Low risk of inhibitor formation in haemophilia A patients following en masse switch in treatment to a third generation full length plasma and albumin-free recombinant factor VIII product (ADVATE®)

Real pandemic world results of pharmacokinetic-tailored personalized prophylaxis of bleeds in Polish children and adolescents with severe hemophilia A

Introduction

In 2020, the new nationwide protocol of prophylaxis in Polish plasma-derived FVIII (pdFVIII) previously treated patients (PTPs) with severe hemophilia A (sHA) was introduced, resulting in the necessity of switching from pdFVIII to recombinant FVIII (octocog-alpha; rFVIII). The study aimed to: (1) assess the safety of switching from pdFVIII to rFVIII, (2) assess the safety and efficacy of pharmacokinetically based (PK-based) personalized prophylaxis in severe hemophilia A.

Patients and methods

151 children and adolescents receiving prophylaxis with a standard dose (40 U/kg 3 x weekly) of pdFVIII were included in this study. Annualized bleeding rate (ABR) and annualized joint bleeding rate (AJBR) were analyzed for all patients before enrollment. Using myPKFiT application, pharmacokinetic (PK) analysis followed by the selection of the optimal model of prophylaxis was performed in all patients. Two possible models of prophylaxis (standard-dose rFVIII versus PK-based rFVIII) were discussed, with parents leaving the choice to their decision. Parents reported all episodes of bleeds. Screening for inhibitor was performed every 3 months. ABR and AJBR were prospectively analyzed again after a minimum follow-up time of 26 weeks.

Results

141/151 (93.4%) patients completed the study. 34 patients decided to continue standard prophylaxis with rFVIII (Group I), whereas 107 were switched to PK-based prophylaxis (Group II). The risk of inhibitor development could be assessed in 137/151 (90.7%) patients. Only 2/137 (1.47%) patients (both on PK-based prophylaxis) developed low-titer inhibitor with its spontaneous elimination. The retrospective analysis of bleeds during the last 12 months of standard pdFVIII prophylaxis revealed that patients who decided to continue standard prophylaxis had historically lower ABR and AJBR than those who started PK-based personalized prophylaxis. After a minimum of 26 weeks, ABR and AJBR improved significantly in both groups. There was no significant difference in ABR and AJBR between Group I and Group II during the follow-up period. However, the rate of reduction of ABR and AJBR was higher in patients on PK-based personalized prophylaxis.

Conclusion

(1) Switching from pdFVIII to rFVIII (octocog-alpha) in PTPs with sHA is safe, (2) PK-based personalized prophylaxis may decrease ABR and AJBR in children and adolescents with sHA.

Achieving access to haemophilia care in low-income and lower-middle-income countries: expanded Humanitarian Aid Program of the World Federation of Hemophilia after 5 years

Highly effective treatment of haemophilia A and B is primarily available to 15% of the world's population, in high-income countries. In low-income countries (LICs) and lower-middle-income countries (LMICs), morbidity and mortality are high because of greatly reduced access to diagnosis, care, and treatment. We report the challenges and impact after the first 5 years (mid-2015-2020) of the expanded World Federation of Hemophilia (WFH) Humanitarian Aid Program (HAP). WFH HAP donated coagulation products were used to treat more than 250 000 acute bleeding episodes, manage approximately 4000 surgeries, and establish bleeding preventive prophylaxis in about 2000 patients in 73 countries. Health-care providers worldwide learned optimal management of patients with complex needs through virtual and in-person training. In response to the programme, some governments increased investment in haemophilia care, including independent purchases of small amounts of treatment products. With unparalleled scope and complexity, and substantial benefits to people with haemophilia and society in general, the WFH HAP is an exemplar of partnership between for-profit and not-for-profit organisations advancing health-care equity in LICs and LMICs, which could be replicated by other organisations supporting people with different monogenic diseases.

Safety and Efficacy of B-domain Deleted Third Generation Recombinant Factor VIII (GreenGene F™) in Korean Patients with Hemophilia A: Data from a Post-marketing Surveillance Study

BACKGROUND

New B-domain deleted third generation recombinant factor VIII (FVIII; GreenGene F™, beroctocog alfa) was launched in 2010. We determined safety and efficacy of GreenGene F™ during routine clinical practice in patients with hemophilia A over a period of 12 months.

METHODS

From July 2010 to July 2014, a total of 136 hemophilia A patients were enrolled in a post-marketing surveillance (PMS) study. Among them, 134 patients were assessed for drug safety and 114 patients were analyzed for drug efficacy. Patients with differing hemophilia A severities and medical histories were monitored during 12 months of prophylactic and/or on-demand therapy.

RESULTS

Among 134 patients evaluated, 85 (63.4%) had severe hemophilia. Ninety-two received a total of 1,266,077 units for prophylaxis, and 42 received 516,491 units for bleeding episodes. Three patients developed inhibitors. In 112 previously treated patients, one patient (0.9%) developed inhibitor after intensive FVIII treatment for surgery. Among 22 previously untreated patients, inhibitors were observed in 2 infants (9.1%). Overall, there were a total of 47 adverse events (other than inhibitors) of all types in 30 patients (22.4%), 11 in 10 patients (7.5%) of which were considered showing serious adverse events (SAEs); most of which were hemorrhages at different sites. None of the SAEs were judged as product related. An excellent/good efficacy rate of 91.3% for hemostasis and 89.4% for hemorrhage prevention was recorded.

CONCLUSION

The results of this PMS study support the use of GreenGene F™ as safe and efficacious in hemorrhage prevention and treatment of hemophilia A. These results are consistent with the findings from previously published GreenGene F™ studies.

Prospective surveillance study of haemophilia A patients switching from moroctocog alfa or other factor VIII products to moroctocog alfa albumin-free cell culture (AF-CC) in usual care settings

This prospective, open-label, postauthorisation safety surveillance study assessed clinically significant inhibitor development in patients with severe haemophilia A transitioning from moroctocog alfa or other factor VIII (FVIII) replacement products to reformulated moroctocog alfa (AF-CC). Males aged12 years with severe haemophilia A (FVIII:C) < 1 IU/dl), > 150 exposure days (EDs) to recombinant or plasma-derived FVIII products, and no detectable inhibitor at screening were enrolled. Primary end point was the incidence of clinically significant FVIII inhibitor development. Secondary end points included annualised bleeding rate (ABR), less-than-expected therapeutic effect (LETE), and FVIII recovery. Patients were assigned to one of two cohorts based on whether they were transitioning to moroctocog alfa (AF-CC) from moroctocog alfa (cohort 1; n=146) or from another recombinant or plasma-derived FVIII product (cohort 2; n=62). Mean number of EDs on study was 94 (range, 1–139). Six positive FVIII inhibitor results, as determined by local laboratories, were reported in four patients; none were confirmed by a central laboratory, no inhibitor-related clinical manifestations were reported, and all anti-FVIII antibody assays were negative. Median ABRs were 23.4 and 3.4 in patients categorised at baseline as following on-demand and prophylactic regimens, respectively; 86.5 % of bleeding episodes resolved after one infusion. LETE incidence was 0.06 % and 0.19 % in the on-demand and prophylaxis settings, respectively. FVIII recovery remained constant throughout the study. No new safety concerns were identified. This study found no increased risk of clinically significant FVIII inhibitor development in patients transitioning from moroctocog alfa or other FVIII replacement products to moroctocog alfa (AF-CC).

Is there a reason for concern or is it just hype? - A systematic literature review of the clinical consequences of switching from originator biologics to biosimilars

INTRODUCTION

While prescribing biosimilars to patients naive to a biologic treatment is a well-accepted practice, switching clinically stable patients from an originator to a biosimilar is an issue for clinicians. Well-designed clinical trials and real-world data which study the consequences of switching from an originator biologic treatment to its biosimilar alternative are limited, especially for monoclonal antibodies. Areas covered: A systematic literature review was conducted on PubMed to identify evidence of the consequences of switching from original biologics to biosimilars. References of included papers were also scrutinized. After a title-, abstract- and full text screening, out of the 153 original hits and 77 additional ones from screening the references, 58 papers (12 empirical papers, 5 systematic reviews and 41 non-empirical papers) were included. Expert opinion: Preventing patients on biologic medicines from switching to biosimilars due to anticipated risks seems to be disproportional compared to the expected cost savings and/or improved patient access. Indeed, it is the opinion of the authors that the concern of switching to biosimilars is overhyped.

Natural history and clinical characteristics of inhibitors in previously treated haemophilia A patients: a case series

BACKGROUND

Development of inhibitors is the most serious complication in haemophilia A treatment. The assessment of risk for inhibitor formation in new or modified factor concentrates is traditionally performed in previously treated patients (PTPs). However, evidence on risk factors for and natural history of inhibitors has been generated mostly in previously untreated patients (PUPs). The purpose of this study was to examine cases of de novo inhibitors in PTPs reported in the scientific literature and to the EUropean HAemophilia Safety Surveillance (EUHASS) programme, and explore determinants and course of inhibitor development.

METHODS

We used a case series study design and developed a case report form to collect patient level data; including detection, inhibitor course, treatment, factor VIII products used and events that may trigger inhibitor development (surgery, vaccination, immune disorders, malignancy, product switch).

RESULTS

We identified 19 publications that reported 38 inhibitor cases and 45 cases from 31 EUHASS centres. Individual patient data were collected for 55/83 (66%) inhibitor cases out of 12 330 patients. The median (range) peak inhibitor titre was 4.4 (0.5-135.0), the proportion of transient inhibitors was 33% and only two cases of 12 undergoing immune tolerance induction failed this treatment. In the two months before inhibitor development, surgery was reported in nine (22%) cases, and high intensity treatment periods reported in seven (17%) cases.

CONCLUSIONS

By studying the largest cohort of inhibitor development in PTPs assembled to date, we showed that inhibitor development in PTPs, is on average, a milder event than in PUPs.

The prevalence of factor VIII and IX inhibitors among Saudi patients with hemophilia: Results from the Saudi national hemophilia screening program

Hemophilia A and B are X-linked diseases that predominantly affect male patients. Patients can develop coagulation factor inhibitors, which exponentially increases the treatment cost. However, the prevalence of factor VIII and IX inhibitors in Saudi Arabia is unclear.This study aimed to determine the Saudi prevalence of factor VIII and IX inhibitors.This 4-year, 7-center, cross-sectional study evaluated the Saudi prevalences of hemophilia A and B. We collected the patients' clinical data, evaluated their disease, and tested for factor inhibitors.We included 202 patients with hemophilia (median age at diagnosis: 0.13 years, range: birth-34.8 years). The patients included 198 male patients (98%), 148 patients with hemophilia A (73.3%), and 54 patients with hemophilia B (26.7%). The patients exhibited severe factor VIII activity (<1%; 121 patients; 5.2%), moderate activity (1-5%; 7 patients; 4.9%), and mild activity (14 patients; 9.9%). Among the patients with care-related data, most patients were treated for episodic bleeding (76.8%) or received prophylaxis (22.6%); 1 patient received both treatments. Among the patients with source-related data, the factor replacements were derived from plasma (48.4%), recombinant concentrates (22.9%), both sources (14.6%), or fresh frozen plasma (14.1%). Factor VIII inhibitors were observed in 43 (29.3%) of the 147 patients, and only 1 of the 54 patients developed factor IX inhibitors. Most patients who developed inhibitors had severe hemophilia (40/44; 90.9%), and inhibitors were also common among patients who received recombinant products (14/43; 32.6%).The Saudi prevalence of factor inhibitors was similar to those among other ethnic populations.

Pharmacokinetics and pharmacodynamics of SCT800, a new recombinant FVIII, in hemophilia A mice

AIM

SCT800 is a new third-generation recombinant FVIII agent that is undergoing promising preclinical study. This study aimed to investigate the pharmacokinetic and pharmacodynamic profiles of SCT800 in hemophilia A mice.

METHODS

After hemophilia A mice were intravenously injected with single dose of SCT800 (80, 180, and 280 IU/kg) or the commercially available product Xyntha (280 IU/kg), pharmacokinetics profiles were evaluated based on measuring plasma

FVIII

C. For pharmacodynamics study, dose-response curves of SCT800 and Xyntha (1-200 IU/kg) were constructed using a tail bleeding model monitoring both bleeding time and blood loss.

RESULTS

Pharmacokinetics profile analysis showed a dose independency of SCT800 ranging from 80 to 280 IU/kg and comparable pharmacokinetic profiles between SCT800 and Xyntha at the doses tested. Pharmacodynamics study revealed comparable ED50 values of SCT800 and Xyntha in the tail bleeding model: 14.78 and 15.81 IU/kg for bleeding time, respectively; 13.50 and 13.58 IU/kg for blood loss, respectively. Moreover, at the doses tested, the accompanying dose-related safety evaluation in the tail bleeding model showed lower hypercoagulable tendency and wider dosage range potential for SCT800 than Xyntha.

CONCLUSION

In hemophilia A mice, SCT800 shows comparable pharmacokinetics and pharmacodynamics to Xyntha at the doses tested, and possibly with better safety properties.

Non-genetic risk factors and their influence on the management of patients in the clinic

The development of inhibitors is the most serious iatrogenic complication affecting patients with haemophilia. This complication is associated with impaired vital or functional prognosis, reduced quality of life and increased cost of treatment. The reasons why some patients develop antibodies to factor replacement and others do not remain unclear. It is however clear that inhibitor development results from a complex multifactorial interaction between genetic and non-genetic risk factors. Environmental influences implicated in increasing the risk of inhibitor formation can be viewed as modifiable risk factors. Therefore, identification of the non-genetic risk factors may offer the possibility of personalising haemophilia therapy by modifying treatment strategies in high-risk patients in the critical early phase of factor VIII exposure. In this article, we review the non-genetic factors reported as well as the potential impact of danger signals and the different scores for inhibitor development risk stratification.

Switching treatments in haemophilia: is there a risk of inhibitor development?

Patients with haemophilia A (and their physicians) may be reluctant to switch factor VIII (FVIII) concentrates, often due to concerns about increasing the risk of inhibitors; this reluctance to switch may contribute to patients missing the clinical benefits provided by the arrival of new factor VIII products. This topic was explored at the Eleventh Zürich Haemophilia Forum. Clinical scenarios for which product switching may be cause for concern were discussed; when there is a clinical need, there are no absolute contraindications to switching, but some patients (e.g. previously untreated patients and those undergoing elective surgery) may require more careful consideration. Both patient and physician surveys indicate that the reluctance to switch, and the fear of inhibitor development, does not appear to be evidence based. The evaluation of more recent data did not support previous studies suggesting that particular products (e.g. recombinant vs. plasma-derived and full length vs. B-domain modified) may be associated with increased risk. In addition, data from three national product switches showed that switching was not associated with increased inhibitor risk, but highlighted the need for regular inhibitor testing and for a centralised, unbiased database of inhibitor incidence. To conclude, current evidence does not suggest that switching products significantly influences inhibitor development.

Murine leukemia virus-derived retroviral vector has differential integration patterns in human cell lines used to produce recombinant factor VIII

Objective

Nowadays recombinant factor VIII is produced in murine cells including in Chinese hamster ovary (CHO) and baby hamster kidney cells (BHK). Previous studies, using the murine leukemia virus-derived retroviral vector pMFG-FVIII-P140K, modified two recombinant human cell lines, HepG2 and Hek293 to produce recombinant factor VIII. In order to characterize these cells, the present study aimed to analyze the integration pattern of retroviral vector pMFG-FVIII-P140K.

Methods

This study used ligation-mediated polymerase chain reaction to locate the site of viral vector integration by sequencing polymerase chain reaction products. The sequences were compared to genomic databases to characterize respective clones.

Results

The retroviral vector presented different and non-random profiles of integration between cells lines. A preference of integration for chromosomes 19, 17 and 11 was observed for HepG2FVIIIdB/P140K and chromosome 9 for Hek293FVIIIdB/P140K. In genomic regions such as CpG islands and transcription factor binding sites, there was no difference in the integration profiles for both cell lines. Integration in intronic regions of encoding protein genes (RefSeq genes) was also observed in both cell lines. Twenty percent of integrations occurred at fragile sites in the genome of the HepG2 cell line and 17% in Hek293.

Conclusion

The results suggest that the cell type can affect the profile of chromosomal integration of the retroviral vector used; these differences may interfere in the level of expression of recombinant proteins.

Switching clotting factor concentrates: considerations in estimating the risk of immunogenicity

The development of neutralizing antibodies to factor VIII (FVIII) is the most serious complication of therapy for haemophilia A. There is now excellent documentation that a large number of both genetic and environmental factors contribute to the risk of FVIII inhibitor incidence. One of the environmental factors that has been proposed as an influence on this complication is the occurrence of FVIII product switching. There are only a small number of clinical studies that have addressed this question, and thus, the amount of objective information available to assess this association is limited. In this review, in addition to summarizing past evidence pertinent to this subject, we present the results of a complementary strategy, a Delphi analysis, to add to the considerations of product switching and FVIII immunogenicity. With the imminent arrival in the clinic of several new FVIII products, the haemophilia community must be prepared to collect prospectively controlled data to better address this important management issue.

Clotting factor concentrate switching and inhibitor development in hemophilia A

The development of alloantibodies or inhibitors is the most serious complication a patient with severe hemophilia can experience from treatment with clotting factor concentrates. Although common in previously untreated patients, inhibitor development is rare in multiply exposed, well-tolerized patients. There has been a nonevidence-based reluctance to change concentrate because of a perceived greater inhibitor risk after the switch, even though most patients are now likely to be using a concentrate on which they did not begin. Inhibitors in previously treated patients are observed in approximately 2 per 1000 patient/years, which makes it difficult to study and compare rates among different products. Because the baseline inhibitor risk in previously treated patients may vary over time, it is important to compare the risk in patients switching to a new product with that in a parallel control group of nonswitching patients or within a case-controlled study. The study designs imposed by regulators are suboptimal in detecting immunogenicity signals. The issue of immunogenicity of new products is likely to gain more relevance in the near future, with a call for effective postmarketing surveillance studies for all of the new engineered factor VIII concentrates with prolonged half-lives that are likely to enter clinical practice.