Updates in clinical trial data of extended half-life recombinant factor IX products for the treatment of haemophilia B

Six-Year, Real-World Use of Prophylaxis with Recombinant Factor IX-Albumin Fusion Protein (rIX-FP) in Persons with Hemophilia B: A Single-Center Retrospective-Prospective Study

Background: Extended half-life (EHL) factor IX (FIX) concentrates allow for prophylaxis with prolonged dosing intervals and high bleeding protection in persons with hemophilia B. Long-term real-world studies are lacking. Methods: In a retrospective-prospective study, the six-year use of prophylaxis with the EHL recombinant FIX-albumin fusion protein (rIX-FP) was analyzed, comparing outcomes with previous standard half-life (SHL) FIX in patients already on prophylaxis. Results: Prophylaxis with rIX-FP was prescribed in 15 patients (10 severe, 5 moderate; follow-up: 57 ± 17 months). Based on a pharmacokinetic assessment and clinical needs, the first regimen was 47 ± 7 IU/Kg every 9 ± 2 days. All but one patient remained on rIX-FP prophylaxis, adjusting infusion frequency and/or dose; the last prescribed frequency was ≥10 days in 10/13 patients, being reduced in seven and increased in four vs. the first regimen. The weekly FIX dose was unchanged; FIX trough levels were >5% in all patients. The annual infusion number and FIX IU/Kg significantly decreased (~60%) in eight patients previously on SHL FIX prophylaxis, with similar concentrate costs. Very low bleeding rates (most traumatic bleeds and the last quartile of the infusion interval), improved orthopedic and pain scores, unchanged HEAD-US scores and problem joints, and high treatment adherence (>90%) and satisfaction were registered. Conclusions: Personalized, carefully adjusted rIX-FP regimens contribute to the diffusion and optimization of prophylaxis in persons with severe and moderate hemophilia B, with long-term favorable bleeding, joint, and patient-reported outcomes.

Eftrenonacog Alfa: A Review in Haemophilia B

Eftrenonacog alfa (Alprolix^®) is an extended half-life recombinant factor IX (rFIX)-Fc fusion protein (hereafter referred to as rFIXFc). Administered as an intravenous bolus, it is approved for prophylactic use and the treatment of bleeding in patients with haemophilia B in various countries worldwide, including those of the EU, as well as the USA. In multinational, phase III trials, rFIXFc was effective for the prophylaxis, perioperative management or on-demand treatment of bleeding in male patients with severe haemophilia B regardless of age and irrespective of whether or not they had been previously treated with FIX replacement products. Prophylactic efficacy was maintained over the longer term (up to 5 years) in previously treated patients. rFIXFc effectiveness in the real-world setting is supported by results of prospective studies, as well as the outcomes of several retrospective trials. rFIXFc was well tolerated in clinical trials in previously treated and untreated children, adolescents and/or adults with severe haemophilia B. Thus, rFIXFc continues to represent a useful treatment option among the haemophilia B patient population.

Investigation of the Bleeding Tendency in Sudanese Female Carriers of Hemophilia B

Background. Hemophilia (HB) is an X-linked, recessive bleeding disorder characterized by the deficiency or absence of the coagulation factor IX. Usually, females are carriers of the trait, while males are affected. FIX deficiency leads to uncontrollable bleeding events, and the severity is dependent on the levels of the clotting factor. The objective of this research was to measure the prevalence of bleeding tendency in Sudanese carriers of HB. Materials and Methods. In this cross-sectional study, 88 Sudanese carriers of HB participated. The activated partial thromboplastin time test (APTT) and FIX test were performed for each carrier. The frequencies of DNA polymorphism and FIX-linked restriction fragments BamHI, HhaI, and MnII were also assessed. The study was conducted in Khartoum, Sudan, during the period from 2015 to 2017. Results. The study showed that 55 (62.5%) HB carriers were from the Laban village in the White Nile State, and all of them were members of the Shinkheb tribe. The mean age of the study population was 26.3 years. Among the carriers, 57 (64.7%) had abnormal coagulation profiles. The mean value of the APTT level among carriers was significantly increased ( $P$ value: 0.000), while the mean concentration of the FIX levels among the carriers was significantly decreased ( $P$ value: 0.000). The study also showed a negative correlation between PTT and F assay with $P$ value of 0.000 and $R$ value of 0.578. Conclusion. The APTT is high in most carriers and the FIX assay level is low in most carriers. Most carriers had no symptoms and were not bleeding. The Shinkheb tribe is the most ethnic tribe carrying HB (62.5%). HhaII is more informative for carrier detection than others, but it is of significant value if both (MnII and HhaII) were performed in parallel. In Sudanese, BamHI was informative but MnII and HhaII were best in the mutation detection and for prenatal diagnosis.

Switching to nonacog beta pegol in hemophilia B: Outcomes from a Canadian real‐world, multicenter, retrospective study

Background

The Canadian Bleeding Disorders Registry (CBDR) captures data from 24 hemophilia treatment centers and patients directly. Nonacog beta pegol (N9‐GP) was approved in Canada in 2018.

Objectives

To assess treatment outcomes following switching to N9‐GP in a real‐world setting.

Methods

CBDR data for Canadian male patients (aged 7–72 years) with hemophilia B receiving prophylactic N9‐GP for ≥6 months as of March 31, 2021, were included. To allow comparison with the previously used products, only patients for whom data were available in the CBDR for at least 6 months before the switch to N9‐GP were included in this retrospective analysis.

Results

Forty‐two patients were included in the analysis (total observation period: 148.0 patient‐years). The distribution of disease severity was 62% severe, 36% moderate, 2% mild, with 62% of patients previously receiving recombinant factor IX‐Fc‐fusion protein (rFIXFc) and 38% previously receiving standard half‐life (SHL) recombinant factor IX (rFIX). During a median follow‐up period of 2.3 years on N9‐GP prophylaxis, 232 bleeds were reported in 30 patients, 29% of patients reported zero bleeds. The median overall annualized bleeding rate on N9‐GP was 0.73 for patients switching from rFIXFc (previously 1.44) and 2.10 for patients switching from SHL rFIX (previously 6.06). Median total annualized factor consumption (IU/kg) was lower with N9‐GP than with previous SHL rFIX (2152 vs 3018) and previous rFIXFc (1766 vs 2278).

Conclusions

Results from this first real‐world study of N9‐GP in patients with hemophilia B suggest optimal bleeding control with low factor consumption after switching to N9‐GP, irrespective of the previous product.

An update of the current pharmacotherapeutic armamentarium for hemophilia A

INTRODUCTION

For several decades, we have seen unprecedented advances in novel therapy development for hemophilia A. These advances address the unmet need of replacement therapy, and they include the development of recombinant products with improved pharmacokinetics, subcutaneously administered products, and those with better efficacy and safety profiles in hemophilia A management.

AREAS COVERED

In this update of hemophilia A treatment, the author summarizes data from completed standard half-life FVIII products, extended half-life FVIII products and FVIII mimetic studies. All products have an acceptable safety profile. The standard half-life products, EHL-FVIII products and emicizumab are efficacious in the prevention and treatment of bleeds and for EHL-FVIII in the perisurgical setting.

EXPERT OPINION

Advances in pharmacotherapy for hemophilia A have been characterized by changing care goals from supportive care to eliminating infections, preventing inhibitors, and more recently achieving zero bleeds in many patients. While gene therapy has the potential for functional cure in hemophilia A, it has many limitations which need to be addressed. Therefore, pharmacotherapy is likely to remain the mainstay in the management of hemophilia A and promises to get better with currently available therapies. Evolving factor and non-factor replacement therapies may also improve current unmet needs in hemophilia A management.

Patient Perspectives on Novel Treatments in Haemophilia: A Qualitative Study

Background and Objective

New treatments for haemophilia are under development or entering the market, including extended half-life products, designer drugs and gene therapy, thereby increasing treatment options for haemophilia. It is currently unknown how people with haemophilia decide whether to switch to a new treatment. Therefore, the objective of this study was to explore what factors may play a role when Dutch patients and parents of boys with moderate or severe haemophilia make decisions about whether to switch to a different treatment, and how disease and treatment characteristics may affect these decisions. This may aid clinical teams in tailored information provision and shared decision making.

Methods

We conducted interviews among adults with moderately severe or severe haemophilia and parents of young boys with severe haemophilia. We aimed to include participants from a variety of backgrounds in terms of involvement in the haemophilia community, age, treatment centre and treatments. Participants were recruited through the Netherlands Haemophilia Society and a haemophilia treatment centre. Semi-structured interviews were recorded and transcribed verbatim. Thematic content analysis was used to analyse the data.

Results

Twelve people with haemophilia and two mothers of boys with haemophilia were included. In general, participants reported to be satisfied with their current treatment. However, they considered ease of use of the medication (fewer injections, easier handling, alternative administration) an added value of new treatments. Participants were aware of the high cost of coagulation factor products and some expressed their concern about the Netherlands Haemophilia Society’s long-term willingness to pay for current and novel treatments, especially for increased usage due to high-risk activities. Participants also expressed their concerns about the short- and long-term safety of new treatments and believed the effects of gene therapy were not yet fully understood. Participants expected their treatment team to inform them when a particular new treatment would be suitable for them.

Conclusions

With the number of treatment options set to increase, it is important for healthcare providers to be aware of how patient experiences shape patients’ decisions about new therapies.

Electronic supplementary material

The online version of this article (10.1007/s40271-019-00395-6) contains supplementary material, which is available to authorized users.

Modulation of the liver immune microenvironment by the adeno-associated virus serotype 8 gene therapy vector

Adeno-associated viruses (AAVs) are emerging as one of the vehicles of choice for gene therapy. However, the potential immunogenicity of these vectors is a major limitation of their use, leading to the necessity of a better understanding of how viral vectors engage the innate immune system. In this study, we demonstrate the immune response mediated by an AAV vector in a mouse model. Mice were infected intravenously with 4 × 10¹² copies (cp)/kg of AAV8, and the ensuing immune response was analyzed using intravital microscopy during a period of weeks. Administration of AAV8 resulted in the infection of hepatocytes, and this infection led to a moderate, but significant, activation of the immune system in the liver. This host immune response involved platelet aggregation, neutrophil extracellular trap (NET) formation, and the recruitment of monocytes, B cells, and T cells. The resident liver macrophage population, Kupffer cells, was necessary to initiate this immune response, as its depletion abrogated platelet aggregation and NET formation and delayed the recruitment of immune cells. Moreover, the death of liver cells produced by this AAV was moderate and failed to result in a robust, sustained inflammatory response. Altogether, these data suggest that AAV8 is a suitable vector for gene therapy approaches.

Clinical, pharmacokinetic and economic analysis of the first switch to an extended half-life factor IX (albutrepenonacog alfa, rFIX-FP) in Spain

Extended half-life of factor IX (FIX) demonstrated clinical benefit and lower treatment burden than standard half-life FIX products in clinical trials. We analysed the impact in efficacy, pharmacokinetics (PKs) and costs of the switch from nonacog alfa (rFIX) to albutrepenonacog alfa (rFIX-FP) in the first patient with haemophilia B (HB) treated in Spain outside clinical trials. A 7-year-old boy presented with HB with poor venous access and repetition infections using rFIX, which was switched to rFIX-FP. Prophylaxis was adjusted by PKs using WAPPS-Hemo tailoring from 100 IU/kg/week of rFIX to 80 IU/kg/3 weeks of rFIX-FP. Comparing 6 months before, rFIX-FP reduced 68.5% FIX consumption/kg and 58.3% infusion frequency, but total costs/weight showed a slight increase. Ratio of half-life between rFIX and rFIX-FP was 3.4–3.7. This case report revealed that switch to rFIX-FP decreased frequency and FIX consumption, without adverse events and bleeds.

Nonacog beta pegol (N9-GP) in hemophilia B: First report on safety and efficacy in previously untreated and minimally treated patients

BACKGROUND/OBJECTIVE

We report the first analysis of an extended half-life recombinant factor IX, nonacog beta pegol (N9-GP), in previously untreated patients (PUPs) and minimally treated patients with hemophilia B.

METHODS

Paradigm 6 (Safety and Efficacy of Nonacog Beta Pegol [N9-GP] in Previously Untreated Patients With Haemophilia B) is a multicenter, open-label, single-arm, phase 3 trial. Main inclusion criteria were males aged < 6 years, with hemophilia B with factor IX (FIX) activity ≤ 2%, who were previously untreated or with ≤ 3 exposure days (EDs) to FIX-containing products. Patients received N9-GP 40 IU/kg once weekly (prophylaxis) or individualized dosing (preprophylaxis). Bleeds were treated with N9-GP 40 IU/kg (80 IU/kg if severe). The primary end point was incidence of anti-FIX inhibitory antibodies (inhibitors). Secondary end points included safety outcomes and annualized bleeding rate (ABR).

RESULTS

At data cutoff (August 31, 2018), 38 patients had been screened, and 37 had received N9-GP (median age, 1.0 years [range, 0-4]). Total in-trial EDs amounted to 2833, representing ~ 65 patient-years. Two (6.1%) of 33 "at-risk" patients (patients with ≥ 10 EDs plus patients who developed inhibitors) developed high-titer inhibitors and were withdrawn. No other safety concerns, including thromboembolic events, were identified. In the prophylaxis group (n = 28), 67.9% were bleed free; all bleeds (n = 15) were treated with one N9-GP injection; and overall, spontaneous, and traumatic ABRs were low (median ABRs of 0.0, 0.0, and 0.0, respectively; modeled mean ABRs of 0.31, 0.08, and 0.23, respectively). Estimated mean FIX trough activity was 15.0%.

CONCLUSION

We report an inhibitor incidence of 6.1%, which is within the expected range for PUPs with hemophilia B. No other safety concerns were identified; moreover, N9-GP provided effective hemostatic coverage.

Prophylaxis Using a Mixture of Plasma-Derived Activated Factor VII and Factor X (pdFVIIa/FX) in a Patient with Hemophilia B Complicated by Inhibitors and Allergy to Factor IX Concentrates: A Case Report

Treating patients with hemophilia and inhibitors is often problematic. The presence of inhibitors negatively impacts the effectiveness of treatment to achieve hemostasis especially in patients with hemophilia B, owing mainly to allergic reactions to factor IX (FIX) concentrates and the low success rate of immune tolerance therapy. A 9-month-old boy had intracranial hemorrhage and was diagnosed with hemophilia B. After replacement therapy, he developed inhibitors and an allergic reaction to FIX. Prophylactic therapy was initiated with recombinant activated factor VII (rFVIIa) and later switched to pdFVIIa/factor X (FX; 120 μg/kg as the FVII dose, every other day) because of a recurrence of intracranial hemorrhage. Since then, he remained well without life-threatening bleeding for more than 2 years. Our case suggests that pdFVIIa/FX may be useful for prophylactic therapy in hemophilia B complicated by inhibitors and allergic reaction to FIX concentrates.

Treatment Options in Hemophilia

BACKGROUND

Approximately 4550 persons were under treatment for hemophilia in Germany in 2017. The condition is currently treated with intravenous supplementa- tion of the missing clotting factor, either prophylactically or as needed. Newer treat- ment options rely on novel mechanisms of action.

METHODS

This review is based on pertinent publications retrieved by a selective search in MEDLINE/PubMed, as well as on expert opinions and the recommenda- tions of specialty societies.

RESULTS

Randomized controlled trials have shown that, in children aged 30 months to 6 years, prophylactic clotting-factor supplementation yields a markedly lower an- nual rate of hemorrhage than supplementation as needed: 3.27 (standard deviation [SD] 6.24) for the former vs. 17.69 (SD 9.25) for the latter. A similar large effect was seen in patients aged 12 to 50 years, with hemorrhage rates of 1.9 (SD 4.1) vs. 28.7 (SD 18.8). Clotting-factor preparations with longer half-lives make it possible to lessen the frequency of administration and to prevent subtherapeutic factor levels. A number of alternatives to clotting-factor supplementation have recently been approved or are currently being clinically tested. These new drugs are injected sub- cutaneously and have a longer half-life, possibly enabling better protection against bleeding than the current standard treatment. A further advantage of some of these drugs is that they can be given even in the presence of inhibitors to factor VIII. In addition, initial (phase I) clinical trials of gene therapy have been performed suc- cessfully for both hemophilia A and hemophilia B.

CONCLUSION

Now that new alternatives to classic supplementation therapy are be- coming available, pertinent treatment algorithms for patients with hemophilia will have to be developed. It is still unclear to what extent the new drugs might supplant clotting factor supplementation as the first line of treatment.

Long-term safety and sustained efficacy for up to 5 years of treatment with recombinant factor IX Fc fusion protein in subjects with haemophilia B: Results from the B-YOND extension study

INTRODUCTION

Recombinant factor IX Fc fusion protein (rFIXFc) has demonstrated efficacy for treatment of haemophilia B in the Phase 3 B-LONG and Kids B-LONG studies. However, long-term rFIXFc safety and efficacy data have not yet been reported.

AIM

To report long-term rFIXFc safety and efficacy in subjects with haemophilia B.

METHODS

B-YOND (NCT01425723) was an open-label extension for eligibl previously treated subjects who completed B-LONG or Kids B-LONG. Subjects received ≥1 treatment regimen: weekly prophylaxis (WP), individualized interval prophylaxis (IP), modified prophylaxis or episodic treatment. Subjects could switch regimens at any time. The primary endpoint was inhibitor development.

RESULTS

Ninety-three subjects from B-LONG and 27 from Kids B-LONG (aged 3-63 years) were enrolled. Most subjects received WP (B-LONG: n = 51; Kids B-LONG: n = 23). For subjects from B-LONG, median (range) treatment duration was 4.0 (0.3-5.4) years and median (range) number of exposure days (EDs) was 146 (8-462) EDs. Corresponding values for paediatric subjects were 2.6 (0.2-3.9) years and 132 (50-256) EDs. No inhibitors were observed (0 per 1000 subject-years; 95% confidence interval, 0-8.9) and the overall rFIXFc safety profile was consistent with prior studies. Annualized bleed rates remained low and extended-dosing intervals were maintained for most subjects. Median dosing interval for the IP group was approximately 14 days for adults and adolescents (n = 31) and 10 days for paediatric subjects (n = 5).

CONCLUSIONS

B-YOND results confirm the long-term (up to 5 years, with cumulative duration up to 6.5 years) well-characterized safety and efficacy of rFIXFc treatment for haemophilia B.

Blood, blood components, plasma, and plasma products

This review of 2018 publications identifies side effects of blood, blood components, and plasma products. In addition, albumin, blood transfusion (erythrocytes, granulocytes, and platelets), blood substitutes (hemoglobin-based oxygen carriers), plasma products (alpha1-antitrypsin, C1 esterase inhibitor concentrate, cryoprecipitate, and fresh frozen plasma), plasma substitutes (etherified starches, and gelatin), globulins (intravenous immunoglobulin, subcutaneous immunoglobulin, and anti-D immunoglobulin), coagulation proteins (factor I, factor II, factor VIIa, factor VIII, factor IX, prothrombin complex concentrate, antithrombin III, and von Willebrand factor/factor VIII concentrates), erythropoietin and derivatives, thrombopoietin and receptor agonists, transmission of infectious agents through blood donation, and stem cells are reviewed. This chapter informs the reader about newly recognized and published data in the blood product domain.