Dr. Noh's research will utilize induced pluripotent stem cells (iPSC) and manipulate them in vitro to expand production of megakaryocytes and platelets that express therapeutic proteins, including FVIII. The project will further determine whether this system of autologous platelets which overexpress FVIII can be delivered directly to the site of injury and hemorrhage, thereby circumventing and evading neutralization by alloantibody inhibitors in hemophilia A. Dr. Noh received her Ph.D. in Preventive Pharmacology from Seoul National University in South Korea. She has been a postdoctoral fellow in Dr. Mitchell Weiss' lab at The Children's Hospital of Philadelphia since 2012. Dr. Noh is currently being mentored in this JGP project by Dr. Mortimer Poncz at CHOP.
Prophylactic factor VIII (FVIII) replacement therapy in hemophilia A requires frequent administration because of the short half-life of FVIII. Polyethylene glycol (PEG) conjugation is thought to extend FVIII half-life by decreasing hepatic clearance. BAY 94-9027 is a rationally designed B-domain–deleted (BDD) FVIII molecule with a 60-kDa PEG molecule attached to a specific amino acid (1804) to increase circulating half-life and reduce the exposure to epitopes reported to cause immunogenicity in the A3 domain while preserving full biological function. BAY 94-9027 is currently in clinical trials and has prolonged half-life and improved efficacy in animal models and humans.
To determine whether half-life extension with BAY 94-9027 is related to PEG steric hindrance, we first investigated whether PEG impacts BAY 94-9027 binding interactions. Direct binding of hybrid of kidney and B cells (HKB)11-derived FVIII, BAY 94-9027 or BDD-FVIII, was assessed by measuring the ability of a panel of immobilized monoclonal antibodies directed toward different FVIII domains to capture FVIII. Interactions with more physiologic partners were indirectly assessed by thrombin generation assay (TGA) and by an in vitro hepatocyte clearance assay.
Our results indicate that the presence of A3-directed PEG reduced BAY 94-9027 capture by immobilized antibodies directed toward FVIII regions at or near the site of conjugation. Capture by antibodies directed toward the A3 and C2 domains were most impacted, while those directed toward A1 and A2 still bound BAY 94-9027. The A3-specific C7F7 antibody showed ~50% lower capture of BAY 94-9027 vs BDD-FVIII at 20 ng/mL of FVIII. C7F7 capture of PEG-BDD-FVIII was further reduced when a di-PEG conjugate of BDD-FVIII was subjected to the same assay, again confirming that PEG sterically modulates PEG-BDD-FVIII reactivity to the antibody. To determine whether steric effects observed with PEG may impact FVIII function globally, TGA was performed with BAY 94-9027 spiked into FVIII-deficient plasma and subjected to 1 pM tissue factor initiation. By TGA, both BDD-FVIII and BAY 94- 9027 generated comparable peak thrombin levels, with EC50 values of 3.9 and 3.2 nM for BDD-FVIII and BAY 94-9027, respectively. These results indicate that the PEG did not disrupt activated PEG-BDD-FVIII interactions with its partners in the factor Xase enzyme complex, consistent with published PEG-BDD-FVIII efficacy. By hepatocyte clearance assay, PEG- BDD-FVIII clearance was reduced ~30-40% compared with BDD-FVIII, regardless of whether von Willebrand factor was present. This reduction in hepatocyte clearance is likely to contribute to the prolonged plasma half-life reported for BAY 94-9027.
Objective:
To assess the effect of digital monitoring on bleeding rates in patients with hemophilia A using prophylaxis.
Methods:
A total of 294 eligible patients with hemophilia A were included in our observational study. Eligible patients used clotting factor concentrates and had no active inhibitors. Patients used a digital health tool powered by MicroHealth to log bleeds and infusions via smartphone, texting, or online. The study observational period was August 2014 to January 2015. Patients using the tool could choose to invite their care professionals for monitoring. For each patient, Hemophilia Treatment Center (HTC) monitoring was defined as having at least one HTC professional: 1. Linked to the patient and with online access to the infusion logs; 2. Receiving notifications when the patient had bleeds and/or had adherence below a threshold, and; 3. Having two or more patients under monitoring. There were a total of 35 and 259 patients in the monitoring and non-monitoring groups, respectively.
We conducted Bayesian analysis using linear mixed models and a negative binomial distribution to compare the relative risk of bleeding rates for patients with and without HTC monitoring.
Summary:
Patients using HTC monitoring had a relative bleeding rate of 0.60 vs. patients without monitoring, which is equivalent to a 40% reduction in bleeding rates for monitored patients (95% credible interval: 0.38—0.96).
Patients on the monitoring and no monitoring groups were comparable except that the monitoring group had 23% more pediatric patients (p<0.001). However, bleeding rates between pediatric and adults were comparable (p=0.500). Subgroup analysis showed no differences in the reductions of bleeding rates due to monitoring between pediatric-only and adult-only subgroups (p=0.353).
Conclusions:
The use of digital tools for chronic care monitoring is a growing global trend.
A reduction in the annualized bleeding rate of 40% (~2 bleeds a year) is both statistically and clinically significant and may have a cumulative protective impact on patients’ long-term outcomes. Observational studies are subject to sample bias, however, patients in both groups were technologically savvy and motivated enough to track their condition using a digital health tool. Given that this intervention is free, safe, and fits the accountable care model, we encourage clinicians to explore its adoption. Confirmatory studies on this topic are encouraged.
Objective:
Hemophilia is a congenital deficiency in a clotting factor resulting in a propensity for severe and disabling bleeds. Joint bleeds can lead to disabling arthropathy and past contamination of blood products resulted in an epidemic of HIV and hepatitis. We hypothesize that these issues may result in declines in quality of life, psychosocial well-being, and socialization (integration into society) and that socialization correlates with health-related quality of life (HR-QoL).
Methods:
We developed a socialization survey and interview for patients age >20 with hemophilia A (n=14) or B (n=4) and their spouses/significant others (SSOs) (n=9). The interviews were analyzed using PROMIS (patient-reported outcomes measurement information system-29) domains. Patients completed surveys in health-related quality of life measures including both A36 Hemofilia-QoL and WHOQOL-BREF. Patients were also scored according to the Colorado Joint Assessment Scale and Karnofsky Performance Scale. IRB approval and informed consent were obtained.
Results:
19 patients were enrolled (ages 24-78), one withdrew. Nine patients had severe hemophilia, 5 had moderate disease, and 4 were mild. Four patients did not have SSOs (22%, 90% CI: [8%; 44%]); these included two severe and two moderate patients, one with HIV, and three with hepatitis C. Five SSOs declined participation. For the WHOQOL-BREF, patients reported overall quality of life in the physical domain an average score of 60 (range 13-94), 66 (31-100) in the psychological domain, 66 (31-100) in the social relationship domain, and 81 (44-100) in the environmental domain, all standardized 0-100. For the A36 Hemofilia-QOL, the median score was 94 (range 43-132) out of 144 (totaling physical health, daily activities, joint damage, pain, treatment satisfaction, treatment difficulties, emotional functioning, mental health, and relationships and social activities). Colorado Joint Assessment Scale-QOL provided scores of 6.1 out of 19 for ankles without gait and 8.3 out of 21 with gait, 4.2 for knees without gait, 6.3 with gait, and 3.6 for elbows. Analysis of interviews reflects social roles and social support as common domains in patients, whereas anxiety and anger predominated for SSOs.
Conclusions:
This study employed established instruments as well as novel questionnaires and interview structures, although the latter have not been validated. Analysis points toward patient concerns regarding their social roles while SSOs expressed higher levels of anxiety and anger compared to patients. Both health-related-QoL and disease severity appear to be associated with social support domains of socialization. Patients with more severe disease may be less likely to have SSOs.
