Acute Vaso-occlusive Crisis Research Articles

Iatrogenic Hyperhydration in Sickle Cell Disease Patients Admitted for Acute Pain Crisis Management: A Retrospective Analysis from a Single Institution

Background: Parenteral fluids are an important component of acute pain crisis management in sickle cell disease patients. However, lack of uniform guidelines for fluid replacement coupled with underlying host comorbidities result in risk to patients from complications associated with hyperhydration. Contributing factors include inappropriate choice of fluid, rapid fluid infusion rates with prolonged time periods and inadequate monitoring of signs of hyperhydration. Complications of fluid replacement include excessive weight gain, extremity swelling, pulmonary edema and heart failure. In our study we examined the prevalence of hyperhydration in sickle cell anemia patients admitted for acute pain crisis management at our hospital. Methods: We conducted a retrospective chart review on EPIC of sickle cell anemia patients treated for acute pain crisis in the inpatient unit of John Dempsey Hospital, University of Connecticut between January 2022-December 2022, following IRB approval. To capture patients with signs and symptoms of hyperhydration and its clinical consequences, we looked at surrogate markers such as excessive weight gain during admission, signs of fluid retention, charting of patient fluid intake and output, increased oxygen use, diuretic (Lasix) administration, bronchodilator use, abnormal chest x ray findings indicative of fluid overload pattern, activation of rapid response team for patients developing acute symptoms of fluid overload, and urgent patient transfer to a higher level of care including intensive care unit. Results: 256 admitted patient charts were analyzed representing a total of 95 unique sickle cell disease patients. The median length of hospital stay (LOS) was 3 days. 168 patients had LOS from 3 to 10 days. We observed that 10.7% of the patients experienced an increase in oxygen requirements during their hospital stay. Daily weight was collected in only 27 patients (10.5%) for 3 or more days limiting its usefulness to detect subclinical hyperhydration( figure 1). 69 patients (27%) received parenteral Lasix injection for acute symptoms whose chest x rays also showed pulmonary edema or pleural effusions. 13 patients (18%) were transferred to a higher level of care that included 9 patients to step-down unit and 4 to intensive care for endotracheal intubations and ventilatory support. The median hospital stay was 4 days in patients requiring Lasix compared to 3 days in those who did not. Conclusion : Hyperhydration is undesirable complication associated with fluid administration of sickle cell anemia patients admitted with acute vaso-occlusive pain crisis. It occurs in a significant proportion of affected patients that can result in life threatening complications and prolonged hospitalization. Hyperhydration were missed in this retrospective analysis since daily weight measurements were not available in the majority of patients. Strict charting of fluid intake and output, choice of half normal saline for hydration, as well as clinical monitoring of signs and symptoms of subclinical hyperhydration will help reduce this complication and improve patient outcomes. Improving awareness of this complication among health care providers is important towards achieving this goals. Findings from this study are used to design a prospective quality improvement project in our hospital to improve outcomes and reduce hospitalization in sickle cell anemia patients admitted for acute vaso-occlusive pain crisis.

Partial Red Cell Exchange Is an Effective Tool for Adequately Reducing Hemoglobin S Levels in Patients with Sickle Cell Disease and Improving Patient Outcomes Including Reduction in Acute Care Utilization

Introduction: Red cell exchange (RCE) is a therapeutic procedure that aims to reduce the number of sickle-shaped red blood cells in circulation and replace them with healthy donor cells. The use of red cell exchange in sickle cell disease (SCD) is primarily aimed at preventing or treating acute complications such as acute chest syndrome, stroke or priapism. However, in patients with inadequate disease control and associated frequent hospitalizations requiring parenteral opioids, we have proposed that prophylactic partial RCE (pRCE) be incorporated into the treatment plan. Implementation of pRCE with resulting limitation of parenteral opioid use may potentially reduce hospitalizations and achieve overall better disease control. Use of pRCE for disease control remains limited as it is labor intensive and requires copious amounts of blood which can be challenging especially in this era of COVID19 pandemic blood shortage. For this reason, we have utilized pRCE at our institution. Here we demonstrate that pRCE with four to five units of packed red blood cells (pRBCs) is equally effective in reducing hemoglobin S to levels below 40% and SCD related complications including VOCs and hospitalizations. Methods and Results: In our center, we identified six individuals with frequent hospitalizations and significant daily oral morphine equivalent requirements. These patients were then placed on a monthly pRCE protocol. Patients with variable genotypes were enrolled including HbSS, HbSC and HbSβthal +. Each patient underwent pRCE initially utilizing four units. Hemoglobin S level was closely monitored and if the target level of <40% was not reached with four units, the number was increased to five units. It is important to note that partial exchange was utilized only in patients whose indication for RCE was pain and frequent hospitalizations rather than history of CVA. In addition to pRCE, each patient was placed on a restricted care protocol that comprised of the administration of only home oral opioids during acute care visits. Prior to initiation of both pRCE and restricted care plan, patients were educated at length and during frequent clinic visits regarding the difference between chronic pain management and acute vaso-occlusive crisis. As shown in Figure 1, partial exchange leads to adequate reduction of hemoglobin S levels immediately post exchange that remains suppressed over the four-week period to predominately below 40 percent. This reduction in hemoglobin S levels results in patient-reported improved sense of well-being and compliance with restricted care plans to limit acute care utilization and move SCD care to the outpatient setting. In fact, we saw a dramatic reduction in hospitalization among patients with sickle cell disease regardless of genotype, age and gender. As shown in Figure 2, for each patient placed on restricted care plan, acute care utilization was reduced compared to each patient's previous year's monthly admission rates. Conclusion: Prolonged uncontrolled SCD with frequent VOCs will undoubtedly result in high acute care utilization, high opioid requirements and risk of development of chronic pain with subsequent opioid induced hyperalgesia and opioid failure. Partial red cell exchange is an effective tool for addressing sickle cell disease complications and improving patient outcomes, particularly in patients with least disease control and highest acute care utilization.

17R-Resolvin D1 Improves Inflammatory Cardiomyopathy in a Mouse Model of Sickle Cell Disease

Sickle cell disease (SCD) is a severely invalidating genetic red cell disorder. Inflammatory vasculopathy and cardiopulmonary complications markedly impact quality of life and survival. Limited studies are available on the pathogenesis of sickle cell related cardiomyopathy. However, the combination of inflammatory vasculopathy, heart ischemia, and myocardial fibrosis have been suggested to play a role in sickle cell related cardiomyopathy. This is supported by the amelioration of cardiomyopathy in SCD patients, early and intensively treated with either hydroxyurea or chronic transfusion regimen (Niss O et al. Blood 140: 1322, 2022). Recently, we have highlighted an impairment of pro-resolving events in SCD with a deleterious effect on acute sickle cell related organ damage (Matte A et al. Blood 133: 252, 2019). Growing evidence links impairment of pro-resolving mechanisms with atherosclerosis and ischemic cardiomyopathy (Kain V et al. J Mol Cell Cardiol 84: 24, 2015; Conte MS et al. JCI 128: 3727, 2018). Among specialized pro-resolving mediators, 17R-resolvin D1 (17R-RvD1) has been shown to play important protective actions in cardiovascular diseases (Kain V et al. J Mol Cell Cardiol 84: 24, 2015). Here, we first determined the appropriate window of time to study cardiac response to hypoxia/reoxygenation (H/R) stress, mimicking sickle cell related acute vaso-occlusive crisis. We show that humanized SCD mice (TT model) exposed to H/R (10 hours hypoxia 8% oxygen, followed by 3 hours reoxygenation) display increased markers of myocardial dysfunction with neutrophil heart infiltration compared to either SCD mice under normoxia or to healthy (AA) animals exposed to H/R stress. With integrated proteomic and miRNA analyses we have identified upregulation of proteins and miRNAs involved in fibrosis, hypertrophy of the heart, and cardiomyocyte apoptosis. Differentially expressed miRNAs in SCD-hearts compared to AA included miR-16-5p, miR-122-5p, and miR-206-3p, which are involved in angiogenesis and heart fibrosis and hypertrophy. Upregulated proteins in SCD hearts in response to H/R encompassed: NF-kB, Nrf2, hemeoxygenase-1, glutathione peroxidase, and peroxiredoxins (associated to response to oxidative stress), the profibrotic factors FGF and PDGF as well as the TGF-ß1 receptor, and the pro-angiogenic VEGF pathway. Treatment with 17R-RvD1 (100 ng administrated by gavage 1 hour before H/R, see also Matte A et al. Blood 133: 252, 2019) protected heart of SCD mice from H/R-induced stress as supported by significant reduction of ANP, a marker of cardiovascular dysfunction, decrease in neutrophil infiltration, and NF-kB activation (Figure 1). 17R-RvD1 also diminished the H/R-driven upregulation of miR-16-5p, while it enhanced miR-206-3p that was downregulated by H/R, suggesting that 17R-RvD1 can reduce cardiac fibrosis and other pathological processes associated with these miRNAs in SCD. We also found that 17R-RvD1 administration to SCD mice blunted the activation of TGF-ß1 pathway and of markers of extracellular remodeling, supporting the beneficial effect of 17R-RvD1 against H/R stress. Taken together, our data show that 17R-RvD1 reduced heart remodeling and fibrosis in SCD mice undergoing H/R, a model of acute VOCs. This improved understanding in basic pathophysiology of SCD-related inflammatory cardiomyopathy, providing new evidence for protective therapeutic effects of 17R-RvD1 on SCD cardiovascular diseases.

How Sensitive Is the Sickle Prep? Clinical Implications

Introduction The sickle cell solubility test, commonly known as “sickle prep” is a qualitative measure that relies on the property that deoxygenated hemoglobin S (HbS) is insoluble. Accordingly, blood samples drawn from individuals with circulating HbS appear cloudy when mixed with sodium hydrosulfite. 1 The sickle cell solubility test has been reported to be very sensitive (99%) and specific (99.9%) for detection of HbS. However, false negatives have been reported to occur in sickle cell disease (SCD) patients with severe anemia or high levels of hemoglobin F. 2,3 In those situations HbS levels may be very low and it remains unclear what level of HbS is required for the solubility test to be positive. To address this issue, we have examined the sickle cell solubility test in a cohort of SCD patients undergoing red cell exchange, acknowledging that in many of these patients, HbS levels fall below 15% when tested immediately after completing the exchange procedure. Methods 118 patients with sickle cell anemia were screened based on outpatient visits to the Inova Adult Sickle Center from January 1, 2023 - March 31 st, 2023. Of these, 6 patients were excluded from analysis due to lack of recent sickle cell solubility test during this period. Of the total number of patients included in the analysis (n=112), 25 (22%) underwent red cell exchange during this period. For each individual, the two most recent HbS percentages with the concurrently-determined sickle cell solubility result (positive or negative) were analyzed. We examined the data in the context of known genotype (HbSS, HbSC, HbSβ 0, HbSβ +positive). In patients undergoing red cell exchange, the most recent pre and post transfusion hemoglobin S percentage were collected. Results: 200 distinct HbS levels were collected and analyzed. Of those, 5/200 tested negative for the sickle cell solubility test, yielding an overall sensitivity rate of 98%. Of those 5 patients, 4/5 had received a red cell exchange during this period, and (1/5) had severe transfusion dependent anemia. Of those with a negative sickle cell solubility test, 4/5 patients had an SS genotype, and 1/5 had SC genotype. In patients who received red cell exchange, the sensitivity rate for the sickle cell solubility test is 84%. For all patient samples with HbS >15%, the sickle solubility test was 100% sensitive. However, among the 11 samples with HbS levels below 15%, 5 were sickle prep negative thereby indicating a reduced sensitivity (55%) below that threshold. Nine (9) out of the 11 samples were of patients who had undergone red cell exchange. Conclusion: The sickle cell solubility is a very sensitive measure to establish the presence of HbS, but must be interpreted with caution in those with HbS concentrations of <15%. Because it is readily available (typically resulted within an hour) it may be of benefit in emergency departments for patients for whom there is question about the validity of the sickle cell diagnosis. At our institution, this has been a valuable addition to the initial management of patients for whom medical records are not available and who present with apparent acute vaso-occlusive crisis. We do not propose withholding analgesia for patients with a reported history of sickle cell disease pending this test, but rather recommend its use as a confirmatory test for patients presenting with a reported history of this disease.

VOC-Free Status Among Patients with Sickle Cell Disease Following Allogeneic Hematopoietic Stem Cell Transplant: A Cohort Study of Medicaid Enrollees

Background: Sickle cell disease (SCD) is characterized by recurrent acute vaso-occlusive crises (VOCs), which diminish patient quality-of-life, contribute to end-organ damage and failure, and increase mortality. Currently, approved therapies for SCD are only partially effective and do not fully eliminate VOCs. Allogeneic hematopoietic stem cell transplant (HSCT) is the only known curative option for patients with SCD, however, HSCT is available to <20% of patients who have a matched sibling donor and is associated with significant risks, such as graft-versus-host disease. Autologous gene therapies that have the potential to provide a one-time functional cure to patients with SCD are currently in pivotal trials. The primary endpoint for these pivotal studies is the proportion of patients who become VOC-free for ≥12 months after treatment. Absence of VOCs for ≥12 months is expected to predict long-term efficacy. Given this, we evaluated patients with SCD in the national US Medicaid database who underwent allogeneic-HSCT to determine whether VOC-free status at 12 months was predictive of VOC-free status at 18 and 24 months after HSCT. Methods: A cohort of patients with SCD who had a record of allogeneic HSCT with at least 12 months of continuous Medicaid enrollment during 2000-2014 was identified. The date of HSCT was defined as the cohort entry date and the covariate assessment window was the 12 months continuous enrollment period preceding the cohort entry date. A VOC event was identified using ICD-9 diagnosis codes in hospitalization and ER visit claims for Hb-SS disease with crisis, other acute pain crisis, acute chest syndrome, priapism, and splenic sequestration. The cohort was further restricted to patients who had ≥24 months of follow-up after cohort entry to accurately assess VOC outcomes. Diagnosis codes associated with the delivery of healthcare and pharmacy claims were used to identify patient characteristics and outcomes of interest. Primary study outcome was the proportion of patients with no VOCs at 6 months, 12 months, 18 months, and 24 months after allogeneic HSCT. Results: During the study period, 44,685 patients with SCD were identified, out of whom 103 patients had undergone allogeneic HSCT, were enrolled for ≥12 months in the Medicaid program and had ≥24 months of follow-up after HSCT. Mean (SD) age was 10.3 (7.2) years, with 55.3% being male and majority (67%) Black. Patients had an average of 2.7 (SD, 7.9) VOC events during the 12-month period prior to HSCT. The most common (>10%) baseline comorbidities were chronic cardiac disease (42.7%), infections (36.9%), chronic pulmonary disease (31.1%), and acute chest syndrome (12.6%). Among the cohort of 103 patients who had undergone HSCT, 79% (n=81) were VOC-free by 12 months. Furthermore, among patients who were VOC-free at 12 months, 91% (n=74) were VOC-free at 18 months and 90% (n=73) were VOC-free at 24 months. Conclusions: This population-based study provides valuable information regarding long-term VOC-free status among patients with SCD who have undergone allogeneic HSCT in routine clinical care. Our findings suggest that patients with SCD who are VOC-free by 12 months post-HSCT are highly likely to stay VOC-free for longer durations (i.e. 18 and 24 months) after HSCT.

Precision, integrative medicine for pain management in sickle cell disease.

Sickle cell disease (SCD) is a prevalent and complex inherited pain disorder that can manifest as acute vaso-occlusive crises (VOC) and/or chronic pain. Despite their known risks, opioids are often prescribed routinely and indiscriminately in managing SCD pain, because it is so often severe and debilitating. Integrative medicine strategies, particularly non-opioid therapies, hold promise in safe and effective management of SCD pain. However, the lack of evidence-based methods for managing SCD pain hinders the widespread implementation of non-opioid therapies. In this review, we acknowledge that implementing personalized pain treatment strategies in SCD, which is a guideline-recommended strategy, is currently fraught with limitations. The full implementation of pharmacological and biobehavioral pain approaches targeting mechanistic pain pathways faces challenges due to limited knowledge and limited financial and personnel support. We recommend personalized medicine, pharmacogenomics, and integrative medicine as aspirational strategies for improving pain care in SCD. As an organizing model that is a comprehensive framework for classifying pain subphenotypes and mechanisms in SCD, and for guiding selection of specific strategies, we present evidence updating pain research pioneer Richard Melzack's neuromatrix theory of pain. We advocate for using the updated neuromatrix model to subphenotype individuals with SCD, to better select personalized multimodal treatment strategies, and to identify research gaps fruitful for exploration. We present a fairly complete list of currently used pharmacologic and non-pharmacologic SCD pain therapies, classified by their mechanism of action and by their hypothesized targets in the updated neuromatrix model.

Alterations of Cerebral Metabolites Are Associated with Frequency of Vasoocclusive Crises and Pain Sensitivity in Patients with Sickle Cell Disease

Purpose Sickle cell disease (SCD) is an inherited hemolytic disorder complicated by acute and chronic pain. Acute vasoocclusive crises (VOCs) associated with SCD are extremely painful episodes that are recurrent, unpredictable, and frequently require hospitalization and opioids for pain control. Changes in brain metabolites were identified in other chronic pain populations but haven't been well studied in SCD. Our ongoing trial (ClinicalTrials.gov Identifier: NCT05045820) aims to evaluate the characteristics of brain metabolites in SCD and understand the relationship between the altered cerebral metabolite(s) and clinical pain in patients with SCD. Materials and Methods Metabolite measurements from a single voxel (size: 2×3×3 cm 3) located within the posterior insula cortex (PIC) were acquired from 26 patients with SCD (31.9 ± 13.9 years, 14-73; 14 females) and 19 healthy controls (HCs) (37.9 ± 16.4 years, 17-62; 10 females) with PRESS (TR/TE = 3000/25 ms, Averages =128) and MEGA-PRESS (TR/TE = 3000/68 ms, Averages =256) sequences using a Siemens Prisma 3T scanner. Written consent was obtained from each participant before scanning. LCModel was used for PRESS analysis to obtain concentration values of glutamine + glutamate (Glx), total creatine (tCr), N-acetylaspartate (NAA), total choline (tCho), and myoinositol (MI). Gannet was used for processing MEGA-PRESS data to estimate GABA+. Ratios of each metabolite to tCr were also quantified. Tissue correction for cerebrospinal fluid was performed for each voxel using the tissue composition estimated from SPM12. The Cramer-Rao Lower Bounds of each metabolite analyzed with LCModel was less than 20%. The frequency of VOCs in the preceding 12 months was recorded for each participant. A moderate pressure pain stimuli (using a 0-100 scale with “0” representing “no pain” and “100” representing “most intense pain imaginable”, pain rating at 40-60 abbreviated as P40 is considered as moderate pain) was delivered via a pressure cuff to the gastrocnemius area of the non-dominant leg using a validated MR-compatible air compressor to induce a tonic pressure pain for 8 min right before MRS scan. Higher pressure intensity (mmHg) of P40 indicated higher pain tolerance and lower pain sensitivity. Correlation between the brain metabolites and pain-related outcomes was studied. Results Due to the large range of age in the SCD group, the brain metabolite profile was compared between 17 SCD patients and 17 ethnicity-, age- and gender-matched HCs. The concentration of Glx (p =0.012) and ratio of Glx to tCr (p =0.034) in PIC were significantly higher in patients with SCD compared to HCs (Figure 1). Within the SCD patient group, there was a significant positive correlation between frequency of VOCs in the preceding 12 months and Glx/tCr (r= 0.39, p=0.047, Spearman's), a significant negative correlation between P40 and Glx (r= -0.46, p=0.019, Spearman's). There were no group differences in any other metabolites. Conclusion We find increased Glx in the PIC in patients with SCD. Previous studies have also found increased Glx and/ or Glx/tCr in the PIC as well as other brain regions including the amygdala, the posterior cingulate, the ventral lateral prefrontal cortex and the anterior insula in fibromyolgia. The PIC is thought to be involved in discriminative activities of sensory pain, which suggests that Glx in PIC is related to pain processing in patients with SCD. Glx/tCr was correlated with frequency of VOCs in patients with SCD, indicating that the SCD patients with higher level of Glx/tCr had more VOCs in the preceding 12 months. In addition, the SCD patients with higher level of Glx had lower pressure intensity of P40, suggesting that elevated Glx in the PIC was related to higher pain sensitivity. Our preliminary data provide the first evidence of a link between alterations in excitatory neurotransmitter levels in the PIC in patients with SCD and indicates new information of potential brain markers for pain in SCD, which may guide treatment. Clinical Relevance Statement: Treatment of pain in SCD remains very challenging in part due to a lack of understanding of the underlying mechanisms and pathophysiology of pain. Brain excitatory neurotransmitters and their relationship with pain have been largely unexplored in SCD. These findings indicate that the relationship between clinical outcomes and excitatory brain neurotransmitters may be a potential objective outcome measure in SCD.

Safety and Pharmacokinetics of Recombinant ADAMTS13 in Patients with Sickle Cell Disease: A Phase 1 Randomized, Double-Blind, Placebo-Controlled Study

Background Sickle cell disease (SCD) is an autosomal recessive hemoglobinopathy associated with chronic hemolysis and vaso-occlusive crises (VOCs). Despite the use of treatments such as hydroxyurea, many patients continue to experience VOCs. There is emerging evidence implicating the dysregulation of the von Willebrand factor (VWF)-ADAMTS13 axis in the pathophysiology of VOCs. The size and platelet-binding activity of ultra-large VWF multimers is regulated by the VWF-cleaving metalloprotease ADAMTS13; therefore, the administration of recombinant ADAMTS13 (rADAMTS13), particularly during VOCs, may be therapeutically beneficial in patients with SCD. Here, we present findings from a phase 1 study (NCT03997760) investigating the safety and pharmacokinetics (PK) of three doses of rADAMTS13 (TAK-755; Takeda Development Center Americas, Inc., Lexington, MA, USA) in patients with SCD. Aims To assess the safety, tolerability, and PK of 40 IU/kg, 80 IU/kg, and 160 IU/kg rADAMTS13 in patients with SCD at baseline health. Methods This phase 1, randomized, double-blind, placebo-controlled, multicenter, ascending single dose study (NCT03997760) enrolled patients aged between 18 and 65 years with a documented history of HbSS or HbSβ o thalassemia. Concurrent treatment with a stable dose of hydroxyurea was permitted. Patients were at baseline health: those diagnosed with acute VOC in the 21 days prior to dose administration were excluded. Patients who had received a blood transfusion within 30 days of screening were also excluded. Patients were randomized 3:1 to receive a single intravenous infusion of either rADAMTS13 or placebo in three sequential dose cohorts: cohort 1, 40 IU/kg; cohort 2, 80 IU/kg; cohort 3, 160 IU/kg. Patients were followed for 28 days post-infusion. Each dose cohort was opened sequentially following a review of safety data by a dose escalation committee. Primary safety endpoints included treatment-emergent adverse events (TEAEs), serious TEAEs, and the incidence of neutralizing antibodies against ADAMTS13. Secondary endpoints included an assessment of PK, comprising the maximum concentration (C max) and the area under the concentration-time curve (AUC) from zero (pre-dose) to 72 hours post-dose (AUC 0-72) estimated from ADAMTS13 antigen and activity levels, among other parameters. Results Five patients received placebo and 14 patients received a single dose of rADAMTS13 (cohort 1, n=4; cohort 2, n=6; cohort 3, n=4). The median age (range) of patients who received placebo was 36.0 (20-43) years and 2 (40.0%) were male. Median age (range) of patients who received rADAMTS13 was 38.5 (23-50) years and 9 (64.3%) were male. TEAEs were reported in 2 (40.0%) patients who received placebo and 8 (57.1%) patients who received rADAMTS13. TEAEs considered related to rADAMTS13 were reported in 4 patients (28.6%; Table). One serious TEAE (sickle cell anemia with crisis) not considered related to rADAMTS13 was reported in a patient who received 40 IU/kg rADAMTS13. No bleeding-related TEAEs were reported during the study and no TEAEs led to study discontinuation or death. No anti-ADAMTS13 neutralizing antibodies were detected within 28 days following rADAMTS13 administration. For the PK assessment, mean (standard deviation [SD]) baseline ADAMTS13 antigen was 0.68 (0.16) μg/mL, and rADAMTS13 demonstrated a dose-proportional increase in ADAMTS13 antigen level ( Figure). For cohorts 1, 2, and 3, respectively, baseline-adjusted ADAMTS13 antigen mean C max was 0.51 μg/mL (n=4), 1.07 μg/mL (n=5), and 2.08 μg/mL (n=4), and mean AUC 0-72 was 18.21 h*μg/mL (n=3), 43.01 h*μg/mL (n=5), and 74.51 h*μg/mL (n=4). Mean (SD) baseline ADAMTS13 activity was 1.06 (0.31) IU/mL. For cohorts 1, 2 and 3, respectively, mean C max for baseline-adjusted ADAMTS13 activity was 0.94 IU/mL (n=4), 2.09 IU/mL (n=5), and 3.08 IU/mL (n=4). Conclusions No safety signals or dose-limiting toxicities, such as bleeding events, were observed for the three evaluated doses of rADAMTS13 up to 160 IU/kg, and no rADAMTS13-related serious TEAEs were reported. No anti-ADAMTS13 neutralizing antibodies were detected during the study. rADAMTS13 demonstrated a dose-proportional increase in ADAMTS13 antigen levels, which is consistent with linear PK. Findings from this study support the further investigation of rADAMTS13 as a potential therapeutic option for patients with SCD.

Impact of Vaso-Occlusive Crises on the Transcriptomes of Patients with Sickle Cell Disease

Introduction: Sickle cell disease (SCD) is an inherited, multisystem blood disorder that affects millions of people worldwide and is particularly common among those of African descent. Vaso-occlusive crises (VOCs) or acute pain events involving complex interactions among sickled erythrocytes, endothelial cells, leukocytes, and activated platelets are hallmark symptoms of SCD. Over time, episodic bouts of acute VOC may develop into chronic pain, defined as pain most days for 6 months. At present, there are no biomarkers that distinguish between acute and chronic pain. Here, we explore differences in gene expression during VOC events in a cohort of pediatric patients with SCD. The objective of this study was to examine transcriptome alterations in CD45+ cells of individuals with SCD during a VOC event compared with steady state (SS) in patients with or without chronic pain. Methods: Patients were aged <21 years, with HbSS or HbSβ 0 genotypes. Informed consent was obtained for all patients. CD45+ cell (lymphohematopoietic lineage) samples were collected from 158 patients with SCD under SS conditions (at the maximum tolerated dose of hydroxyurea; some patients were also on metformin) during a VOC event, and at a follow-up visit after a VOC. RNA sequencing (RNA-Seq) was performed using a 101-base pair, paired-end protocol run on the NovaSeq 6000 system. We applied supervised normalization of microarrays to adjust the normalized gene expression values for the effect of multiple covariates. ToppGene Suite was used for over-representation analysis (ORA; Chen et al. Nucleic Acid Res 2009). Analysis of differentially expressed genes was performed using limma software and gene set enrichment analysis using the Molecular Signature Database. Results: A summary of the study cohort is presented (Table). Most patients (98.7%) were on hydroxyurea. We collected RNA-Seq data from unpaired and paired samples at SS and during a VOC. After adjusting for age, sex, chronic pain status, and metformin status, analyses of RNA-Seq data showed upregulated genes linked to TNFα signaling via NFΚB, IL-6/JAK/STAT3 signaling, complement activation, and coagulation were enriched in CD45+ cells during VOCs compared with SS (Figure). Differentially expressed genes were also compared with whole blood transcriptome samples collected at baseline and during a VOC event as reported by Creary et al (Sci Rep 2020). Approximately 290 upregulated and 33 downregulated genes were shared in both studies. ORA analysis of the shared genes revealed upregulation of pathways such as neutrophil degranulation and complement activation during a VOC event. Analysis of samples from patients without chronic pain at SS indicated similar immune-related pathways, such as complement activation and interferon α response, were upregulated during a VOC event. In contrast, analysis of samples from patients reporting chronic pain revealed no significant differences in gene expression between a VOC event and SS. Conclusions: Samples collected during a VOC event showed significant changes in the transcriptome of CD45+ cells compared with SS in pediatric patients who had the most severe disease, or sickle cell anemia characterized by HbSS and HBSβ 0/+ genotypes, without a diagnosis of chronic pain, with multiple pathways altered by VOC. However, when VOC transcriptomes in patients with chronic pain were compared with SS, these pathways were not significantly altered. Our pediatric patient population had low rates of chronic pain; therefore, our sample size was limited. Additional analyses of SS and VOC transcriptomes, particularly in patients with chronic pain, will expand our understanding of the impact of VOC events on transcriptomes in individuals with and without chronic pain. This may lead to identification of quantitative biomarkers for a VOC, facilitating testing of new therapies for the treatment of pain in people with SCD.

Comparative analysis of opioid use in sickle cell crisis in an urban facility in Ghana.

Vaso-occlusive crises (VOC) is common and opioids are the treatment of choice.This study compared parenteral pethidine and morphine in the elimination/reduction of pain in acute VOC to tolerable levels. This open-label randomized study compared intravenous morphine 5mg 4 hourly to intramuscular pethidine 75mg 4 hourly. Eighty-two consenting adult sickle cell disease participants were recruited from the Korle-Bu Polyclinic. (Forty-one participants in each arm). There were 42 male and 40 female participants. Median age was 25 years. Pethidine participants totalling 31.7% (13/41) and 53.7% (22/41) in the morphine arm had a sustained response within 6h, p=0.027. In the pethidine and morphine arms 60.0% (24/40) and 62.5% (25/40) of participants respectively achieved adequate pain control within 72h of initiating therapy, p=0.296. Most participants, 96.3% (79/82) had no side effects to opioids. The commonest side effects were generalized pruritus, nausea and vomiting, and headaches. More pethidine than morphine participants experienced side effects 29.3% and 22.0% respectively; p=0.448. In conclusion, more morphine participants achieved a sustained pain response compared to the pethidine participants. There was no difference in the tolerability and side effect profile of the opioids. No participant experienced respiratory suppression.

5610845 A PHASE 1 STUDY OF CSL888 (HEMOPEXIN) IN ADULT PATIENTS WITH SICKLE CELL DISEASE

Background: Episodes of vaso-occlusive crisis (VOC) are the primary reason for hospitalization among patients with sickle cell disease (SCD). The release of heme from the breakdown of damaged red blood cells is thought to play an important role in contributing to vaso-occlusion in SCD. Free heme promotes activation of endothelium, expression of endothelial cell adhesion molecules and activation of blood cells (neutrophils, monocytes, and platelets) which “stick” to the blood vessel walls. The net result is blockage of blood circulation, resulting in the characteristic pain of VOC. Hemopexin is a 60 kilodalton (kDa) plasma glycoprotein that is mainly expressed in the liver and belongs to the family of acute-phase proteins whose synthesis is induced after an inflammatory event. Hemopexin binds extracellular heme with the highest known affinity (KD < 1pM) of all plasma proteins. In patients with SCD, hemopexin levels are significantly reduced (approximately 85%) compared to healthy controls due to increased consumption. CSL889 is human plasma-derived hemopexin. It is hypothesized that pharmacological administration of CSL889 may decrease heme toxicity, restore normal blood circulation and therefore have beneficial effects in the management of acute VOC in SCD patients. Translation to the clinic is supported by studies performed in vitro demonstrating protection of heme-mediated endothelial cell damage and in vivo using the Townes mouse model of SCD, in which hemopexin was shown ameliorate vaso-occlusion following hemoglobin or hypoxia/reperfusion challenges (Gentinetta et al. 2022). Preclinical repeat dose toxicity studies in animals have evidenced favorable tolerability up to the highest dose level tested. Methods: We describe the design of a Phase 1, first in human, multicenter, open-label study to evaluate the safety, tolerability, and pharmacokinetics (PK) of CSL889 in adult patients with SCD following single intravenous (IV) doses of CSL889 [NCT04285827]. The study will comprise 2 parts. Part A will include patients with SCD in their usual health (not in VOC) who will receive a single dose of CSL889 at one of up to 6 different dose levels. In Part B, patients with SCD who present in VOC requiring intravenous (IV) opioid injections and admission to hospital for further management, will receive a single dose of CSL889 at a level that has been shown to be safe and tolerable in Part A within 36 hours of in-patient admission. All subjects will be followed up for 32 days post-infusion of CSL889. The range of doses to be studied is based on a translational PK model based on data derived from the study of CSL889 in the Townes mouse model of SCD. Results: The primary objective is to determine the safety and tolerability of single doses of CSL889 given to patients with SCD both without (Part A) and with (Part B) active VOC. The secondary objectives are to determine the PK and immunogenicity of CSL889. Exploratory objectives are to determine changes in biomarkers of target engagement (including changes in cell-free heme) and pharmacodynamic biomarkers related to the mechanism of action. Change in pain scores (as measured by Numeric Rating Scale [NRS]) will be additionally evaluated in Part B. Conclusions: Enrollment is in progress. No serious adverse events considered related to the administration of CSL889 have been reported as of 01-Sep-2022. Disclosures: F Wilson, J Jochems, L Lindqvist, K Jung,T Gentinetta, S Costin and GJ Kato are employed by CSL Reference 1. Gentinetta et al, J Clin Med 2022, 11:630

In Humanized Sickle Cell Mice, Imatinib Protects Against Sickle Cell-Related Injury.

Drug repurposing is a valuable strategy for rare diseases. Sickle cell disease (SCD) is a rare hereditary hemolytic anemia accompanied by acute and chronic painful episodes, most often in the context of vaso-occlusive crisis (VOC). Although progress in the knowledge of pathophysiology of SCD have allowed the development of new therapeutic options, a large fraction of patients still exhibits unmet therapeutic needs, with persistence of VOCs and chronic disease progression. Here, we show that imatinib, an oral tyrosine kinase inhibitor developed for the treatment of chronic myelogenous leukemia, acts as multimodal therapy targeting signal transduction pathways involved in the pathogenesis of both anemia and inflammatory vasculopathy of humanized murine model for SCD. In addition, imatinib inhibits the platelet-derived growth factor-B-dependent pathway, interfering with the profibrotic response to hypoxia/reperfusion injury, used to mimic acute VOCs. Our data indicate that imatinib might be considered as possible new therapeutic tool for chronic treatment of SCD.

Improving the Emergency Department Management of Sickle Cell Vaso-Occlusive Pain Crisis: The Role and Options of Sublingual and Intranasally Administered Analgesia.

Vaso-occlusive crisis (VOC), characterized by periods of excruciating pain is the most common clinical manifestation of sickle cell disease (SCD), often resulting in emergency room presentation. These patients often experience long wait times in the emergency department before receiving their first dose of analgesia. This delay results from the complexities of the emergency care system. Using the intranasal or sublingual approach to administering analgesia to SCD patients with VOC offers a fast, safe, noninvasive, atraumatic, and easily accessible route of administration which could reduce the time to first dose of analgesia. With the evolving advances in the development and delivery of analgesic medications, providers should be conversant with the nuances of intranasal and sublingual analgesia in the management of acute vaso-occlusive pain crisis. This review explores the pharmacokinetic profiles, dosages, and administration of intranasal and sublingual analgesics with relevance to the SCD population.

664: A RARE CASE OF NEUROPSYCHIATRIC LUPUS VASCULITIS: TREATING A DIAGNOSTIC DILEMMA

Introduction: Fat emboli syndrome (FES) in the setting of sickle cell disease (SCD) occurs secondary to bone ischemia, releasing fatty acids into the blood, and leading to infarct and microhemorrhages to the brain through either pulmonary or cardiac shunt. The characteristic MRI findings of cerebral FES are a “starfield” appearance of scattered micro-infarcts. Cerebral FES is uncommon in pediatrics, in patients without evidence of a shunt and in patients without inciting bone injury. Description: 16 year old male with HbSS presented with low back pain concerning for acute vaso-occlusive pain crisis that progressed to acute chest syndrome, respiratory failure and ARDS requiring intubation. He had respiratory acidosis and prolonged hypoxia on arrival. His initial HgbS fraction was 76%, requiring multiple exchange transfusions. He developed multiorgan dysfunction including acute renal failure, bilateral cortical renal infarcts, and biventricular cardiac dysfunction with ejection fraction of 35-40% and no shunt. He received therapeutic plasma exchange (TPE) in the setting of thrombocytopenia with schistocytes. A week later, his respiratory failure had improved and sedation was lifted for extubation when he was found to have increased tone, myoclonic movements, clonus, extensor posturing, gaze deviation and bilateral Hoffman sign. EEG showed no evidence of seizures. MRI demonstrated diffuse microhemorrhages and diffusion restriction in the white matter of the brain, localized heavily in the corpus callosum, as well as extensive bone ischemia of cervical vertebrae consistent with a microvascular occlusive process. The bony changes and starfield pattern seen on MRI were suggestive of cerebral FES. He tested positive for parvovirus B19, commonly seen in FES. He was extubated 6 days after diagnosis of FES and transferred to rehab facility after a month. Discussion: Although well described in adults, we found only a single other case describing FES with SCD in a child. Also notable are his delayed development of FES after recovery from other organ injuries and in the absence of cardiac shunt, and unknown intrapulmonary shunt. Prognosis for this disease, particularly in pediatrics, is unclear and treatment is mostly supportive aside from exchange transfusions.

Real-World Outcomes in Adult Sickle Cell Disease Patients Treated with Crizanlizumab, Voxelotor or Both

Background Crizanlizumab and voxelotor are new disease modifying therapies that have been shown respectively as single agents to reduce the frequency of vaso-occlusive crises (VOCs) and improve anemia. Clinical effects of these drugs in combination have not been examined in clinical trials. Objectives Evaluate the rates of VOC-related acute care utilization, lengths of stay (LOS) of hospitalizations and hemoglobin levels in sickle cell disease (SCD) patients treated with crizanlizumab, voxelotor, or both. Methods A single center, retrospective chart review was performed of all adult SCD patients to identify those treated with crizanlizumab and voxelotor, alone and in combination, for at least 12 months. Number of acute care utilization visits which includes emergency department (ED) visits, infusion room visits and hospitalizations for management of VOCs, lengths of stay of hospitalizations, as well as steady state hemoglobin values in the 12 months before and after initiation of crizanlizumab, voxelotor, or both were obtained for each patient. Acute care visits and hospitalizations for management of conditions other than acute VOC were excluded. A descriptive analysis was conducted to summarize patient characteristics and outcomes including changes from baseline over time for the three treatment groups separately. Fisher's exact tests were applied to compare categorical variables among the three treatment groups. Kruskal-Wallis tests were used instead for outcomes at a given time point or changes from baseline. A significant Kruskal-Wallis test was followed by pairwise Dunn tests adjusted for multiple testing using the Benjamini-Hochberg method. P-values smaller than 5% were considered statistically significant. All the statistical analyses were performed in R version 4.1.2. Results Of 266 adult SCD patients, 77 (29%) had ever taken crizanlizumab, voxelotor or both. 48 out of 77 (62%) patients met inclusion criteria of being on these therapies alone or in combination for at least 12 months. Of the included patients, 19 patients were treated with crizanlizumab alone, 18 patients were treated with voxelotor alone, and 11 patients were treated with both crizanlizumab and voxelotor. Baseline characteristics are summarized by treatment group in Table 1. Patients on crizanlizumab alone had a broader distribution of hemoglobin genotypes with a significantly smaller proportion having the Hb SS genotype (42.1%) compared to those on voxelotor alone (88.9%) or on a combination of crianlizumab and voxelotor (81.8%). Age, gender, and hydroxyurea (HU) use were not statistically significantly different among the three treatment groups. There was no statistically significant difference in acute care utilization in patients on crizanlizumab, voxelotor, or both (Table 2). Specifically, there was no evidence of difference in VOC related ED visits, infusion room visits, hospitalizations and LOS in the 12 months following initiation of these therapies compared to the 12 months preceding it. Of note, in patients on both crizanlizumab and voxelotor, the mean number of VOC related hospitalizations before initiation of treatment was 2.45 ± 2.54 compared to 1.18 ± 1.78 after, although these results did not reach statistical significance (P = 0.189). Likewise, the Mean total LOS before initiation of treatment was 12.18 ± 12.80 days compared to 6.45 ± 10.99 days after, although the results also did not reach statistical significance (P 0.274). At the 12 month mark, there was a significant difference in the distribution of change in hemoglobin level among the three treatment groups (P=0.008) (Table 2). Specifically, when compared to baseline hemoglobin, patients on voxelotor alone had a greater increase in hemoglobin than those on crizanlizumab alone (0.90 ± 1.19 g/dl vs -0.17 ± 0.56 g/dl, P = 0.008). Similarly, when compared to baseline hemoglobin, patients on both crizanlizumab and voxelotor had a greater increase in hemoglobin than those on crizanlizumab alone (0.70 ± 1.03 g/dl vs -0.17 ± 0.56 g/dl, P = 0.010). Conclusion This study suggests that patients treated with both crizanlizumab and voxelotor had an improvement in number of VOC related hospitalizations, LOS and hemoglobin level but our results could not achieve statistical significance due to our small sample size. Further real-world studies are needed to further understand the effects of combination therapies on acute care utilization. Figure 1View largeDownload PPTFigure 1View largeDownload PPT Close modal

Resolvins Modulate Netosis and Autoimmunity in Sickle Cell Disease

Sickle cell disease (SCD) is a genetically determined hematological disease which is characterized by anemia, chronic hemolysis, and multi-organ chronic inflammatory vasculopathy with acute vaso-occlusive painful crises and chronic organ damage. The pathophysiology of SCD is complex and involves several other cell types and metabolic pathways than erythrocytes, including neutrophils and soluble factors such as cytokines or alternative complement pathway which affect the function of vascular endothelium. An inflammatory vasculopathy with chronically activated neutrophils releasing Neutrophil Extracellular Traps (NETs) is a key component of the pathophysiology of sickle cell disease (SCD). Chiang et al. have recently shown that resolvins (Rv) reduce NETS and improve NETs clearance in a model of sepsis by Staphylococus aureus, a known trigger of NETosis (Chiang N et al. Blood 139 (8): 1222, 2022). We previously reported that targeting pro-resolution mechanisms with Rv improves SCD vasculopathy and organ damage in humanized sickle mice. Here, we studied 23 adult patients with SCD, followed by the Comprehensive center for hemoglobinopathies and rare anemias, University of Verona and AOUI Verona from January 2019 to December 2021. For each patient the presence/absence of concomitant rheumatological condition such as rheumatoid arthritis, other inflammatory arthropathies, immune-mediated dermatological conditions, Sicca syndrome and Raynaud's phenomenon, were assessed. Eight age, and ethnicity matched healthy controls were analyzed. Blood was collected for hematological and biochemical assay as part of the standard clinical care for these patients. Additional blood was collected for research studies on whole blood and on plasma cytokines. SCD patients display significant increase in tumor- necrosis-factor (TNF)- α (p = 0.011) and interleukin (IL)-10, suggesting both active inflammatory state and an upregulated counterregulatory mechanism to limit inflammation. We observed that antinuclear antibodies (ANA), but not extractable nuclear antibodies (ENA), were significantly increased in SCD patients (provide specific data here). Previous reports have reported the presence of this type of autoantibodies in the absence of autoimmune clinical manifestations in patients with SCD (Toly-Ndour C et al J Rheumatol 38: 302, 2011). ANA+ SCDsubjects (defined by a cell nuclei homogenous pattern, and positive dilution in the 1:80 to 1: 160 range) had a higher inflammatory and hemolytic status, as demonstrated by increased WBC and neutrophil counts and LDH values compared to ANA- subjects. NETosis plays a key role in modification and externalization of autoantigens involved in production of autoantibodies such as ANA. Here, we found basal NETosis was higher, though not significant, in ANA+ SCD subjects compared to ANA-SCD patients. This was associated with lower expression of receptors for RvD1 and D2, namely ALX, GPR32/DRV1, and GPR18/DRV2 on PMN, monocytes, and lymphocytes from ANA+ SCD patients when compared to ANA- SCD subjects, who were also characterized by relatively low LDH compared to ANA+ SCD patients. Exogenous treatment of SCD neutrophils with RvD1 and D4 significantly dampened NETs release and enhanced NETs clearance by macrophages. RvD4 along with other pro-resolving mediators also stimulated ex vivo clearance of P. aeruginosa and S. aureus by SCD neutrophils. Our findings provide a novel link between autoimmunity and neutrophil-mediated vasculopathy in SCD and highlight the importance of Rv and their immune-pro-resolution effects in limiting disease progression in SCD but also to modulate the host response to infections and sepsis, which is altered in SCD.

Cold Exposure Induces Vaso-Occlusion and Hyperalgesia in Mice with Sickle Cell Disease That Is Dependent on Complement Activation

BACKROUND AND AIM: Vaso-occlusive crises (VOC) cause severe pain in patients with sickle cell disease (SCD). To date, epidemiological studies have shown seasonably colder temperatures exacerbate SCD-related pain. Although literature and clinical observations suggest a connection between cold and triggering of acute VOC pain, the biologic mechanisms underlying VOC-evoked pain in SCD patients are poorly understood. Repeated cold or painful events results in vasoconstriction and decreased perfusion, which increases red cell transit time, deoxygenation, and hemoglobin S polymerization [Veluswamy et al. Blood. 2020;136:1191]. SCD mice exhibit ischemia-reperfusion (I/R) pathophysiology in response to hypoxia-reoxygenation with a concomitant increase in hyperalgesia, inflammation, and complement activation. Because complement activation plays a crucial role in animal pain models, we used a new model of cold-evoked VOC and I/R in HbSS mice to examine complement C5a/C5aR signaling as a mechanistic link between vaso-occlusion and acute pain in SCD. MATERIALS AND METHODS: We used a dorsal skinfold chamber model to measure microvascular stasis (vaso-occlusion) and von Frey filaments applied to the plantar surface of the hind paws to assess mechanical hyperalgesia (pain) in Townes HbSS and control HbAA mice. Non-hyperalgesic mice were exposed to cold (10oC/50oF) for 1 hour (h) and then returned to room temperature. Measurements of VOC and paw withdrawal threshold were collected at baseline before cold and at 1-4 h after cold exposure. After the 4 h stasis measurement, mice were sacrificed, and livers removed and frozen. Hepatic microsomes and nuclear extracts were isolated by differential centrifugation and liver inflammation markers were assessed on Western blots. Hepatic nuclear extracts were blotted with antibodies to NF-ĸB phospho-p65 and total p65. Hepatic microsomes were blotted with antibodies to VCAM-1 and ICAM-1. Plasma samples were blotted with antibodies to alternative pathway factor B activation fragment Bb and complement anaphylatoxin C5a. To examine the role of complement activation in stasis and hyperalgesia produced by cold-evoked VOC, HbSS mice were infused 30 minutes before cold exposure with an inhibitory monoclonal antibody (mAb) to murine C5 to prevent C5 cleavage or C5aR to prevent C5a binding to C5aR and subsequent C5a/C5aR signaling, or a control mAb (1.2 mg/kg body weight). RESULTS: Cold exposure induced more microvascular stasis (vaso-occlusion), 1, 2, 3, and 4 h after cold exposure in subcutaneous venules of HbSS mice as compared to HbAA mice exposed to cold and HbSS mice left at room temperature (p<0.001). Cold exposure also evoked mechanical hyperalgesia in HbSS mice 1, 2, and 24 h after cold as compared to baseline prior to cold (p<0.01) and cold exposed HbAA mice (p<0.05). Vaso-occlusion and mechanical hyperalgesia were accompanied by an increase in Bb and C5a levels in the plasma of HbSS, but not HbAA mice 4 h after cold exposure (p<0.01). In addition, there was an increase in NF-κB activation and VCAM-1 and ICAM-1 adhesion molecule expression in the livers of HbSS mice after cold as compared to HbAA mice exposed to cold and HbSS mice unexposed to cold (p<0.01). Importantly, pretreatment of HbSS mice before cold exposure with a blocking mAb to C5 or C5aR inhibited vaso-occlusion (Figure 1A), mechanical hyperalgesia (Figure 1B), and complement activation (Figure 1C) as compared to cold-exposed HbSS mice treated with a control mAb. CONCLUSION: This mouse model of cold-evoked VOC provides an opportunity to examine potential mediators between vaso-occlusion and pain in SCD. Our results demonstrate that in response to cold temperatures, complement activation contributes to vaso-occlusion and acute hyperalgesia, suggesting a linkage between complement activation, vaso-occlusion, and pain during cold-induced VOC. These studies provide a rationale for clinical use of complement inhibitors to prevent and treat pain in SCD. Figure 1View largeDownload PPTFigure 1View largeDownload PPT Close modal

A randomized clinical trial of the efficacy and safety of rivipansel for sickle cell vaso-occlusive crisis

AbstractThe efficacy and safety of rivipansel, a predominantly E-selectin antagonist, were studied in a phase 3, randomized, controlled trial for vaso-occlusive crisis (VOC) requiring hospitalization (RESET). A total of 345 subjects (204 adults and 141 children) were randomized and 320 were treated (162 with rivipansel, 158 with placebo) with an IV loading dose, followed by up to 14 additional 12-hourly maintenance doses of rivipansel or placebo, in addition to standard care. Rivipansel was similarly administered during subsequent VOCs in the Open-label Extension (OLE) study. In the full analysis population, the median time to readiness for discharge (TTRFD), the primary end point, was not different between rivipansel and placebo (−5.7 hours, P = .79; hazard ratio, 0.97), nor were differences seen in secondary end points of time to discharge (TTD), time to discontinuation of IV opioids (TTDIVO), and cumulative IV opioid use. Mean soluble E-selectin decreased 61% from baseline after the loading dose in the rivipansel group, while remaining unchanged in the placebo group. In a post hoc analysis, early rivipansel treatment within 26.4 hours of VOC pain onset (earliest quartile of time from VOC onset to treatment) reduced median TTRFD by 56.3 hours, reduced median TTD by 41.5 hours, and reduced median TTDIVO by 50.5 hours, compared with placebo (all P < .05). A similar subgroup analysis comparing OLE early-treatment with early-treatment RESET placebo showed a reduction in TTD of 23.1 hours (P = .062) and in TTDIVO of 30.1 hours (P = .087). Timing of rivipansel administration after pain onset may be critical to achieving accelerated resolution of acute VOC. Trial Registration: Clinicaltrials.gov, NCT02187003 (RESET), NCT02433158 (OLE).

Heme Interferes With Complement Factor I-Dependent Regulation by Enhancing Alternative Pathway Activation.

Hemolysis, as a result of disease or exposure to biomaterials, is characterized by excess amounts of cell-free heme intravascularly and consumption of the protective heme-scavenger proteins in plasma. The liberation of heme has been linked to the activation of inflammatory systems, including the complement system, through alternative pathway activation. Here, we investigated the impact of heme on the regulatory function of the complement system. Heme dose-dependently inhibited factor I-mediated degradation of soluble and surface-bound C3b, when incubated in plasma or buffer with complement regulatory proteins. Inhibition occurred with factor H and soluble complement receptor 1 as co-factors, and the mechanism was linked to the direct heme-interaction with factor I. The heme-scavenger protein hemopexin was the main contaminant in purified factor I preparations. This led us to identify that hemopexin formed a complex with factor I in normal human plasma. These complexes were significantly reduced during acute vasoocclusive pain crisis in patients with sickle cell disease, but the complexes were normalized at their baseline outpatient clinic visit. Hemopexin exposed a protective function of factor I activity in vitro, but only when it was present before the addition of heme. In conclusion, we present a mechanistic explanation of how heme promotes uncontrolled complement alternative pathway amplification by interfering with the regulatory capacity of factor I. Reduced levels of hemopexin and hemopexin-factor I complexes during an acute hemolytic crisis is a risk factor for heme-mediated factor I inhibition.

P1483: EPELEUTON, A NOVEL SYNTHETIC SECOND GENERATION W-3 FATTY ACID, PROTECTS HUMANIZED SICKLE CELL MICE AGAINST HYPOXIA/REOXYGENATION ORGAN DAMAGE

Background: Sickle cell disease (SCD) is a hereditary red cell disorder with high mortality and morbidity. Although crizanlizumab, a P-selectin inhibitor, and voxelotor, an oral anti-sickling agent, have been recently approved for clinical management of SCD, therapeutic options to limit acute events and to reduce disease progression are still required. An attempt to target inflammatory vasculopathy and to modulate inflammatory response has been made based on evidence in other diseases such as in cardiovascular disease looking to administration of ω-3 fatty acids. In humanized SCD mice, we previously showed that polyunsaturated fatty acid supplementation protects against acute sickle cell-related lung and liver damages during hypoxia/reoxygenation (H/R) induced vaso-occlusive crisis (VOCs) (Kalish B et al. Haematologica 2016). This agrees with the observation that the resolution process actively controlled by specialized pro-resolving lipid mediators is defective in SCD (Matte A et al, Blood 2019). Epeleuton (15-HEPE, 15 hydroxy eicosapentaenoic acid) is a novel synthetic second generation w-3 fatty acid which (i) has a favorable clinical safety profile, (ii) modulates systemic inflammation and triglyceride synthesis in patients with cardiometabolic disease (Climax J et al J Am Heart As 2020) and (ii) beneficially affects red cell indices in long-term studies in rats. Aims: To evaluate the impact of epeleuton on acute organ damage in a humanized mouse model of SCD. Methods: 3-4 month old male and female mice healthy control (Hbatm1(HBA)Tow Hbbtm3(HBG1,HBB)Tow) and Tim Townes sickle mice (SCD, Hba tm1(HBA)Tow Hbb tm2(HBG1,HBB*)Tow) were used. Animals were treated for 6 weeks with epeleuton 1,000 mg/kg once daily or vehicle by gavage. Mice underwent 10 hours of hypoxia (8% oxygen), followed by 3 hours of reoxygenation (21% oxygen) to mimic acute VOCs (Matte A et al, Blood 2019). Hematologic parameters and molecular analysis of target organs for SCD such as lung were carried out. Results: In SCD mice exposed to H/R stress, we found that epeleuton (i) reduces H/R induced hemolysis; (ii) normalizes tyrosine-phosphorylation profile of red cell membrane proteins; and (iii) decreases neutrophil count. In lungs of SCD mice exposed to H/R stress, we observed that epeleuton prevents the H/R induced activation of inflammatory and redox related transcription factors NF-kB, p65 and Nrf2 local inflammatory response compared with vehicle-treated animals. Epeleuton treated SCD mice exposed to H/R stress showed down-regulation of VCAM-1 and E-selectin, markers of inflammatory vasculopathy as well as reduction of lung protein oxidation and expression of anti-oxidant systems such as heme-oxygenase-1 (HO-1) or peroxiredoxin-2. Similar changes were also observed in livers of epeleuton-treated SCD mice exposed to H/R stress compared with vehicle-treated SCD animals. Of note, epeleuton prevented the H/R induced up-regulation of both VCAM-1 and ICAM-1, suggesting a direct impact of treatment on vascular activation and inflammation. Summary/Conclusion: In humanized SCD mice exposed to H/R stress to mimic acute VOCs, epeleuton acts as a multimodal agent targeting red cells, hemolysis, inflammatory response, and vascular dysfunction. Our data provide the rationale for epeleuton as a potential novel therapeutic option for clinical management of patients with SCD.