Improvement in clinical outcomes and replacement factor VIII use in patients with haemophilia A after factor VIII pharmacokinetic-guided prophylaxis based on Bayesian models with myPKFiT®

The Role of Clot Waveform Analysis and Related Parameters in the Diagnosis and Treatment of Hemophilia A

BACKGROUND

 Hemophilia A (HA) is an inherited bleeding disorder caused by a deficiency or defect in factor VIII (FVIII).

METHODS

 We investigated the role of clot waveform analysis (CWA) of activated partial thromboplastin time in the diagnosis and therapeutic monitoring of HA. The changes in CWA parameters the maximum clotting velocity (|Min1|), maximum clotting acceleration (|Min2|), and maximum clotting deceleration (|Max2|) were detected among mild, moderate, and severe HA groups.

RESULTS

 As the severity of HA subtypes increased, the levels of |Min1|, |Min2|, and |Max2| progressively decreased (p < 0.05). Receiver operating characteristic curve analysis showed that |Max2| and |Min2| were more effective than |Min1| in distinguishing different types of HA patients, with higher diagnostic efficacy. The standard curves based on Actin FSL reagent for normal and low levels of FVIII:C-|Max2| were established, with R2 values of 0.98 and 0.99, respectively. These curves can be utilized for monitoring during replacement therapies involving full-length recombinant FVIII and B-domain-deleted FVIII. Thirty cases of HA patients utilized the FVIII-|Max2| standard curve to obtain individual pharmacokinetics characteristic parameters. The clearance, half-life (t1/2), time to FVIII:C of 1% above baseline (tt1%), and predicted dosage showed no statistically significant differences compared with one-stage assay (p > 0.05).

CONCLUSION

 CWA is an economical and practical tool, and its related parameters are associated with the severity of HA. It has promising clinical prospects in predicting FVIII:C levels and individualized treatment when HA patients undergo replacement therapy.

Exploring the relationship between condition severity and health-related quality of life in people with haemophilia A across Europe: a multivariable analysis of data from the CHESS II study

BACKGROUND

Haemophilia A (HA; Factor VIII deficiency) is a congenital X-linked bleeding disorder characterized by trauma-related or spontaneous bleeding events, most notably arising within the intraarticular space and resulting in chronic inflammation and degeneration of affected joints. Endogenous clotting factor activity relative to normal levels determines the severity of HA symptoms, as mild (> 5-40%), moderate (1-5%), or severe (< 1%). Within the current environment of rapid evolution in HA management, we seek to understand the interplay of condition severity and health-related quality of life (HRQoL) to characterise and differentiate unmet needs among people with HA (PwHA).

METHODS

A generalised linear regression model (GLM) was developed to explore the relationship between HA severity and EQ-5D-5 L index score from adult HA patients sampled in the "Cost of Haemophilia across Europe - a Socioeconomic Survey II" (CHESS II) cross-sectional, retrospective burden of illness study among adults with hereditary haemophilia A or B from eight European countries. HA patients of any severity with no active inhibitors during the 12 months prior to data capture and a completeEQ-5D-5 L response were included. A base GLM model was specified with covariates for demographic and clinical characteristics (age, body mass index, country, employment, HA severity, annual bleeding rate, problem joints, and chronic pain).

RESULTS

Of 381 evaluable patients, 221 (58.0%) had severe HA, 96 (25.2%) had moderate HA, and 64 (16.8%) had mild HA. Among the covariates included in the GLM model and after controlling for haemophilia-related outcomes, a significant association was observed between mild HA and higher EQ-5D-5 L index score (average marginal effects, 0.084; p = 0.016) relative to severe HA. Patient country of residence and magnitude of HA-related chronic pain were also associated with significant differences in index scores, with the latter showing a negative relationship with HRQoL outcomes.

CONCLUSIONS

Condition severity and chronic pain are significant predictors of HRQoL in PwHA. Durable bleeding protection and effective management of chronic pain have the potential to address unmet treatment needs in this population.

Classification of recombinant factor VIII products and implications for clinical practice: A systematic literature review

INTRODUCTION

Consensus over the definition of recombinant factor VIII (rFVIII) product classification in haemophilia A is lacking. rFVIII products are often classified as standard half-life (SHL) or extended half-life (EHL); despite this, no universally accepted definition currently exists. One proposed definition includes half-life, area under the curve, and technology designed to extend half-life; however, the International Society on Thrombosis and Haemostasis defines activity over time as the most intuitive information for building treatment regimens and the World Federation of Hemophilia describes rFVIII product classification in terms of infusion frequency.

AIM

To summarise published data on the clinical and pharmacokinetic criteria used to define rFVIII product classification.

METHODS

PubMed and EMBASE database searches of English-language articles (2002-2022) were conducted using search strings to identify the relevant population, intervention, and outcomes (e.g., clinical and pharmacokinetic parameters). Articles then underwent title/abstract and full-text screens.

RESULTS

Among 1147 identified articles, 62 were included. Half-life was the most widely reported outcome with no clear trends or product groupings observed. No clear groupings emerged among other outcomes, including infusion frequency, consumption, and efficacy. As activity over time was reported in few articles, further investigation of its relevance to rFVIII product classification is warranted.

CONCLUSION

The findings of this systematic literature review suggest that parameters other than half-life might be important for the development of a comprehensive and clinically relevant rFVIII product classification definition. There seems to be an opportunity to consider parameters that are clinically meaningful and useful for shared decision-making in haemophilia A treatment.

Predictive performance of pharmacokinetic-guided prophylactic dosing of factor concentrates in hemophilia A and B

Background

Pharmacokinetic (PK)-guided dosing is used to individualize factor (F)VIII and FIX replacement therapy.

Objectives

This study investigates the reliability and feasibility of PK-guided prophylactic dosing of factor concentrates in hemophilia A and B.

Methods

In this multicenter, prospective cohort study, people of all ages with hemophilia received prophylactic treatment with factor concentrates based on individual PK parameters. During follow-up, at least 4 measured FVIII/FIX levels per patient were compared with corresponding predicted levels obtained by Bayesian forecasting. Predictive performance was defined as adequate when ≥80% of measured FVIII/FIX levels were within ±25% of prediction (relative error). Additionally, mean absolute error and mean error were calculated. In post hoc analyses, predictive performance was assessed allowing maximum absolute errors of 1 (trough), 5 (mid), and 15 (peak) IU/dL. Five-point scale questionnaires addressed feasibility of PK guidance.

Results

We included 50 patients (median age, 19 years; range: 2-72 years). Median follow-up was 36 weeks. Seventy-one percent of levels (58% trough, 83% mid, and 80% peak) were within ±25% of prediction. Mean absolute errors were 0.8 (trough), 2.0 (mid), and 8.6 (peak) IU/dL. In post hoc analyses, 81% (trough), 96% (mid), and 82% (peak) of levels were within set limits. Patients reported low burden and high satisfaction.

Conclusion

PK-guided dosing was reliable according to post hoc analyses, based on low absolute errors that were regarded as clinically irrelevant in most cases. The predefined predictive performance was achieved in mid and peak factor levels but not in trough factor levels due to measurement inaccuracy. PK guidance also seemed feasible.

Comparison Pharmacokinetic Dosing Tools in Hemophilia A Children

Prophylaxis is the gold standard for the management of hemophilia A patients. It has been shown that prophylaxis regulated with pharmacokinetic (PK) data reduces frequency of bleeding and cost of treatment. To determine the best prophylaxis regimen, PK dosing tools using the Bayesian method have been developed. We aimed to compare two PK dosing tools. Blood samples were drawn before, 4, 24, and 48 h after FVIII infusions from patients with severe hemophilia A and inhibitor negative. FVIII levels were measured by PTT-based one-stage assay method. PK parameters obtained using WAPPS and myPKFiT, which are web-accessible PK dosing tools using Bayesian algorithm, and daily prophylaxis dose estimated by the programs were compared. Forty-two hemophilia A patients [median age 13 years (IQR 8.9-16.4)] included in the study. There was no difference between the daily dose of FVIII given for prophylaxis and the dose recommended by the myPKFiT for the 1% trough level; whereas, a significant difference was found with the WAPPS. The half-lives of FVIII did not differ between the two dosing tools; however, significant differences were found in the estimated dose, clearances, and times to 1% trough level. There was no significant difference between PK data of patients who received Advate® and those who received non-Advate® factor concentrates. Choice of PK dosing tool can affect recommended FVIII dose. However, target trough levels should be individualized according to bleeding phenotype and daily activity of patient.

Supplementary Information

The online version contains supplementary material available at 10.1007/s12288-023-01671-0.

Pharmacokinetic-guided versus standard prophylaxis in hemophilia: a systematic review and meta-analysis

BACKGROUND

With population pharmacokinetic (PK) modeling more readily available and PK-guided prophylaxis endorsed by current hemophilia guidelines, we conducted a systematic review to summarize current evidence in the literature.

OBJECTIVES

To assess the efficacy of PK-guided compared with non-PK-guided prophylaxis.

METHODS

We did not restrict inclusion to specific study design labels and included all studies consisting of at least one distinct cohort arm receiving PK-guided prophylaxis. We searched the following databases from inception to date of search: MEDLINE, Embase, CENTRAL, ClinicalTrials.gov, and the EU Clinical Trial Register. Following title, abstract, and full-text screening conducted independently by 2 review authors, we summarized studies qualitatively and synthesized included randomized clinical trials (RCTs) quantitatively by fitting random-effects models.

RESULTS

Search of databases on February 3, 2023, yielded 25 studies fitting our inclusion criteria. Of those, only 2 RCTs and 17 nonrandomized studies included a standard prophylaxis comparator group. Furthermore, risk of bias in the latter was substantial, primarily due to before-after study designs and retrospective comparator groups. Thus, nonrandomized studies were only presented qualitatively. A random-effects meta-analysis of the 2 identified RCT remained inconclusive with regards to bleeding outcomes (ratio of means, 1.15; 95% CI, 0.85-1.56) and factor consumption (ratio of means, 0.82; 95% CI, 0.58-1.18).

CONCLUSION

Evidence in the literature suggesting a clinical benefit of PK-guided over standard fixed-dose prophylaxis was weak and mainly found in nonrandomized studies limited by lack of concurrent controls, heterogeneity in outcome reporting, small sample sizes, and high risk of bias.

Effects of PK-guided prophylaxis on clinical outcomes and FVIII consumption for patients with moderate to severe Haemophilia A

INTRODUCTION

In recent years, there has been increased focus on individualizing treatment for persons with hemophilia including pharmacokinetic-guided (PK) dosing.

AIMS

In this retrospective study clinical outcomes before and after PK-guided prophylaxis were examined.

MATERIALS AND METHODS

Eight Haemophilia Treatment Centres from the United States participated in the study and included 132 patients classified into two cohorts: those undergoing a PK-assessment for product switch (switchers) or to optimize treatment (non-switchers). Subset analyses for the two most common products and patients with dosing per prescription label were included for annual bleeding rates (ABR), mean weekly consumption outcomes, and annualized cost of prophylaxis.

RESULTS

The most common products before and after index date were octocog alfa, rurioctocog alfa pegol, and efmoroctocog alfa. Seventy-four (56%) patients were identified as switchers and 58 (44%) patients were classified as non-switchers. The majority of patients (78.0%) experienced either a decrease in ABR post-index or maintained 0 ABR during pre- and post-index time periods, with similar proportions identified in both switchers (77.0%) and non-switchers (79.3%) populations. Non-switchers were identified as having no significant change in cost of therapy, while switchers experienced increased cost of therapy driven by higher price of extended half-life products. Within subset analyses, patients receiving rurioctocog alfa pegol and efmoroctocog alfa had mean ABR under 1 after index date.

CONCLUSION

PK-guided prophylaxis has the potential to improve clinical outcomes without increase in cost of therapy for patients maintaining product and can aid in maintaining effective protection against bleeds in those switching product.

The road to implementation of pharmacokinetic-guided dosing of factor replacement therapy in hemophilia and allied bleeding disorders. Identifying knowledge gaps by mapping barriers and facilitators

Clinical guidelines and expert groups recommend the use of pharmacokinetic (PK)-guided dosing of factor replacement therapy for the treatment of bleeding disorders, especially for patients with hemophilia. Although PK-guided dosing is increasingly applied, it is generally not considered standard clinical practice. The aim of this scoping review is to map barriers and facilitators for the implementation of PK-guided dosing in clinical practice and to identify knowledge gaps. A literature search was performed and 110 articles were included that describe PK-guided dosing in patients with bleeding disorders, mostly hemophilia A. We defined two overarching themes, efficacy and feasibility, and discuss five topics within each theme. For each topic, barriers, facilitators and knowledge gaps were described. Although consensus was found with regard to some topics, contradicting reports were found for others, especially with respect to the efficacy of PK-guided dosing. These contradictions highlight the need for future research to elucidate current ambiguities.

Clinical outcomes of low-dose pharmacokinetic-guided extended half-life versus low-dose standard half-life factor VIII concentrate prophylaxis in haemophilia A patients

INTRODUCTION

Despite receiving standard half-life (SHL) factor VIII (FVIII) concentrates prophylaxis, some severe haemophilia A (HA) patients still encounter spontaneous breakthrough bleeding. Individualized pharmacokinetic (PK)-guided dosing of extended half-life (EHL) FVIII concentrates may reduce their bleeding events.

AIM

To compare clinical outcomes before and after switching low-dose prophylaxis using weight-based SHL FVIII to PK-guided EHL FVIII concentrates, taking into consideration of a trough FVIII activity at 1 IU/dl above natural baseline.

METHODS

In this single-centre prospective cohort, Thai severe or moderate HA (FVIII activity ≤3 IU/dl) patients receiving low-dose weight-based SHL FVIII prophylaxis were enrolled. After a 3-day wash-out period, participants underwent low-dose EHL FVIII prophylaxis with PK-based adjustment (myPKFiT^® ) for 6 months. The annualized bleeding rates (ABR), the annualized joint bleeding rates (AJBR), the haemophilia-specific quality-of-life (Haemo-QoL or Haemo-QoL-A) scores, the Hemophilia Joint Health Scores (HJHS) and the annualized FVIII consumption were compared between the two prophylactic periods.

RESULTS

Of 15 eligible subjects (mean age 18.7 ± 6.7 years), ABR, AJBR and HJHS were significantly reduced (mean differences of -11.1 ± 4.9 bleeds/year, -10.4 ± 5.2 joint bleeds/year and -5.1 ± 1.5 marks, respectively; P < .001 for all comparisons) after switching regimen. The quality-of-life scores had also improved (P = .001). Nonetheless, FVIII consumption tended to increase despite no statistical significance (means of 1240.9 ± 531.3 SHL FVIII IU/kg/year versus 1591.7 ± 438.9 EHL FVIII IU/kg/year; P = .05).

CONCLUSIONS

This is the first low-dose, PK-guided, EHL FVIII prophylaxis clinical study in Thailand. Benefits and practicability of this personalized regimen may support the implementation of regular FVIII prophylaxis in developing countries with budget constraints.

CLINICALTRIALS

gov NCT05281185.

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.

Individualised prophylaxis based on personalised target trough FVIII level optimised clinical outcomes in paediatric patients with severe haemophilia A

INTRODUCTION

As standard care of severe haemophilia A (SHA), prophylaxis should be individualised.

AIM

This study aimed to investigate the effectiveness of this new-proposed individualised prophylaxis protocol.

METHODS

Boys with SHA were enrolled and followed a PK-guided, trough-level escalating protocol of prophylaxis after a six-month observational period. In the next 2 years, clinical assessments including joint bleeds, ultrasound (US) scores and Haemophilia Joint Health Score (HJHS) in both sides of ankles, knees and elbows were conducted every 6 months as a scoring system, which determined whether the trough level's escalation. Adjustment of dosing regimen was based on WAPPS-Hemo.

RESULTS

Fifty-eight SHA boys were finally analysed. Their age and bodyweight were 5.3(2.8,6.9) years and 21.5(16,25) kg. During the study, 47 escalations were conducted. At study exit, the patient number and proportion of different trough level groups were: < 1 IU/dl, 17.2% (10/58); 1-3 IU/dl, 53.5% (31/58); 3-5 IU/dl, 15.5% (9/58); > 5 IU/dl, 13.8% (8/58). Significantly reduced annualised bleeding rate [4(0,8) to 0(0,2), p < .0001] and annualised joint bleeding rate [2(0,4) to 0(0,.25), p < .0001] was observed at study exit as well as the continuous trend of increased zero bleeding proportion (ZBP) (27.6%-69.0%) and zero joint bleeding proportion (46.5%-81.3%). Besides, 85% (6/7) of the target joints vanished. Statistical improvements of US scores (p = .04) and HJHS (p = .02) were also reported at study exit.

CONCLUSION

Our results showed the effectiveness of our protocol based on individualised target trough level and emphasise the importance of personalised prophylaxis.

The Impact of Pharmacokinetic-Guided Prophylaxis on Clinical Outcomes and Healthcare Resource Utilization in Hemophilia A Patients: Real-World Evidence from the CHESS II Study

Background

Using a pharmacokinetic (PK)-guided approach to personalize the dose and frequency of prophylactic treatment can help achieve and maintain targeted factor VIII (FVIII) trough levels in patients with hemophilia A.

Objective

Investigate clinical and healthcare resource use outcomes in patients with hemophilia A treated with or without PK-guided prophylaxis using data from the Cost of Haemophilia in Europe: A Socioeconomic Survey (CHESS) II database.

Methods

CHESS II was a cross-sectional, retrospective, burden-of-illness study incorporating data from eight European countries. Patients were eligible for this analysis if they were male, ≥18 years of age, and diagnosed with congenital hemophilia A of any severity. The clinical endpoints included annualized bleeding rate (ABR), presence and number of problem/target joints, and occurrence of joint surgeries. Healthcare resource utilization endpoints included the number of hematologist consultations and bleed-related hospitalizations or emergency department admissions. Data from November 2018 to October 2020 were included and were stratified according to treatment regimen and use of PK-guided dosing.

Results

Altogether, 281 patients on prophylaxis had available FVIII trough level data. Mean (SD) age was 35.7 (13.8) years. A specific FVIII trough level was targeted in 120 (42.7%) patients and 47 (39.2%) received PK-guided dosing. Patients receiving PK-guided dosing had a mean (SD) ABR of 2.8 (2.1) and target joint number of 0.5 (0.7), compared with 3.9 (2.7) and 0.9 (1.4), respectively, for patients receiving non-PK-guided treatment. The mean (SD) number of hematologist consultations was 7.1 (5.3) for patients receiving PK-guided dosing versus 10.7 (5.7) for those who were not. A higher proportion of patients in the non-PK-guided group required hospitalization during their lifetime compared with the PK-guided group.

Conclusion

This analysis of real-world data suggests that PK-guided dosing for prophylaxis has a beneficial impact on clinical and healthcare resource utilization outcomes in patients with hemophilia A.

Cost-Effectiveness Analysis of Pharmacokinetic-Guided Prophylaxis Versus Standard Prophylaxis in Adults with Severe Hemophilia A in China

INTRODUCTION

Multiple studies have demonstrated the effectiveness of pharmacokinetic (PK)-guided individualized prophylaxis with human coagulation factor VIII (FVIII) compared with standard prophylaxis, but no studies have evaluated the economics of PK-guided prophylaxis in China. Hence, we conducted this study to assess the cost-effectiveness of PK-guided prophylaxis with recombinant FVIII (rFVIII) versus standard prophylaxis in Chinese adult patients with severe hemophilia A.

METHODS

A discrete event simulation model was developed to simulate 10,000 patients with hemophilia A who received rFVIII treatment over a 1-year time horizon. The standard prophylaxis rFVIII dose was 30 IU/kg by intravenous injection. The PK-guided prophylaxis dosage was adjusted for each patient to maintain FVIII trough level at 1-5 IU/dL. Dosing interval for both approaches was kept fixed at 48 h. The health outcomes included annual joint bleed rate (AJBR) and quality-adjusted life years (QALYs). The model considered the costs of drug. Incremental cost-effectiveness ratio (ICER) was estimated and scenario analysis was performed.

RESULTS

A total of 94.3% of patients receiving PK-guided individualized prophylaxis achieved the goal of maintaining the trough concentration at 1-5 IU/dL compared with 62.7% on standard prophylaxis. AJBR and QALYs gained in PK-guided and standard prophylaxis were 1.527 vs 1.601, and 0.8384 vs 0.8383, respectively. Costs of drug prophylaxis and costs of treatment for bleeding events in PK-guided prophylaxis (148,641.47 USD; 4546.43 USD) were lower than those in standard prophylaxis (159,620.93 USD; 4753.39 USD). An average saving of USD 11,186.47 was obtained by the PK-guided approach. The prophylaxis treatment scenarios were the most influential factors.

CONCLUSION

PK-guided individualized prophylaxis appeared to be a dominant treatment compared with standard prophylaxis, with slightly higher QALYs but lower total costs.

Real-World Clinical Outcomes and Replacement Factor VIII Consumption in Patients with Haemophilia A in Italy: A Comparison between Prophylaxis Pre and Post Octocog Alfa (BAY 81-8973)

(1) Background: new generations of rFVIII products offered the possibility to improve personalized therapeutic approaches, reducing the number of infusions or increasing the protection against bleeding risk. The aim of this study was to assess the effectiveness of prophylaxis with BAY 81-8973 (octocog alfa, Kovaltry^®, Bayer Pharma AG) in the real-world setting and its impact on FVIII consumption compared to previous standard half-life treatments. (2) Methods: a retrospective observational study was conducted in five Italian Haemophilia Centers. Patients with haemophilia A under prophylactic treatment with BAY 81-8973 for at least one year, and previously on prophylaxis with a different product were included in the study. Annual bleeding rate (ABR) and annual FVIII consumption were compared. (3) Results: forty-four patients were included in the study. After switching to BAY 81-8973, ABR was significantly reduced (1.76 vs. 0.23; p = 0.015), the percentage of patients with zero bleeds increased from 54.6% to 84.1% (p = 0.003), and the overall FVIII consumption decreased by 25,542 (-7.2%, p = 0.046) IU per patient-year. Patients treated every 3 days or 2 times per week increased from 0% to 27.3%. (4) Conclusion: our results suggest that prophylaxis with BAY 81-8973 can improve clinical outcomes and reduce FVIII consumption, in the real-world practice, compared with the previous prophylaxis regimen with standard half-life products.

Aerobic exercise in patients with haemophilia: A systematic review on safety, feasibility and health effects

BACKGROUND

Haemophilia is a congenital bleeding disorder going along with disease-specific joint complications and general health implications attributed to the lack of daily movement. Recent guidelines recommend physical activity for people with haemophilia (PwH). Yet, aerobic exercise in PwH is little studied and seldomly prescribed by clinicans.

AIM

The aim of this systematic review is to investigate the safety, feasibility and health-related efficiency of AE in PwH.

METHODS

A systematic literature search according to the PRISMA guidelines was conducted (PubMed, Web of Science). Inclusion criteria were defined using PICOS. Methodological quality was assessed via TESTEX.

RESULTS

Out of 789 studies identified, seven studies (three randomized controlled, two controlled, two single-group prospective trails) were included. The TESTEX mean score was 8.1 (±3.8). AE was realized as aquatic exercise, nordic walking, treadmill running, bicycle riding and swimming. Neither bleeding rates nor the factor amount increased and AE led to diverse health-related improvements.

CONCLUSIONS

Little research has been conducted evaluating AE in PwH. Yet, AE can be considered as safe and feasible when being supervised by experts. However, disease-specific recommendations for AE are difficult to provide. Therefore, experts can currently only back AE recommendations on experience and nonhaemophilia-specific general guidelines.

Clinical benefits of a Bayesian model for plasma-derived factor VIII/VWF after one year of pharmacokinetic-guided prophylaxis in severe/moderate hemophilia A patients

INTRODUCTION

Individual pharmacokinetic (PK) profiling in hemophilia A (HA) helps to individualize prophylaxis using population PK models (popPK). A specific popPK model for plasma-derived factor VIII containing von-Willebrand Factor (pdFVIII/VWF) was developed.

AIM

To compare standard versus PK-driven prophylaxis, using a generic or a specific popPK model for pdFVIII/VWF.

MATERIALS AND METHODS

A prospective study conducted in HA patients in prophylaxis with pdFVIII/VWF (Fanhdi®) comparing three one-year study periods: (1) standard prophylaxis, (2) PK-guided prophylaxis using a generic pdFVIII popPK model which described FVIII activity irrespective of FVIII concentrate, and (3) PK-guided prophylaxis with specific pdFVIII/VWF popPK model. PK parameters analyzed were half-life, trough levels (TL) at 24, 48 and 72 h, and time to reach FVIII levels of 1, 2, 5% (T5%). Clinical outcomes were dose/kg, FVIII consumption, annualized bleeding rate (ABR), annualized joint bleeding rate (AJBR), spontaneous and traumatic bleeds.

RESULTS

Of the 30 analyzed patients, 28 had severe HA and the median age was 31.2. Fifteen patient's prophylaxis doses were PK-adjusted. After the generic PK-guided prophylaxis period, younger patients showed more joint bleeds, a shorter half-life, and lower TL48, TL72 and T5%. Using the specific pdFVIII/VWF popPK model compared with standard prophylaxis, a lower spontaneous AJBR was observed in the entire cohort and in patients aged >15 years. Additionally, lower spontaneous ABR was reported in patients aged ≤15 years comparing specific and generic models.

CONCLUSIONS

PK-guided prophylaxis with a specific pdFVIII/VWF popPK model allowed treatment individualization and improved bleeding control in routine clinical practice, especially in younger patients with short pdFVIII/VWF half-lives.

A comparison of MyPKFiT and WAPPS-Hemo as dosing tools for optimizing prophylaxis in patients with severe haemophilia A treated with Octocog alfa

INTRODUCTION

MyPKFiT and the Web-Accessible Population Pharmacokinetic service-Hemophilia (WAPPS-Hemo) are web-based population-based applications developed for helping physicians individualize and optimize replacement therapy. Although MyPKFiT is intended for Octocog alfa and Rurioctocog alfa pegol use only, the WAPPS-Hemo is applicable to all factor VIII concentrates.

AIM

To compare MyPKFiT and WAPPS-Hemo as dosing tools for optimizing treatment of patients with severe haemophilia A on regular prophylaxis with Octocog alfa in a real-world setting.

METHODS

Fourteen patients with severe haemophilia A (median age 30.8 years; range 20-71) were enrolled. The FVIII activity was measured twice after a regular dose of Octocog alfa by the chromogenic and the one-stage assays. PK analyses were performed using each tool and dosing estimations to reach trough levels of 1%, 3% or 5% after 48 h. Findings were calculated and compared.

RESULTS

The two PK algorithms yielded similar t½ independent of the type of FVIII assay used. However, there were significant differences in the time to reach 1%, 3% and 5%. The WAPPS-Hemo generated 10-12 h longer time to a trough of 1% and up to 4 h for the troughs of 3% and 5%. Accordingly, the doses estimated by WAPPS-Hemo for a daily regimen were between 28% and 100% of those proposed by MyPKFiT.

CONCLUSIONS

MyPKFiT and WAPPS-Hemo provided similar half-life estimations for Octocog alfa independent of the FVIII assay used. The doses suggested by WAPPS-Hemo to reach specific troughs were overall lower, which may have implications for treatment optimization.

Pharmacokinetic variability of factor VIII concentrates in Chinese pediatric patients with moderate or severe hemophilia A

IMPORTANCE

The use of factor VIII (FVIII) concentrates under pharmacokinetic (PK) guidance has become the main approach for treatment of hemophilia. However, limited PK research has been conducted in Chinese pediatric patients.

OBJECTIVE

To investigate the PK parameters of various FVIII concentrates in Chinese pediatric patients.

METHODS

Seventy-nine patients were enrolled (28 treated with Kogenate FS®, 23 treated with Advate ®, and 28 treated with GreenMono™). All enrolled patients participated in single-dose PK analysis after at least a 3-day washout period. Blood samples were collected predose, as well as at 1 h, 9 h, 24 h, and 48 h after infusion; FVIII levels were measured using a one-stage clotting assay. von Willebrand Factor Antigen (VWF:Ag) levels and blood types were also determined. PK parameters were evaluated by WAPPS-Hemo.

RESULTS

Mean values of terminal elimination half-life time (t1/2) for the Kogenate FS®, Advate®, and GreenMono™ FVIII groups were 12.24 h, 10.18 h, and 9.62 h; median clearance values were 4.16, 6.23, and 5.11 mL·kg-1·h-1; and median in vivo recovery values were 1.97, 1.55, and 1.61 IU/dL per IU/kg. Longer t1/2, higher in vivo recovery, and lower clearance were observed in patients with higher VWF:Ag level who were treated with recombinant concentrates.

INTERPRETATION

Chinese pediatric patients with hemophilia had FVIII PK characteristics similar to those previously observed in non-Chinese children, including large variation among individuals. VWF:Ag level and FVIII brand were associated with differences in FVIII PK. Thus, PK-guided dosing should be used to optimize individualized therapy in Chinese children.

A Practical, One-Clinic Visit Protocol for Pharmacokinetic Profile Generation with the ADVATE myPKFiT Dosing Tool in Severe Hemophilia A Subjects

Standard pharmacokinetic (PK) assessments are demanding for persons with hemophilia A, requiring a 72-hour washout and 5 to 11 timed blood samples. A no-washout, single-clinic visit, sparse sampling population PK (PPK) protocol is an attractive alternative. Here, we compared PK parameters obtained with a traditional washout, 6-sampling time point PPK protocol with a no-washout, single-clinic visit, reverse 2-sampling time point PPK protocol in persons with severe hemophilia A (SHA) receiving ADVATE. A total of 39 inhibitor-negative males with SHA (factor VIII activity [FVIII:C] < 2%) were enrolled in a prospective sequential design PK study. Participants completed a washout, 6-sampling time point PPK protocol as well as a no-washout, reverse 2-sampling time point protocol, with samples taken during a single 3-hour clinic visit 24 hours post home infusion of FVIII and then 3 hours post infusion in clinic. FVIII:C levels were analyzed by one-stage and chromogenic assays; blood group and von Willebrand factor antigen (VWF:Ag) were determined; and PK parameters were analyzed using the ADVATE myPKFiT dosing tool. There was moderate to almost perfect agreement for the PK parameters obtained with the 2- and the 6- point PPK protocols using a one-stage FVIII:C assay and a substantial to almost perfect agreement using a chromogenic FVIII:C assay. Significant associations between specific PK parameters and blood group and VWF:Ag were observed. The no-washout, single-clinic visit, reverse 2-sampling time point PPK protocol can be used in the routine clinical setting since it demonstrates sufficient accuracy compared with the more demanding and less practical washout, 6-sampling time point PPK protocol in persons with SHA receiving ADVATE.

Delivering on the promise of gene therapy for haemophilia

The promise of gene therapy is a single treatment ('one and done') that leads to steady-state expression of endogenous factor VIII or factor IX sufficient to achieve a functional cure (free of recurrent haemophilic bleeding) if not normalized haemostasis. The elimination of the need for continued prophylaxis, or factor replacement following trauma or prior to surgery would lead to annual cost savings. Such optimized health and well-being would be reaching a level of health equity that was unimaginable several decades ago. 'Before anything else, preparation is the key to success'-Alexander Graham Bell. This quote from the famous inventor, scientist and engineer highlights that, although we currently stand on the threshold of this achievement, delivering on this promise will require broad-based multistakeholder preparation (scientists, manufacturers, federal regulators, health technology assessors, persons with haemophilia, national advocacy groups and multidisciplinary healthcare teams) with a focused emphasis on education, approval of safe and effective therapies, removal of barriers to access and excellence in clinical delivery.

Precision Dosing Priority Criteria: Drug, Disease, and Patient Population Variables

The administered dose of a drug modulates whether patients will experience optimal effectiveness, toxicity including death, or no effect at all. Dosing is particularly important for diseases and/or drugs where the drug can decrease severe morbidity or prolong life. Likewise, dosing is important where the drug can cause death or severe morbidity. Since we believe there are many examples where more precise dosing could benefit patients, it is worthwhile to consider how to prioritize drug-disease targets. One key consideration is the quality of information available from which more precise dosing recommendations can be constructed. When a new more precise dosing scheme is created and differs significantly from the approved label, it is important to consider the level of proof necessary to either change the label and/or change clinical practice. The cost and effort needed to provide this proof should also be considered in prioritizing drug-disease precision dosing targets. Although precision dosing is being promoted and has great promise, it is underutilized in many drugs and disease states. Therefore, we believe it is important to consider how more precise dosing is going to be delivered to high priority patients in a timely manner. If better dosing schemes do not change clinical practice resulting in better patient outcomes, then what is the use? This review paper discusses variables to consider when prioritizing precision dosing candidates while highlighting key examples of precision dosing that have been successfully used to improve patient care.

Joint Bleeding Tendencies in Adult Patients With Hemophilia: It's Not All Pharmacokinetics

Hemophilic arthropathy from joint bleeding remains a complication with major morbidity in the increasingly aging patients with hemophilia. Prophylactic clotting factor infusions, based on pharmacokinetic dosing to reduce bleeding rates, are being explored more and more. However, there is little evidence on the benefits of pharmacokinetic dosing in direct association with bleeding events. Here, we prospectively followed a cohort of adult patients with hemophilia A and B (n = 26) and arthropathic joints on various clotting factor products over a period of 2 years with clinical and radiographic joint health assessments, frequent joint ultrasound, and pharmacokinetic studies. Joint bleeds and synovitis with synovial vascularity changes were objectively diagnosed by musculoskeletal ultrasound and power Doppler and analyzed in relation to pharmacokinetic, joint- and patient-specific parameters. Results revealed that, contrary to common beliefs, bleeding episodes were not readily explained by pharmacokinetic features, as they were not associated with more time spent below certain clotting factor thresholds. Joint bleeding was found to be associated with prominent vascularity changes, suggesting that vascular remodeling and leakiness may contribute to joint bleeding that cannot be prevented by clotting factor replacement alone.

Economic impact model of delayed inhibitor development in patients with hemophilia a receiving emicizumab for the prevention of bleeding events

Aims: Cumulative exogenous factor VIII (FVIII) exposure is an important predictor of developing neutralizing antibodies (inhibitors) to FVIII in patients with persons with hemophilia A (PwHA). The aim of this study was to model the costs of emicizumab versus FVIII prophylaxis and total treatment costs for patients with severe HA.Materials and Methods: An Excel-based decision model was developed to calculate cumulative costs in PwHA over a 20-year time horizon from the US payer perspective. The model considered persons with severe HA beginning at age 12 months with no prior FVIII exposure and initiating prophylaxis with emicizumab or FVIII. PwHA could develop inhibitors on accumulation of 20 FVIII exposure days. PwHA with inhibitors replaced FVIII with bypassing agents until inhibitors resolved spontaneously, following immune tolerance induction (ITI), or at the end of the time horizon. The primary model outcome was the difference in emicizumab versus FVIII treatment costs in 2019 USD. Sensitivity analyses were performed to test the robustness of results.Results: Total incremental cost over 20 years was -$1,945,480 (emicizumab arm, $4,919,058; FVIII arm, $6,864,538). Prophylaxis costs (emicizumab arm, $4,096,105; FVIII arm, $6,290,919) comprised the majority of costs in both groups, followed by breakthrough bleed treatment for the FVIII arm ($342,652) and ITI costs for the emicizumab arm ($733,671). Higher costs in the FVIII group reflected earlier inhibitor development (FVIII, 4 months; emicizumab, 162 months) and switch to bypassing agents.Limitations: The model design reflects a simplified treatment pathway for patients with severe HA who initiate FVIII or emicizumab prophylaxis. In the absence of clinical data, a key conservative assumption of the model is that patients receiving emicizumab and FVIII prophylaxis have the same risk of developing inhibitors.Conclusions: This study suggests that prophylaxis with emicizumab results in cost savings compared to FVIII prophylaxis in HA.