Markers Of Hemolysis Research Articles

Development of a double shmiR lentivirus effectively targeting both BCL11A and ZNF410 for enhanced induction of fetal hemoglobin to treat β-hemoglobinopathies

A promising treatment for β-hemoglobinopathies is the de-repression of γ-globin expression leading to increased fetal hemoglobin(HbF) by targeting BCL11A. Here, we aim to improve a lentivirus vector (LV) containing a single BCL11A shmiR (SS) to further increase γ-globin induction. We engineered a novel LV to express two shmiRs simultaneously targeting BCL11A and the γ-globin repressor ZNF410. Erythroid cells derived from human HSCs transduced with the double shmiR (DS) showed up to a 70% reduction of both BCL11A and ZNF410 proteins. There was a consistent and significant additional 10% increase in HbF compared to targeting BCL11A alone in erythroid cells. Erythrocytes differentiated from SCD HSCs transduced with the DS demonstrated significantly reduced invitro sickling phenotype compared to the SS.Erythrocytes differentiated from transduced HSCs from β-thalassemia major patients demonstrated improved globin chain balance by increased γ-globin with reduced microcytosis. Reconstitution of DS-transduced cells from Berkeley SCD mice was associated with a statistically larger reduction in peripheral blood hemolysis markers compared with the SS vector. Overall, these results indicate that the DS LV targeting BCL11A and ZNF410 can enhance HbF induction for treating β-hemoglobinopathies and could be used as a model to simultaneously and efficiently target multiple gene products.

Use of Carboxyhemoglobin as an Early Sign of Oxygenator Dysfunction in Patients Supported by Extracorporeal Membrane Oxygenation.

IntroductionPlasma free hemoglobin is the gold standard for monitoring hemolysis in extracorporeal membrane oxygenation (ECMO) but its routine use has some limitations. Carboxyhemoglobin (HbCO) is also a marker of intravascular hemolysis. We aimed to investigate HbCO as a marker of both hemolysis and oxygenator dysfunction in patients supported by ECMO.MethodsRetrospective analysis of patients on ECMO in an adult ICU in a tertiary hospital. HbCO was recorded every 6 h in the 48 h before and after oxygenator change in adult patients on ECMO support with an oxygenator dysfunction and replacement.ResultsThe investigation of 27 oxygenators replacements in 19 patients demonstrated that HbCO values progressively increased over time and then significantly decreased after oxygenator change. Median oxygenator lifespan was 14 days [interquartile range (IQR) 8–21] and there was no correlation between HbCO and oxygenator lifespan [Spearman coefficient 0.23 (p = 0.23)]. HbCO values at oxygenator change [HbCO median 2.7 (IQR 2.5–3.5)] were significantly higher than the HbCO values 1 week before [HbCO median 2.07 (IQR 1.86–2.8)] (p value < 0.001).ConclusionOur data highlight the potential role of HbCO as a novel marker for ECMO oxygenator dysfunction.

Association of hemolysis markers and cortisol level with different severity of sickle cell disease among Sudanese patients

Background: Sickle cell anemia (SCA) is an inherited disorder of hemoglobin. Several biomarkers have been identified, which is essential in the different clinical presentations of the disease. This study aimed to determine the association between hemolysis markers and cortisol level with varying severity groups of Sudanese patients with SCA.Methods: This descriptive cross-sectional study included 100 patients with sickle cell disease between February 2016 and April 2017. According to Hedo et al scoring, medical history was obtained to conduct disease severity. A total of 3 ml of venous blood was collected from each patient. A complete hemogram was performed using an automated hematology analyzer (Sysmix®-KX-21N). Bilirubin and lactate dehydrogenase (LDH) were estimated using a spectrophotometer, while cortisol was measured using the Elecsys® system 2010 E170. The reticulocyte count was performed manually. Data were analyzed using statistical package for the social sciences (SPSS) version 21 computer software program.Results: Disease severity was variable and was categorized into; eighteen (18%) patients had mild symptoms, while 70 (70%) patients had moderate disease, and 12 (12%) patients had severe disease. The analysis of variance (ANOVA) test showed that hemoglobin, reticulocyte count, LDH, and direct bilirubin were positively correlated with disease severity, p value: 0.001, 0.04, 0.00, and 0.02, respectively. While indirect bilirubin, total bilirubin, and cortisol did not correlate with disease severity, the p value was (0.248, 0.083, and 0.868, respectively).Conclusions: This study confirmed that the hemolysis markers (Hb, reticulocyte count, direct bilirubin and LDH) were positively associated with disease severity. In contrast, indirect bilirubin, total bilirubin, and cortisol levels were not associated with the disease severity.

Safety and efficacy of voxelotor in pediatric patients with sickle cell disease aged 4 to 11 years

Sickle cell disease (SCD) is a devastating, multisystemic disorder that affects millions of people worldwide. The earliest clinical manifestations of SCD can affect infants as young as 6months of age, and pediatric patients are at risk for acute and life-threatening complications. Early intervention with treatments that target the underlying pathophysiological mechanism of SCD, sickle hemoglobin (HbS) polymerization, are expected to slow disease progression and circumvent disease-associated morbidity and mortality. The HOPE-KIDS 1 trial (NCT02850406) is an ongoing four-part, phase 2a, open-label, single- and multiple-dose study to evaluate the pharmacokinetics, efficacy, and safety of voxelotor-a first-in-class HbS polymerization inhibitor-in patients aged 6months to 17years with SCD. Initial findings from a cohort of 45 patients aged 4 to 11years who received voxelotor treatment for up to 48weeks are reported. Hemoglobin (Hb) response, defined as a >1.0g/dl increase from baseline, was achieved at week 24 by 47% (n = 16/34) of patients with Hb measurements at baseline and week 24. At week 24, 35% (n = 12/34) and 21% (n = 7/34) of patients had a >1.5g/dl increase and a >2.0g/dl increase from baseline in Hb concentration, respectively. Concurrent improvements in hemolytic markers were observed. Voxelotor was well tolerated in this young cohort, with no newly emerging safety signals. Based on its mechanism as an HbS polymerization inhibitor, voxelotor improves Hb levels and markers of hemolysis and has the potential to mitigate SCD-related complications; these results support its use in patients aged ≥4years.

Pregnancy associated TMA in 13-year-old patient successfully treated with Eculizumab: case report

BackgroundThis report introduces an unusual cause of kidney failure in a previously healthy pediatric patient. She developed thrombotic microangiopathy (TMA) that was diagnosed post-partum, requiring dialysis and eculizumab, with eventual recovery of kidney function ([chronic kidney disease (CKD) stage 3].Case presentationThe patient was induced at term due to preeclampsia, with delivery complicated by severe postpartum hemorrhage from uterine atony. She continued to have severe hypertension post-delivery and further developed acute kidney injury (AKI) with decreased urinary output and respiratory distress requiring dialysis therapy. Labs revealed hemolysis with elevated lactate dehydrogenase, low haptoglobin, anemia, and thrombocytopenia, but otherwise unremarkable immunology labs. Once clinically stabilized the patient underwent kidney biopsy, which was consistent with TMA. Treatment was initiated with eculizumab, a monoclonal antibody for terminal complement blockade. Her clinical status improved (including markers of hemolysis and inflammation) with kidney replacement therapy and complement blockade. On discharge, she had increasing urine output and was prescribed 3 day per week hemodialysis and twice monthly eculizumab infusions. By 6 weeks post-delivery, hemodialysis was discontinued and her eculizumab was weaned to monthly infusions. Eculizumab was discontinued at 12 months postpartum. Genetic testing for mutations of the complement system was negative. The patient has residual stage 3 CKD with stable kidney function, requiring two agents for blood pressure control, including an ACE inhibitor for antiproteinuric effect.ConclusionsThis case report showcases an unusual cause of renal failure in a pediatric patient due to TMA in the post-partum period. She required intermittent hemodialysis (iHD) for a brief period, however she was treated successfully with eculizumab that was able to be weaned off 1 year after delivery. She has residual stage 3 CKD and no further signs or symptoms of TMA.

Mitapivat versus Placebo for Pyruvate Kinase Deficiency

BackgroundPyruvate kinase deficiency is a rare, hereditary, chronic condition that is associated with hemolytic anemia. In a phase 2 study, mitapivat, an oral, first-in-class activator of erythrocyte pyruvate kinase, increased the hemoglobin level in patients with pyruvate kinase deficiency.MethodsIn this global, phase 3, randomized, placebo-controlled trial, we evaluated the efficacy and safety of mitapivat in adults with pyruvate kinase deficiency who were not receiving regular red-cell transfusions. The patients were assigned to receive either mitapivat (5 mg twice daily, with potential escalation to 20 or 50 mg twice daily) or placebo for 24 weeks. The primary end point was a hemoglobin response (an increase from baseline of ≥1.5 g per deciliter in the hemoglobin level) that was sustained at two or more scheduled assessments at weeks 16, 20, and 24. Secondary efficacy end points were the average change from baseline in the hemoglobin level, markers of hemolysis and hematopoiesis, and the change from baseline at week 24 in two pyruvate kinase deficiency–specific patient-reported outcome measures.ResultsSixteen of the 40 patients (40%) in the mitapivat group had a hemoglobin response, as compared with none of the 40 patients in the placebo group (adjusted difference, 39.3 percentage points; 95% confidence interval, 24.1 to 54.6; two-sided P<0.001). Patients who received mitapivat had a greater response than those who received placebo with respect to each secondary end point, including the average change from baseline in the hemoglobin level. The most common adverse events were nausea (in 7 patients [18%] in the mitapivat group and 9 patients [23%] in the placebo group) and headache (in 6 patients [15%] and 13 patients [33%], respectively). Adverse events of grade 3 or higher occurred in 10 patients (25%) who received mitapivat and 5 patients (13%) who received placebo.ConclusionsIn patients with pyruvate kinase deficiency, mitapivat significantly increased the hemoglobin level, decreased hemolysis, and improved patient-reported outcomes. No new safety signals were identified in the patients who received mitapivat. (Funded by Agios Pharmaceuticals; ACTIVATE ClinicalTrials.gov number, NCT03548220.)

Factors associated with left ventricular hypertrophy in children with sickle cell disease: results from the DISPLACE study.

Cardiopulmonary complications remain a leading cause of morbidity and mortality in sickle cell disease (SCD). The overall goals of this study were to evaluate the relationship between left ventricular hypertrophy (LVH) and laboratory markers of hemolysis and determine the association between LVH and SCD-specific therapies (hydroxyurea and chronic red cell transfusion). Data from the DISPLACE (Dissemination and Implementation of Stroke Prevention Looking at the Care Environment) study cohort was used. LVH was defined based on the left ventricular mass indexed to the body surface area as left ventricular mass index >103.0 g/m2 for males and >84.2 g/m2 for females. There were 1,409 children included in the analysis and 20.3% had LVH. Results of multivariable analysis of LVH showed baseline hemoglobin levels were associated with the lower odds of having LVH (odds ratio [OR]: 0.71, 95% confidence interval [CI]: 0.60– 0.84). The odds of LVH increases for every 1-year increase in age (OR: 1.07, 95% CI: 1.02-1.13). Similarly, the odds of LVH were lower among males than females (OR: 0.59, 95% CI: 0.38-0.93). The odds of LVH were higher among those on hydroxyurea compared to no therapy (OR: 1.83, 95% CI: 1.41–2.37). Overall results of the study showed that LVH occurs early in children with SCD and the risk increases with increasing age and with lower hemoglobin. Further, we found higher use of hydroxyurea among those with LVH, suggesting that the need for hydroxyurea conveys a risk of cardiovascular remodeling.

Investigation of D-dimer as an Alternative Biomarker of Thrombosis in HeartMate 3 Recipients

<h3>Purpose</h3> Lactate dehydrogenase (LDH), a sensitive marker of hemolysis, is used to diagnose pump thrombosis in patients on left ventricular assist device (LVAD) support. Given the wider gaps for blood passage for the HeartMate 3 pump, LDH may not be as sensitive. We sought to define the expected ranges of D-dimer after HeartMate 3 implantation and to assess this as a biomarker of thrombotic events. <h3>Methods</h3> D-dimer and LDH were prospectively collected in a cohort of HeartMate 3 recipients (n=168) at both routine and non-routine clinic visits. Association between LDH and D-dimer was assessed in patients with these measurements occurring on the same day (repeated measures analysis, 707 measurements). Patients with outlier D-dimer values (higher than quartile 3 + 1.5 interquartile range) were investigated for a potential cause. <h3>Results</h3> The plot of D-dimer after HeartMate 3 implantation is displayed <b>(Figure A).</b> D-dimer is high initially and trends down over time, however, remains abnormal at all follow up time points (reference 0.0-0.5 ug/mL). D-dimer and LDH were positively correlated (repeated correlation coefficient 0.123, p=0.002, <b>Figure B).</b> Patients with outlier D-dimer values (n=11) did not have ischemic events (thrombosis or ischemic stroke) within 3 months of elevation, however 82% were associated with clinically meaningful events (33% suction, 33% gaps in anticoagulation, 22% cancer, and 22% infection). <h3>Conclusion</h3> Median D-dimer remains abnormal at all time points on HeartMate 3 support. LDH and D-dimer are positively correlated. While D-dimer did not correlate with thrombotic events, significant elevations in D-dimer were associated with clinically meaningful events.

Gene Therapy for Sickle Cell Disease

Gene Therapy for Sickle Cell Disease

Thrombotic Thrombocytopenic Purpura (ADAMTS13 [a Disintegrin and Metalloproteinase With a Thrombospondin Type 1 Motif, Member 13] Deficiency) as Cause of Recurrent Multiterritory Ischemic Strokes.

Thrombotic Thrombocytopenic Purpura (ADAMTS13 [a Disintegrin and Metalloproteinase With a Thrombospondin Type 1 Motif, Member 13] Deficiency) as Cause of Recurrent Multiterritory Ischemic Strokes.

Body composition, energy expenditure, and markers of hemolysis in adults with sickle cell disease

Background: Historically, malnutrition is described in individuals with SCD. However, more recent studies have shown a change in the profile of the nutritional status and distribution of body composition of SCD patients, mainly adult individuals. Aims: To assess the body composition (BC), resting energy expenditure (REE), and the biomarkers of hemolysis in adults with sickle cell disease (SCD). Subjects and Methods: A cross-sectional observational study was performed with 64 individuals over 39 years old in the treatment from two reference centers for SCD located in the city of Rio de Janeiro, Brazil. The dual-energy X-ray absorptiometry (DXA) and indirect calorimetry were used to assess BC and REE, respectively. Blood levels of hemoglobin, reticulocytes, lactate dehydrogenase (LDH), leukocytes, platelets, total and direct bilirubin, total protein, and albumin were measured to assess the hemolysis and protein status. The descriptive and inferential analysis was composed of the different methods (one-way ANOVA with the multiple comparison test of Tukey, Student t-test, and Pearson's correlation coefficient). Were considered statistically significant when the p-values were ≤ 0.05. Results: Most participants with SCD were female sex, colored (brown/black), and mean age of 51.2 years old. The obesity prevalence was 70.7% according to the body fat (BF%), with a major mean among women (p &lt; 0.0001). Men had a higher mean of lean mass (LM) (p=0.0005) and fat-free mass (FFM) (p=0.0007). There was no difference for REE in comparing the genotypes (p= 0.53), and genders (p=0.075). The hemolysis markers (LDH, reticulocytes, and TB) correlated inversely with BMI (p=0.013), FM (p=0.022), and FFM (p=0.034). Conclusions: The important change observed in body composition in people with sickle cell disease was characterized by a high percentage of fat body and a decrease in lean mass. The hemolysis markers LDH, reticulocytes, and BT correlated inversely with BMI, FM, and FFM indicating that high levels of hemolysis may affect nutritional status, without influencing the REE. Keywords: sickle cell disease, body composition, fat mass, fat-free mass, energy expenditure, hemolysis.

Levitt’s CO breath test in the differential diagnosis of chronic isolated hyperbilirubinemia

A key component of the differential diagnosis of isolated hyperbilirubinemia (HB) is distinguishing between hemolytic and non-hemolytic types. Routine hemolysis screening markers have unsatisfactory sensitivity and specificity. Erythrocyte (RBC) lifespan shortening, the gold standard marker of hemolysis, is seldomly measured due to the cumbersome and protracted nature of standard methods. A new Levitt’s CO breath test method may enable simple, rapid RBC lifespan measurement. In this pilot prospective diagnostic study, Levitt’s CO breath test was evaluated to discriminate hemolytic from non-hemolytic HB in adults. One hundred and thirty eligible non-smoking adult patients who were aged 18 or older, referred for chronic (>6 months) isolated HB or had a known diagnosis of isolated HB of a rare cause, were recruited, including 77 with non-hemolytic HB and 53 with hemolytic HB. ROC curve analysis was applied to determine the optimal cutoff for discriminating between hemolytic and non-hemolytic HB, and the performance was calculated. Results showed that the mean RBC lifespan in non-hemolytic HB (93 ± 26 d) was reduced (p = 0.001 vs. normal reference value of 126 d), but longer than that in hemolytic HB (36 ± 17 d; p = 0.001). RBC lifespans did not differ significantly between 26 patients with simple hemolytic HB (32 ± 14 d) and 27 patients with a Gilbert syndrome comorbidity (40 ± 18 d). ROC curve analysis revealed an optimal lifespan cutoff for discriminating between hemolytic and non-hemolytic HB of 60 d (AUC = 0.982), with a diagnostic accuracy of 95.4%, 94.3% sensitivity and 96.1% specificity respectively. These results indicate that Levitt’s CO breath test seems to be very sensitive and specific for detecting hemolysis in adult patients with chronic isolated HB, and could enable simple, rapid, and reliable differential diagnosis of isolated HB. A large-scale validation study of the method is warranted.

Influence of Peripherally Inserted Central Catheters With Proximal Valves on Red Blood Cell Hemolysis During Transfusion.

The aim of this study was to verify the occurrence of hemolysis after infusion of packed red blood cells (PRBCs) in 12 peripherally inserted central catheters (PICCs) with a proximal valve, according to size and infusion rate. This was an experimental in vitro study performed under laboratory-controlled conditions, and the sample was composed of 12 PICCs with proximal valves (3F and 4F catheter). Twelve type A+ aliquots from 10 PRBCs were analyzed preinfusion and postinfusion according to PICC size and infusion rate. Hemolysis markers, total hemoglobin (g/dL), hematocrit (%), free hemoglobin (g/dL), potassium (mmol/L), lactate dehydrogenase (U/L), and rate of hemolysis (%) were studied. Data were analyzed using analysis of variance and Bonferroni multiple comparison tests. After the infusions in 3F PICCs, an increase was seen in rate of hemolysis (P = .003) and free hemoglobin (P = .014), in addition to a reduction in total hemoglobin (P = .002), with significant influence of minimum and maximum flow rates on the rate of hemolysis. The study finding indicated that the smaller catheter size and the infusion rate influenced variations in some hemolysis markers, but the alterations observed in the hemolysis markers would not contraindicate the infusion of PRBCs by 3F and 4F PICCs with proximal valves.

A retrospective analysis of the hemolysis occurrence during extracorporeal membrane oxygenation in a single center.

Extracorporeal membrane oxygenation (ECMO)-associated hemolysis still represents a serious complication. The present study aimed to investigate those predictive factors, such as flow rates, the use of anticoagulants, and circuit connected dialysis, that might play a pivotal role in hemolysis in adult patients. This is a retrospective single-center case series of 35 consecutive adult patients undergoing veno-venous ECMO support at our center between April 2014 and February 2020. Daily plasma-free hemoglobin (pfHb) and haptoglobin (Hpt) levels were chosen as hemolysis markers and they were analyzed along with patients' characteristics, daily laboratory findings, and corresponding ECMO system variables, as well as continuous renal replacement therapy (CRRT) when administered, looking for factors influencing their trends over time. Among the many settings related to the ECMO support, the presence of CRRT connected to the ECMO circuit has been found associated with both higher daily pfHb levels and lower Hpt levels. After correction for potential confounders, hemolysis was ascribable to circuit-related variables, in particular the membrane oxygenation dead space was associated with an Hpt reduction (B = -215.307, p = 0.004). Moreover, a reduction of ECMO blood flow by 1L/min has been associated with a daily Hpt consumption of 93.371mg/dL (p = 0.001). Technical-induced hemolysis during ECMO should be monitored not only when suspected but also during quotidian management and check-ups. While considering the clinical complexity of patients on ECMO support, clinicians should not only be aware of and anticipate possible circuitry malfunctions or inadequate flow settings, but they should also take into account the effects of an ECMO circuit-connected CRRT, as an equally important key factor triggering hemolysis.

Biologic and Clinical Efficacy of LentiGlobin for Sickle Cell Disease

BackgroundSickle cell disease is characterized by the painful recurrence of vaso-occlusive events. Gene therapy with the use of LentiGlobin for sickle cell disease (bb1111; lovotibeglogene autotemcel) consists of autologous transplantation of hematopoietic stem and progenitor cells transduced with the BB305 lentiviral vector encoding a modified β-globin gene, which produces an antisickling hemoglobin, HbAT87Q.MethodsIn this ongoing phase 1–2 study, we optimized the treatment process in the initial 7 patients in Group A and 2 patients in Group B with sickle cell disease. Group C was established for the pivotal evaluation of LentiGlobin for sickle cell disease, and we adopted a more stringent inclusion criterion that required a minimum of four severe vaso-occlusive events in the 24 months before enrollment. In this unprespecified interim analysis, we evaluated the safety and efficacy of LentiGlobin in 35 patients enrolled in Group C. Included in this analysis was the number of severe vaso-occlusive events after LentiGlobin infusion among patients with at least four vaso-occlusive events in the 24 months before enrollment and with at least 6 months of follow-up.ResultsAs of February 2021, cell collection had been initiated in 43 patients in Group C; 35 received a LentiGlobin infusion, with a median follow-up of 17.3 months (range, 3.7 to 37.6). Engraftment occurred in all 35 patients. The median total hemoglobin level increased from 8.5 g per deciliter at baseline to 11 g or more per deciliter from 6 months through 36 months after infusion. HbAT87Q contributed at least 40% of total hemoglobin and was distributed across a mean (±SD) of 85±8% of red cells. Hemolysis markers were reduced. Among the 25 patients who could be evaluated, all had resolution of severe vaso-occlusive events, as compared with a median of 3.5 events per year (range, 2.0 to 13.5) in the 24 months before enrollment. Three patients had a nonserious adverse event related or possibly related to LentiGlobin that resolved within 1 week after onset. No cases of hematologic cancer were observed during up to 37.6 months of follow-up.ConclusionsOne-time treatment with LentiGlobin resulted in sustained production of HbAT87Q in most red cells, leading to reduced hemolysis and complete resolution of severe vaso-occlusive events. (Funded by Bluebird Bio; HGB-206 ClinicalTrials.gov number, NCT02140554.)

Red Blood Cell Abnormalities as the Mirror of SARS-CoV-2 Disease Severity: A Pilot Study.

PurposeUnraveling the pathophysiology of COVID-19 disease is of crucial importance for designing treatment. The purpose of this study is to investigate the effects of the disease on erythrocytes (RBCs) and to correlate the findings with disease severity.Materials and MethodsHospitalized patients (n = 36) with COVID-19 and control group of healthy volunteers (n = 18) were included in the study. Demographic data, clinical, laboratory and chest Computed Tomography (CT) findings at time of admission were recorded. Laboratory measurements included: Hemoglobin (H b), indirect billirubin, LDH, D-Dimers, and plasma free hemoglobin (plasma free-Hb). On RBCs were performed: osmotic fragility (MCF), Free-Hb after mechanical stress (Free-Hb-MECH), intracellular RBC concentration of calcium ions (iCa2+), intracellular ROS (iROS), G6PD, intracellular active caspase-3 (RBC-caspase-3), IgG immunoglobulins (RBC-IgGs), which are bound on RBCs’ senescent neo-antigen proteins and RBC surface phosphatidylserine (RBC-PS).ResultsThe percentage of males was 50 and 66% and the mean age was 65.16 ± 14.24 and 66.33 ± 13.48 years among patients and controls respectively (mean ± SD, p = 0.78). Upon admission patients’ PO2/FiO2 ratio was 305.92 ± 76.75 and distribution of infiltration extend on chest CT was: 0–25% (N = 19), 25–50%: (N = 7), and 50–75% (N = 9). Elevated hemolysis markers (LDH and plasma free-Hb) were observed in patients compared to the control group. Patients’ RBCs were more sensitive to mechanical stress, and exhibited significantly elevated apoptotic markers (iCa2+, RBC-PS). Plasma free Hb levels correlated with the extend of pulmonary infiltrates on chest CT in COVID-19 patients. Surprisingly, patients’ RBC-iROS were decreased, a finding possibly related with the increased G6PDH levels in this group, suggesting a possible compensatory mechanism against the virus. This compensatory mechanism seemed to be attenuated as pulmonary infiltrates on chest CT deteriorated. Furthermore, RBC-IgGs correlated with the severity of pulmonary CT imaging features as well as the abnormality of lung function, which are both associated with increased disease severity. Lastly, patients’ D-Dimers correlated with RBC surface phosphatidylserine, implying a possible contribution of the red blood cells in the thrombotic diathesis associated with the SARS-CoV-2 disease.ConclusionThis pilot study suggests that SARS-CoV-2 infection has an effect on red blood cells and there seems to be an association between RBC markers and disease severity in these patients.

(More than) doubling down: Effective fibrinolysis at a reduced rt-PA dose for catheter-directed thrombolysis combined with histotripsy.

Deep vein thrombosis is a major source of morbidity and mortality worldwide. For acute proximal deep vein thrombosis, catheter-directed thrombolytic therapy is an accepted method for vessel recanalization. Thrombolytic therapy is not without risk, including the potential for hemorrhagic bleeding that increases with lytic dose. Histotripsy is a focused ultrasound therapy that generates bubble clouds spontaneously in tissue at depth. The mechanical activity of histotripsy increases the efficacy of thrombolytic therapy at doses consistent with current pharmacomechanical treatments for venous thrombosis. The objective of this study was to determine the influence of lytic dose on histotripsy-enhanced fibrinolysis. Human whole blood clots formed in vitro were exposed to histotripsy and a thrombolytic agent (recombinant tissue plasminogen activator, rt-PA) in a venous flow model perfused with plasma. Lytic was administered into the clot via an infusion catheter at concentrations ranging from 0 (control) to 4.54 μg/mL (a common clinical dose for catheter-directed thrombolysis). Following treatment, perfusate samples were assayed for markers of fibrinolysis, hemolysis, and intact red blood cells and platelets. Fibrinolysis was equivalent between the common clinical dose of rt-PA (4.54 μg/mL) and rt-PA at a reduction to one-twentieth of the common clinical dose (0.23 μg/mL) when combined with histotripsy. Minimal changes were observed in hemolysis for treatment arms with or without histotripsy, potentially due to clot damage from insertion of the infusion catheter. Likewise, histotripsy did not increase the concentration of red blood cells or platelets in the perfusate following treatment compared to rt-PA alone. At the highest lytic dose, a refined histotripsy exposure scheme was implemented to cover larger areas of the clot. The updated exposure scheme improved clot mass loss and fibrinolysis relative to administration of lytic alone. Overall, the data collected in this study indicate the rt-PA dose can be reduced by more than a factor of ten and still promote fibrinolysis when combined with histotripsy.

P112: ENERGIZE AND ENERGIZE-T: TWO PHASE 3, RANDOMIZED, DOUBLE-BLIND, PLACEBO-CONTROLLED STUDIES OF MITAPIVAT IN ADULTS WITH NON--TRANSFUSION-DEPENDENT OR TRANSFUSION-DEPENDENT ALPHA- OR BETA-THALASSEMIA

Background: Thalassemias are characterized by imbalanced globin-chain production resulting in excess α- or β-globin precipitation, hemolytic anemia, and ineffective erythropoiesis.1,2 ATP levels are reduced in thalassemic red blood cells (RBCs), despite increased energy demands.3,4 Mitapivat is an oral activator of RBC pyruvate kinase (PKR), a glycolytic enzyme that regulates ATP production.5 In a phase 2 study of patients with α- or β-non–transfusion-dependent thalassemia (NTDT), twice-daily (BID) dosing with mitapivat increased hemoglobin (Hb) levels by ≥1.0 g/dL in 80% of patients,6 supporting the broadening of mitapivat’s development in thalassemia. Aims: To report the study designs of ENERGIZE (2021-000211-23) and ENERGIZE-T (2021-000212-34), two phase 3 trials to assess the efficacy and safety of mitapivat in adults with α- or β-NTDT or transfusion-dependent thalassemia (TDT), respectively. Methods: Both studies are phase 3, multicenter, randomized, double-blind, placebo-controlled trials (Figure). In ENERGIZE, approximately 171 eligible adults with NTDT will be randomized (2:1) to receive 100 mg mitapivat BID or placebo for 24 weeks. Upon completion, eligible patients can transition to a 5-year, open-label extension. Key inclusion criteria: documented diagnosis of thalassemia (β-thalassemia ± α-globin mutations, Hb E β-thalassemia, or α-thalassemia [Hb H disease]), Hb concentration ≤10.0 g/dL, and NTDT defined as ≤5 RBC units during the 24-week period before randomization and no RBC transfusion ≤8 weeks prior. The primary endpoint is an Hb response defined as a ≥1.0 g/dL increase in average Hb concentration from Week 12 through 24 compared with baseline. Secondary endpoints include patient-reported outcomes, changes in Hb, markers of hemolysis and erythropoiesis, and safety. In ENERGIZE-T, approximately 240 eligible adults with TDT will be randomized (2:1) to receive 100 mg mitapivat BID or placebo for 48 weeks. Upon completion, eligible patients can transition to a 5-year, open-label extension. Key inclusion criteria: documented diagnosis of thalassemia (same genotypes as detailed for the ENERGIZE study), and TDT defined as 6–20 RBC units transfused and no transfusion-free period ≥6 weeks during the 24 weeks before randomization. The primary endpoint is a transfusion reduction response, defined as a ≥50% reduction in transfused RBC units with a reduction of ≥2 units of transfused RBCs in any consecutive 12-week period through Week 48 compared with baseline. Secondary endpoints include additional measures of transfusion burden, changes in iron markers, and safety. Results: Not yet available. Conclusions: ENERGIZE and ENERGIZE-T are the first pivotal studies to assess a potential treatment across a broad spectrum of patients with thalassemia (ie, patients with TDT and NTDT; α- and β-thalassemias). ENERGIZE and ENERGIZE-T will evaluate the efficacy and safety of mitapivat, a novel, first-in-class oral activator of PKR. Both studies are actively recruiting.

P118: THE ROLE OF HEMOGLOBIN AND HEMOLYSIS ON TRANSCRANIAL DOPPLER VELOCITIES IN CHILDREN WITH SICKLE CELL DISEASE: DATA FROM A NATURAL HISTORY COHORT

Background: Children with sickle cell disease (SCD) are at increased risk of cerebrovascular events that can impact neurocognitive development and quality of life (Colombatti 2016). Transcranial Doppler ultrasound (TCD) is a validated screening tool to identify pediatric SCD patients with the highest risk of stroke, to start on a preventive chronic blood transfusion regimen (Estcourt 2020; Inusa 2019). We aimed to evaluate the distribution of TCD velocities in a pediatric natural history cohort and investigate their correlation with hematological variables and treatments. Methods: We performed a retrospective analysis on data from a prospective pediatric cohort followed from January 1, 2009, to December 31, 2020 (censoring date). We used transcranial Doppler imaging (TCDi) and classified results according to STOP criteria, considering terminal internal carotid artery (TICA) and middle cerebral artery (MCA) time-averaged maximum mean velocities (TAMMVs). Hematological, clinical, and treatment variables were available from the natural history cohort database. Two-sample and Welch t-tests for unequal variances were used to compare mean hemoglobin (Hb) values and hemolysis markers in patients with and without abnormal/conditional TCDi results. Fisher and chi-square tests were used to compare categorical variables. Linear regression models were used to assess the effects of MCA and TICA TAMMVs as continuous variables on Hb. Odds ratios (ORs) for neurological events at different Hb levels were estimated using generalized estimated equations (GEE) with a binomial distribution, logistic function, and exchangeable correlation structure, allowing for correlation among repeated observations for the same patient. Multivariable GEE including characteristics and treatment variables were used to evaluate the association between neurological events and Hb. Results: Of the 182 SCD patients in the cohort, 169 had assessments of cerebral vasculopathy, and 155 had evaluable TCDi (583 exams). The median follow-up of the entire cohort was 79.8 months (range: 2.1–298.6 months) (interquartile range [IQR]: 36.9–126.3 months). The median age at the censoring date was 13.4 years (IQR: 9.1–17.5 years). Patients with abnormal/conditional TCDi results had lower Hb (8.4 vs 8.9 g/dL, P≤0.0001) and higher reticulocyte counts (317,766 vs 262,750/mm3, P≤0.0001), lactate dehydrogenase (843 vs 690 U/L, P=0.0012), and aspartate aminotransferase (61 vs 54 U/L, P=0.0007) compared with patients with normal/low results. We detected an inverse linear correlation between TICA/MCA TAMMVs and Hb (Figure 1A and 1B). Univariate analysis showed significant inverse correlation between abnormal/conditional TCDi results and Hb considered as a continuous variable (OR: 0.484, P<0.001). In the multivariate analysis, the correlation between TCDi results and Hb remained significant; moreover, the risk of presenting abnormal/conditional TCDi results decreased with age (OR: 0.833, P<0.0064). Conclusions: This analysis from our natural history cohort shows a significant inverse correlation between Hb and MCA and TICA velocities, supporting the beneficial effect of higher Hb levels in reducing TAMMV.

SOD2 V16A amplifies vascular dysfunction in sickle cell patients by curtailing mitochondria complex IV activity

AbstractSuperoxide dismutase 2 (SOD2) catalyzes the dismutation of superoxide to hydrogen peroxide in mitochondria, limiting mitochondrial damage. The SOD2 amino acid valine-to-alanine substitution at position 16 (V16A) in the mitochondrial leader sequence is a common genetic variant among patients with sickle cell disease (SCD). However, little is known about the cardiovascular consequences of SOD2V16A in SCD patients or its impact on endothelial cell function. Here, we show SOD2V16A associates with increased tricuspid regurgitant velocity (TRV), systolic blood pressure, right ventricle area at systole, and declined 6-minute walk distance in 410 SCD patients. Plasma lactate dehydrogenase, a marker of oxidative stress and hemolysis, significantly associated with higher TRV. To define the impact of SOD2V16A in the endothelium, we introduced the SOD2V16A variant into endothelial cells. SOD2V16A increases hydrogen peroxide and mitochondrial reactive oxygen species (ROS) production compared with controls. Unexpectedly, the increased ROS was not due to SOD2V16A mislocalization but was associated with mitochondrial complex IV and a concomitant decrease in basal respiration and complex IV activity. In sum, SOD2V16A is a novel clinical biomarker of cardiovascular dysfunction in SCD patients through its ability to decrease mitochondrial complex IV activity and amplify ROS production in the endothelium.