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Cardiovascular diseases after high-dose chemotherapy and autologous stem cell transplant for lymphoma: A Danish population-based study. Br J Haematol 2024; 204:967-975. [PMID: 38155503 DOI: 10.1111/bjh.19272] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2023] [Revised: 12/06/2023] [Accepted: 12/11/2023] [Indexed: 12/30/2023]
Abstract
Cardiovascular diseases, especially congestive heart failure (CHF), are known complications of anthracyclines, but the risk for patients undergoing high-dose chemotherapy and autologous stem cell transplant (HDT-ASCT) is not well established. With T-cell therapies emerging as alternatives, studies of long-term complications after HDT-ASCT are warranted. Danish patients treated with HDT-ASCT for aggressive lymphoma between 2001 and 2017 were matched 1:5 on sex, birth year and Charlson comorbidity score to the general population. Events were captured using nationwide registers. A total of 787 patients treated with HDT-ASCT were identified. Median follow-up was 7.6 years. The risk of CHF was significantly increased in the HDT-ASCT population compared to matched comparators with an adjusted hazard ratio (HR) of 5.5 (3.8-8.1). The 10-year cumulative incidence of CHF was 8.0% versus 2.0% (p < 0.001). Male sex, ≥2 lines of therapy, hypertension and cumulative anthracycline dose (≥300 mg/m2 ) were risk factors for CHF. In a separate cohort of 4089 lymphoma patients, HDT-ASCT was also significantly associated with increased risk of CHF (adjusted HR of 2.6 [1.8-3.8]) when analysed as a time-dependent exposure. HDT-ASCT also increased the risk of other cardiac diseases. These findings are applicable for the benefit/risk assessment of HDT-ASCT versus novel therapies.
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Second primary malignancies in patients with lymphoma in Denmark after high-dose chemotherapy and autologous haematopoietic stem-cell transplantation: a population-based, retrospective cohort study. Lancet Haematol 2023; 10:e838-e848. [PMID: 37689081 DOI: 10.1016/s2352-3026(23)00212-0] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2023] [Revised: 06/29/2023] [Accepted: 07/10/2023] [Indexed: 09/11/2023]
Abstract
BACKGROUND Second primary malignancies (SPMs) are known complications after chemotherapy, but the risk is not well characterised for patients with lymphoma treated with high-dose chemotherapy and autologous haematopoietic stem-cell transplantation (HSCT). We aimed to investigate the rate of SPMs in this population relative to matched control individuals from the general population. METHODS In this retrospective, population-based cohort study, patients aged 18 years or older with an aggressive lymphoma who received high-dose chemotherapy and autologous HSCT in Denmark between Jan 1, 2001, and Dec 31, 2017, were included from the Danish Lymphoma Registry and matched (1:5) to control individuals from the general population on birth year and sex via the Danish Civil Registration System. Patients were eligible if they had a registered date of autologous HSCT and patients with primary CNS lymphoma were excluded. Exclusion criteria for both patients and matched control individuals were HIV infection, organ transplantation, or other malignancies before inclusion. The key endpoint was the incidence of SPMs assessed in all study participants. The effect of treatment on SPMs was also investigated in patients who were followed up from first lymphoma diagnosis, with high-dose chemotherapy and autologous HSCT as a time-dependent exposure. FINDINGS Of 910 patients with lymphoma assessed, 803 were included (537 [67%] were male and 266 [33%] were female); 4015 matched control individuals were included (2685 [67%] were male and 1330 [33%] were female). Ethnicity data were not available. Median follow-up was 7·76 years (IQR 4·77-11·73). The SPM rate was higher among patients receiving high-dose chemotherapy and autologous HSCT than matched control individuals (adjusted hazard ratio [HR] 2·35, 95% CI 1·93-2·87, p<0·0001). Patients receiving high-dose chemotherapy and autologous HSCT had a higher rate of non-melanoma skin cancer (2·94, 2·10-4·11, p<0·0001) and of myelodysplastic syndrome or acute myeloid leukaemia (AML; 41·13, 15·77-107·30, p<0·0001) than matched control individuals, but there was no significant difference in the rate of solid tumours (1·21, 0·89-1·64, p=0·24). The cumulative risk of SPMs at 10 years was 20% (95% CI 17-23) in patients compared with 14% (13-15) in matched control individuals. High-dose chemotherapy and autologous HSCT was associated with an increased risk of SPMs when analysed as a time-dependent exposure from first lymphoma diagnosis (adjusted HR 1·58, 95% CI 1·14-2·17, p=0·0054). INTERPRETATION High-dose chemotherapy and autologous HSCT was associated with an increased risk of non-melanoma skin cancer and myelodysplastic syndrome or AML but not with increased risk of solid tumours in patients treated for lymphoma. These findings are relevant for future individualised risk-benefit assessments when choosing between high-dose chemotherapy and autologous HSCT and chimeric antigen receptor T-cell therapy in this setting. FUNDING Danish Cancer Society.
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Combination of thrombopoietin receptor agonists, immunosuppressants and intravenous immunoglobulin as treatment of severe refractory immune thrombocytopenia in adults and children. Br J Haematol 2020; 189:e37-e40. [PMID: 32096213 DOI: 10.1111/bjh.16426] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2019] [Accepted: 11/20/2019] [Indexed: 01/06/2023]
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Ruxolitinib treatment reduces monocytic superoxide radical formation without affecting hydrogen peroxide formation or systemic oxidative nucleoside damage in myelofibrosis. Leuk Lymphoma 2019; 60:2549-2557. [PMID: 30785365 DOI: 10.1080/10428194.2019.1579323] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
The role of excess reactive oxygen species (ROS) with consequent DNA/RNA damage is now recognized as a hallmark of cancer. In JAK2V617F mutated myeloproliferative neoplasms, ROS have been suggested to be important factors in disease initiation and progression. Ruxolitinib is the most widely used drug for myelofibrosis, because it improves symptom-score. However, both the anti-clonal potential and improvement in overall survival are limited. We investigated the impact of ruxolitinib on formation of superoxide radical and hydrogen peroxide by monocytes in sequentially acquired blood samples from patients with myelofibrosis. We also investigated the impact on RNA and DNA damage by measuring urinary excretion of 8-oxo-Guo and 8-oxo-d-Guo. The formation of superoxide by monocytes was reduced significantly during ruxolitinib therapy, but no impact on the formation of hydrogen peroxide by monocytes or the systemic amount of oxidatively damaged RNA or DNA could be demonstrated. We conclude that ruxolitinib holds little anti-oxidative potential.
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Immune thrombocytopenia is associated with persistently deranged fibrosis-related seromarker profiles but low bone marrow fibrosis grades: A 2-year observational study on thrombopoietin receptor agonist treatment. Platelets 2018; 30:222-228. [PMID: 29293383 DOI: 10.1080/09537104.2017.1411586] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
Bone marrow (BM) fibrosis is a potential side effect of thrombopoietin receptor agonist (TPO-RA) treatment. We aimed to investigate stromal seromarker profiles and growth factors in order to elucidate pathogenic and dynamic aspects of immune thrombocytopenia (ITP)-related BM fibrosis before and during TPO-RA treatment. Connective tissue metabolites [procollagen I and III peptides (PINP/PIIINP); hyaluronan (HYA), C-terminal-telopeptide (ICTP), and fibrosis-related growth factors (transforming growth factor-beta (TGF-beta), HGF, basic fibroblast growth factor)] were measured in blood samples acquired before initiation of TPO-RA and subsequently at 6-month intervals for up to 2 years. BM fibrosis was graded MF-0 in 8 (18%), MF-1 30 (65%), and MF-2 8 (18%) in the last available BM biopsy. In the 21 patients having more than one biopsy, the grade of fibrosis from the first to the last available biopsy decreased in 2 (10%), remained unchanged in 15 (71%), and increased in 4 (19%). Pretreatment levels of PIIINP, PINP, ICTP, and HYA were significantly increased in ITP versus controls. PINP, PIIINP, and HYA decreased on TPO-RA; ICTP remained unchanged. PINP:ICTP was lower before and during treatment compared to controls. Pretreatment, TGF-beta was lower than in controls; HGF exhibited the opposite pattern. HYA, ICTP, and TGF-beta tended to increase while PINP and platelet-derived growth factor tended to decrease with increasing fibrosis grade. In conclusion, ITP is associated with deranged patterns of extracellular matrix seromarkers and growth factors, indicating that BM stromal remodeling is enhanced. During TPO-RA treatment for up to 2 years, this profile was partially reversed while mild BM reticulin fibrosis was still present in the majority of patients. These observations likely reflect a BM injury by autoimmunity that is modified by TPO-RA.
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Effects of rituximab and dexamethasone on regulatory and proinflammatory B-cell subsets in patients with primary immune thrombocytopenia. Eur J Haematol 2017; 100:45-52. [PMID: 28960473 DOI: 10.1111/ejh.12978] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 09/17/2017] [Indexed: 11/30/2022]
Abstract
OBJECTIVE To investigate the cytokine production and surface marker composition of B cells in adult patients with newly diagnosed primary immune thrombocytopenia (ITP) before and 12 months after treatment with rituximab + dexamethasone (RTX+DXM) or dexamethasone (DXM). METHODS Peripheral blood mononuclear cells were isolated from nine patients treated with RTX+DXM, seven patients treated with DXM, and seven healthy donors. Expression of the cell-surface markers CD5, CD27, CD25, and CD19, and intracellular content of IL-6 and IL-10 were measured by flow cytometry. RESULTS PBMCs from ITP patients at baseline contained a lower proportion of IL-10+ B cells (P < .01) and IL-6+ B cells (P < .01) than healthy controls. All patients responded to therapy and levels were normalized at 12 months. The proportion of CD5+ B cells increased (P < .01) and CD27+ memory B cells decreased (P < .05) 12 months after treatment with RTX+DXM compared to baseline, with an inverse correlation between platelet numbers and the proportion of CD27+ B cells (R = -0.71; P < .05). CONCLUSION Both treatment regimens normalized the frequencies of cytokine-producing B cells. The additional increase in CD5+ B cells after RTX+DXM is compatible with induction of Bregs.
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Effect of thrombopoietin-receptor agonists on circulating cytokine and chemokine levels in patients with primary immune thrombocytopenia (ITP). Platelets 2016; 28:478-483. [DOI: 10.1080/09537104.2016.1235691] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
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A novel canine model of immune thrombocytopenia: has immune thrombocytopenia (ITP) gone to the dogs? Br J Haematol 2014; 167:110-20. [PMID: 25039744 DOI: 10.1111/bjh.13005] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2014] [Accepted: 05/11/2014] [Indexed: 01/25/2023]
Abstract
Canine immune thrombocytopenia (ITP) is analogous to human ITP, with similar platelet counts and heterogeneity in bleeding phenotype among affected individuals. With a goal of ultimately investigating this bleeding heterogeneity, a canine model of antibody-mediated ITP was developed. Infusion of healthy dogs with 2F9, a murine IgG2a monoclonal antibody to the canine platelet glycoprotein GPIIb (a common target of autoantibodies in ITP) resulted in profound, dose-dependent thrombocytopenia. Model dogs developed variable bleeding phenotypes, e.g. petechiae and haematuria, despite similar degrees of thrombocytopenia. 2F9 infusion was not associated with systemic inflammation, consumptive coagulopathy, or impairment of platelet function. Unexpectedly however, evaluation of cytokine profiles led to the identification of platelets as a potential source of serum interleukin-8 (IL8) in dogs. This finding was confirmed in humans with ITP, suggesting that platelet IL8 may be a previously unrecognized modulator of platelet-neutrophil crosstalk. The utility of this model will allow future study of bleeding phenotypic heterogeneity including the role of neutrophils and endothelial cells in ITP.
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Activated Platelets Enhance IL-10 Secretion and Reduce TNF-α Secretion by Monocytes. THE JOURNAL OF IMMUNOLOGY 2013; 191:4059-67. [DOI: 10.4049/jimmunol.1201103] [Citation(s) in RCA: 86] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
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Abstract
The objective of this study was to investigate the use of thrombopoietin-receptor agonists (TPO-ra) in patients with refractory primary immune thrombocytopenia (ITP) as well as off-label use of TPO-ra in Danish haematology departments. Hospital medical records from 32 of the 39 patients having received TPO-ra from 2009 to 1 May 2011 were available for data collection and included in the study. Of these patients, 15 received TPO-ra for refractory primary ITP, 7 for secondary ITP (chronic lymphatic leukaemia, systemic lupus erythematosus, Evans syndrome, human immunodeficiency virus and celiac disease) and 10 were treated for non-ITP (chemotherapy-induced, acute myeloid leukaemia, myelodysplastic syndrome, hereditary spherocytosis and suspected chemically induced thrombocytopenia). Initial response to TPO-ra defined as platelet counts >30 × 10(9)/l after 4 weeks of treatment was found in 59% of primary ITP patients, 57% of patients with secondary ITP and 40% of patients with non-ITP. There were four deaths in the cohort, three of which were related to pre-existing medical conditions. Otherwise adverse effects were in general mild. This Danish retrospective registration study has demonstrated that in the off-protocol setting, the use of TPO-ra is associated with response rates largely similar to those seen in previous protocol-monitored studies and no new adverse events were reported.
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Fibroproliferative activity in patients with immune thrombocytopenia (ITP) treated with thrombopoietic agents. Br J Haematol 2011; 155:248-55. [DOI: 10.1111/j.1365-2141.2011.08845.x] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
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[The pathogenesis of primary immune thrombocytopenia]. Ugeskr Laeger 2011; 173:274-277. [PMID: 21262172] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
Primary immune thrombocytopenia (ITP)--formerly known as idiopathic thrombocytopenic purpura--is an autoimmune disorder characterized by immune-mediated thrombocytopenia. The aetiology of ITP remains unknown, but studies have shown that multiple immunological mechanisms are involved in the pathogenesis of ITP.This article aims to provide an overview of our knowledge of the pathogenesis of ITP.
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[New treatment options for primary immune thrombocytopenia]. Ugeskr Laeger 2011; 173:271-274. [PMID: 21262171] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
Primary immune thrombocytopenia (ITP)--formerly known as idiopathic thrombocytopenic purpura--is an autoimmune disorder characterized by immune mediated thrombocytopenia. The aetiology of ITP remains unknown, but studies have shown that multiple immunological mechanisms are involved in the pathogenesis of ITP. This article aims to provide an overview of current treatment options, with particular emphasis on new biological therapies: rituximab, a monoclonal anti-CD20 antibody, and the thrombopoietin receptor agonists romiplostim and eltrombopag.
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Plasma TNF-Binding Capacity and Soluble TNF Receptors in Patients with Juvenile Idiopathic Arthritis. Scand J Immunol 2008. [PMCID: PMC7169560 DOI: 10.1111/j.0300-9475.2004.01423b.x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Background: Unbalanced production of proinflammatory cytokines may be related to disease progression in rheumatoid arthritis and juvenile idiopathic arthritis (JIA). Within the TNF system, the two agonists, TNF‐α and TNF‐β, also called lymphotoxin‐α (LT), are bound by soluble TNF receptors (sTNFR‐I and ‐II) that act as natural inhibitors of TNF‐induced inflammation. We investigated the plasma levels of sTNFR‐I in parallel with LT‐binding capacity (LTBC) in patients with JIA. Methods: The levels of sTNFR‐I were measured by ELISA (R&D). LTBC was determined by spiking diluted plasma samples with recombinant LT. Detectable LT was measured by an in‐house ELISA measuring unbound LT only. LTBC was expressed in arbitrary units (AUs) as the percentage value of bound LT to added LT. Result: In contrast to previous findings of elevated sTNFR levels in patients with various chronic inflammatory diseases, we found slightly reduced sTNFR‐I levels in JIA patients (n = 123) compared with age‐matched healthy controls (n = 37): 1077 pg/ml (819–2280) versus 1185 pg/ml (625–2303) [median (range)], P = 0015. However, the sTNFR‐I levels correlated positively with the number of active joints, physicians' global assessment and CRP. In contrast, patient LTBC values were elevated compared to healthy controls: 44 AU (36–52) versus 31 AU (13–41), P < 0.0001. Conclusion: Despite overall slightly reduced plasma levels of sTNFR‐I, the capacity to bind TNF was increased in plasma samples from JIA patients. Studies to identify the TNF‐binding substances in plasma are in progress.
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Plasma TNF binding capacity profiles during treatment with etanercept in rheumatoid arthritis. Scand J Rheumatol 2005; 33:385-8. [PMID: 15794196 DOI: 10.1080/03009740410000921] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
Abstract
BACKGROUND Etanercept (Enbrel) induces a rapid and sustained decline in disease activity in the majority of patients with refractory rheumatoid arthritis (RA). In these patients neutralization of TNFalpha and lymphotoxin (LT), previously termed TNFbeta is mediated by etanercept itself, as well as by naturally occurring soluble TNF receptors. However, the clinical response to treatment with etanercept may vary. Previously, pharmacokinetic studies have focused on the molar concentrations of etanercept, but very little is known about the kinetics of bioactive etanercept in patients treated with etanercept. The purpose of this study was to evaluate kinetics, including inter- and intraindividual variations of the total TNF binding capacity, in RA patients who were on a standard treatment schedule with etanercept. METHODS Plasma samples were collected daily from 16 RA patients who were in the steady-state phase during treatment with etanercept 25 mg subcutaneous once (n = 2) or twice (n = 14) weekly. The inflammatory activity, including Health Assessment Questionnaire (HAQ) score, numbers of painful and swollen joints, and ESR, was assessed at inclusion; CRP was measured on a daily basis. The samples were incubated with human recombinant LT to a concentration of 1000 pg/mL and the levels of detectable LT were measured by ELISA specific for free LT. The LT binding capacity (LTBC) was expressed in arbitrary units (AU) as the percentage value of bound LT to added LT. RESULTS The median LTBC values measured during the treatment schedule from Day 1 (before the injection) to Day 4 (before the next injection) were 47 AU. The LTBC values in each individual patient generally remained fairly stable through the treatment schedule, and there were no significant differences in LTBC levels in samples obtained on a daily basis during the treatment schedule. However, a pronounced variation between the patients was noticed with LTBC values ranging from 10-82 AU (coefficient of variation=38%). No significant association was found between LTBC levels and clinical measures of disease activity, including HAQ and numbers of swollen or painful joints. However, among patients with high LTBC levels (> or =65 AU), elevated levels of ESR and CRP were less frequent (0%) compared with patients who had lower LTBC levels, in which the frequencies of elevated ESR and CRP were 53% and 37%, respectively. Soluble TNF receptor 1 (sTNFR1) remained stable between the injections and correlated with the number of swollen joints, but did not correlate with LTBC values. CONCLUSION LTBC levels appeared stable in each individual RA patient who was on the standard treatment schedule with weekly injections of etanercept, but the inter-individual variations were considerable.
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Abstract
INTRODUCTION Tumour necrosis factor (TNF)-alpha and TNF-beta, also called lymphotoxin (LT), are bound by soluble truncated TNF receptors (sTNFRI and II) that are released from cell surfaces and act as natural inhibitors of TNF-induced inflammation. We investigated the plasma levels of sTNFRI and II in parallel with LT binding capacity (LTBC) in 44 patients with juvenile chronic arthritis (JIA). METHODS LTBC was determined by spiking diluted plasma samples with 1000 pg/ml of human recombinant LT. Detectable LT was measured by an in-house ELISA and LTBC was expressed in arbitrary units (AU) as the percentage value of bound LT to added LT. The levels of sTNFRI and-II were measured by ELISA (R&D). RESULTS We found slightly reduced sTNFRI and II levels in JIA patients (n=44) compared with healthy controls sTNFRI: 1118 pg/ml (656-2074) [mean (range)] vs. 1262 pg/ml (819-2280) p=0.015; sTNFRII: 1953 pg/ml (889-4476) vs. 2311 pg/ml (1309-4186) p=0.008. The sTNFRI levels correlated positively with morning stiffness (r=0.30, p=0.044), physician's global assessment (r=0.39; p=0.009) and CRP (r=0.43; p=0.0048). sTNFRII did not correlate with measures of disease activity. In contrast, patient LTBC values were elevated compared to controls: 44 AU (36-52) vs. 31 AU (13-41) [mean (range)], p<0.0001, but did not correlate with disease activity. CONCLUSION Despite overall slightly reduced plasma levels of sTNFRI and II, the capacity to bind TNF appeared to be increased in plasma samples from JIA patients.
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MESH Headings
- Adolescent
- Arthritis, Juvenile/blood
- Arthritis, Juvenile/metabolism
- Child
- Child, Preschool
- Enzyme-Linked Immunosorbent Assay
- Female
- Humans
- Infant
- Lymphotoxin-alpha/metabolism
- Male
- Receptors, Tumor Necrosis Factor, Type I/blood
- Receptors, Tumor Necrosis Factor, Type I/metabolism
- Receptors, Tumor Necrosis Factor, Type II/blood
- Receptors, Tumor Necrosis Factor, Type II/metabolism
- Recombinant Proteins/metabolism
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TNF and LT binding capacities in the plasma of arthritis patients: effect of etanercept treatment in juvenile idiopathic arthritis. Clin Exp Rheumatol 2004; 22:118-24. [PMID: 15005015] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/29/2023]
Abstract
BACKGROUND Etanercept (Enbrel) induces a rapid and sustained decline in disease activity in the majority of patients with refractory juvenile idiopathic arthritis (JIA). For unknown reasons, however, a number of JIA patients fail to respond to this therapy. During this treatment neutralisation of tumour necrosis factor (TNF, previously termed TNF alpha) and lymphotoxin (LT, previously termed TNF beta) may be mediated by etanercept itself as well as by naturally occurring soluble TNF receptors. In light of this, it was of interest to study the total TNF neutralizing capacity in plasma before and during treatment with etanercept. RESULTS In initial experiments plasma samples from healthy individuals were incubated with etanercept, and spiked with TNF or LT to a final concentration of 1000 pg/mL. Detection of TNF and LT by ELISA was found to be reduced by approximately 50% and 80% respectively, at a concentration of etanercept of 5-500 ng/mL, which is close to the pharmacological plasma concentrations. Plasma samples (n = 80) were then collected from 12 JIA patients (5 with pauciarticular, 5 with polyarticular and 2 with the systemic onset type) during treatment with etanercept (0.4 mg/kg twice weekly) for a period of 20.8 (15.6-23.9) months (median, range). The plasma samples were spiked with LT, and the inhibition of LT detection in ELISA was measured. In samples obtained 3 months after the start of etanercept, the inhibition of LT detection was augmented [72% (60-85)] compared with pre-treatment samples [16% (0.32)] (p = 0.0039). These findings were confirmed in binding assays using radiolabelled TNF. Among patients who responded insufficiently to therapy, reduced LT binding capacity, coinciding with flares of disease activity, was observed. CONCLUSION We have developed an assay by which LT binding capacity, reflecting the level of free, pharmacologically active etanercept, may be monitored in the blood of patients treated with etanercept. This assay may prove to be useful in guiding dose adjustments in patients with an incomplete response to etanercept.
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