Patient preferences for gene therapy in haemophilia: Results from the PAVING threshold technique survey

OBJECTIVES

The aim of the Patient preferences to Assess Value IN Gene therapies (PAVING) study was to investigate trade-offs that adult Belgian people with haemophilia (PWH) A and B are willing to make when choosing between prophylactic factor replacement therapy (PFRT) and gene therapy.

METHODS

The threshold technique was used to quantify the minimum acceptable benefit (MAB) of a switch from PFRT to gene therapy in terms of 'Annual bleeding rate' (ABR), 'Chance to stop prophylaxis' (STOP), and 'Quality of life' (QOL). The design was supported by stakeholder involvement and included an educational tool on gene therapy. Threshold intervals were analysed using interval regression models in Stata 16.

RESULTS

A total of 117 PWH completed the survey. Mean thresholds were identified for all benefits, but substantial preference heterogeneity was observed; especially for the STOP thresholds, where the distribution of preferences was bimodal. Time spent on the educational tool and residence were found to impact MAB thresholds. The most accepted (88% of PWH) gene therapy profile investigated in this study comprised of zero bleeds per year (vs. six for PFRT), 90% chance to stop prophylaxis, no impact on QoL, and 10 years of follow-up on side effects (vs. 30 for PFRT).

CONCLUSIONS

Results from this study proved the value of educating patients on novel treatments. Moreover, preference heterogeneity for novel treatments was confirmed in this study. In gene therapy decision-making, preference heterogeneity and the impact of patient education on acceptance should be considered.

Serum calprotectin (S100A8/A9): a promising biomarker in diagnosis and follow-up in different subgroups of juvenile idiopathic arthritis

Introduction

In the management of juvenile idiopathic arthritis (JIA), there is a lack of diagnostic and prognostic biomarkers. This study assesses the use of serum calprotectin (sCal) as a marker to monitor disease activity, and as a classification and prognosis tool of response to treatment or risk of flares in patients with JIA.

Methods

Eighty-one patients with JIA from the CAP48 multicentric cohort were included in this study, as well as 11 non-paediatric healthy controls. An ELISA method was used to quantify sCal with a commercial kit.

Results

Patients with an active disease compared with healthy controls and with patients with inactive disease showed an eightfold and a twofold increased level of sCal, respectively. sCal was found to be correlated with the C-reactive protein (CRP) and even more strongly with the erythrocyte sedimentation rate. Evolution of DAS28 scores correlated well with evolution of sCal, as opposed to evolution of CRP. With regard to CRP, sCal could differentiate forms with active oligoarthritis from polyarthritis and systemic forms. However, sCal brought an added value compared with the CRP as a prognosis marker. Indeed, patients with active disease and reaching minimal disease activity (according to Juvenile Arthritis Disease Activity Score) at 6 months following the test had higher sCal levels, while patients with inactive disease had higher sCal levels if a flare was observed up to 3–9 months following the test.

Conclusions

This study confirms the potential uses of sCal as a biomarker in the diagnosis and follow-up of JIA.

Is There Any Improvement of the Coagulation Imbalance in Sickle Cell Disease after Hematopoietic Stem Cell Transplantation?

Several components of the clotting system are modified towards hypercoagulability in sickle cell disease (SCD). To date, hematopoietic stem cell transplantation (HSCT) is the only validated curative treatment of SCD. Here, we investigated the changes in the hemostatic potential of SCD children who've received a successful HSCT. Seventeen children with severe SCD were enrolled in the study. Thrombin generation (TG) was performed on citrated platelet-poor plasma, obtained before and 3, 6, 9, 12 and 15 months after HSCT. TG was triggered using 1 pM tissue factor and 4 µM phospholipids with or without thrombomodulin (TM). Before the HSCT, SCD children showed a higher endogenous thrombin potential (ETP), higher peak, higher velocity and shorter time-to-peak of TG than the normal controls (NC). ETP did not significantly change following the HSCT. However, the peak, velocity and time-to-peak of TG reversed to normal ranges from 3 months post-HSCT and remained so up to 15 months post-HSCT. The reduction of ETP after the addition of thrombomodulin (RETP) was dramatically reduced in SCD children before HSCT as compared with the NC. A partial reversal of RETP was observed from 3 months through 15 months post-HSCT. No statistical difference was observed for patient age or donor hemoglobinopathy status. In summary, successful HSCT improves the kinetics of TG but not the total thrombin capacity in SCD children.

Automated RBC exchange compared to manual exchange transfusion for children with sickle cell disease is cost-effective and reduces iron overload

BACKGROUND

Chronic transfusion in sickle cell disease (SCD) remains the gold standard therapy for stroke prevention and for patients with severe disease despite adequate hydroxyurea treatment. The aim of our study was to assess the safety and efficacy of automated red blood cell exchange (aRBX) in patients with SCD previously treated with manual exchange transfusion (MET). Costs related to transfusion and chelation overtime were evaluated.

STUDY DESIGN AND METHODS

Beginning in January 2012, children with SCD who weighed 30 kg or more on MET could switch to aRBX. Clinical, biological, and procedures' data, including costs, were recorded for the last 6 months on MET and compared to those after the first and the second year on aRBX.

RESULTS

Ten patients switched from MET to aRBX at a median age of 11.8 years. After the switch, median hemoglobin S (HbS) increased significantly (33.5% on MET compared to 45% on aRBX; p < 0.001) but remained in the target values for all patients. Median ferritin decreased significantly (663.3 µg/L on MET compared to 126.8 µg/L on aRBX; p < 0.001) and intervals between procedures were significantly longer. The requirements of red blood cells (RBCs)/kg/year were not different on MET (0.88 unit/kg/year) than during the second year on aRBX (1.07 unit/kg/year; p = NS). MET costs were similar compared to aRBX since chelation was stopped in previously treated patients.

CONCLUSION

Erythrocytapheresis reduces iron overload and allows a longer interval between procedures without a higher RBC requirement from the second year on aRBX. The cost did not increase as estimated in our Belgian Health Care System.

Different profile of thrombin generation in children with acute lymphoblastic leukaemia treated with native or pegylated asparaginase: A cohort study

BACKGROUND

Asparaginase (Asp) and corticosteroid (CS) treatment in patients with acute lymphoblastic leukaemia (ALL) is associated with an increased risk of thrombotic events.

OBJECTIVE

Characterization of global haemostatic phenotypes of patients with ALL during Asp therapy.

PROCEDURE

Thrombin generation (TG) was monitored in platelet-poor plasma of 56 children treated for a B lineage ALL (36 with native, 20 with PEG Asp) using 1 pM tissue factor and 4 μM phospholipids, with and without thrombomodulin. Protein C activity (PC), free protein S (PS), antithrombin (AT) and fibrinogen levels were also measured.

RESULTS

Elevated endogenous thrombin potential (ETP) and peak of TG were noted at diagnosis, throughout the Induction phase and Late Intensification but was significantly less for PEG than for native Asp (P < 0.001), while age, sex, type of corticosteroid during Induction and molecular response had no significant effect. The reduction of ETP after addition of thrombomodulin was significantly lower in ALL children compared with that in controls, suggesting impairment in PS/PC pathway. Three patients experienced thrombosis: two treated with native and one with PEG Asp. The two patients with native Asp had, at the time of thrombosis, a prothrombotic profile.

CONCLUSIONS

Treatment with Asp, in combination with CS, enhances TG in children with ALL, more significantly with native than PEG Asp, which is present early at diagnosis, persists during Induction and reappears during Late Intensification. This is consistent with the high incidence of thrombotic events described during these phases of therapy. The less pronounced effect of PEG Asp remains to be elucidated.

Survival among children and adults with sickle cell disease in Belgium: Benefit from hydroxyurea treatment

OBJECTIVE

To evaluate the survival of patients with sickle cell disease (SCD) recorded in the Belgian SCD Registry and to assess the impact of disease-modifying treatments (DMT).

METHOD

The Registry created in 2008 included patients of eight centers. All available data in 2008 were retrospectively encoded in the database. After 2008 and until 2012, all data were recorded prospectively for already registered patients as well as newly diagnosed subjects. Data were registered from neonatal screening or from diagnosis (first contact) until last follow-up or death. Data included diagnosis, demography, and outcome data.

RESULTS

We collected data from 469 patients over a 5,110 patient years (PY) follow-up period. The global mortality rate was low (0.25/100 PY), although 13 patients died (2.8%) and was similar between children, adolescents (10-18 years), and young adults (P = 0.76). Out of the cohort, 185 patients received hydroxyurea at last follow-up (median duration of treatment: 10.3 years), 90 underwent hematopoietic stem cell transplantation (HSCT), 24 were chronically transfused, and 170 had never had any DMT. Hydroxyurea showed significant benefit on patients outcome as reflected by a lower mortality rate compared to transplanted individuals or people without DMT (0.14, 0.36, and 0.38 per 100 PY, respectively) and by higher Kaplan-Meier estimates of 15 year survival (99.4%) compared to HSCT (93.8%; P = 0.01) or no DMT groups (95.4%; P = 0.04).

CONCLUSION

SCD mortality in Belgium is low with no increase observed in young adults. Patients treated with hydroxyurea demonstrate a significant benefit in survival when compared to those without DMT or transplanted.

Reduction of the six-minute walk distance in children with sickle cell disease is correlated with silent infarct: results from a cross-sectional evaluation in a single center in Belgium

Background

The 6-minute walk test (6MWT) is used in adults and children affected by a wide range of chronic diseases to evaluate their sub-maximal exercise capacity. It reflects the global response of various physiological systems in a situation simulating a daily life activity.

Methods

We analyzed factors affecting the 6MWT in 46 Sickle Cell Disease children. Forty-two were treated with hydroxyurea (HU). Patients with normal test (>80% of the age-standardized predicted value) were compared to patients with abnormal test (≤80%). Baseline hematological values, clinical events, cerebrovascular disease, cardio-pulmonary parameters and disease-modifying treatment were compared according to the performance of the test.

Results

Among the 46 patients, 14 had an abnormal 6MWT. In univariate analysis, both groups were similar for biological and clinical data. Six of the 14 patients with an abnormal 6MWT had silent infarct (SI) compared to 6/32 with a normal test (P = 0.09). When excluding chronically transfused patients, 4 of the 11 patients with an abnormal 6MWT had SI compared to 1/26 (P = 0.02). Baseline pulse oximetry was normal in both groups but slightly lower in patients with abnormal 6MWT (P = 0.02). No patient presented exercise-induced desaturation. In multivariate analysis, the only factor associated with abnormal 6MWT was the presence of SI (P = 0.045).

Conclusions

In our cohort of 46 patients characterized by high exposure rate to HU and by the absence of severe cardiopulmonary disease, the sole factor independently associated with 6MWT was the presence of SI. The lower exercise capacity of children with SI may reflect some subclinical neurological impairment as they do not differ by hemoglobin level or cardiopulmonary parameters.

[Respiratory complications of sickle cell anemia in children: the acute chest syndrome]

The acute chest syndrome (ACS) is one of the most frequent complications of sickle cell disease. It affects mostly young children and counts for one quarter of mortality in the young sickle cell disease (SCD) population. This retrospective study evaluates the impact of ACS among hospitalizations for other complications of SCD in patients at the University Childrens' Hospital Reine Fabiola (Brussels, Belgium) in order to isolate clinical conditions associated with a high risk of ACS development. The medical records of all SCD patients aged up to 18 years admitted for all SCD related acute complications over a period of 13 month have been reviewed. Two patient groups have been formed based on the presence of an ACS within the study period. Epidemiologic data, medical history, the clinical presentation at admission but also blood counts in steady state, at admission and along the hospital stay were compared for a total of 96 hospital stays. There is no difference for age or hemoglobin phenotype between the two major patient groups. Male sex and having had a previous ACS episode in the past were significantly more important in the group of patients hospitalized for ACS. Thoracic pain in an SCD patient who doesn't show typical ACS symptoms should be interpreted as a risk factor for ACS. In conclusion, male sex, medical history of at least one ACS and thoracic pain at hospital admission are associated with high risk of developing ACS.

Thrombin generation reveals high procoagulant potential in the plasma of sickle cell disease children

Changes in several components of the clotting system are well documented in sickle cell disease (SCD) patients. However, whether the global hemostatic potential of these patients is altered is still unclear. Calibrated automated thrombogram(®) method of thrombin generation (TG) was used to characterize the hemostatic potential of 83 SCD children (75 SS, 6 SC, and 2 Sβ (thal)) at steady-state as compared with 50 controls of the same range of age. TG was triggered using 1 pM tissue factor and 4 μM phospholipids with and without thrombomodulin. Thirteen SCD children were also evaluated during vaso-occlusive crisis. Protein C activity, free protein S and D-dimers levels were measured in parallel. SCD patients showed higher rates of thrombin formation, higher thrombin peak height (with and without thrombomodulin), and higher endogenous thrombin potential (ETP) than controls in the presence of thrombomodulin. Reduction of ETP (RETP) in the presence of thrombomodulin was lower in SCD group compared with controls and correlated both with protein C and protein S levels. ETP, RETP, peak height, and velocity index of TG correlated with D-dimers. Compound heterozygous patients showed an intermediate hemostatic phenotype at steady-state. No significant difference was observed when comparing TG parameters during vaso-occlusive crisis to those obtained at steady-state in the same patients. The global hemostatic potential is increased and reflects the hypercoagulable state of SCD patients even at steady-state. The relevance of this finding with respect to the risk of thrombotic complications of the disease needs further investigation.

[Thrombin generation test: establishment of reference values according to age and tissue factor concentration is essential before implementation into the laboratory]

The calibrated and automated thrombinography (CAT) developed by H.C. Hemker is a simple and reproducible technique that can be potentially used in coagulation laboratories. This test is able to record the complete thrombin generation in vitro, giving an interesting approach in the evaluation of the haemostatic potential at the individual level. We aimed to implement this test in our laboratory to follow patients with haemorrhagic or thrombotic pathologies. Haemorrhagic and thrombotic disorders are incompletely explored by the coagulation tests used presently in routine labs. These tests don't indeed reflect the real haemostatic phenotype of the patient neither the individual response to haemostatic treatments. Furthermore, they don't have any predictive value for the occurrence of haemorrhage and/or thrombosis. We report here reference values we established in a population of children and adults in pre-analytical conditions easily applicable in coagulation labs. Platelet poor plasma is prepared by a double centrifugation and analyzed immediately or frozen at -80 degrees C for delayed analysis.

Sickle cell disease from Africa to Belgium, from neonatal screening to clinical management

AIM

To describe the severity of sickle cell disease (SCD) in newborns in Belgium and evaluate the impact of neonatal screening (NS) on clinical outcome.

METHODS

Universal NS of umbilical cord blood for hemoglobinopathy was progressively deployed in Brussels and Liège starting in 1994. No particular population was targeted. Samples were analyzed initially using the isoelectric focusing technique and since 2008 the capillary electrophoresis technique. If a hemoglobin variant was suspected, further analysis was carried out using high performance liquid chromatography. Children presenting major hemoglobinopathy, especially SCD, were referred to a specialized centre for comprehensive management. Preventive measures included antipneumococcal prophylaxis immunization/antibiotic therapy, parental training to recognize severe anemia and splenic sequestration, and transcranial ultrasound recording for early detection of intracranial stenosis. A database was set up in Belgium to collect clinical and laboratory data including parental phenotype, diagnostic technique (neonatal screening or not), major clinical events (episodes of dactylitis, acute chest syndrome, severe anemia, infection, etc), number and duration of required hospitalizations, and treatment used.

RESULTS

Screening of 222352 newborns in maternity units in Brussels led to diagnosis of SCD in 145 patients, Adequate data for analysis of clinical outcome was available for 96 of these children born before 2007. Median age in the study group was 4.2 years and the total duration of follow-up was 510 years. Most cases occurred in families from the Democratic Republic of Congo. (64/96 patients; 66.7%) and involved homozygous hemoglobin S disease (80/96 patients; 83.3%). Twenty-seven percent of patients (26/96) presented no severe clinical events during the study (17 SS, median age 2,1 years (0-13.1 years). Conversely 33% presented an episode of dactylitis and 47.9% (46/96) presented recurrent vasoocclusive crises. Severe anemia was observed in 39.6% (38/96) of cases. Six patients (6.3%) developed septicemia despite prophylactic antibiotic therapy and anti-pneumococcal immunization using heptavalent conjugate vaccine and polysaccharide vaccine, No penicillin-resistant strains were observed. The incidence of stroke was 2.1% (3/96). Two patients presenting homozygous hemoglobin S disease died due to septicemia due to non-compliance with antibiotic therapy in one case and severe anemia in one case. All episodes of septicemia and both deaths occurred at the beginning of the NS program. Hydroxyurea therapy was used in 30 patients (31.2%) including 7 in whom transcranial Doppler depicted blood flow abnormalities and 8 in whom allogeneic bone marrow transplantation was performed.

CONCLUSIONS

Sickle cell disease is still associated with high morbidity and mortality but clinical care has improved and no death has occurred in the last 10 years. NS is an effective tool for early detection and management of SCD. Neonates with SCD diagnosed by NS in Belgium presented severe manifestations, but clinical outcomes were improved by comprehensive management.

GCMB mutation in familial isolated hypoparathyroidism with residual secretion of parathyroid hormone

Isolated hypoparathyroidism is an uncommon metabolic disorder characterized by hypocalcemia and hyperphosphatemia, with absent or low levels of PTH. It may present as an apparently sporadic disorder or may be transmitted in families as a genetic trait. Mutations of the calcium-sensing receptor gene and of the preproPTH gene have been reported in occasional cases, and a mutation of the parathyroid-specific transcription factor GCMB gene has been reported in one familial case. We report a second family with isolated hypoparathyroidism and a GCMB mutation. The patients were two siblings from asymptomatic, first-cousin parents, indicating autosomal recessive inheritance. The mutation consisted of the substitution of a glycine residue with a serine at position 63 (G63S) in the DNA-binding GCM domain of GCMB. Functional studies in transfected cells showed that the mutation caused loss of GCMB function, as it abolished transactivation capacity, despite normal subcellular localization, protein stability, and DNA-binding specificity. Contrary to the previously reported family, our patients displayed low but clearly detectable levels of PTH in plasma. This residual hormone secretion probably results from a very small residual activity of the G63S mutant GCMB.