Correction: Optimization of prophylaxis for hemophilia A.
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ABSTRACT:
SUBMITTER: Herbert RD
PROVIDER: S-EPMC5927422 | biostudies-literature | 2018
REPOSITORIES: biostudies-literature
Publications
Correction: Optimization of prophylaxis for hemophilia A.
Herbert Robert D RD Broderick Carolyn R CR Barnes Chris C Billot Laurent L Zhou Albert A Latimer Jane J
PloS one 20180430 4
[This corrects the article DOI: 10.1371/journal.pone.0192783.]. ...[more]
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Project description:Background & aimsProphylactic injections of factor VIII reduce the incidence of bleeds and slow the development of joint damage in people with hemophilia. The aim of this study was to identify optimal person-specific prophylaxis regimens for children with hemophilia A.MethodsAnalytic and numerical methods were used to identify prophylaxis regimens which maximize the time for which plasma factor VIII concentrations exceed a threshold, maximize the lowest plasma factor VIII concentrations, and minimize risk of bleeds.ResultsIt was demonstrated analytically that, for any injection schedule, the regimen that maximizes the lowest factor VIII concentration involves sharing doses between injections so that all of the trough concentrations in a prophylaxis cycle are equal. Numerical methods were used to identify optimal prophylaxis schedules and explore the trade-offs between efficacy and acceptability of different prophylaxis regimens. The prophylaxis regimen which minimizes risk of bleeds depends on the person's pattern of physical activity and may differ greatly from prophylaxis regimens that optimize pharmacokinetic parameters. Prophylaxis regimens which minimize risk of bleeds also differ from prophylaxis regimens that are typically prescribed. Predictions about which regimen is optimal are sensitive to estimates of the effects on risk of bleeds of factor VIII concentration and physical activity.ConclusionThe methods described here can be used to identify optimal, person-specific prophylaxis regimens for children with hemophilia A.
| S-EPMC5813962 | biostudies-literature
Project description:Background:Standard of care for persons with severe hemophilia A includes regular replacement of factor VIII (FVIII). Prophylaxis regimens using standard half-life (SHL) FVIII concentrates, while effective, are costly and require frequent intravenous infusions. Aim:This study evaluated the adherence of 56 boys with severe hemophilia A to tailored, frequency-escalated prophylaxis with an SHL recombinant FVIII concentrate. Methods:We reviewed the factor infusion and bleeding logs of study subjects. Adherence to the prescribed regimen was calculated on a weekly basis, and bleeding rates were determined from self/proxy-reported bleeding logs. The primary outcome was adherence to the prescribed prophylaxis regimen. Results:The median (range of values [ROV]) weekly adherence to prophylaxis was 85.7% (37.4%-99.8%). The median (ROV) adherent weeks on steps 1 (weekly), 2 (twice weekly), and 3 (alternate-day) were 92.9% (50%-100%), 80.3 (32%-96%), and 72.6% (14%-98%); relative to step 1, subjects were less likely to be adherent on steps 2 and 3 (P < 0.00). On step 1, our cohort had higher adherence than previously reported rates. The median (ROV) adherence to the breakthrough bleeding protocol was 47.1% (0%-100%). At any given time, bleeding risk was reduced by 15% for each 10% increase in adherence during the preceding 12 weeks (hazard ratio, 0.85; 95% confidence interval, 0.81-0.90). Conclusion:This cohort had high rates of adherence to the prescribed prophylaxis regimen. Initiating prophylaxis with once-weekly infusions facilitated adherence to the prophylaxis regimen in this cohort of boys with severe hemophilia A started on primary prophylaxis at a very young age.
| S-EPMC7040543 | biostudies-literature
Project description:Hemophilia is caused by various mutations in blood coagulation factor genes, including factor VIII (FVIII) and factor IX (FIX), that encode key proteins in the blood clotting pathway. Although the addition of therapeutic genes or infusion of clotting factors may be used to remedy hemophilia's symptoms, no permanent cure for the disease exists. Moreover, patients often develop neutralizing antibodies or experience adverse effects that limit the therapy's benefits. However, targeted gene therapy involving the precise correction of these mutated genes at the genome level using programmable nucleases is a promising strategy. These nucleases can induce double-strand breaks (DSBs) on genomes, and repairs of such induced DSBs by the two cellular repair systems enable a targeted gene correction. Going beyond cultured cell systems, we are now entering the age of direct gene correction in vivo using various delivery tools. Here, we describe the current status of in vivo and ex vivo genome-editing technology related to potential hemophilia gene correction and the prominent issues surrounding its application in patients with monogenic diseases.
| S-EPMC4999461 | biostudies-literature
Project description:Results from the main parts (24 weeks) of 2 concizumab phase 2 trials are presented: explorer4 in hemophilia A (HA) or B (HB) with inhibitors (HAwI/HBwI) and explorer5 in HA. The trials aimed to evaluate the efficacy of daily subcutaneous concizumab prophylaxis (evaluated as annualized bleeding rate [ABR] at last dose level), with secondary objectives being safety and immunogenicity (assessed as number of adverse events [AEs] and antidrug antibodies [ADAs]). Patients received 0.15 mg/kg concizumab, with potential dose escalation to 0.20 and 0.25 mg/kg (if ≥3 spontaneous bleeding episodes within 12 weeks of concizumab treatment). Relevant pharmacokinetic/pharmacodynamic (PK/PD) parameters were assessed. Thirty-six HA, 9 HAwI, and 8 HBwI patients were exposed to concizumab. Most inhibitor patients (15 of 17; 88.2%) did not escalate the dose; all patients chose to continue to the extension phase of the trials. Clinical proof of concept for prevention of bleeding episodes was demonstrated in both trials. Estimated ABRs in HAwI and HBwI were lower vs HA: 3.0 (95% confidence interval [CI], 1.7; 5.3) and 5.9 (95% CI, 4.2; 8.5) vs 7.0 (95% CI, 4.6; 10.7), respectively. PK/PD results were as expected, with no difference between hemophilia subtypes for concizumab exposure, free tissue factor pathway inhibitor, thrombin generation, prothrombin fragment 1+2, and d-dimers. Concizumab was safe and well tolerated (no severe AEs, AE-related withdrawals, or thromboembolic events). Three patients had (very low to medium titer) ADA+ tests in each trial, with no observed clinical effect. These results support further development of concizumab as a daily prophylactic treatment in all hemophilia patients. These trials were registered at www.clinicaltrials.gov as #NCT03196284 and #NCT03196297.
| S-EPMC6895373 | biostudies-literature
Project description:Introduction:Macroscopic hematuria is considered a significant risk factor for urologic disease, and it is highly prevalent in people with hemophilia. Aim:To determine whether prophylactic factor replacement therapy is associated with reduced occurrence of macroscopic hematuria in people with hemophilia in a post hoc analysis using data from a cross-sectional study conducted by the Age-Related Developments and Comobordities in Hemophilia (ADVANCE) Working Group that included males with hemophilia ?40 years of age. Methods:Data from 16 contributing centers, in 13 European countries and Israel, were analyzed using logistic regression. Of 532 recruited individuals, this analysis included 370 patients with moderate or severe hemophilia who received on-demand or prophylactic therapy. Results:For patients with a history of macroscopic hematuria, we analyzed the association between prophylaxis and reoccurrence of macroscopic hematuria within the past 5 years (n = 235 patients). Frequent (?3 times/wk) prophylaxis was negatively associated with a recent episode of macroscopic hematuria (odds ratio [OR], 0.38; 95% confidence interval [CI], 0.18-0.76). We also analyzed whether prophylaxis corresponded to a lower lifetime number of macroscopic hematuria episodes (n = 285 patients). Frequent prophylaxis for >15 years was associated with a lower number of episodes compared to on-demand treatment (OR, 0.29; 95% CI, 0.16-0.54), whereas nonsteroidal anti-inflammatory drugs (NSAIDs) and severe hemophilia were associated with a higher number. There was no association of prophylaxis <3 times/wk with hematuria. Conclusion:Frequent prophylaxis was negatively associated with the number of episodes of macroscopic hematuria in people with hemophilia. Prevalence of macroscopic hematuria was higher among individuals with severe hemophilia and those regularly using NSAIDs.
| S-EPMC7040553 | biostudies-literature
Project description:IntroductionIn countries with restricted access to clotting factor concentrates, early implementation of low-dose prophylaxis is recommended over episodic treatment.ObjectiveThe objective of this 1-year prospective secondary prophylaxis study was to evaluate the efficacy of a dose/frequency escalating protocol in young boys with hemophilia A in China.MethodsBoys were started on a low-dose protocol (minimum 10-15 IU/kg of factor VIII [FVIII] twice weekly). Escalation was based on index joint bleeding, swelling/persistent joint swelling, and serial ultrasound (gray scale and color Doppler) examinations of index joints.ResultsThirty-three boys, median age 4.8 years (interquartile range, 3.8-6.1) were enrolled in a 3-month observation period that preceded a 1-year prophylaxis phase. A significant reduction in total bleeding events (43.0%, P = .001), index joint bleeds (53.2%, P = .002), and target index joint bleeds (70.0%, P = 0.02) was observed during the prophylaxis phase. During the prophylaxis period, 40% of target joints resolved. The percentage of boys with zero index joint bleeds increased significantly (P = .004) from 51.5% during the observation phase to 81.8% in last quarter of the prophylaxis phase (months 10-12). There was no progression of arthropathy based on physical examination (Hemophilia Joint Health Score), X-ray, and ultrasound obtained at entry into the prophylaxis phase and at study exit. The median FVIII consumption over the prophylaxis phase was 1786 IU/kg/y.ConclusionA low-dose, individualized prophylaxis protocol, guided by individual bleeding profiles and serial assessment of joint status, enables escalation of treatment intensity in boys with severe hemophilia A, leading to a significant reduction in bleeding events and reduction in target joint bleeding.
| S-EPMC8449287 | biostudies-literature
Project description:A sizable proportion of hemophilia inhibitor patients fails immune tolerance induction and requires bypass agents for long-term bleed management. Recombinant human-activated coagulation Factor VII (rhFVIIa) is an on-demand bypass hemostatic agent for bleeds in hemophilia inhibitor patients. Prophylactic use of rhFVIIa may enable sustained hemostatic management of inhibitor patients, but the critical relationship of rhFVIIa circulating levels and clinical outcome in that setting remains unclear. To address this in vivo, we used the rat hemophilia A (HA) model that exhibits spontaneous bleeds and allows longitudinal studies with sufficient statistical power. We simulated activated Factor VII (FVIIa) prophylaxis by adeno-associated virus (AAV) gene transfer of a rat FVIIa transgene. Compared with naive HA animals, rat FVIIa continuous expression affected the overall observed bleeds, which were resolved with on-demand administration of recombinant rat FVIIa. Specifically, although 91% of naive animals exhibited bleeds, this was reduced to 83% and 33% in animals expressing less than 708 ng/mL (<14 nM) and at least 708 ng/mL (≥14 nM) rat FVIIa, respectively. No bleeds occurred in animals expressing higher than 1250 ng/mL (>25 nM). Rat FVIIa expression of at least 708 ng/mL was also sufficient to normalize the blood loss after a tail vein injury. Continuous, AAV-mediated rat FVIIa transgene expression had no apparent adverse effects in the hemostatic system of HA rats. This work establishes for the first time a dose dependency and threshold of circulating FVIIa antigen levels for reduction or complete elimination of bleeds in a setting of FVIIa-based HA prophylaxis.
| S-EPMC6373746 | biostudies-literature
Project description:Hemophilia B (HB) is a life-threatening inherited disease caused by mutations in the FIX gene, leading to reduced protein function and abnormal blood clotting. Due to its monogenic nature, HB is one of the primary targets for gene therapy. Indeed, successful correction of HB has been shown in clinical trials using gene therapy approaches. However, application of these strategies to non-adult patients is limited due to high cell turnover as young patients develop, resulting in vector dilution and subsequent loss of therapeutic expression. Gene editing can potentially overcome this issue by permanently inserting the corrective gene. Integration allows replication of the therapeutic transgene at every cell division and can avoid issues associated with vector dilution. In this study, we explored adenovirus as a platform for corrective CRISPR/Cas9-mediated gene knock-in. We determined as a proof-of-principle that adenoviral delivery of CRISPR/Cas9 is capable of corrective gene addition, leading to long-term augmentation of FIX activity and phenotypic correction in a murine model of juvenile HB. While we found on-target error-free integration in all examined samples, some mice also contained mutations at the integration target site. Additionally, we detected adaptive immune responses against the vector and Cas9 nuclease. Overall, our findings show that the adenovirus platform is suitable for gene insertion in juveniles with inherited disease, suggesting this approach may be applicable to other diseases.
| S-EPMC6636336 | biostudies-literature
Project description:Hemophilia A is caused by mutations within the Factor VIII (FVIII) gene that lead to depleted protein production and inefficient blood clotting. Several attempts at gene therapy have failed for various reasons-including immune rejection. The recent generation of induced pluripotent stem (iPS) cells from somatic cells by the ectopic expression of 3 transcription factors, Oct4, Sox2, and Klf4, provides a means of circumventing the immune rejection barrier. To date, iPS cells appear to be indistinguishable from ES cells and thus provide tremendous therapeutic potential. Here we prepared murine iPS cells from tail-tip fibroblasts and differentiated them to both endothelial cells and endothelial progenitor cells by using the embryoid body differentiation method. These iPS cells express major ES cell markers such as Oct4, Nanog, SSEA-1, alkaline phosphatase, and SALL4. Endothelial/endothelial progenitor cells derived from iPS cells expressed cell-specific markers such as CD31, CD34, and Flk1 and secreted FVIII protein. These iPS-derived cells were injected directly into the liver of irradiated hemophilia A mice. At various times after transplantation (7-90 days) hemophilia A mice and their control mice counterparts were challenged by a tail-clip bleeding assay. Nontransplanted hemophilia A mice died within a few hours, whereas transplanted mice survived for more than 3 months. Plasma FVIII levels increased in transplanted hemophilia A mice during this period to 8% to 12% of wild type and corrected the hemophilia A phenotype. Our studies provide additional evidence that iPS cell therapy may be able to treat human monogenetic disorders in the future.
| S-EPMC2630078 | biostudies-literature
Project description:Prophylaxis with factor (F)VIII is considered the optimal treatment for managing hemophilia A patients without inhibitors.To compare the efficacy of two prophylaxis regimens (primary outcome) and of on-demand and prophylaxis treatments (secondary outcome), and to continue the evaluation of immunogenicity and overall safety of the ADVATE Antihemophilic Factor (Recombinant), Plasma/Albumin Free Method (rAHF-PFM).Previously on-demand-treated patients aged 7-59 years (n = 66) with FVIII levels ? 2% received 6 months of on-demand treatment and then were randomized to 12 months of either standard (20-40 IU kg(-1) every other day) or pharmacokinetic (PK)-tailored (20-80 IU kg(-1) every third day) prophylaxis, both regimens intended to maintain FVIII trough levels at or above 1%. Efficacy was evaluated in terms of annualized bleeding rates (ABRs). As subjects were first treated on-demand and then on prophylaxis, statistical comparisons between these treatments were paired.Twenty-two (33.3%) subjects on prophylaxis experienced no bleeding episodes, whereas none treated on-demand were free from an episode of bleeding. ABRs for the two prophylaxis regimens were comparable, whereas differences between on-demand and either prophylaxis were statistically significant (P < 0.0001): median (interquartile range [IQR]) ABRs were 43.9 (21.9), 1.0 (3.5), 2.0 (6.9) and 1.1 (4.9) during on-demand treatment, standard, PK-tailored and any prophylaxis, respectively. There were no differences in FVIII consumption or adverse event rates between prophylaxis regimens. No subject developed FVIII inhibitors.The present study demonstrates comparable safety and effectiveness for two prophylaxis regimens and that prophylaxis significantly reduces bleeding compared with on-demand treatment. PK-tailored prophylaxis offers an alternative to standard prophylaxis for the prevention of bleeding.
| S-EPMC3488301 | biostudies-literature