Recombinant ADAMTS13 reduces abnormally up-regulated von Willebrand factor in plasma from patients with severe COVID-19.

Thrombosis affecting the pulmonary and systemic vasculature is common during severe COVID-19 and causes adverse outcomes. Although thrombosis likely results from inflammatory activation of vascular cells, the mediators of thrombosis remain unconfirmed. In a cross-sectional cohort of 36 severe COVID-19 patients, we show that markedly increased plasma von Willebrand factor (VWF) levels were accompanied by a partial reduction in the VWF regulatory protease ADAMTS13. In all patients we find this VWF/ADAMTS13 imbalance to be associated with persistence of ultra-high-molecular-weight (UHMW) VWF multimers that are highly thrombogenic in some disease settings. Incubation of plasma samples from patients with severe COVID-19 with recombinant ADAMTS13 (rADAMTS13) substantially reduced the abnormally high VWF activity, reduced overall multimer size and depleted UHMW VWF multimers in a time and concentration dependent manner. Our data implicate disruption of normal VWF/ADAMTS13 homeostasis in the pathogenesis of severe COVID-19 and indicate that this can be reversed ex vivo by correction of low plasma ADAMTS13 levels. These findings suggest a potential therapeutic role for rADAMTS13 in helping restore haemostatic balance in COVID-19 patients.

Patient Experience with Congenital (Hereditary) Thrombotic Thrombocytopenic Purpura: A Conceptual Framework of Symptoms and Impacts.

BACKGROUND AND OBJECTIVE: Thrombotic thrombocytopenic purpura is a rare, life-threatening disorder characterized by microangiopathic hemolytic anemia and thrombocytopenia, with variable clinical manifestations (e.g., central nervous system, renal, gastrointestinal, and cardiac effects). This study's objective was to gain an in-depth understanding of patients' experiences with the congenital form of thrombotic thrombocytopenic purpura, including the most salient symptoms and impacts associated with congenital thrombotic thrombocytopenic purpura and its treatment. METHODS: An initial conceptual model of thrombotic thrombocytopenic purpura symptoms and impacts was derived from a targeted literature review, refined by interviews with expert hematologists, and further refined by concept elicitation telephone interviews with adults with congenital thrombotic thrombocytopenic purpura in the USA. Patients reported the duration, frequency, and severity experienced for each concept, and rated level of disturbance on a minimum to maximum scale of 0-10. RESULTS: Interviews were conducted with 11 patients (mean age, 38.2 years; range 21-52 years) in three waves (n = 4, n = 4, n = 3). The most salient symptoms (reported most frequently and rated by patients as most disturbing) were fatigue, headache, bruising, joint pain, muscular pain, forgetfulness, and difficulty communicating. The most salient impacts included diminished ability to work/study, financial distress, feeling depressed, feeling anxious, and mood swings. Patients' comments reflected the pervasive nature of congenital thrombotic thrombocytopenic purpura symptoms and impacts, and unmet treatment needs. CONCLUSIONS: The final conceptual model, which includes salient symptoms and impacts of congenital thrombotic thrombocytopenic purpura and reflects the disease burden, was derived by integrating inputs from the literature review, expert opinion, and patient interviews, and will be used to develop a congenital thrombotic thrombocytopenic purpura-specific, patient-reported outcome instrument.

Use of Bypassing Agents and Risk of Thromboembolic Events in Patients with Haemophilia and Inhibitors.

Patients with haemophilia and inhibitors to factors VIII or IX require bypassing therapy. The primary safety concern of bypassing agents is thromboembolism; however, the incidence of thromboembolic adverse events (TAEs) in haemophilia patients with inhibitors remains poorly characterized. The aim of this study was to assess the incidence of TAEs following exposure to bypassing agents in patients with haemophilia. Using U.S. Medicaid database (2000­2010), we identified a cohort of 719 males (mean age: 10 years at cohort entry) with haemophilia A or B and use of either recombinant factor VIIa (rFVIIa) or activated prothrombin complex concentrate (aPCC). Patients were followed up until loss of insurance eligibility, end of study period, or the first occurrence of TAE. Exposure was assessed on as-treated basis, and outcomes were adjudicated through review of healthcare claims. During the observation of a total of 2,823 person-years (py; mean follow-up: 3.9 years), 22 TAEs were identified, leading to incidence rates of 4.2 events (95% confidence interval [CI]: 1.8­8.3) per 1,000 unexposed py; 15.4 events (95% CI: 6.7­30.3) per 1,000 aPCC-exposed py; 18.2 events (95% CI: 8.3­34.6) per 1,000 rFVIIa-exposed py; and 29.7 events (95% CI: 6.1­86.7) per 1,000 py of concomitant exposure to both agents. The results were consistent across sensitivity analyses. In conclusion, we found no difference in the rate of TAEs across agents, but the data are compatible with a possibly increased rate associated with a combination therapy, highlighting the need for continuing safety monitoring through prospective registries or observational data.

The role of ultralarge multimers in recombinant human von Willebrand factor - a review of physico-and biochemical studies and findings in in vivo models and in humans with von Willebrand disease.

Ultralarge multimers (ULM) of VWF are considered to be the most active with respect to binding to platelets and to subendothelial structures and therefore are of critical importance for the function of VWF in stabilizing the primary hemostatic plug. In contrast to plasma-derived FVIII-VWF concentrates, human rVWF obtained from mammalian cell culture retains the full-spectrum of intact multimers, including ULM, as physiologically formed in the Golgi apparatus and stored in platelet α-granules and endothelial cell Weibel-Palade bodies. In the course of physico and biochemical, functional and animal studies, rVWF exhibited superiority in structure and function compared to pdVWF. These effects seemed to correlate with the multimer size and therefore might be attributed to the presence of ULM in rVWF preparations. The pharmacokinetic (PK), safety and efficacy characteristics seen in preclinical studies were further demonstrated in clinical trials.

Advancing personalized care in hemophilia A: ten years' experience with an advanced category antihemophilic factor prepared using a plasma/albumin-free method.

Detailed analysis of data from studies of recombinant antihemophilic factor produced using a plasma/albumin-free method (rAHF-PFM) in previously treated patients showed a substantial level of interpatient variation in pharmacokinetics (PKs), factor VIII dosing, and annualized bleed rate (ABR), suggesting that individual patient characteristics contributed to outcome. For example, plasma half-life (t1/2), recovery, and clearance appeared to differ between patients aged <6 years and 10-65 years. Prophylaxis resulted in lower ABRs than episodic treatment in both age groups; better adherence to the prophylactic regimen resulted in a lower ABR in patients aged 10-65 years. The weekly frequency of dosing and adherence to dosing were both significantly and inversely related to the rate of bleeding (young children, P<0.0001 for both all bleeds and joint bleeds; older patients, P<0.0001 for all bleeds and P<0.05 for joint bleeds), as was adherence to dosing frequency (P<0.0001 for all comparisons). A post-marketing randomized study of prophylaxis demonstrated that a PK-guided dosing regimen, based on an individual patient's rAHF-PFM PK (infusion interval, estimated t1/2, and recovery), was as effective as standard prophylaxis and that both prophylactic regimens were superior to episodic treatment with respect to ABR and quality of life measures. Thus, compared with standard prophylaxis, the PK-guided regimen achieved comparable efficacy with fewer weekly infusions. A two-compartment population PK model describes the PK data across the entire age range and forms the basis for future PK-guided therapy with rAHF-PFM. The model confirmed a shorter t1/2 and faster clearance of rAHF-PFM in children <6 years of age versus patients ≥10 years and predicted similar PK parameters with either a full or reduced blood sampling schedule, offering the potential for the use of PK-guided, individualized treatment in the routine clinical care setting.

Pharmacokinetics and safety of a novel recombinant human von Willebrand factor manufactured with a plasma-free method: a prospective clinical trial.

Safety and pharmacokinetics (PK) of recombinant von Willebrand factor (rVWF) combined at a fixed ratio with recombinant factor VIII (rFVIII) were investigated in 32 subjects with type 3 or severe type 1 von Willebrand disease (VWD) in a prospective phase 1, multicenter, randomized clinical trial. rVWF was well tolerated and no thrombotic events, inhibitors, or serious adverse events were observed. The PK of rVWF ristocetin cofactor activity, VWF antigen, and collagen-binding activity were similar to those of the comparator plasma-derived (pd) VWF-pdFVIII. In vivo cleavage of ultra-large molecular-weight rVWF multimers by ADAMTS13 (a disintegrin and metalloproteinase with a thrombospondin type 1 motif, member 13; the endogenous VWF protease) and generation of characteristic satellite bands were demonstrated. In 2 subjects with specific nonneutralizing anti-VWF-binding antibodies already detectable before rVWF infusion, a reduction in VWF multimers and VWF activity was observed. Stabilization of endogenous FVIII was enhanced following post-rVWF-rFVIII infusion as shown by the difference in area under the plasma concentration curve compared with pdVWF-pdFVIII (AUC0-∞) (P < .01). These data support the concept of administering rVWF alone once a therapeutic level of endogenous FVIII is achieved.

Population pharmacokinetics of recombinant factor VIII: the relationships of pharmacokinetics to age and body weight.

Comparison of the pharmacokinetics (PK) of a coagulation factor between groups of patients can be biased by differences in study protocols, in particular between blood sampling schedules. This could affect clinical dose tailoring, especially in children. The aim of this study was to describe the relationships of the PK of factor VIII (FVIII) with age and body weight by a population PK model. The potential to reduce blood sampling was also explored. A model was built for FVIII PK from 236 infusions of recombinant FVIII in 152 patients (1-65 years of age) with severe hemophilia A. The PK of FVIII over the entire age range was well described by a 2-compartment model and a previously reported problem, resulting from differences in blood sampling, to compare findings from children and adults was practically abolished. The decline in FVIII clearance and increase in half-life with age could be described as continuous functions. Retrospective reduction of blood sampling from 11 to 5 samples made no important difference to the estimates of PK parameters. The obtained findings can be used as a basis for PK-based dose tailoring of FVIII in clinical practice, in all age groups, with minimal blood sampling.

Intramyocardial, autologous CD34+ cell therapy for refractory angina.

RATIONALE: A growing number of patients with coronary disease have refractory angina. Preclinical and early-phase clinical data suggest that intramyocardial injection of autologous CD34+ cells can improve myocardial perfusion and function. OBJECTIVE: Evaluate the safety and bioactivity of intramyocardial injections of autologous CD34+ cells in patients with refractory angina who have exhausted all other treatment options. METHODS AND RESULTS: In this prospective, double-blind, randomized, phase II study (ClinicalTrials.gov identifier: NCT00300053), 167 patients with refractory angina received 1 of 2 doses (1×10(5) or 5×10(5) cells/kg) of mobilized autologous CD34+ cells or an equal volume of diluent (placebo). Treatment was distributed into 10 sites of ischemic, viable myocardium with a NOGA mapping injection catheter. The primary outcome measure was weekly angina frequency 6 months after treatment. Weekly angina frequency was significantly lower in the low-dose group than in placebo-treated patients at both 6 months (6.8±1.1 versus 10.9±1.2, P=0.020) and 12 months (6.3±1.2 versus 11.0±1.2, P=0.035); measurements in the high-dose group were also lower, but not significantly. Similarly, improvement in exercise tolerance was significantly greater in low-dose patients than in placebo-treated patients (6 months: 139±151 versus 69±122 seconds, P=0.014; 12 months: 140±171 versus 58±146 seconds, P=0.017) and greater, but not significantly, in the high-dose group. During cell mobilization and collection, 4.6% of patients had cardiac enzyme elevations consistent with non-ST segment elevation myocardial infarction. Mortality at 12 months was 5.4% in the placebo-treatment group with no deaths among cell-treated patients. CONCLUSIONS: Patients with refractory angina who received intramyocardial injections of autologous CD34+ cells (10(5) cells/kg) experienced significant improvements in angina frequency and exercise tolerance. The cell-mobilization and -collection procedures were associated with cardiac enzyme elevations, which will be addressed in future studies.

Integrated analysis of safety and efficacy of a plasma- and albumin-free recombinant factor VIII (rAHF-PFM) from six clinical studies in patients with hemophilia A.

BACKGROUND: Hemophilia A is an X-linked bleeding disorder that results from insufficient levels of factor VIII (FVIII) coagulant activity. OBJECTIVE: To evaluate the efficacy and safety of ADVATE rAHF-PFM (Baxter Healthcare Corporation), a recombinant FVIII concentrate manufactured without human or bovine blood-derived additives, and to assess the effect of compliance with prophylactic use in preventing bleeding episodes (BEs). METHODS: Clinical data were integrated from six prospective studies. Two hundred thirty-four hemophilia A subjects (FVIII levels < or = 2%) (median age 14.7 (range: 0.02 - 72.7) years) were included. RESULTS: BEs were managed with one or two infusions and nearly all (1953/1956) responded to treatment. Compliance with a prophylactic treatment regimen significantly reduced the incidence of BEs (p = 0.0061) and prevented non-traumatic joint BEs (median annualized BE rate was 0). One previously treated subject developed an inhibitor; no other safety concerns were observed. CONCLUSIONS: These results reinforce the efficacy and safety of rAHF-PFM and suggest that compliance is an essential contributor to the effectiveness of prophylaxis in the treatment of hemophilia A.

Pharmacokinetic analysis of plasma-derived and recombinant F IX concentrates in previously treated patients with moderate or severe hemophilia B.

BACKGROUND: Hemophilia B is an X-linked bleeding disorder that affects approximately 1 in 25,000 males. Therapy for acute bleeding episodes consists of transfusions of plasma-derived (pd-F IX) or recombinant (r-F IX) concentrates. STUDY DESIGN AND METHODS: A double-blind, two-period crossover study was initiated to assess the pharmacokinetics of pd-F IX and r-F IX and to address patient-specific variables that might influence in vivo recovery. Study product was administered by a single bolus infusion (50 IU/kg) to 43 previously treated patients in the nonbleeding state, and F IX:C levels were measured over a period of 48 hours after infusion. RESULTS: The mean in vivo recovery in the pd-F IX group was 1.71 +/- 0.73 IU per dL per IU per kg compared with 0.86 +/- 0.31 IU per dL per IU per kg with r-F IX (p

Treatment of von Willebrand disease with a high-purity factor VIII/von Willebrand factor concentrate: a prospective, multicenter study.

Among patients with von Willebrand disease (VWD) who are unresponsive to desmopressin therapy, replacement with plasma-derived concentrates is the treatment of choice. Because prospective studies are lacking, such treatment has been largely empirical. A multicenter, prospective study has been conducted in 81 patients with VWD (15 patients with type 1, 34 with type 2, and 32 with type 3 disease) to investigate the efficacy of a high-purity factor VIII/von Willebrand factor (FVIII/VWF) concentrate for treatment of bleeding and surgical prophylaxis. Two preparations of the concentrate-one virally inactivated with solvent detergent, the other with an additional heat-treatment step--were evaluated. Pharmacokinetic parameters were similar for both preparations. Using pre-established dosages based on the results of pharmacokinetic studies, 53 patients were administered either preparation for the treatment of 87 bleeding episodes, and 39 patients were treated prophylactically for 71 surgical or invasive procedures. Sixty-five (74.7%) and 10 (11.5%) of the bleeding episodes were controlled with 1 or 2 infusions, respectively. Patients with severe type 3 VWD typically required more infusions and higher doses, at shorter time intervals, than did patients with generally milder types 1 and 2. Among patients undergoing surgical procedures, blood loss was lower than that predicted prospectively, and losses exceeding the predicted value did not correlate with the postinfusion skin bleeding time. In conclusion, the concentrate effectively stopped active bleeding and provided adequate hemostasis for surgical or invasive procedures, even in the absence of bleeding time correction.