified Jadad scales. Results: Four studies involving 517 previously treated severe hemophilia A patients were included in this study. The pooled mean of total annualized bleeding rate (ABR) and hemostatic efficacy was 2.59 (95% CI = 2.04-3.14) and 92% (95% CI = 85%-97%), respectively. Only 30 (2.3%) non-serious and one (1.4%) serious adverse events were considered related to rurioctocog alfa pegol treatment. At the end of the studies, no development of FVIII inhibitory antibodies was observed. None of the developed binding antibodies to FVIII, PEG-FVIII, or PEG was correlated to the treatment efficacy and safety. Conclusions: Despite the limited availability of direct comparison studies, our analyses indicate that rurioctocog alfa pegol could serve as a safe and effective alternative for bleeding prophylaxis in previously treated hemophilia A patients. Moreover, it appears to have low immunogenicity, which further increases the safety profile of the drug in such clinical conditions.

Matching-Adjusted Indirect Comparison of Efficacy and Consumption of rVIII-SingleChain Versus Two Recombinant FVIII Products Used for Prophylactic Treatment of Adults/Adolescents with Severe Haemophilia A

Introduction

Given the relatively small number of patients with haemophilia A, head-to-head comparisons between recombinant FVIII (rFVIII) products are difficult to conduct. This study compared the efficacy and consumption of rVIII-SingleChain (lonoctocog alfa, AFSTYLA^®) with rAHF-PFM (octocog alfa, Advate^®) and rFVIIIFc (efmoroctocog alfa, Elocta^®), for the prophylaxis and treatment of bleeding episodes in previously treated adolescents/adults with severe haemophilia A, through a matching-adjusted indirect comparison (MAIC).

Methods

A systematic literature review identified published clinical trials for rAHF-PFM and rFVIIIFc. Individual patient data for rVIII-SingleChain were used to match baseline patient characteristics to those from published trials, using an approach similar to propensity score weighting. After matching, annualized bleeding rates (ABR), percentage of patients with zero bleeds, and rFVIII consumption were compared across trial populations.

Results

Published data were identified from two rAHF-PFM trials and one rFVIIIFc trial. rVIII-SingleChain had similar ABR (risk ratio [RR]: 0.74 [0.16; 3.48]; RR: 1.18 [0.85; 1.65]) and percentage of patients with zero bleeds (odds ratio [OR]: 1.34 [0.56; 3.22]; OR: 0.78 [0.47; 1.31]) versus rAHF-PFM and rFVIIIFc, respectively. Annual rVIII-SingleChain consumption was significantly lower than rAHF-PFM (mean difference: − 1507.66 IU/kg/year [− 2011.71; − 1003.61]) and equivalent to rFVIIIFc (RR: 0.96 [0.62; 1.49]).

Conclusion

Although limited to published information for comparator trials, these results suggest that with an annualized rFVIII consumption comparable to rFVIIIFc, but significantly lower than rAHF-PFM, routine prophylaxis with rVIII-SingleChain is able to maintain a similar ABR and percentage of patients with zero bleeds, attesting to the long-acting nature of rVIII-SingleChain.

Supplementary Information

The online version contains supplementary material available at 10.1007/s12325-021-01853-0.

It is difficult to directly compare different recombinant FVIII products in head-to-head studies because there are few patients with haemophilia A. This study aimed to indirectly compare the efficacy and consumption of different recombinant FVIII products in the prophylactic treatment of haemophilia A using published clinical data. A proven method for performing indirect comparisons of products is referred to as a matching-adjusted indirect comparison. Using this approach, we were able to compare rVIII-SingleChain with two other recombinant FVIII products (rAHF-PFM and rFVIIIFc). Our results suggest that annual FVIII consumption with rVIII-SingleChain is comparable to rFVIIIFc, but is significantly lower than rAHF-PFM, while maintaining a similar bleeding rate. These results highlight the long-acting nature of the product.