ABSTRACT
To balance the risk of bleeding versus circuit thrombosis during extracorporeal life support (ECLS), it is important to monitor anticoagulants and hemostasis. We evaluated the prothrombin time (PT), partial thromboplastin time (PTT), activated clotting time (ACT), and antifactor Xa heparin activity (aXa) correlation with changes in coagulation factor and heparin levels using in vitro and in vivo samples. aXa correlated with heparin (r = 0.97) and antithrombin (r = 0.98) but was unaffected by other parameters. PT correlated with coagulation factors (r = 0.88) but was minimally affected by heparin or other parameters. When single parameters were changed, ACT was insensitive to <0.5 U/ml heparin, correlated with coagulation factors (r = 0.99), and was affected by factor XII and platelets. When multiple parameters changed in vitro and in vivo, ACT was not correlated with heparin or coagulation factors. PTT correlated with heparin and coagulation factors individually but had low correlation when multiple parameters changed in vitro and in vivo. In conclusion, aXa is the most specific for heparin levels, and PT is most specific for coagulation factor levels making these assays well suited to monitor anticoagulation and hemostasis for patients on ECLS. PTT is highly variable when multiple parameters are changing in vitro and in vivo, but may be useful when aXa cannot be used because of interference. ACT is too insensitive to heparin, sensitive to too many other factors, and too imprecise to be useful for monitoring hemostasis during ECLS.
Subject(s)
Blood Coagulation Tests , Extracorporeal Membrane Oxygenation/adverse effects , Thrombosis , Anticoagulants/therapeutic use , Antithrombins/therapeutic use , Blood Coagulation/drug effects , Female , Hemorrhage/etiology , Hemorrhage/prevention & control , Hemostasis , Humans , Male , Thrombosis/etiology , Thrombosis/prevention & controlABSTRACT
OBJECTIVE: This study had 2 objectives. First, to determine the behavior of physicians evaluating premobile infants with bruises. Second, and most importantly, to learn whether infants with unexplained bruising who had been initially evaluated by primary care and emergency department (ED) physicians are as likely to have their bruises attributed to child abuse as those children evaluated by child abuse physicians. METHODS: Primary care, ED, and child abuse pediatricians (CAPs) in King County, Washington, San Mateo, Calif, Albuquerque, NM, La Crosse, Wis, and Torrance, Calif prospectively identified and studied infants younger than 6 months with less than 6 bruises, which were judged by the evaluating clinician to be explained or unexplained after their initial clinical examination. RESULTS: Between March 1, 2010, and March 1, 2017, 63 infants with initially explained and 46 infants with initially unexplained bruises were identified. Infants with unexplained bruises had complete coagulation and abuse evaluations less frequently if they were initially identified by primary care pediatricians or ED providers than by CAPs. After imaging, laboratory, and follow-up, 54.2% (26) of the infants with initially unexplained bruises, including 2 who had been initially diagnosed with accidental injuries, were diagnosed as abused. Three (6.2%) infants had accidental bruising, 6 (12.4%) abuse mimics, 1 (2.5%) self-injury, 1 (2.5%) medical injury, and 11 (22.9%) remained of unknown causation. None had causal coagulation disorders. A total of 65.4% of the 26 abused infants had occult injuries detected by their imaging and laboratory evaluations. Six (23.1%) abused infants were not diagnosed until after they sustained subsequent injuries. Three (11.5%) were recognized abused by police investigation alone. Thirty-eight percent of the abused, bruised infants had a single bruise. Clinicians' estimates of abuse likelihood based on their initial clinical evaluation were inaccurate. Primary care, ED, and child abuse physicians identified abused infants at similar rates. CONCLUSIONS: More than half of premobile infants with initially unexplained bruises were found to be abused. Abuse was as likely for infants identified by primary care and ED providers as for those identified by CAPs. Currently, physicians often do not obtain full abuse evaluations in premobile infants with unexplained bruising. Their initial clinical judgment about abuse likelihood was inadequate. Bruised infants often have clinically occult abusive injuries or will sustain subsequent serious abuse. Bruised infants should have full abuse evaluations and referral for Protective Services and police assessments.
Subject(s)
Child Abuse/diagnosis , Contusions/diagnosis , Contusions/etiology , Physical Examination , Child Abuse/statistics & numerical data , Contusions/epidemiology , Emergency Service, Hospital , Health Personnel/psychology , Humans , Infant , Infant, Newborn , Likelihood Functions , Movement , Primary Health Care , Prospective Studies , United StatesABSTRACT
Despite the use of evidence-based platelet transfusion therapy during periods of hypoproliferative thrombocytopenia, a large proportion of pediatric hematology/oncology patients continue to suffer from clinically significant bleeding. Antifibrinolytic (AF) drugs have been shown in certain surgical and trauma settings to decrease bleeding, blood transfusion, and improve survival. We conducted a retrospective assessment of the safety of using AF drugs in pediatric patients with hypoproliferative thrombocytopenia at our center as well as the impact on bleeding occurrence and severity.
Subject(s)
Antifibrinolytic Agents/therapeutic use , Thrombocytopenia/drug therapy , Adolescent , Child , Child, Preschool , Humans , Retrospective Studies , Treatment OutcomeABSTRACT
Factor VIII (FVIII)-neutralizing antibodies ("inhibitors") are a serious problem in hemophilia A (HA). The aim of this study was to characterize HLA-restricted T-cell responses from a severe HA subject with a persistent inhibitor and from 2 previously studied mild HA inhibitor subjects. Major histocompatibility complex II tetramers corresponding to both of the severe HA subject's HLA-DRA-DRB1 alleles were loaded with peptides spanning FVIII-A2, C1, and C2 domains. Interestingly, only 1 epitope was identified, in peptide FVIII2194-2213, and it was identical to the HLA-DRA*01-DRB1*01:01-restricted epitope recognized by the mild HA subjects. Multiple T-cell clones and polyclonal lines having different avidities for the peptide-loaded tetramer were isolated from all subjects. Only high- and medium-avidity T cells proliferated and secreted cytokines when stimulated with FVIII2194-2213 T-cell receptor ß (TCRB) gene sequencing of 15 T-cell clones from the severe HA subject revealed that all high-avidity clones expressed the same TCRB gene. High-throughput immunosequencing of high-, medium-, and low-avidity cells sorted from a severe HA polyclonal line revealed that 94% of the high-avidity cells expressed the same TCRB gene as the high-avidity clones. TCRB sequencing of clones and lines from the mild HA subjects also identified a limited TCRB gene repertoire. These results suggest a limited number of epitopes in FVIII drive inhibitor responses and that the T-cell repertoires of FVIII-responsive T cells can be quite narrow. The limited diversity of both epitopes and TCRB gene usage suggests that targeting of specific epitopes and/or T-cell clones may be a promising approach to achieve tolerance to FVIII.
Subject(s)
Epitopes, T-Lymphocyte , Factor VIII , Hemophilia A , Receptors, Antigen, T-Cell, alpha-beta , T-Lymphocytes/immunology , Adolescent , Autoantibodies/genetics , Autoantibodies/immunology , Blood Coagulation Factor Inhibitors/genetics , Blood Coagulation Factor Inhibitors/immunology , Child , Child, Preschool , Epitopes, T-Lymphocyte/genetics , Epitopes, T-Lymphocyte/immunology , Factor VIII/genetics , Factor VIII/immunology , HLA Antigens/genetics , HLA Antigens/immunology , Hemophilia A/genetics , Hemophilia A/immunology , Humans , Male , Receptors, Antigen, T-Cell, alpha-beta/genetics , Receptors, Antigen, T-Cell, alpha-beta/immunologyABSTRACT
BACKGROUND: The oral thrombopoietin receptor agonist eltrombopag is approved for treatment of adults with chronic immune thrombocytopenia. In the PETIT trial, we aimed to investigate the efficacy and safety of eltrombopag in children with persistent or chronic immune thrombocytopenia. METHODS: PETIT was a three-part, randomised, multicentre, placebo-controlled study done at 22 centres in the USA, UK, Canada, Spain, France, and the Netherlands. Patients aged 1-17 years with immune thrombocytopenia lasting for 6 months or longer and platelets less than 30 × 10(9) per L who had received at least one previous treatment were enrolled. We enrolled patients into three cohorts consisting of patients aged 12-17, 6-11, and 1-5 years. We established patients' starting doses with an open-label, dose-finding phase with five patients in each cohort. During the dose-finding phase, patients aged 6-17 years started eltrombopag at 25 mg once per day (12·5 mg for those weighing <27 kg) and patients aged 1-5 years received 0·7 mg/kg per day to a maximum of 2 mg/kg unless otherwise approved. We permitted dose adjustments on the basis of platelet response up to a maximum dosage of 75 mg per day. Additional patients were then recruited and randomly assigned (2:1) to receive either eltrombopag or placebo tablets (or oral suspension formulation if aged 1-5 years) once per day for 7 weeks at the previously established doses. Starting doses for the double-blind phase were 37·5 mg/day for patients aged 12-17 years; 50 mg/day for patients weighing 27 kg or more (25 mg for east Asian patients) and 25 mg/day for patients weighing less than 27 kg (12·5 mg once per day for east Asian patients) for patients aged 6-11 years; and 1·5 mg/kg once per day (0·8 mg/kg once per day for east Asian patients) for patients aged 1-5 years. Randomisation was done by the GlaxoSmithKline Registration/Medication Ordering System and both patients and study personnel were masked to treatment assignments. Patients who completed treatment were then enrolled into an open-label phase and all patients could receive up to 24 weeks of eltrombopag. The primary outcome was the proportion of patients achieving a platelet count of 50 × 10(9) per L or more at least once from weeks 1-6 (days 8 to 43) of the randomised phase of the study in the absence of rescue therapy. We assessed efficacy in the intent-to-treat population, which consisted of all patients assigned to treatment, and we assessed safety in all patients who received at least one dose of study treatment. This trial is registered with ClinicalTrials.gov, number NCT00908037. FINDINGS: Between Oct 2, 2009, and June 22, 2011, we recruited 15 patients, with five patients in each age cohort, into the open-label dose-finding phase who did not progress into the double-blind phase. From March 17, 2010, to Jan 15, 2013, we randomly assigned 67 patients to treatment, with 45 patients assigned to receive eltrombopag (16 children aged 12-17 years, 19 aged 6-11 years, and ten aged 1-5 years) and 22 to receive placebo (eight children aged 12-17 years, nine aged 6-11 years, and five aged 1-5 years). However, two patients assigned to receive eltrombopag did not receive the study drug and one was lost to follow-up, and one patient assigned to receive placebo was given eltrombopag. From weeks 1 to 6, 28 (62%) patients who received eltrombopag, compared with seven (32%) who received placebo, achieved the primary endpoint of platelet count 50 × 10(9) per L or more at least once without rescue (odds ratio 4·31, 95% CI 1·39-13·34, p=0·011). The most common adverse events with eltrombopag were headache (13 [30%] patients receiving eltrombopag vs nine [43%] patients receiving placebo), upper respiratory tract infection (11 [25%] patients vs two [10%] patients), and diarrhoea (seven [16%] patients vs one [5%] patient). Grade 3 or 4 adverse events occurred in five (11%) patients receiving eltrombopag and four (19%) patients receiving placebo, and serious adverse events (four [9%] patients receiving eltrombopag and two (10%) patients receiving placebo) were similarly infrequent in both groups. No thrombotic events or malignancies occurred. Increased alanine aminotransferase concentrations caused two (3%) of 65 patients to discontinue eltrombopag in the open-label phase. INTERPRETATION: Our results showed that eltrombopag could be used to increase platelet counts and reduce clinically significant bleeding in children with persistent or chronic immune thrombocytopenia. Prevalence of increased liver laboratory values was similar to that seen in adults. FUNDING: GlaxoSmithKline.
Subject(s)
Benzoates/therapeutic use , Hydrazines/therapeutic use , Purpura, Thrombocytopenic, Idiopathic/drug therapy , Pyrazoles/therapeutic use , Receptors, Thrombopoietin/agonists , Adolescent , Canada , Child , Child, Preschool , Double-Blind Method , Female , France , Humans , Infant , Male , Netherlands , Platelet Count , Spain , Treatment Outcome , United Kingdom , United StatesABSTRACT
Hemolytic disease of the fetus and newborn (HDFN) affects 3/100 000 to 80/100 000 patients per year. It is due to maternal blood group antibodies that cause fetal red cell destruction and in some cases, marrow suppression. This process leads to fetal anemia, and in severe cases can progress to edema, ascites, heart failure, and death. Infants affected with HDFN can have hyperbilirubinemia in the acute phase and hyporegenerative anemia for weeks to months after birth. The diagnosis and management of pregnant women with HDFN is based on laboratory and radiographic monitoring. Fetuses with marked anemia may require intervention with intrauterine transfusion. HDFN due to RhD can be prevented by RhIg administration. Prevention for other causal blood group specificities is less studied.
Subject(s)
Erythroblastosis, Fetal/pathology , Anemia/complications , Blood Group Antigens , Blood Transfusion, Intrauterine , Erythroblastosis, Fetal/diagnosis , Erythroblastosis, Fetal/therapy , Erythrocytes/cytology , Female , Fetus/physiology , Humans , Hyperbilirubinemia/complications , Infant, Newborn , Isoantibodies/blood , Mothers , Practice Guidelines as Topic , Pregnancy , Rh-Hr Blood-Group SystemABSTRACT
African American hemophilia A (HA) patients experience a higher incidence of neutralizing anti-factor VIII (FVIII) antibodies ("inhibitors") vis-à-vis white patients. Nonsynonymous single-nucleotide polymorphisms (ns-SNPs) in the F8 gene encoding FVIII-H484, FVIII-E1241, and FVIII-V2238 are more prevalent in African Americans. This study tested the hypothesis that immune responses to these sites provoke inhibitors. Blood samples were obtained from 174 African American and 198 white HA subjects and their F8 gene sequences determined. Major histocompatibility complex class II binding and T-cell recognition of polymorphic sequences were evaluated using quantitative binding assays and HLA-DRB1 tetramers. Peptides corresponding to 4 common ns-SNPs showed limited binding to 11 HLA-DRB1 proteins. CD4 T cells from 22 subjects treated with FVIII products having sequences at residues FVIII-484, 1241, and 2238 differing from those of putative proteins encoded by their F8 genes did not show high-avidity tetramer binding, whereas positive-control staining of tetanus-specific CD4 T cells was routinely successful. African Americans with an intron-22 inversion mutation showed a 2-3 times-higher inhibitor incidence than whites with the same mutation (odds ratio = 2.3 [1.1-5.0, P = .04]), but this did not correlate with any of the ns-SNPs. We conclude that immune responses to "sequence-mismatched" FVIII products are unlikely to contribute appreciably to the inhibitor incidence in African Americans.
Subject(s)
Antibodies, Neutralizing/blood , Black or African American/genetics , Factor VIII/antagonists & inhibitors , Factor VIII/genetics , Hemophilia A/genetics , Hemophilia A/immunology , Adolescent , Adult , Amino Acid Sequence , Autoantibodies/blood , CD4-Positive T-Lymphocytes/immunology , Child , Child, Preschool , Epitope Mapping , Factor VIII/immunology , Genetic Variation , HLA-DRB1 Chains/metabolism , Haplotypes/genetics , Haplotypes/immunology , Hemophilia A/blood , Humans , Male , Molecular Sequence Data , Mutant Proteins/antagonists & inhibitors , Mutant Proteins/genetics , Mutant Proteins/immunology , Peptide Fragments/blood , Peptide Fragments/genetics , Polymorphism, Single Nucleotide , Protein Binding , Risk Factors , White People/genetics , Young AdultABSTRACT
OBJECTIVE: To investigate whether receipt of any antithrombin concentrate improves laboratory and clinical outcomes in children undergoing extracorporeal membrane oxygenation for respiratory failure during their hospitalization compared with those who did not receive antithrombin. DESIGN: Retrospective cohort study. SETTING: Single, tertiary-care pediatric hospital. PATIENTS: Sixty-four neonatal and pediatric patients who underwent extracorporeal membrane oxygenation for respiratory failure between January 2007 and September 2011. INTERVENTION: Exposure to any antithrombin concentrate during their extracorporeal membrane oxygenation course compared with similar children who never received antithrombin concentrate. MEASUREMENTS AND MAIN RESULTS: Thirty patients received at least one dose of antithrombin during their extracorporeal membrane oxygenation course and 34 patients did not receive any. The median age at admission was less than 1-month old. Age, duration of extracorporeal membrane oxygenation, or first antithrombin level did not differ significantly between the two cohorts. The mean plasma antithrombin level in those who never received antithrombin was 42.2% compared with 66% in those who received it. However, few levels reached the targeted antithrombin level of 120% and those who did fell back to deficient levels within an average of 6.8 hours. For those who received antithrombin concentrate, heparin infusion rates decreased by an average of 10.2 U/kg/hr for at least 12 hours following administration. No statistical differences were noted in the number of extracorporeal membrane oxygenation circuit changes, in vivo clots or hemorrhages, transfusion requirements, hospital or ICU length of stay, or in-hospital mortality. CONCLUSIONS: Intermittent, on-demand dosing of antithrombin concentrate in pediatric patients on extracorporeal membrane oxygenation for respiratory failure increased antithrombin levels, but not typically to the targeted level. Patients who received antithrombin concentrate also had decreased heparin requirements for at least 12 hours after dosing. However, no differences were noted in the measured clinical endpoints. A prospective, randomized study of this intervention may require different dosing strategies; such a study is warranted given the unproven efficacy of this costly product.
Subject(s)
Antithrombins/blood , Antithrombins/therapeutic use , Extracorporeal Membrane Oxygenation/adverse effects , Extracorporeal Membrane Oxygenation/methods , Respiratory Insufficiency/therapy , Adolescent , Anticoagulants/therapeutic use , Antithrombins/administration & dosage , Blood Transfusion/statistics & numerical data , Child , Child, Preschool , Female , Hemorrhage/chemically induced , Heparin/administration & dosage , Hospital Mortality , Humans , Infant , Infant, Newborn , Intensive Care Units, Pediatric , Length of Stay/statistics & numerical data , Male , Respiratory Insufficiency/blood , Respiratory Insufficiency/mortality , Respiratory Insufficiency/physiopathology , Retrospective Studies , Treatment Outcome , Young AdultABSTRACT
Inherited platelet function disorders are of variable severity and unknown frequency and may be difficult to diagnose. Nevertheless, they are increasingly recognized as an important cause of bleeding in pediatrics, particularly in adolescent girls with menorrhagia, where they may be more common than von Willebrand disease. This article reviews the presentation of these disorders, summarizes the most common types of platelet function disorders, discusses the challenges in diagnostic testing, and details treatment and supportive care options.
Subject(s)
Blood Platelet Disorders/genetics , Hemostasis/physiology , Adolescent , Blood Platelet Disorders/complications , Blood Platelet Disorders/diagnosis , Blood Platelet Disorders/drug therapy , Blood Platelets/pathology , Child , Child, Preschool , Diagnosis, Differential , Female , Hemorrhage/diagnosis , Hemorrhage/drug therapy , Hemorrhage/etiology , Hemostasis/drug effects , Humans , Platelet Function TestsABSTRACT
We describe a newborn female with a de novo interstitial deletion of chromosome 21q21.1-22.12 including the RUNX1 gene who had developmental delay, multiple congenital anomalies, tetralogy of Fallot, anemia, and chronic thromobocytopenia requiring frequent platelet transfusions from birth. Because of her physical and hematologic abnormalities, she was tested for Fanconi anemia (FA). Lymphocytes and fibroblasts from this patient demonstrated increased chromosome breakage with exposure to the clastogen mitomycin C, but not, in contrast to most FA patients, to diepoxybutane. Further testing by Western analysis and complementation testing did not show a defect in the function of known Fanconi proteins. Her constitutional deletion was later found to span 13.2 Mb by chromosome microarray analysis, encompassing the RUNX1 gene that has been implicated in thrombocytopenia and predisposition to acute myelogenous leukemia (AML) when in the haploinsufficient state. We compare her phenotype to other individuals with similar 21q deletions and thrombocytopenia, as well as those with FA. We suggest that deletion of RUNX1 or another critical gene within the deleted region may result in chromosomal instability similar to that seen in FA.
Subject(s)
Chromosome Deletion , Chromosomes, Human, Pair 21/genetics , Core Binding Factor Alpha 2 Subunit/genetics , Fanconi Anemia/genetics , Chromosome Breakage/drug effects , Fanconi Anemia/diagnosis , Fatal Outcome , Female , Humans , Infant , Infant, Newborn , Karyotyping , Mutagens/pharmacology , PhenotypeABSTRACT
GT, a rare disorder of platelet function, can lead to life-threatening bleeding, particularly following the development of antiplatelet antibodies. Curative therapy includes HCT but previous reports are limited predominantly to matched siblings and have excluded CBT. Delayed or non-engraftment of platelets because of antiplatelet antibodies might be particularly concerning after CBT for GT. Here, we report two successful unrelated cord blood transplants for GT. Recurrent life-threatening bleeding was the primary indication for HCT, with one patient developing antiplatelet antibodies pre-HCT. Bleeding risks associated with delivery of the conditioning regimen and the toxicity that follows should be carefully considered, including tunneled central venous line catheter placement, inclusion of B cell-specific therapy to potentially decrease antiplatelet antibody production, and targeted busulfan dosing. This is the first report of successful unrelated cord blood HCT for GT and indicates that modifications to supportive care can improve the safety of this potentially curative therapy for patients with severe, life-threatening disease manifestations.
Subject(s)
Fetal Blood/cytology , Hematopoietic Stem Cell Transplantation/methods , Thrombasthenia/therapy , Blood Platelet Disorders/therapy , Blood Platelets/cytology , Catheterization, Central Venous , Catheters , Child , Child, Preschool , Hemorrhage/prevention & control , Humans , Male , Platelet Glycoprotein GPIIb-IIIa Complex/immunology , Treatment OutcomeABSTRACT
We conducted a study to estimate the maximum tolerated dose (MTD) of (131)I-anti-CD45 antibody (Ab; BC8) that can be combined with a standard reduced-intensity conditioning regimen before allogeneic hematopoietic cell transplantation. Fifty-eight patients older than 50 years with advanced acute myeloid leukemia (AML) or high-risk myelodysplastic syndrome (MDS) were treated with (131)I-BC8 Ab and fludarabine plus 2 Gy total body irradiation. Eighty-six percent of patients had AML or MDS with greater than 5% marrow blasts at the time of transplantation. Treatment produced a complete remission in all patients, and all had 100% donor-derived CD3(+) and CD33(+) cells in the blood by day 28 after the transplantation. The MTD of (131)I-BC8 Ab delivered to liver was estimated to be 24 Gy. Seven patients (12%) died of nonrelapse causes by day 100. The estimated probability of recurrent malignancy at 1 year is 40%, and the 1-year survival estimate is 41%. These results show that CD45-targeted radiotherapy can be safely combined with a reduced-intensity conditioning regimen to yield encouraging overall survival for older, high-risk patients with AML or MDS. This study was registered at www.clinicaltrials.gov as #NCT00008177.
Subject(s)
Hematopoietic Stem Cell Transplantation/methods , Leukemia, Myeloid/therapy , Myelodysplastic Syndromes/therapy , Transplantation Conditioning/methods , Acute Disease , Aged , Antibodies/administration & dosage , Antibodies/immunology , Combined Modality Therapy , Female , Humans , Iodine Radioisotopes/pharmacokinetics , Leukemia, Myeloid/mortality , Leukemia, Myeloid/pathology , Leukocyte Common Antigens/immunology , Male , Middle Aged , Myelodysplastic Syndromes/mortality , Myelodysplastic Syndromes/pathology , Risk Factors , Survival Analysis , Survival Rate , Tissue Distribution , Transplantation, Homologous , Treatment Outcome , Vidarabine/administration & dosage , Vidarabine/analogs & derivatives , Whole-Body IrradiationABSTRACT
Radioimmunotherapy (RIT) for treatment of hematologic malignancies frequently fails because of disease recurrence. We therefore conducted pretargeted (P)RIT studies to augment the efficacy in mice of therapy using a pretargeted anti-human (h)CD45 antibody (Ab)-streptavidin (SA) conjugate followed by a biotinylated clearing agent and radiolabeled 1,4,7,10-tetraazacylodode cane N,N',N",N'''-tetraacetic (DOTA)-biotin. Tumor-to-blood ratios at 24 hours were 20:1 using pretargeted anti-hCD45 RIT and <1:1 with conventional RIT. In vivo imaging studies confirmed that the PRIT approach provided high-contrast tumor images with minimal blood-pool activity, whereas directly labeled anti-hCD45 Ab produced distinct tumor images but the blood pool retained a large amount of labeled Ab for a prolonged time. Therapy experiments showed that (90)Y-DOTA-biotin significantly prolonged survival of mice treated with pretargeted anti-hCD45 Ab-SA compared with mice treated with conventional RIT using (90)Y-labeled anti-hCD45 Ab at 200 muCi. Because human CD45 antigens are confined to xenograft tumor cells in this model, and all murine tissues are devoid of hCD45 and will not bind anti-hCD45 Ab, we also compared one-step and PRIT using an anti-murine (m)CD45 Ab where the target antigen is present on normal hematopoietic tissues. After 24 h, 27.3% +/- 2.8% of the injected dose of activity was delivered per gram (% ID/g) of lymph node using (131)I-A20-Ab compared with 40.0 +/- 5.4% ID/g for pretargeted (111)In-DOTA-biotin. These data suggest that pretargeted methods for delivering RIT may be superior to conventional RIT when targeting CD45 for the treatment of leukemia and may allow for the intensification of therapy, while minimizing toxicities.
Subject(s)
Antibodies, Monoclonal/administration & dosage , Immunotoxins/administration & dosage , Leukemia, Myeloid/radiotherapy , Leukocyte Common Antigens/immunology , Radioimmunotherapy/methods , Yttrium Radioisotopes/administration & dosage , Animals , Antibodies, Monoclonal/immunology , Antibodies, Monoclonal/pharmacokinetics , Biotin/administration & dosage , Biotin/analogs & derivatives , Biotin/pharmacokinetics , Female , Humans , Immunotoxins/immunology , Immunotoxins/pharmacokinetics , Indium Radioisotopes/administration & dosage , Indium Radioisotopes/pharmacokinetics , Leukemia, Myeloid/immunology , Leukemia, Myeloid/metabolism , Lymphoid Tissue/immunology , Lymphoid Tissue/metabolism , Male , Mice , Mice, Inbred BALB C , Organometallic Compounds/administration & dosage , Organometallic Compounds/pharmacokinetics , Tissue Distribution , Xenograft Model Antitumor Assays , Yttrium Radioisotopes/pharmacokineticsABSTRACT
The authors report a case of a 16-year-old girl who presented with a 1-week history of progressive low-back pain, buttock paresthesias, and bilateral lower extremity pain and weakness. Magnetic resonance (MR) imaging and MR venography studies of her lumbar spine revealed engorgement of the epidural venous plexus and mild compression of the cauda equina. A lower extremity and pelvic venogram revealed occlusive thrombosis of the femoral and iliac veins as well as of the inferior vena cava (IVC). The patient required an IVC thrombectomy due to progressive symptoms, after which she improved and returned to baseline status in 1 week. Imaging studies afterwards showed resolution of the venous engorgement and decompression of the cauda equina. This is the second published report of an association between IVC thrombosis and cauda equina syndrome.
Subject(s)
Polyradiculopathy/etiology , Venous Thrombosis/complications , Acute Disease , Adolescent , Female , Humans , Magnetic Resonance Imaging , Polyradiculopathy/pathology , Treatment Outcome , Vena Cava, Inferior/pathology , Venous Thrombosis/surgeryABSTRACT
In an attempt to improve outcomes for patients with acute myeloid leukemia (AML) after allogeneic hematopoietic cell transplantation (HCT), we conducted a phase 1/2 study in which targeted irradiation delivered by 131I-anti-CD45 antibody was combined with targeted busulfan (BU; area-under-curve, 600-900 ng/mL) and cyclophosphamide (CY; 120 mg/kg). Fifty-two (88%) of 59 patients receiving a trace 131I-labeled dose of 0.5 mg/kg anti-CD45 murine antibody had higher estimated absorbed radiation in bone marrow and spleen than in any other organ. Forty-six patients were treated with 102 to 298 mCi (3774-11 026 MBq) 131I, delivering an estimated 5.3 to 19 (mean, 11.3) Gy to marrow, 17-72 (mean, 29.7) Gy to spleen, and 3.5 Gy (n = 4) to 5.25 Gy (n = 42) to the liver. The estimated 3-year nonrelapse mortality and disease-free survival (DFS) were 21% and 61%, respectively. These results were compared with those from 509 similar International Bone Marrow Transplant Registry patients who underwent transplantation using BU/CY alone. After adjusting for differences in age and cytogenetics risk, the hazard of mortality among all antibody-treated patients was 0.65 times that of the Registry patients (95% CI 0.39-1.08; P = .09). The addition of targeted hematopoietic irradiation to conventional BU/CY is feasible and well tolerated, and phase 2 results are sufficiently encouraging to warrant further study.
Subject(s)
Antineoplastic Combined Chemotherapy Protocols/administration & dosage , Hematopoietic Stem Cell Transplantation , Leukemia, Myeloid, Acute/therapy , Adolescent , Adult , Age Factors , Antibodies, Monoclonal/administration & dosage , Bone Marrow/pathology , Busulfan/administration & dosage , Cyclophosphamide/administration & dosage , Disease-Free Survival , Female , Follow-Up Studies , Humans , Iodine Isotopes/administration & dosage , Leukemia, Myeloid, Acute/mortality , Leukemia, Myeloid, Acute/pathology , Male , Middle Aged , Radiotherapy/methods , Remission Induction , Risk Factors , Spleen/pathology , Transplantation, HomologousABSTRACT
PURPOSE: Radioimmunotherapy may improve the outcome of hematopoietic cell transplantation for hematologic malignancies by delivering targeted radiation to hematopoietic organs while relatively sparing nontarget organs. We evaluated the organ localization of yttrium-90-labeled anti-CD45 ((90)Y-anti-CD45) antibody in macaques, a model that had previously predicted iodine-131-labeled anti-CD45 ((131)I-anti-CD45) antibody biodistribution in humans. EXPERIMENTAL DESIGN: Twelve Macaca nemestrina primates received anti-CD45 antibody labeled with 1 to 2 mCi of (90)Y followed by serial blood sampling and marrow and lymph node biopsies, and necropsy. The content of (90)Y per gram of tissue was determined by liquid scintillation spectrometry. Time-activity curves were constructed using average isotope concentrations in each tissue at measured time points to yield the fractional residence time and estimate radiation absorbed doses for each organ per unit of administered activity. The biodistribution of (90)Y-anti-CD45 antibody was then compared with that previously obtained with (131)I-anti-CD45 antibody in macaques. RESULTS: The spleen received 2,120, marrow 1,060, and lymph nodes 315 cGy/mCi of (90)Y injected. The liver and lungs were the nontarget organs receiving the highest radiation absorbed doses (440 and 285 cGy/mCi, respectively). Yttrium-90-labeled anti-CD45 antibody delivered 2.5- and 3.7-fold more radiation to marrow than to liver and lungs, respectively. The ratios previously observed with (131)I-anti-CD45 antibody were 2.5-and 2.2-fold more radiation to marrow than to liver and lungs, respectively. CONCLUSIONS: This study shows that (90)Y-anti-CD45 antibody can deliver relatively selective radiation to hematopoietic tissues, with similar ratios of radiation delivered to target versus nontarget organs, as compared with the (131)I immunoconjugate in the same animal model.
Subject(s)
Antibodies, Monoclonal/therapeutic use , Immunoconjugates/pharmacokinetics , Leukocyte Common Antigens/immunology , Yttrium Radioisotopes/pharmacokinetics , Animals , Bone Marrow/immunology , Bone Marrow/metabolism , Bone Marrow/radiation effects , Disease Models, Animal , Lymph Nodes/immunology , Lymph Nodes/metabolism , Lymph Nodes/radiation effects , Macaca nemestrina , Male , Radiation Dosage , Spleen/immunology , Spleen/metabolism , Spleen/radiation effects , Tissue DistributionABSTRACT
One of the limitations of therapy with radiolabeled monoclonal antibodies (mAbs) is that significant toxicities can arise from circulating non-tumor-bound radiolabeled conjugate. Here, we describe a new method to reduce systemic radiation exposure from radiolabeled mAbs involving the attachment of the radioisotope through a linker that can be cleaved by an administered enzyme. To demonstrate the feasibility of this approach, we prepared a conditionally cleavable radioimmunoconjugate (RIC) composed of (131)I-labeled cephalosporin conjugated to Tositumomab, a mAb against the CD20 antigen. The cleavable RIC bound antigen identically to directly iodinated antibody, and in the presence of beta-lactamase, about 80-85% of the radioisotope was released. In vivo studies in mice revealed that the cleavable RIC and the directly iodinated anti-CD20 antibody had similar biodistribution patterns. Systemically administered beta-lactamase induced a 2-3-fold decrease in the percent injected dose (ID) of the cleavable RIC/g of blood, marrow, spleen, lung, and liver 1 h after enzyme treatment, and a 4-6-fold decrease 20 h after enzyme treatment. This was accompanied by a 20-fold increase in % ID/g in urine 1 h after enzyme treatment, indicating that the released radiolabel was rapidly excreted through the kidneys. In mice with human tumor xenografts, there was no decrease in the %ID/g in tumor 1 h after enzyme treatment, but by 4 h after enzyme injection, decreases in tumor radioactive content began to diminish the targeting advantage. These studies demonstrate that the cleavable RIC substrate is able to bind to tumor antigens and localize within human tumor xenografts and that accelerated systemic clearance can be induced with beta-lactamase.
Subject(s)
Immunoconjugates/chemistry , Immunoconjugates/pharmacokinetics , Radioisotopes/chemistry , Radioisotopes/pharmacokinetics , Animals , Cell Line, Tumor , Humans , Immunoconjugates/therapeutic use , Mice , Mice, Inbred NOD , Mice, SCID , Radioisotopes/therapeutic use , Tissue Distribution/physiology , Xenograft Model Antitumor Assays/methodsABSTRACT
We performed a multivariable comparison of 125 consecutive patients with follicular lymphoma (FL) treated at our centers with either high-dose radioimmunotherapy (HD-RIT) using 131I-anti-CD20 (n = 27) or conventional high-dose therapy (C-HDT) (n = 98) and autologous hematopoietic stem cell transplantation. The groups were similar, although more patients treated with HD-RIT had an elevated pretransplantation level of lactate dehydrogenase (41% versus 20%, P =.03) and elevated international prognostic score (41% versus 19%, P =.02). Patients treated with HD-RIT received individualized therapeutic doses of 131I-tositumomab (median, 19.7 GBq [531 mCi]) to deliver 17 to 31 Gy (median, 27 Gy) to critical organs. Patients treated with C-HDT received total body irradiation plus chemotherapy (70%) or chemotherapy alone (30%). Patients treated with HD-RIT experienced improved overall survival (OS) (unadjusted hazard ratio [HR] for death = 0.4 [95% confidence interval (95% CI), 0.2-0.9], P =.02; adjusted HR, 0.3, P =.004) and progression-free survival (PFS) (unadjusted HR =.6 [95% C.I., 0.3-1.0], P =.06; adjusted HR, 0.5, P =.03) versus patients treated with C-HDT. The estimated 5-year OS and PFS were 67% and 48%, respectively, for HD-RIT and 53% and 29%, respectively, for C-HDT. One hundred-day treatment-related mortality was 3.7% in the HD-RIT group and 11% in the C-HDT group. The probability of secondary myelodysplastic syndrome/acute myeloid leukemia (MDS/AML) was estimated to be.076 at 8 years in the HD-RIT group and.086 at 7 years in the C-HDT group. HD-RIT may improve outcomes versus C-HDT in patients with relapsed FL.
Subject(s)
Antigens, CD20/immunology , Hematopoietic Stem Cell Transplantation , Iodine Radioisotopes/therapeutic use , Lymphoma, Follicular/radiotherapy , Lymphoma, Non-Hodgkin/radiotherapy , Radioimmunotherapy/methods , Adult , Cohort Studies , Combined Modality Therapy , Disease Progression , Dose-Response Relationship, Radiation , Female , Humans , Lymphoma, Follicular/mortality , Lymphoma, Non-Hodgkin/mortality , Male , Middle Aged , Multivariate Analysis , Neoplasm Recurrence, Local/mortality , Neoplasm Recurrence, Local/radiotherapy , Radioimmunotherapy/adverse effects , Survival Rate , Treatment OutcomeABSTRACT
Despite advances in therapy for acute leukemia, relapse continues to be the major cause of treatment failure. Hematopoietic stem cell transplant can rescue some patients after relapse, but the ability to escalate the intensity of preparative regimens is limited by toxicity to normal organs. Radiolabeled monoclonal antibodies against hematopoietic antigens have emerged as an alternative to deliver targeted supplemental radiation to sites of leukemic involvement while relatively sparing normal organs. This paper will review the rationale for using this approach, our current experience with radiolabeled anti-CD45 antibody, and the potential challenges encountered in treating children with radiolabeled antibodies.
Subject(s)
Antibodies, Monoclonal/therapeutic use , Immunoconjugates/therapeutic use , Leukemia, Lymphoid/therapy , Leukemia, Myeloid/therapy , Leukocyte Common Antigens/immunology , Acute Disease , Bone Marrow Transplantation , Child , Humans , Leukemia, Lymphoid/immunology , Leukemia, Myeloid/immunology , Treatment OutcomeABSTRACT
Radiolabeled anti-CD20 antibodies produce responses in 60% to 95% of patients with relapsed non-Hodgkin lymphoma (NHL); however, absorbed radiation ratios between tumors and normal organs are relatively low, and many patients have relapses. In this study we compared the abilities of anti-CD45 (BC8) and anti-CD20 (1F5) antibodies to target human Ramos lymphoma xenografts in athymic mice. When direct radioiodination was performed with conventional methods, BC8 delivered 2- to 4-fold more radioiodine to tumors than 1F5, with tumor-to-normal organ ratios as high as 20:1 using radiolabeled BC8 compared with a maximal ratio of 9.8:1 using radioiodinated 1F5. To optimize the biodistribution of radioactivity, we performed studies following a pretargeting method using streptavidin (SA)-conjugated BC8 and 1F5. Injection of a synthetic clearing agent decreased the circulating level of conjugates by 80% to 90% within 1 hour. Pretargeting with BC8-SA resulted in a 2- to 4-fold greater tumor uptake of radiolabeled biotin than with 1F5-SA, with maximal tumor-to-normal organ ratios of more than 80:1 and approximately 16:1, respectively. Therapy experiments demonstrated that 400 microCi (14.8 MBq) or more of yttrium-90-1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid (DOTA)-biotin cured 100% of mice treated with BC8-SA and more than 90% of mice pretargeted with 1F5-SA, with complete remission occurring 8 to 10 days sooner in mice receiving BC8-SA. After treatment with 200 microCi (7.4 MBq) (90)Y-DOTA-biotin, 70% of the mice treated with BC8-SA were cured, but no mice were cured using 1F5-SA. Doses up to 800 microCi (29.6 MBq) (90)Y-DOTA-biotin were delivered with minor toxicity using either antibody conjugate. These lymphoma xenograft data suggest that pretargeted radioimmunotherapy using either anti-CD20 or anti-CD45 conjugates is highly effective and minimally toxic.