Hepatic Sequestration Research Articles

The usefulness of indium‐111 platelet scintigraphy beyond predicting efficacy of splenectomy

There are no clear indicators to predict the outcome of patients with immune thrombocytopenia or the response to drugs. The work of Durand et al. shows that Indium‐111 platelet scintigraphy is useful in identifying those patients who will benefit from splenectomy and lays the groundwork for studies demonstrating the increased corticosteroid dependency and rituximab refractoriness of the hepatic platelet sequestration group.Commentary on: Durand et al. Course of immune thrombocytopenia according to the site of platelet destruction identified by indium‐111 platelet scintigraphy. Br J Haematol 2024 (Online ahead of print). doi: 10.1111/bjh.19833.

Course of immune thrombocytopenia according to the site of platelet destruction identified by indium-111 platelet scintigraphy.

In primary immune thrombocytopenia (ITP), predictors of disease evolution and treatment response are needed. Data based on the site of platelet destruction are scarce. We performed a retrospective single-centre study of adult patients with primary ITP undergoing at least one Indium-111 platelet scintigraphy (IPS) between 2009 and 2018. Thirty-three patients had isolated hepatic platelet destruction (H-group), and 97 isolated splenic destruction (S-group). Median age at diagnosis (p < 0.001), proportion of associated cardiovascular (p < 0.001), organ-specific autoimmune diseases (p = 0.02), dependence on steroids (p = 0.003) and failure to rituximab (p = 0.01) were higher and relapse more frequent (p = 0.03) in H-group compared to non-splenectomized patients in S-group. Splenectomy was only performed in patients from S-group (as patients with hepatic sequestration are not splenectomized in our centre): 79% were in relapse-free remission at the end of a median 3.4-year post-IPS follow-up, 16% relapsed. In multivariate analyses, only a history of organ-specific autoimmune or inflammatory disease was significantly associated with hepatic sequestration (OR = 4.3, 95% CI = 1.2-15, p = 0.02). Patients with isolated hepatic sequestration were older, had more cardiovascular events and organ-specific autoimmune diseases, greater dependence on steroids, more relapses and a decreased response rate to rituximab suggesting an increased refractoriness to immunomodulatory therapies. Patients with isolated splenic sequestration responded well to splenectomy.

An Engineered Self-biomineralized Oncolytic Adenovirus Induces Effective Antitumor Immunity and Synergizes With Immune Checkpoint Blockade.

Oncolytic adenoviruses (oADV) are promising cancer treatment agents. However, in vivo hepatic sequestration and the host immunologic response against the agents limit the therapeutic potential of oADVs. In this study, we present a combined method with a rational design for improving oADV infection efficiency, immunogenicity, and treatment efficacy by self-biomineralization. We integrated the biomimetic nucleopeptide W6p into the capsid of oADV using reverse genetics, allowing calcium phosphate mineralization to be biologically induced on the surface of oADV under physiologic conditions, resulting in a mineral exterior. This self-biomineralized, modified oADV (oADV-W6-CaP) enhanced infection efficiency and therapeutic efficacy in coxsackievirus and adenovirus receptor (CAR)-negative cancer cells wherein protecting them against neutralization by preexisting neutralizing antibodies. In subcutaneous mouse tumor models, systemic injection of oADV-W6-CaP demonstrated improved antitumor effectiveness, which was associated with increased T-cell infiltration and CD8+ T-cell activation. In addition, the anticancer immune response elicited by oADV-W6-CaP was dependent on CD8+ T cells, which mediated long-term immunologic memory and systemic antitumor immunity against the same tumor. Finally, the addition of PD1 or CD47 inhibition boosted the anticancer effects of oADV-W6-CaP and increased the rate of complete tumor clearance in tumor-bearing animals. The self-biomineralized oADV shifted the suppressive tumor microenvironment from a "cold" to "hot" state and synergized with immune checkpoint blockade to exert outstanding tumoricidal effects, demonstrating promising potential for cancer immunotherapy.

Hepatobiliary complications in children with sickle cell disease; retrospective single-center study

Objective: This study aimed to determine how common hepatobiliary complications were in children with sickle cell disease (SCD). Methods: This was a retrospective descriptive study conducted at a single tertiary health care center, King Saud Medical City (KSMC), Pediatric Hospital, Riyadh from April 2023 to April 2024. Patient recruitment was done by reviewing the medical records. All pediatric patient cases under 14 years, with SCD in both genders were included without specifying any race or ethnic characteristic. Results: A total of 143 patient cases with SCD were included from the hospital database. More than half of them were males. Hepatobiliary complications were observed in 19.5% of patients with SCD, cholelithiasis occurred in 26 (18.2%), cholangiopathy (bile duct stenosis) occurred in 3 (2.1%) and only one patient had acute hepatic sequestration (AHS). Biliary complication (cholelithiasis) was significantly associated with age and raised alanine aminotransferase (ALT) (p-value 0.042). Raised ALT was associated significantly with age, hemoglobin (Hb) level, and AHS. Total bilirubin &amp;gt; 2 mg/dl (&amp;gt; 34 micro mol/L) and direct bilirubin &amp;gt; 1 mg/dl (&amp;gt; 17 micro mol/L) were observed in 26.9% and 61.5% of patients who had cholelithiasis respectively, low Hb in 46.2% and low platelet in 30.8%. Conclusion: Hepatobiliary complications were observed in less than one-fifth of patients with SCD. The most common complication observed was cholelithiasis, rare complications were cholangiopathy and AHS.

A Phase 2/3, Double-Blind, Randomized, Placebo-Controlled, Multicenter Study of Mitapivat in Patients with Sickle Cell Disease: RISE UP Phase 2 Results

Background: Sickle cell disease (SCD) is characterized by the presence of hemoglobin S (HbS), a structural variant caused by a mutation in the HBB gene. Deoxygenated HbS molecules polymerize into “fibers”, causing red blood cells (RBCs) to sickle and hemolyze. Sickled RBCs have a shortened lifespan and impede blood flow to tissues, causing painful vaso-occlusive crises. Recurrent microvascular damage and chronic hemolytic anemia result in progressive multi-organ damage. Mitapivat is an oral, small-molecule allosteric activator of pyruvate kinase, a key enzyme in RBC metabolism, with a dual mechanism of action under investigation in SCD: it increases adenosine triphosphate (ATP) in RBCs, improving survival, and decreases 2,3−diphosphoglycerate, increasing Hb oxygen affinity and thus diminishing HbS polymerization and RBC sickling. RISE UP is a global Phase (Ph) 2/3 double-blind, randomized, placebo (PBO)-controlled trial evaluating the efficacy and safety of mitapivat in patients (pts) with SCD (NCT05031780). Methods: In the Ph 2 double-blind period (DBP), 2 dose levels of mitapivat were evaluated against PBO for 12 weeks (wks). Eligible pts were ≥16 years with ≥5.5 to ≤10.5 g/dL Hb and ≥2 to ≤10 sickle cell pain crises (SCPCs, including pain, priapism, acute chest syndrome, hepatic sequestration, and splenic sequestration) in year prior to entry. Pts were randomized 1:1:1 to mitapivat 50 mg twice daily (BID), mitapivat 100 mg BID, or matched PBO. Pts completing the DBP were eligible to receive mitapivat in a 216-wk open-label extension. Primary endpoints were Hb response (≥1.0 g/dL increase in average Hb concentrations from Wks 10 through 12 compared with baseline [BL], tested with Fisher's exact test at 2-sided 0.05 significance level) and adverse events (AEs), including the type, severity, and relationship to study drug. Prespecified secondary endpoints included average change from BL from Wks 10 through 12 in Hb, markers of hemolysis, markers of erythropoiesis, and pt-reported fatigue score, as well as annualized rate of SCPCs. Results: In the Ph 2 DBP, 79 pts were randomized and treated with mitapivat 50 mg BID (n=26), mitapivat 100 mg BID (n=26), or PBO (n=27). In the 50 mg BID, 100 mg BID, and PBO arms, mean (SD) age was: 29.9 (7.79), 30.2 (10.52), and 28.5 (10.30) years; female: 57.7%, 61.5%, and 74.1%; mean (SD) BL Hb: 8.76 (1.295), 8.82 (0.898), and 8.49 (1.141) g/dL; mean (SD) number of SCPCs during previous year: 3.1 (1.83), 3.2 (1.65), and 3.4 (1.91), respectively. The primary endpoint was achieved; 46.2% (12/26) of pts in the 50 mg BID arm and 50.0% (13/26) in the 100 mg BID arm demonstrated a significant increase in Hb response compared with 3.7% (1/27) of pts in the PBO arm (2-sided p=0.0003 and p=0.0001, respectively). Mitapivat was generally well tolerated; observed safety profile was consistent with previously reported data of mitapivat in SCD and other hemolytic anemias. No serious treatment-emergent AEs were related to study drug; no AEs led to study drug discontinuation or death. Least-squares mean (LSM [95% CI]) for average change from BL in Hb levels from Wks 10 through 12 was 1.11 (0.77, 1.45) g/dL, 1.13 (0.79, 1.47) g/dL, and 0.05 (−0.28, 0.39) g/dL for 50 mg BID, 100 mg BID, and PBO arms, respectively ( Figure). Improvements were observed in markers of hemolysis and erythropoiesis. SCPCs annualized rates (95% CI) were 0.83 (0.34, 1.99) and 0.51 (0.16, 1.59) for 50 mg BID and 100 mg BID arms, respectively, compared to 1.71 (0.95, 3.08) for PBO. LSM (95% CI) for average changes from BL in pt-reported fatigue score from Wks 10 through 12 was −3.80 (−7.16, −0.45), −0.10 (−3.27, 3.08), and −0.17 (−3.40, 3.07) for 50 mg BID, 100 mg BID, and PBO arms, respectively ( Table). Conclusion: During the Ph 2 DBP of RISE UP, treatment with mitapivat demonstrated statistically significant and clinically meaningful improvement in Hb response at both dose levels (50 mg BID and 100 mg BID) compared to PBO. Improvements in markers of hemolysis/erythropoiesis and annualized rate of SCPCs were observed for both doses as compared with PBO; the magnitude of improvement in markers of hemolysis and annualized rate of SCPCs was larger in the mitapivat 100 mg BID arm. Mitapivat was well tolerated with a safety profile consistent with previous studies. These data suggest that mitapivat, through its dual mechanism of action, may provide clinical benefit to pts with SCD and support continued development in the Ph 3 portion of the RISE UP trial.

Liver Disease and Sickle Cell Disease: Auto-Immune Hepatitis more than a Coincidence; A Systematic Review of the Literature.

In patients with SCD, chronic liver damage is a common manifestation. More than 50% of SCD patients have elevated liver enzymes. Common underlying aetiologies include sickle cell hepatic crisis, viral hepatitis, sickle cell intrahepatic cholestasis and hepatic sequestration in the acute setting, and cholelithiasis and iron overload in the chronic setting. Autoimmune hepatitis (AIH) is a rare disease that appears to occur more commonly in the sickle cell disease (SCD) population than in the general population. There are many schools of thought as to why this is the case, including the phosphatidylserine hypothesis, the heme inflammatory hypothesis, the complement generation hypothesis, and the transfusion alloimmunization hypothesis. Due to the natural history of the two illnesses, SCD is almost always diagnosed first in cases of dual pathology. Symptoms such as jaundice, fatigue, and abdominal pain are common in SCD, as are abnormal liver function tests (LFTs). These abnormalities, attributed to the other more frequent liver involvements in SCD, can lead to delays in AIH diagnosis in this population. Corticosteroids, sometimes with other immunosuppressive agents, such as azathioprine, are the cornerstone of acute AIH treatment. However, corticosteroid use in the SCD population has been shown to carry an increased risk of vaso-occlusive crises, providing a treatment dilemma. The following is a review of AIH in the SCD population, where we explore the pathophysiology behind the association between the two disorders, discuss an approach to investigating abnormal LFTs in SCD, and examine treatment options in this population with co-existing diseases.

Successful Use of Plasma Exchange Preceding RBC Exchange in Sickle Cell Disease Hyperhemolytic Crisis with Hepatic Sequestration: A Case Report

Successful Use of Plasma Exchange Preceding RBC Exchange in Sickle Cell Disease Hyperhemolytic Crisis with Hepatic Sequestration: A Case Report

Sickle Cell Disease in Pregnancy: Obstetrician’s Nightmare in Resource-Poor Countries!

Sickle Cell Disease in Pregnancy: Obstetrician’s Nightmare in Resource-Poor Countries!

Galactosyl, alkyl, and acidic groups modify uptake and subcellular deposition of pyropheophorbide-a by epithelial tumor cells and determine photosensitizing efficacy

Photosensitizers currently used for photodynamic therapy of cancer show enhanced accumulation in tumor tissue but lack cancer cell specificity. To augment cellular uptake, the targeting of pyropheophorbide-a to carbohydrate-binding components of cancer cells was explored. Galactose was attached to pyropheophorbide-a at positions 172 and 20. Since the modification at position 172 removed a carboxylic group, which is relevant for cell specificity, this study evaluated the relative contribution of galactosyl and carboxyl groups at either position 172 or 20, with or without a (hexyloxy)ethyl at position 3, to cellular uptake by human epithelial cancer cells. The subcellular deposition was monitored using fluorescence microscopy and the photoreaction was quantified using biomarkers. The results demonstrated that any galactose addition suppresses transmembrane diffusion and promotes endocytosis and lysosomal accumulation. An anionic group at position 172 or 20 enhances lysosomal retention. Neutralization of the carboxylic group at position 172 facilitates transfer to mitochondria/endoplasmatic reticulum and promotes tumor cell-specific retention. Replacing (hexyloxy)ethyl with an ethyl group at position 3 increased both cellular uptake and egress but did not alter subcellular localization. These findings suggest that specific neutral galactosylated pheophorbides may provide an enhanced therapeutic effect for those tumor types that do not retain unmodified pyropheophorbide. However, the galactose conjugates also serve as substrates for preferential uptake by liver cells resulting in hepatic sequestration, reduced systemic distribution, and lower accumulation in tumor tissue.

The interplay between GPIb/IX antibodies, platelet hepatic sequestration, and TPO levels in patients with chronic ITP.

Immune thrombocytopenia (ITP) is an autoimmune bleeding disorder with an incompletely understood pathophysiology but includes platelet-clearance in the spleen and liver via T cells and/or platelet autoantibodies. Strikingly, thrombopoietin (TPO) levels remain low in ITP. Platelet-glycoprotein (GP)Ibα has been described to be required for hepatic TPO generation; however, the role of GPIb antibodies in relation to platelet hepatic sequestration and TPO levels, with consideration of platelet counts, remains to be elucidated. Therefore, we examined 53 patients with chronic and nonsplenectomized ITP for whom we conducted indium-labeled autologous platelet scintigraphy and measured platelet antibodies and TPO levels. Upon stratification toward the severity of thrombocytopenia, no negative association was observed between GPIb/IX antibodies and TPO levels, suggesting that GPIb/IX antibodies do not inhibit or block TPO levels. Surprisingly, we observed a positive association between GPIb/IX antibody levels and TPO levels and GPIb/IX antibodies and platelet hepatic sequestration in patients with severe, but not mild or moderate, thrombocytopenia. In addition, platelet hepatic sequestration and TPO levels were positively associated. This collectively indicates that GPIb/IX antibodies may be associated with increased platelet hepatic sequestration and elevated TPO levels in patients with severe thrombocytopenic ITP; however, further research is warranted to elucidate the pathophysiologic mechanisms.

Insights into Vaso-Occlusive Crises-Related Readmissions in Patients with SCD across Geographic Regions

Background: Sickle cell disease (SCD) is an inherited red blood cell disorder characterized by chronic anemia and hemolysis, inflammation, and vaso-occlusion that manifests clinically as recurrent, painful vaso-occlusive crises (VOCs) and widespread organ damage. VOCs are the main reason for admission to a healthcare facility (eg, hospital, emergency department [ED], observation unit, or day care). Frequent admission for VOCs is an indicator of severe disease and is associated with early mortality. In the United States, 33% of patients admitted to a healthcare facility for VOCs are readmitted within 30 days, and approximately 50% of patients are readmitted within 90 days. These high readmission rates place an enormous burden on patients, caregivers, and the healthcare system. US readmission rates may not represent 90-day readmission rates among individuals with SCD outside of the United States due to variability in healthcare settings, practices, access, and other potentially confounding factors. Objective: To explore regional differences in 90-day readmission rates for VOCs, this retrospective chart review was conducted in a sample of patients with SCD at selected sites across geographic regions. Methods: Medical records from patients with SCD (all genotypes), aged ≥12 years, who were admitted to the ED or hospital for management of a VOC during a 2-year period were evaluated for this retrospective chart review. The evaluation took place at 8 sites on 5 continents (North America, Africa, Asia, Europe, and South America). Eligible patients had a history of painful VOC episodes, including complicated VOCs of acute chest syndrome, hepatic sequestration, splenic sequestration, and priapism, requiring admission to a medical facility (hospital, ED, observation unit, or day care) for treatment. For each patient, dates of admission for a VOC requiring treatment with parenteral (intravenous or intramuscular) pain medications (eg, nonsteroidal anti-inflammatory drugs, narcotics) in the selected time were collected. Patients with SCD who had 2 to 10 VOCs within year 1 were eligible for inclusion in the chart analysis. The first admission for VOC during the second year of the study was designated as the index VOC. A subsequent VOC occurring within 90 days of the index VOC was used to determine the 90-day readmission rate. Results: The study included a review of 500 patient charts across 8 geographic regions in 6 countries: Brazil, Egypt, Italy, Lebanon, Nigeria, and the United States (Figure 1). Out of the 500 patient charts reviewed, 290 (58%) were eligible for this study. Of the eligible patients with SCD who were admitted for a VOC, those who were readmitted within 90 days were included for analysis. The proportion of patients readmitted for a VOC within 90 days ranged from 30% to 51% (Figure 2). Conclusions: Recurrent and prolonged VOC-related hospitalizations substantially disrupt the daily lives and emotional well-being of patients with SCD and are associated with increased risk of mortality. VOCs also remain the main cause for inpatient admissions, and there is an urgent need to reduce the burden of VOC-related hospitalizations. This study provides insights into 90-day readmission rates for VOCs in patients with SCD across different geographic regions. Rates of readmission due to VOCs were generally similar across the sites and consistent with rates observed in the United States. The 90-day readmission rates observed in this study suggest that similar factors may influence VOC hospitalization rates. Identification of these factors is critical for formulating interventions to reduce readmissions and the associated social and economic burden, and for facilitating efficient allocation of resources. Future analyses will include the assessment of site and practice-specific factors contributing to these results to inform physicians treating patients with SCD on potential ways to alleviate this burden on patients, caregivers, and the medical community. Funding: Global Blood Therapeutics. Figure 1View largeDownload PPTFigure 1View largeDownload PPT Close modal

Development of a Humanized Mouse Model of Cholestatic Sickle Cell Disease

Sickle cell disease (SCD) is a group of autosomal recessive inherited disorders that affect approximately 100,000 people in the United States and millions worldwide. Liver or biliary complications including cirrhosis and cholestatic injury are evident in about 40% of hospitalized SCD patients. However, the molecular mechanisms responsible for sickle cell hepatopathy (SCH) remain poorly understood. Recently published studies and our preliminary data demonstrated impaired bile secretion and altered bile acid homeostasis accompanied red blood cell sequestration and fibrosis in the livers of humanized sickle cell mice. Although promising, a limitation of this model for the study of SCH is the predominance of hydrophilic bile acids in mice, which contrasts with a more hydrophobic and injurious bile acid pool in humans. A recent breakthrough in this area was the identification of murine-specific cytochrome P450 (Cyp2c70) as the enzyme responsible for the synthesis of mouse hydrophilic primary bile acids. Therefore, we hypothesize that the human hydrophobic bile acid composition would promote the development of cholestatic sickle cell disease. Methods:Tibias and femurs were excised from 2-month-old SCD SS and AA control mice and the bone marrow (BM) was collected. After lethal irradiation (2x 4.5Gy 4 hours apart), 2-month-old male recipient Cyp2c70-/- and their wildtype controls received BM-derived cells from either AA or SS mice. Cyp2c70-/- (KO) mice (C57Bl/6) were generated using CRISPR/Cas9 technology. Recipient Cyp2c70-/- and WTmice were reconstituted with SS and AA bone marrow and were euthanized 4 months after BMT. Standard growth parameters were recorded; liver, spleen, gallbladder bile, and blood were collected at necropsy for histologic, RNA, and chemical analyses. Results: Recipient Cyp2c70-/- (KO) SS mice had a significantly increased liver-to-body weight ratio compared to their controls. There was an increase in serum bile acids, direct bilirubin, and total bilirubin in SS recipient Cyp2c70-/- and WT mice compared to AA recipient mice. Serum alanine aminotransferase (ALT) and aspartate aminotransferase (AST) were increased in Cyp2c70-/- (KO) overall with no observable difference in Cyp2c70-/- (KO) transplanted with AA or SS. An evaluation of liver histology by H&E revealed increased portal bridging and hepatic sequestration in sinusoids of recipient Cyp2c70-/- SS mice compared to control mice. Liver surface nodularity and morphological heterogeneity were also present in recipient Cyp2c70-/- SS mice compared to their controls. We observed increased collagen deposition as measured by Sirius Red staining in recipient Cyp2c70-/- SS mice compared to control mice. Liver histology revealed increased hepatic inflammation by F4/80 staining and bile duct proliferation by CK-19 and CK-8 staining in recipient Cyp2c70-/- SS mice. Conclusion: Coupled with the humanized sickle cell disease mouse, this novel sickle cell cholestatic liver mouse model can be used to investigate the role of hydrophobic bile acid-induced injury in sickle cell-related hepatobiliary disease and screen new therapeutic approaches for SCH. Figure 1View largeDownload PPTFigure 1View largeDownload PPT Close modal

S3160 Sickle Hepatopathy: An Uncommon Sickle Cell Crisis

Introduction: Intrahepatic vaso-occlusive syndrome, or sickle cell hepatopathy (SCH), is a rare complication of sickle cell disease. We present a case of acute hepatic sequestration in the setting of bacteremia. Case Description/Methods: 32 male with history of sickle cell disease, auto-splenectomy and end stage renal disease presented with fatigue and diffuse myalgia. Physical exam was notable for scleral icterus, left knee swelling and erythema, and crackles in bilateral lungs. Initial labs showed leukocytosis (WBC 43,000/μL), profound anemia (Hgb 3.7 g/dL) and coagulopathy (INR 2.1). Liver enzymes were elevated at ALP 527 U/L, ALT 48 U/L, AST 209 U/L. Total bilirubin was 39 mg/dL with conjugated fraction 34.4 mg/dL, blood urea nitrogen 67mg/dL, creatinine of 4.34mg/dL, and ferritin >10,000. Blood cultures revealed Staphylococcus Aureus, likely due to left knee septic joint. US showed hepatomegaly with liver span of 24 cm. Clinical picture consistent with sepsis secondary to MSSA bacteremia in setting of sickle cell crisis and hepatopathy. Patient was admitted to ICU for hypoxic respiratory failure due to fluid overload. Clinical course was complicated by septic shock with multi-organ dysfunction including acute liver failure due to hepatic sequestration crisis, hemochromatosis, encephalopathy and disseminated intravascular coagulation. Patient required CRRT and supportive care including treatment of underlying infection, PRBC transfusions, and vitamin K administration to reverse coagulopathy (Figure). Discussion: Hepatopathy occurs in 10% of homozygous sickle cell patients. It can be self resolving or lead to fulminant hepatic failure. Subsets of SCH include Acute Hepatic Crisis(AHC), Hepatic Sequestration, Intrahepatic Cholestasis(IC). Sickling in the sinusoids leading to hepatocellular necrosis, engorgement of Kupffer cells and bile stasis. Common presentation of all three conditions includes acute RUQ pain, nausea, fever, and elevated liver enzymes. IC is severe presentation of SCH with hypoxic injury leading to blockage and cholestasis. Presentation overlaps with AHC with addition of hyperbilirubinemia, severe jaundice, renal impairment, and encephalopathy. Total bilirubin is typically markedly elevated due to combination of hemolysis, cholestasis and renal dysfunction. Sequestration presents with significant rapid onset hepatomegaly, drop in hemoglobin with RUQ pain, which can ultimately lead to cardiac and pulmonary instability. Treatment is supportive with exchange transfusion, fresh plasma for coagulopathy.Figure 1.: Top: Contrast enhanced spiral CT of the chest, abdomen and pelvis showing markedly enlarged measuring 20 cm in craniocaudal dimension with lobulated contour and non visualized spleen Bottom: Liver biopsy showing dilated sinusoids with aggregates of sickled red blood cells. There is also presence of canalicular cholestasis.

A PHASE 2/3, RANDOMIZED, DOUBLE-BLIND, PLACEBO-CONTROLLED STUDY OF MITAPIVAT IN PATIENTS WITH SICKLE CELL DISEASE

The key pathology in sickle cell disease (SCD), a life-threatening, hereditary hemoglobin (Hb) disorder, is red blood cell (RBC) sickling due to polymerization of deoxygenated sickle Hb (HbS), which can be exacerbated by increased levels of the glycolytic metabolite 2,3-diphosphoglycerate (2,3-DPG) and decreased ATP. Sickled RBCs are rigid, non-deformable, and fragile, resulting in vaso-occlusive pain and chronic hemolysis. Current SCD treatment options are limited; therefore, there is an unmet need for safe, effective therapies that alleviate both anemia and pain. Activation of the key RBC glycolytic enzyme pyruvate kinase (PKR) by oral mitapivat decreases 2,3-DPG and increases ATP, which may reduce HbS polymerization, RBC sickling, and hemolysis in SCD. Data from the phase (ph) 1 National Institutes of Health multiple ascending dose study of up to 100 mg mitapivat twice daily (BID) in patients with SCD (NCT04000165) showed that mitapivat was safe and tolerable, increased ATP and decreased 2,3-DPG in a dose-dependent manner, and improved anemia and hemolysis. Here we report the study design of RISE UP (NCT05031780, EudraCT: 2021-001674-34), a ph 2/3, double-blind, randomized, placebo (PBO)-controlled, multicenter study evaluating the efficacy and safety of mitapivat in patients (pts) with SCD. Eligible: pts aged ≥16 yrs (≥18 yrs [France and Germany]) with documented SCD (HbSS, HbSC, HbSβ 0 /HbSβ + thalassemia, other variants), 2–10 sickle cell pain crises (SCPCs; acute pain requiring intervention, acute chest syndrome, priapism, hepatic or splenic sequestration) in the prior 12 months, and Hb 5.5–10.5 g/dL. If on hydroxyurea (HU), the dose must be stable for ≥ 90 days before starting study drug. Ineligible: pts receiving regular blood transfusions, with severe kidney or hepatobiliary disease, current SCD therapies except HU, or prior gene therapy, bone marrow or stem cell transplantation. In the double-blind ph 2 part, 69 pts will be randomized (1:1:1) to 50 mg or 100 mg mitapivat, or PBO BID for 12 weeks (wk). The primary objective is to determine the recommended ph 3 mitapivat dose by evaluating anemia and safety vs PBO via the following endpoints: Hb response (≥ 1.0 g/dL increase in average (avg) Hb concentration over Wk 10–12 vs baseline [BL]), and type, severity, and relationship of adverse events (AEs) and serious AEs. In the double-blind ph 3 part, 198 pts who did not participate in ph 2 will be randomized (2:1) to the selected ph 3 mitapivat dose or PBO BID for 52 wk. The primary objectives are to determine the effect of mitapivat vs PBO on anemia, measured by Hb response (≥ 1.0 g/dL increase in avg Hb concentration over Wk 24–52 vs BL), and the effect of mitapivat vs PBO on SCPC, measured by annualized rate of SCPCs. Key secondary endpoints: avg change from BL in Hb concentration, indirect bilirubin, percent reticulocyte, and Pt-Reported Outcomes Measurement Information System ® Fatigue 13a Short Form score over Wk 24–52; and annualized frequency of SCPC admissions. Pts who complete the double-blind period will be eligible to receive mitapivat in the open-label extension period in each ph. Pending. N/A. This ph 2/3 study will investigate the efficacy and safety of mitapivat in pts with SCD. Enrollment is currently ongoing.

P-096: ACUTE SICKLE CELL INTRAHEPATIC CHOLESTASIS: RARE DISEASE WITH UNUSUAL PRESENTATION, LESSONS LEARNT FROM AN INTERESTING CASE.

Purpose: Management of Sickle cell disease in India the is evolving. The pediatric fatal disease is shifting to adult chronic organ disease. Sickle hepatopathy is an umbrella term which covers hepatic sickle crisis, acute hepatic sequestration crisis although uncommon but manageable. Acute sickle cell intrahepatic cholestasis (SCIC) is a rare phenomenon, difficult to treat and has very high mortality. The pathogenesis of Acute sickle cell intrahepatic cholestasis involves sickling within the hepatic sinusoids leading to vascular stasis, hypoxia, and ballooning of the hepatocytes, resulting in intracanalicular cholestasis. We describe a difficult case of Acute sickle cell intrahepatic cholestasis which has a subacute course, challenges faced, and lessons learnt from managing it. Materials and methods: A 14-year-old girl with sickle cell anemia who was non-compliant with hydroxyurea treatment presented to us with complaints of pain in the right side of abdomen, drowsiness, lethargy, nausea and loss of appetite. She was transfused twice at another center before reaching our center. On examination, she was disoriented, febrile, icteric, severely pale with active bleeding from gums and mouth and moderate hepatosplenomegaly. Hemoglobin was 7.2 grams/ dl with reticulocyte count of 2%, with neutrophilic leukocytosis and normal platelet count. Hemoglobin S was 42%. Serum bilirubin was 68 mg/dl with direct fraction of 65.3mg/dl. SGPT and SGOT were 263 and 202 IU/dl respectively and prothrombin time was raised with INR of 1.79. Viral hepatitis A, B, C and E were ruled out. Bacterial infections were ruled out. The possibility of Acute sickle cell intrahepatic cholestasis was considered, and the child was managed with partial exchange transfusion till Hemoglobin S was brought to <10%. She also received fresh frozen plasma in view of raised prothrombin time and active bleeding. Results: She did not improve until 14 days after admission.Gradually after 20 days she started talking and eating. However, liver enzymes and bilirubin normalized only after 40 days. She was discharged in stable condition and is continued on follow up. Conclusion: Sickle cell hepatopathy is an umbrella diagnosis for all the varied causes of hepatic dysfunction ranging from sickling crisis to transfusion transmitted viral infections. In our case, viral hepatitis was ruled out conclusively.A very rare condition Acute sickle cell intrahepatic cholestasis was considered in view of the clinical presentation serum bilirubin was extremely high and mildly elevated transaminases. However. Hepatic sequestration was unlikely based on the hemoglobin level and reticulocyte count. Differentiating the varied causes in resource constrained centers can be often a daunting task and multipronged management needs to be initiated at the earliest to ensure a positive outcome. The authors do not declare any conflict of interest

PB2219: A REAL-WORLD EXPERIENCE WITH HEALTHCARE RESOURCE UTILIZATION PATTERNS AND RELATED COSTS IN PATIENTS WITH SICKLE CELL DISEASE IN NORTH LEBANON

Background: Sickle cell disease (SCD) remains associated with high healthcare resource utilization (HRU), despite a reduction in morbidity and mortality associated with the use of disease-modifying therapies, mostly because of vaso-occlusive crises (VOC). In Lebanon, there are limited national estimates on HRU, cost of medical care, and treatment expenditures for patients with SCD. A better understanding of these estimates may provide new perspectives to improve access to high-quality cost-effective health care services. Aims: Aim of our study is to evaluate patterns of HRU and related cost in a cohort of patients with SCD receiving care in a Comprehensive SCD referral center at NINI hospital in North Lebanon. Methods: An observational, non-interventional, retrospective study of 136 patients (54.4% females) with confirmed diagnosis of SCD was conducted in North Lebanon. Data on HRU, including ED visits, ambulatory visits, and hospitalizations, was collected in a patient health information (PHI)-anonymized format from patients’ paper and electronic medical files, as well as hospital and ED files, from May 1, 2018 to April 30, 2020. Uncomplicated VOCs were defined as pain crises, whereas complicated VOCs were defined as acute chest syndrome, acute splenic sequestration, acute hepatic sequestration or priapism. The annual rate of HRU visits was calculated as a ratio of the total number of visits to the total number of years of follow-up across all patients. Based on the available data, the average yearly cost was determined as the ratio of the total cost of these visits to the total number of years of follow-up. Results: The median age of patients in this study was 10.8 years (IQR 5.3 to 19.6 years) at the time of investigation. Majority of patients were diagnosed with SS (72.1%) and Sβ0 (21.3%) genotype across all age groups. The most prevalent SCD-related complications were pain crisis (90.4%), fever (43.4%), acute chest syndrome (33.1%), and acute splenic sequestration (22.8%). Most of hospitalizations, ICU visits, and ED visits in adult patients (age >16 years) were due to uncomplicated VOCs. The average annual costs of HRU were 8,270,920 Lebanese pounds (LBP) amounting to 5,514 USD (per patient per year) of which 92.1% was for hospitalizations, 4% for ED visits and 3.9% for ambulatory visits. Uncomplicated VOCs had the highest annual costs for ED, ICU and hospitalizations. Costs related to medications, diagnostics, non-hematologist medical consults, uncompensated care and lost productivity are not included in this analysis. Analgesics, folic acid and hydroxyurea were the most commonly prescribed drugs across all age categories, with hydroxyurea being prescribed to 84% of patients. Image:Summary/Conclusion: SCD and associated complications resulted in significant acute HRU, according to this real world study. VOCs continues to be most important factor for resource use, ICU admission and costs, with hospitalizations accounting for majority of annual costs. Despite the high HRU rate in this relatively young SCD cohort, the cost of HRU in a comprehensive setting with effective outpatient management as that in North Lebanon appears affordable for the health care system. However when additional SCD related and non SCD related costs of care are factored in, the economic burden of SCD care is likely to be far higher than the figures presented here.

Indium-labelled autologous platelet sequestration studies predict response to splenectomy in immune thrombocytopenia: an Australian experience.

Splenectomy is an effective intervention in primary immune thrombocytopenia (ITP). Attempts to define pre-clinical predictors of platelet response to splenectomy are inconsistent. Based on international studies defining the likelihood of platelet response using platelet sequestration, patients with relapsed/refractory ITP being considered for splenectomy at a regional Australian hospital were assessed with 111 indium-labelled autologous platelet sequestration (ILAPS) studies. To audit the use of ILAPS in an Australian setting and define its role in predicting response to splenectomy. A retrospective review of all patients referred for an ILAPS study at a regional hospital was performed. Results for each patient were expressed as an 'R' value (spleen/ liver uptake ratio) to quantify the platelet sequestration pattern and outcome post-splenectomy, based on platelet counts. A total of 45 patients was identified: 13 underwent splenectomy and 32 were medically managed. Patients with favourable ILAPS scans (pure or predominant splenic sequestration) demonstrated a superior response post-splenectomy (100% overall response rate (ORR); 83.5% complete remission (CR)) compared with those with unfavourable ILAPS scans (mixed or pure hepatic sequestration) (71.4% ORR; 57.1% CR) over 12 months. The use of ILAPS in the Australian setting is feasible and this experience confirms larger international studies demonstrating its utility as a predictor of response to splenectomy in ITP. An unfavourable ILAPS scan could be considered a negative predictor of response prompting consideration for other emerging ITP treatments such as thrombopoietin-receptor agonists or B-cell depleting therapy such as Rituximab.

Development of a low-seroprevalence, αvβ6 integrin-selective virotherapy based on human adenovirus type 10

Oncolytic virotherapies (OV) hold immense clinical potential. OV based on human adenoviruses (HAdV) derived from HAdV with naturally low rates of pre-existing immunity will be beneficial for future clinical translation. We generated a low-seroprevalence HAdV-D10 serotype vector incorporating an αvβ6 integrin-selective peptide, A20, to target αvβ6-positive tumor cell types. HAdV-D10 has limited natural tropism. Structural and biological studies of HAdV-D10 knob protein highlighted low-affinity engagement with native adenoviral receptors CAR and sialic acid. HAdV-D10 fails to engage blood coagulation factor X, potentially eliminating “off-target” hepatic sequestration in vivo. We engineered an A20 peptide that selectively binds αvβ6 integrin into the DG loop of HAdV-D10 fiber knob. Assays in αvβ6+ cancer cell lines demonstrated significantly increased transduction mediated by αvβ6-targeted variants compared with controls, confirmed microscopically. HAdV-D10.A20 resisted neutralization by neutralizing HAdV-C5 sera. Systemic delivery of HAdV-D10.A20 resulted in significantly increased GFP expression in BT20 tumors. Replication-competent HAdV-D10.A20 demonstrated αvβ6 integrin-selective cell killing in vitro and in vivo. HAdV-D10 possesses characteristics of a promising virotherapy, combining low seroprevalence, weak receptor interactions, and reduced off-target uptake. Incorporation of an αvβ6 integrin-selective peptide resulted in HAdV-D10.A20, with significant potential for clinical translation.

P107: A PHASE 2/3, RANDOMIZED, DOUBLE-BLIND, PLACEBO-CONTROLLED STUDY OF MITAPIVAT IN PATIENTS WITH SICKLE CELL DISEASE

Background: The key pathology in sickle cell disease (SCD), a life-threatening, hereditary hemoglobin (Hb) disorder, is red blood cell (RBC) sickling due to polymerization of deoxygenated sickle Hb (HbS), which can be exacerbated by increased levels of the glycolytic metabolite 2,3-diphosphoglycerate (2,3-DPG), and decreased ATP.1–3 Sickled RBCs are rigid, not deformable, and fragile, resulting in vaso-occlusion triggering pain and chronic hemolysis.4–6 SCD treatment options are limited, with an unmet need for safe and effective therapies to improve anemia and reduce pain. Mitapivat is an oral, activator of RBC pyruvate kinase (PKR), a key glycolytic enzyme. PKR activation decreases 2,3-DPG and increases ATP, which may reduce HbS polymerization, RBC sickling, and hemolysis in SCD.3,7–9 Data from the phase (ph) 1 National Institutes of Health multiple ascending dose study of up to 100 mg mitapivat twice daily (BID) in SCD (NCT04000165) showed that mitapivat was safe and tolerable, increased ATP and decreased 2,3-DPG in a dose-dependent manner, and improved anemia and hemolysis.8,10 Aims: To report the study design of RISE UP (NCT05031780, EudraCT: 2021-001674-34), a ph 2/3, double-blind, randomized, placebo-controlled, multicenter study evaluating the efficacy and safety of mitapivat in patients (pts) with SCD. Methods: Eligible: pts aged ≥16 yrs with documented SCD (HbSS, HbSC, HbSβ0/HbSβ+ thalassemia, other SCD variants), 2–10 sickle cell pain crises (SCPCs; acute pain needing medical contact, acute chest syndrome, priapism, hepatic or splenic sequestration) in the prior 12 months, and Hb 5.5–10.5 g/dL. If taking hydroxyurea (HU), the dose must be stable for ≥90 days before starting study drug. Ineligible: pts receiving regularly scheduled blood transfusions, with severe kidney disease or hepatobiliary disorders, currently receiving SCD therapies (excluding HU) or who have received gene therapy, bone marrow or stem cell transplantation. In the double-blind ph 2 part, 69 pts will be randomized (1:1:1) to 50 mg or 100 mg mitapivat, or placebo BID for 12 weeks (wks). The primary objective of ph 2 is to determine the recommended ph 3 mitapivat dose by evaluating anemia and safety vs placebo via the following endpoints: Hb response (≥1.0 g/dL increase in average Hb concentration over Wks 10–12 vs baseline [BL]), and type, severity, and relationship of adverse events and serious AEs. In the double-blind ph 3 part, 198 pts who did not participate in ph 2 will be randomized (2:1) to the selected ph 3 mitapivat dose or placebo BID for 52 wks, stratified by number of SCPCs in the prior yr (<5, ≥5) and HU use. The primary objectives of ph 3 are to determine the effect of mitapivat vs placebo on anemia, measured by Hb response (≥1.0 g/dL increase in average Hb concentration over Wks 24–52 vs BL), and the effect of mitapivat vs placebo on SCPC, measured by annualized rate of SCPCs. Key secondary endpoints include average change from BL in Hb concentration, indirect bilirubin, percent reticulocyte, and Pt-Reported Outcomes Measurement Information System® Fatigue 13a Short Form score over Wks 24–52; and annualized frequency of hospitalizations for SCPC. Pts who complete the double-blind period will be eligible to receive mitapivat in the open-label extension period in each ph. Results: Not yet available. Conclusion: This ph 2/3 study will investigate the efficacy and safety of mitapivat in pts aged ≥16 yrs with SCD. Enrollment is currently ongoing.

P127: HEALTHCARE RESOURCE UTILIZATION PATTERNS AND RELATED COSTS IN PATIENTS WITH SICKLE CELL DISEASE IN NORTH LEBANON- A REAL-WORLD EXPERIENCE

Background: Despite a reduction in morbidity and mortality associated with the use of disease modifying therapies, sickle cell disease (SCD) remains associated with high healthcare resource utilization (HRU), primarily attributed to vaso-occlusive crisis (VOC). (1, 2) There are limited national estimates on HRU, cost of medical care, and treatment expenditures for patients with SCD in Lebanon. A better understanding of these estimates may provide new perspectives to improve access to high-quality cost-effective health care services. Aims: We aimed to evaluate patterns of HRU and related cost in a cohort of patients with SCD receiving care in a Comprehensive SCD referral center at NINI hospital in North Lebanon. Methods: A retrospective non-interventional observational study was conducted among 136 patients (54.4% females) with confirmed diagnosis of SCD in North Lebanon. Data on HRU including emergency department (ED) visits, ambulatory visits and hospitalizations collected in a patient health information (PHI)-anonymized format during the period 01 May2018 - 30 Apr 2020 were obtained from patients’ paper and electronic medical files, as well as hospital and ED files. Uncomplicated VOCs were defined as pain crises, whereas complicated VOCs were defined as acute chest syndrome, acute splenic sequestration, acute hepatic sequestration or priapism. The annual rate of HRU visits was calculated as a ratio of the total number of visits to the total number of years of follow-up across all patients. The average annual cost was similarly calculated as the ratio of total cost of these visits to the total number of years of follow-up, based on available data. Results: In the present study, the median age of patients at the time of study was 10.8 years (IQR 5.3 to 19.6 years). Majority of patients were diagnosed with SS (72.1%) and Sβ0 (21.3%) genotype across all age groups. Pain crisis (90.4%), fever (43.4%), acute chest syndrome (33.1%), and acute splenic sequestration (22.8%) were the most common SCD-related complications. The annual rate of HRU visits (per patient) was 5.7. Uncomplicated VOCs led to majority of hospitalizations, ICU and ED visits in adult patients (age >16 years). The average annual costs of HRU were 8,270,920 Lebanese pounds (LBP) amounting to 5,514 USD (per patient per year) of which 92.1% was for hospitalizations, 4% for ED visits and 3.9% for ambulatory visits. Annual costs for ED, ICU and hospitalizations were highest for uncomplicated VOC. Costs related to medications, diagnostics, non-hematologist medical consults, uncompensated care and lost productivity are not included in this analysis. Analgesics, folic acid and hydroxyurea were the most frequently administered medications across all age groups with 84% of patients being treated with hydroxyurea. Conclusion: This real world study reveals that SCD and its related complications resulted in significant acute HRU. VOCs remain the primary factor for resource use, ICU admission and costs with the largest proportion of annual cost being attributed to hospitalizations. Despite the high HRU rate in this relatively young SCD cohort, the cost of HRU in a comprehensive setting with effective outpatient management as that in North Lebanon appears affordable for the health care system. However when additional SCD related and non SCD related costs of care are included, the economic burden of SCD care is likely to be significantly higher than the figures reported.