Primary Hemophagocytic Lymphohistiocytosis Research Articles

Isolated CNS Hemophagocytic Lymphohistiocytosis in Children:What We Know, What We Don't Know ?

The presence of central nervous system involvement has a profound impact on the prognosis, treatment, and clinical outcome of the primary hemophagocytic lymphohistiocytosis (pHLH). However, isolated CNS-HLH is a challenging disease with a high mortality and morbidity , possibly resulting from a spsecific neuroinflammation that leads to isolated disease only without systemic activation under some additional genetic modifiers. In this study, we retrospectively reviewed our isolated CNS-HLH cases and there were 73 patients (36 male, 37 female) with a median age of 20 months (range, 1- 226 months) diagnosed as primary hemophagocytic lymphohistiocytosis at Hacettepe University Faculty of Medicine, between January 2005 and June 2021. Among these, 39 (53%) patients had central nervous system involvement either on admission or during the recurrence. On admission, the number of patients who had both CNS and sytemic involvement was 19 (49%), moreover 2 had CNS infiltration both initially and during the course of relapse. 8 patient did show CNS involvement only during the relapse. Ten (25%) patients (5 male, 5 female) with isolated CNS involvement are the main subject of this study and none of them had infectious trigger. What we know is they were presented with mostly unexplained neurological findings and /or cranial nerve paralysis. In this group median age at presentation was 101 months ( range 6 - 180 months). They all had primary HLH associated patogenic mutation and in some of them diagnosed was also confirmed by brain biopsy. Neither family history and /or consanguinity nor HLH criteria are fullfilling in this devastating disorder. Cranial MRI gives many clues during admission in experienced hands. Two of our published cases were initially diagnosed as lymphomatoid granulomatosis and acute disseminated encephalomyelitis ; they were diagnosed as hemophagocytic lymphohistiocytosis after developing systemic symptoms 3 and 12 months later. Interestingly 6 of 10 patients in this group never developed systemic symptomps, 7 patients underwent allogeneic bone marrow transplantation. Spinal cord involvement was determined in 8 patients(20%), including 4 at diagnosis and 4 during follow up ; including one previously published case, 4 out of 8 had isolated cases did show spinal involvement as well. Even though few number of cases with isolated CNS-HLH has been reported in the recent years, we believe that the number of such cases is not limited to those who have been reported because it is rather difficult to diagnose patients with isolated CNS symptoms, which leads to misdiagnosis and/or mistreatment. What we don't know is how to specifically treat patients with CNS directed therapy, and exactly which mutations are associated with isolated CNS-HLH or whether there is a known tendency in this group and perhaps unknown mutations ? Does it have a facilitating effect ? DisclosuresNo relevant conflicts of interest to declare.

Trials in Progress: A Two-Cohort, Open-Label, Single-Arm Study of Emapalumab, an Anti-Interferon Gamma (IFNγ) Monoclonal Antibody, in Patients with Macrophage Activation Syndrome (MAS) in Rheumatic Diseases

▪Introduction: MAS is a severe, life-threatening complication of rheumatic diseases such as Still's disease and systemic lupus erythematosus (SLE). MAS is a form of secondary hemophagocytic lymphohistiocytosis, characterized by a hyperinflammatory state caused by immune cell dysregulation which can lead to multiorgan damage. Sustained activation and expansion of T lymphocytes and macrophages stimulates the hypersecretion of proinflammatory cytokines such as IFNγ.The mainstay of treatment for MAS is high doses of glucocorticoids (GCs); however, they do not always provide adequate control in all patients. Additional treatments are used without a standardized approach; however, morbidity and mortality remain high. Preliminary data from a pilot study including 9 patients with inadequate response to high-dose intravenous GCs (NCT03311854) showed that emapalumab, a fully human anti-IFNγ monoclonal antibody, led to rapid neutralization of IFNγ and was efficacious in controlling MAS with a favorable safety profile [De Benedetti et al. Annals Rheumatic Dis 2020;79(Suppl. 1):194]. A study to further evaluate the efficacy and safety of emapalumab in patients with MAS in Still's disease and SLE is enrolling patients.Objective: To describe the design and objectives of a Phase 2/3 study aiming to confirm the efficacy and safety of emapalumab in the treatment of MAS in rheumatic disease.Study Design and Methods: This open-label, single arm, multicenter, interventional study (Figure 1) is enrolling pediatric and adult subjects into two cohorts 1) MAS in Still's disease (systemic juvenile idiopathic arthritis and adult onset Still's disease; n=25) and 2) MAS in SLE (n=16). Eligible patients must present with an inadequate response to high doses of GCs. Each cohort is a single-arm study composed of two phases: an optional run-in phase and an interventional phase. Key eligibility criteria vary by cohort and phase (Table 1). During the run-in phase, patients are treated with GCs according to the investigators' clinical practice and followed until MAS remission or inadequate response, or for a maximum of 12 weeks. Patients with an inadequate response to GCs (and potentially to other therapies) enroll in the interventional phase to be treated with intravenous emapalumab (initial dose 6mg/kg, subsequent doses 3mg/kg) for 4 weeks or until a complete response (CR) is achieved, and are followed off-drug for 1 year.Based on the assumptions of a successful treatment with GCs (null hypothesis) of up to 40% for cohort 1 (i.e. CR rate of 40%) and 30% for cohort 2 (i.e. CR rate of 30%), if the truth is 70% complete responders (for both cohorts), then a total of 25 and 16 patients, respectively, is required to demonstrate a statistically significant proportion of CR with a power of 80% using a one-sided exact binomial test at a significance level of 2.5%. The study design for cohort 1 is a group sequential design, including an interim analysis assessing efficacy with an adjusted type 1 error after 16 patients have reached Week 8 after the first dose of emapalumab.The primary endpoint of the study is CR (response criteria defined in Table 2) at Week 8 after first emapalumab administration. Secondary efficacy endpoints include GC tapering, survival, time to first CR, overall response (CR and partial response), time to first overall response, MAS recurrence, PK/PD profile of emapalumab, and patient-reported outcomes. Safety endpoints include assessments of adverse events, abnormal laboratory parameters, and anti-drug antibodies.Summary: This ongoing trial is designed to address the unmet need for new efficacious and safe therapies for the treatment of MAS. [Display omitted] DisclosuresGrom: AB2 Bio: Consultancy; Novartis: Consultancy. Bachir: Sobi: Current Employment. Asnaghi: Sobi: Current Employment. De Benedetti: Novimmune: Consultancy, Research Funding; Novartis: Consultancy, Research Funding; Sanofi: Consultancy, Research Funding; Roche: Consultancy, Research Funding; Pfizer: Consultancy, Research Funding; Sobi: Consultancy, Research Funding; AbbVie: Consultancy, Research Funding. OffLabel Disclosure:Emapalumab-lzsg is an IFN-gamma blocking antibody indicated for the treatment of adult and pediatric (newborn and older) patients with primary hemophagocytic lymphohistiocytosis (HLH) with refractory, recurrent, or progressive disease or intolerance with conventional HLH therapy.

Macrophage Activation Syndrome (MAS) in Systemic Juvenile Idiopathic Arthritis (sJIA): Treatment with Emapalumab, an Anti-Interferon Gamma (IFNγ) Monoclonal Antibody

▪Introduction: MAS is a severe, life-threatening complication of rheumatic diseases that occurs most frequently in patients with sJIA. The mainstay of treatment for MAS is high dose glucocorticoids (GCs); however, GCs do not always provide adequate control in all patients. Additional treatments are used without a standardized approach; however, morbidity and mortality remain high. Data from animal models of MAS and from observational studies in patients suggest that overproduction of IFNγ is a driver of the hyperinflammation observed in MAS; neutralization of IFNγ has been shown to revert the signs and symptoms of MAS in murine models, and high IFNγ levels are strongly correlated with laboratory parameters of disease severity in patients.Objective: To assess the efficacy and safety of intravenous (IV) infusions of emapalumab, a fully human anti-IFNγ monoclonal antibody, in patients with MAS associated with sJIA.Methods: This was a pilot, open-label, single-arm, phase 2 study (NCT03311854) that included patients with MAS (2016 ACR/EULAR criteria) associated with sJIA and who had not responded adequately to high dose IV GC and other treatments. Emapalumab was initiated at a dose of 6 mg/kg on Day 0 and continued at 3 mg/kg every 3 days until Day 15, and then twice weekly for an additional 2 weeks (i.e. until Day 28). As per protocol, 10 infusions were planned over the 4 weeks; however, treatment could be shortened if MAS remission was achieved earlier, or extended if required to achieve response. All patients were followed up for 4 weeks after the last emapalumab infusion and were offered to enter a long-term, follow-up study.Results: We report preliminary results from 14 patients with a median age of 11 (range 2-25) years who were enrolled in the trial (11 in Europe and 3 in the USA). All patients had failed high-dose GC; in addition, several patients had received cyclosporine A and/or anakinra within 10 days of being enrolled in the study. Treatment with emapalumab resulted in rapid IFNγ neutralization, as demonstrated by a decrease in the levels of the IFNγ-induced chemokine (C-X-C motif) ligand 9 (CXCL9), and subsequent deactivation of T cells, as indicated by the decrease in soluble interleukin-2 receptor levels. A progressive improvement in all clinical and laboratory parameters of MAS was observed. Emapalumab infusions were well tolerated by all patients, with no discontinuations. A cytomegalovirus reactivation was reported in 1 patient as a serious event related to emapalumab and resolved with antiviral therapy. During the study, GC doses were tapered in all patients. Administration of anakinra for the treatment of underlying sJIA was maintained/introduced during the study, as required.Conclusion: Emapalumab administration led to rapid neutralization of IFNγ, as indicated by a rapid decrease in CXCL9 levels, and was efficacious in controlling MAS in all patients. Emapalumab was well tolerated and had a favorable safety profile. These results support the pathogenic role of IFNγ in MAS/sJIA and the therapeutic value of IFNγ neutralization in MAS patients who have failed high-dose GCs and other treatments. DisclosuresDe Benedetti: Novimmune: Consultancy, Research Funding; Novartis: Consultancy, Research Funding; Sanofi: Consultancy, Research Funding; Roche: Consultancy, Research Funding; Pfizer: Consultancy, Research Funding; Sobi: Consultancy, Research Funding; AbbVie: Consultancy, Research Funding. Grom: AB2 Bio: Consultancy; Novartis: Consultancy. Brogan: Sobi: Consultancy; Novartis: Consultancy; Roche: Consultancy; UCB: Consultancy. Eleftheriou: Sobi: Speakers Bureau. Papadopoulou: Sobi: Speakers Bureau. Quartier: Pfizer: Consultancy, Speakers Bureau; AbbVie: Consultancy, Speakers Bureau; Chugai-Roche: Consultancy, Speakers Bureau; Lilly: Consultancy, Speakers Bureau; Novartis: Consultancy, Speakers Bureau; Sobi: Consultancy, Speakers Bureau. Antón: Sobi: Consultancy; Novartis: Consultancy; Roche: Consultancy; Pfizer: Consultancy; GSK: Consultancy; AbbVie: Consultancy. Frederiksen: Sobi: Current Employment. Asnaghi: Sobi: Current Employment. Ballabio: Sobi: Consultancy, Ended employment in the past 24 months. de Min: Sobi: Consultancy, Ended employment in the past 24 months. OffLabel Disclosure:Emapalumab is an IFN-y blocking antibody indicated for the treatment of adult and pediatric (newborn and older) patients with primary hemophagocytic lymphohistiocytosis (HLH) with refractory, recurrent, or progressive disease or intolerance with conventional HLH therapy.

Immunodeficiency Genes Are Associated with EBV Positive Malignancies and Hemophagocytic Lymphohistiocytosis That Can be Cured By Allogeneic Hematopoietic Stem Cell Transplantation

Background: Epstein-Barr virus (EBV) positive hematological malignancies and EBV-associated hemophagocytic lymphohistiocytosis (HLH) are serious illness that is related with chronic active EBV infection (CAEBV). Recently, more and more immune-related gene mutations have been identified to associate with the EBV positive hematological diseases. Allogeneic hematopoietic stem cell transplantation (allo-HSCT) is a curative therapy for above diseases.Aim: In present clinical study, the germline gene mutations associated with EBV positive hematological malignancies and EBV positive HLH were analyzed and the outcomes of allo-HSCT in those diseases were investigated.Methods: Between January 2018 and June 2021, 7 patients with EBV positive hematological diseases (lymphoma 3, aggressive NK-cell leukemia (ANKL) 1, secondary HLH 3) who received allo-HSCT in our hospital were included. Blood samples from patients, parents and potential related donors were collected before transplantation and whole exome sequencing of the blood DNA samples was performed to detect and analyze their relevance with the clinical features before and after allo-HSCT. The median age was 23 (5-31) years old. The median disease course before transplant was 6 (3-38) months. Before allo-HSCT, 3 patients (HLH 1, lymphoma 1, ANKL 1) were in non-remission (NR), 2 patients with lymphoma were in partial remission (PR) and the other two patients with HLH were in complete remission (CR). Five patients received allo-HSCT from haploidentical donors and 2 patients from unrelated donors (HLA 10/10, 9/10 matched). Myeloablative conditioning regimen with busulfan (0.8mg/kg iv q6h, 3 days)/etoposide (200mg/m 2, 3 days)/fludarabine (30mg/m 2, 5 days) /rabbit anti-T-cell globulin was used. Cyclosporine, mycophenolate mofetil and short-term methotrexate were employed for graft-versus-host disease (GVHD) prophylaxis.Results: All patients achieved durable engraftment. Plasma EBV-DNA was positive in three patients (1200, 880, 84000 copies/ml, respectively) before transplant and has been negative in all patients after transplant. One patient had gastrointestinal bleeding caused by EBV enteritis. Two patients had CMV viremia. Three patients developed grade III acute GVHD and two had extensive chronic GVHD. All GVHD was resolved with immune-suppressants. With the median follow-up time of 21 (7-36) months, all patients are alive and free of their diseases. Seven disease-related gene mutations were detected including FANCA p.S1088F, TGFBR2 p.T315M, IRF7 p.K446R, PRF1 p.R4C, MPEG1 p.P316S, STX11 p.R49Q, and UNC13D p.G863D. The first 5 gene mutations were detected in the patients with lymphoma and ANKL, and the last 2 gene mutations were detected in the patients with HLH. FANCA is associated with bone marrow failure and the other genes are associated with primary immunodeficiency, all of these gene mutations have been reported and affect in part the function of the genes. In particular, STX11 p.R49Q and UNC13D p.G863D have also been reported in HLH patients and the NK cell activity of these patients is lower than normal levels. Apart from the defined gene mutations in primary HLH, recently, many new immunodeficiency gene mutations have been reported to associate with EBV positive malignancies and HLH which suggests immunodeficiency might play a role in the etiology of the diseases. The gene mutations we reported here might be the main gene mutations associated with disease susceptibility and infection risk.Conclusion: Our preliminary results have shown the gene mutation profile related to EBV positive hematological malignancies and HLH. With our transplant protocol, durable reconstitution of hematopoiesis and immune from healthy donors has been achieved successfully which has resulted in 100% disease-free survival and no transplant-related death. Allo-HSCT is a safe and effective curative modality for EBV positive hematological malignancies and HLH. DisclosuresNo relevant conflicts of interest to declare.

What Plasma Level of Interferon-γ Indicates in Systemic Chronic Active Epstein-Barr Virus Infection

Background and AimSystemic chronic active Epstein-Barr virus infection (sCAEBV) is an intractable and progressive disease of which the symptoms include persistent or recurrent inflammation and harboring EBV-infected clonally proliferating T- or NK-cells. 24% of sCAEBV patients progress to hemophagocytic lymphohistiocytosis (HLH), a life-threatening condition. (Blood Adv. 2020;4:p2918) The presence of HLH at hematopoietic stem cell transplantation is associated with poor survival in sCAEBV (BMT. 2016;15;p879).Interferon-γ (IFN-γ) plays pivotal roles in developing HLH, and antagonistic anti-IFN-γ antibody is effective against HLH (N Engl J Med 2020;382:p1811). In this study, we examined the plasma level of IFN-γ to investigate its impact on disease conditions of sCAEBV and its possibility as a therapeutic target.MethodssCAEBV was diagnosed based on following criteria which confirm with the definition of CAEBV in the WHO 2017 classification:(1) elevated EBV-DNA load in peripheral blood (PB) (>10 2.5 copies/μg DNA)(2) EBV infection of T- or NK-cells (see below) in the affected tissues or PB(3) systemic inflammatory symptoms persisting for more than three months(4) exclusion of other possible diagnoses: primary infection of EBV, autoimmune disease, congenital immunodeficiency, HIV, and other immunodeficiencies or underlying diseases with potential immunosuppressionPatients who fulfilled all criteria (1) to (4) were diagnosed as sCAEBV. (Blood Adv. 2020;4(13):2918-2926.)We defined a patient's condition as active disease when presenting any of following persistent inflammation: fever, liver dysfunction, progressive skin lesions, vasculitis, or uveitis. The plasma concentration of IFN-γ was measured by high sensitivity cytokine beads assay. mRNA was measured by real-time RT-PCR using TaqMan ® system.ResultsWe examined 18 sCAEBV patients (CD4 type n = 7, CD8 type n = 1, and CD56 type n = 10). Their IFN-γ plasma levels were significantly higher than those of healthy donors. The levels in sCAEBV patients with active disease were higher than those with inactive disease. The mRNA expression of IFN-γ was detected in EBV-infected cells of all patients. A patient whose plasma IFN-γ was extremely high harbored HLH with markedly high expression of the mRNA of IFN-γ in EBV-infected cells, but there was no statistical correlation between the plasma IFN-γ levels and the mRNA levels of EBV-infected cells.DiscussionOur findings infer IFN-γ's role in the inflammation of sCAEBV. The mRNA expression of IFN-γ was detected in EBV-infected cells of all patients. We discovered earlier that STAT3, a responsible transcriptional factor for IFN-γ expression, is constitutively activated in EBV-infected T- or NK-cells of CAEBV (Oncotarget.2018; 9;31077). Thus, we suspected that IFN-γ is produced by EBV-infected cells. Meanwhile, there was no statistical correlation between the plasma IFN-γ levels and the mRNA levels of EBV-infected cells as a whole. The proliferation of non-infected immunocompetent cells, such as NK cells, CD8-positive T cells, macrophages, and histiocytes, are often detected in the lesions of CAEBV. These cells also possibly produce IFN-γ.sCAEBV patients accompanied by hemophagocytic lymphohistiocytosis (HLH) had significantly higher IFN-γ levels in the serum compared to those without HLH. There was a report on emapalumab's effect on primary HLH. We expect emapalumab, a human anti-IFN-γ, is effective to sCAEBV patients, particularly who is harboring HLH．ConclusionPlasma IFN-γ in sCAEBV indicates disease activity and potentially be a therapeutic target. DisclosuresArai: Abbvie GK: Honoraria; BMS: Honoraria; Chugai Pharmaceutical Co Ltd: Honoraria, Research Funding; Eisai Co Ltd: Research Funding; Abbott Japan LLC: Honoraria; Kyowa Kirin Co ltd: Honoraria, Research Funding; Ono Pharmaceutical Co ltd: Honoraria, Research Funding; Nippon Shinyaku Co Ltd: Honoraria, Research Funding; Otsuka Pharmaceutical Co ltd: Research Funding; Novartis Pharma KK: Honoraria; Takeda Pharmaceuticals Co Ltd: Honoraria, Research Funding; Shionogi & Co ltd: Research Funding; Asahi Kasei Pharma Corporation: Research Funding; Sanofi KK: Honoraria; Pfizer Japan Inc: Honoraria; Astellas Pharma Inc: Honoraria.

Outcomes with Hematopoietic Stem Cell Transplantation in Secondary Hemophagocytic Lymphohistiocytosis: A Systematic Review and Meta-Analysis

Background:Secondary hemophagocytic lymphohistiocytosis (HLH) is a disorder characterized by the hyper-stimulation of the immune system. HLH has a poor prognosis with up to a 100% mortality without an adequate therapy. Contrary to primary HLH, an efficient management approach has yet to be established for secondary HLH in adults. We conducted a systematic review and meta-analysis to evaluate the efficacy and safety of hematopoietic stem cell transplantation (HSCT) in this context.MethodsFollowing the preferred reporting items for systemic reviews and Mata-analysis (PRISMA) guidelines, a comprehensive literaturesearch was performed on 4 databases (PubMed, Cochrane Register of Controlled Trials, Embase and Clinicaltrials.gov) using MeSHterms and keywords for “Lymphohistiocytosis, Hemophagocytic” AND “Hematopoietic stem cell transplantation” AND“Therapeutics” AND “Treatment Outcome” from the date of inception to June 2021. Our search produced 2346 results and duplicateswere removed. After excluding irrelevant and review articles during primary and secondary screening, seven original studies reportingHSCT as the treatment for secondary HLH in pediatric and adult patient population were included. The methodological quality of theincluded studies was evaluated using NIH quality assessment tool. Inter-study variance was calculated using the Der Simonian-LairdEstimator. Proportions along with 95% confidence Interval (CI) were extracted to compute pooled analysis using the ‘meta’ packageby Schwarzer et al. in the R programming language (version 4.16-2).Results:A total of 136 patients from 7 studies were included. The median age of the patients was 32 (0.5-77) years and 57.4% (62/108) weremales as reported by 4 studies. (Table 1) Allogeneic HSCT was used as a treatment modality for 100% (n=136) of the patients. Themedian time from diagnosis to HSCT was 4.9 (0.1-24) months as reported by 3 studies and median follow-up time was 22 (3-192)months as reported by 4 studies. The pooled overall response rate (ORR) after HSCT was 80% (95% CI 0.66-0.91, I 2 =21%, n=59)with pooled complete response (CR) of 54.5% (95% CI 0.19-0.87, I 2 =86%, n=59) and pooled partial response (PR) of 22.4% (95% CI0.04-47, I 2 =72%, n=59). At a median follow-up of 30 (3-120) months, the pooled overall survival (OS) was 78.8% (95% CI 0.67-0.89,I 2 =41%, n=136). The pooled relapse rate (RR) was 12.2% (95 CI 0.045-0.22, I 2 =0%, n=61). The pooled incidence of acute graft versushost disease (GVHD) grade I/II and grade III/IV was 37.5% (95% CI 0.24-0.51, I 2 =0%, n=48) and 19.8% (95% CI 0.09-0.32, I 2 =0%,n=50) respectively, while pooled incidence of chronic GVHD was 26% (95% CI 0.13-0.41, I 2 =25%, n=50).Conclusion:HSCT shows excellent response rates and survival in patients with secondary HLH with an acceptable safety profile and should beconsidered. However, it is imperative that large prospective studies should be done to consolidate these findings. [Display omitted] DisclosuresMcGuirk: Novartis: Research Funding; Gamida Cell: Research Funding; Astelllas Pharma: Research Funding; EcoR1 Capital: Consultancy; Magenta Therapeutics: Consultancy, Honoraria, Research Funding; Fresenius Biotech: Research Funding; Juno Therapeutics: Consultancy, Honoraria, Research Funding; Kite/ Gilead: Consultancy, Honoraria, Other: travel accommodations, expense, Kite a Gilead company, Research Funding, Speakers Bureau; Bellicum Pharmaceuticals: Research Funding; Novartis: Research Funding; Allovir: Consultancy, Honoraria, Research Funding; Pluristem Therapeutics: Research Funding.

Study of secondary hemo-phagocytic lympho-histiocytosis in children at a tertiary centre

Background: Hemophagocytic lympho-histiocytosis (HLH) is fatal condition characterised by aggressive immune activation, dysregulation and up regulation of inflammatory cytokines leading to uncontrolled activation of T-cells, defective granule mediated cytotoxicity. HLH is classified into primary and secondary HLH.Methods: This is retrospective study of case-records of children who fulfilled criteria of HLH-2004 guidelines from November 2016 to November 2020.Results: Total number of patients with HLH was 33, excluding 4 cases of primary HLH, 29 cases met the inclusion criteria. 19 (65.5%) were children less than 5 years of age at the time of diagnosis. Six (20.7%) children were between 6 to 10 years and the rest 4 (13.8%) ten years. Average age at presentation was 4.93 years. Male to female ratio was 0.8 to 1. Fever was the chief complaint present in 29 (100%) of cases. Laboratory parameters showed anaemia, thrombocytopenia, hyper-ferritinemia and hypertriglyceridemia in all 29 (100%) cases. CRP elevated in 28 (96.6%) cases. Infections found in 29 (100%) of cases, bacteria in 19 (65.5%), viral in 10 (34.5%). Mortality seen in 11 (37.9%) cases. Average time of diagnosis from admission was 5.6 days. 4 children out of 11 had dengue as cause for secondary HLH and 4 had bacterial sepsis one each CMV, scrub typhus and SLE. Following factors affected the outcome by multivariate analysis, coagulopathy, elevated liver enzymes, bone marrow biopsy and immunosuppressive therapy.Conclusions: HLH should be considered in differential diagnosis of children with sepsis. High index of suspicion for HLH with early initiation of treatment should be considered for better outcome.

Incidence of paediatric multiple sclerosis and other acquired demyelinating syndromes: 10-year follow-up surveillance study.

To describe a 10-year follow-up of children (<16y) with acquired demyelinating syndromes (ADS) from a UK-wide prospective surveillance study. Diagnoses were retrieved from the patients' records via the patients' paediatric or adult neurologist using a questionnaire. Demyelinating phenotypes at follow-up were classified by an expert review panel. Twenty-four out of 125 (19.2%) children (64 males, 61 females; median age 10y, range 1y 4mo-15y 11mo), identified in the original study, were diagnosed with multiple sclerosis (incidence of 2.04/million children/year); 23 of 24 fulfilled 2017 McDonald criteria at onset. Aquaporin-4-antibody neuromyelitis optica spectrum disorders were diagnosed in three (2.4%, 0.26/million children/year), and relapsing myelin oligodendrocyte glycoprotein antibody-associated disease in five (4%, 0.43/million children/year). Three out of 125 seronegative patients relapsed and 85 of 125 (68%) remained monophasic over 10 years. Five of 125 patients (4%) originally diagnosed with ADS were reclassified during follow-up: three children diagnosed initially with acute disseminated encephalomyelitis were subsequently diagnosed with acute necrotising encephalopathy (RAN-binding protein 2 mutation), primary haemophagocytic lymphohistiocytosis (Munc 13-4 gene inversion), and anti-N-methyl-d-aspartate receptor encephalitis. One child initially diagnosed with optic neuritis was later diagnosed with vitamin B12 deficiency, and one presenting with transverse myelitis was subsequently diagnosed with Sjögren syndrome. The majority of ADS presentations in children are monophasic, even at 10-year follow-up. Given the implications for treatment strategies, multiple sclerosis and central nervous system autoantibody mimics warrant extensive investigation.

Molecular Genetics Diversity of Primary Hemophagocytic Lymphohistiocytosis among Polish Pediatric Patients

Hemophagocytic lymphohistiocytosis (HLH) is a clinical syndrome of life-threatening inflammation caused by an excessive, prolonged and ineffective immune response. An increasing number of HLH cases is recognized in Poland, but the genetic causes of familial HLH (FHL) have not been reported. We investigated the molecular genetics and associated outcomes of pediatric patients who met HLH criteria. We studied 54 patients with HLH, 36 of whom received genetic studies. Twenty-five patients were subjected to direct sequencing of the PRF1, UNC13D, STX11, XIAP and SH2D1A genes. Additionally, 11 patients were subjected to targeted next-generation sequencing. In our study group, 17 patients (31%) were diagnosed with primary HLH, with bi-allelic FHL variants identified in 13 (36%) patients whereas hemizygous changes were identified in 4 patients with X-linked lymphoproliferative diseases. In addition, one patient was diagnosed with X-linked immunodeficiency with magnesium defect, Epstein–Barr virus infection and neoplasia due to a hemizygous MAGT1 variant; another newborn was diagnosed with auto-inflammatory syndrome caused by MVK variants. The majority (65%) of FHL patients carried UNC13D pathogenic variants, whereas PRF1 variants occurred in two patients. Novel variants in UNC13D, PRF1 and XIAP were detected. Epstein–Barr virus was the most common trigger noted in 23 (65%) of the patients with secondary HLH. In three patients with secondary HLH, heterozygous variants of FHL genes were found. Overall survival for the entire study group was 74% with a median of 3.6 years of follow-up. Our results highlight the diversity of molecular causes of primary HLH in Poland.

Targeting interferon-γ in hyperinflammation: opportunities and challenges.

Interferon-γ (IFNγ) is a pleiotropic cytokine with multiple effects on the inflammatory response and on innate and adaptive immunity. Overproduction of IFNγ underlies several, potentially fatal, hyperinflammatory or immune-mediated diseases. Several data from animal models and/or from translational research in patients point to a role of IFNγ in hyperinflammatory diseases, such as primary haemophagocytic lymphohistiocytosis, various forms of secondary haemophagocytic lymphohistiocytosis, including macrophage activation syndrome, and cytokine release syndrome, all of which are often managed by rheumatologists or in consultation with rheumatologists. Given the effects of IFNγ on B cells and T follicular helper cells, a role for IFNγ in systemic lupus erythematosus pathogenesis is emerging. To improve our understanding of the role of IFNγ in human disease, IFNγ-related biomarkers that are relevant for the management of hyperinflammatory diseases are progressively being identified and studied, especially because circulating levels of IFNγ do not always reflect its overproduction in tissue. These biomarkers include STAT1 (specifically the phosphorylated form), neopterin and the chemokine CXCL9. IFNγ-neutralizing agents have shown efficacy in the treatment of primary haemophagocytic lymphohistiocytosis in clinical trials and initial promising results have been obtained in various forms of secondary haemophagocytic lymphohistiocytosis, including macrophage activation syndrome. In clinical practice, there is a growing body of evidence supporting the usefulness of circulating CXCL9 levels as a biomarker reflecting IFNγ production.

CARDIAC TAMPONADE AS A PRESENTING FEATURE OF METASTATIC GI CARCINOMA

TOPIC: Critical Care TYPE: Fellow Case Reports INTRODUCTION: Hemophagocytic lymphohistiocytosis (HLH) is a rare but life-threatening disease. It is characterized by abnormalities in immunoregulation due to a non-malignant proliferation of lymphocytes and secretion of inflammatory cytokines. HLH is typically associated with acquired immunodeficiencies such as in hematopoietic stem cell transplantation. We present a case of a young woman who was treated in our ICU for confirmed HLH which was attributed to an Epstein-Barr virus (EBV) infection that reactivated during her post-transplant immunosuppression. CASE PRESENTATION: A 46-year-old female presented to her primary care physician with gradual dyspnea, spontaneous gum bleeding and lower extremity bruising. She was diagnosed with anemia during her pregnancy. Eventually developed leukopenia and pancytopenia. She was later diagnosed with aplastic anemia and underwent a conditioning regimen prior to peripheral blood stem cell transplantation (PBSCT) with cyclophosphamide, fludarabine, total body irradiation, and rabbit anti-thymocyte globulin (ATG). She had an allogeneic PBSCT from a 10/10 HLA-matched unrelated donor (MUD). Her pre-transplant workup was positive EBV IgG. Donor pre-transplant workup was negative for EBV. Post-transplant immunosuppression consisted of rituximab and tacrolimus. Two months post-transplant, she was admitted for non-neutropenic fevers and diagnosed with Clostridium difficile colitis, acute kidney injury, EBV viremia (>800000 IU/ml), and widespread lymphadenopathy concerning for EBV-associated biopsy proven monomorphic PTLD. She was treated with two doses of Rituximab. Due to worsening encephalopathy, liver function tests and metabolic acidosis, ICU transfer initiated for continuous renal replacement therapy (CRRT). She developed acute respiratory failure and septic shock; was intubated, requiring vasopressors. During her ICU stay, HLH was considered. Bone marrow aspiration and biopsy performed confirmed HLH. High dose dexamethasone therapy was initiated. She also received two doses of Etoposide and a dose of tocilizumab in ICU. She was successfully extubated to high flow nasal cannula. Next Day, given her worsening mental status; Emapalumab (GAMIFANT, Novimmune SA), a fully human anti–IFN-gamma monoclonal antibody for HLH, was administered. Her cognitive function further declined, and she progressed to multiorgan failure and death. DISCUSSION: Aplastic anemia is a hematologic disorder characterized by pancytopenia and bone marrow aplasia. Bone marrow transplantation and immunosuppressive therapy are the modalities currently used, with success rates ranging 60% to 80%. Most treatment options for EBV-HLH have unclear effectiveness in adults. CONCLUSIONS: Despite trying rituximab, dexamethasone, etoposide, tocilizumab and Emapalumab, our transplant patient exhibits a unique and ambiguous intersection of EBV-associated refractory HLH, unresponsive to treatments. REFERENCE #1: Imashuku S, Kuriyama K, Sakai R, Nakao Y, Masuda S, Yasuda N, et al. Treatment of Epstein-Barr virus-associated hemophagocytic lymphohistiocytosis (EBV-HLH) in young adults: a report from the HLH study center. Med Pediatr Oncol. 2003;41(2):103-9. REFERENCE #2: Fox CP, Shannon-Lowe C, Gothard P, Kishore B, Neilson J, O'Connor N, et al. Epstein-Barr virus-associated hemophagocytic lymphohistiocytosis in adults characterized by high viral genome load within circulating natural killer cells. Clin Infect Dis. 2010;51(1):66-9. REFERENCE #3: Locatelli F, Jordan MB, Allen C, Cesaro S, Rizzari C, Rao A, et al. Emapalumab in Children with Primary Hemophagocytic Lymphohistiocytosis. N Engl J Med. 2020;382(19):1811-22. DISCLOSURES: No relevant relationships by Padmastuti Akella, source=Web Response No relevant relationships by Saira Imran, source=Web Response No relevant relationships by Aizaaz Khan, source=Web Response No relevant relationships by Kevin Lazo, source=Web Response

Haemophagocytic lymphohistiocytosis in pregnancy.

Haemophagocytic lymphohistiocytosis is a life-threatening systemic inflammatory syndrome defined by persistent fever, cytopenia and multi-organ dysfunction. Primary haemophagocytic lymphohistiocytosis classically presents in childhood as a result of genetically abnormal perforin or inflammasome function, leading to the aberrant release of pro-inflammatory cytokines causing a hyperinflammatory state. Secondary haemophagocytic lymphohistiocytosis is an acquired phenomenon occurring at any age as a result of immune dysregulation to a specific trigger such as infection, haematological malignancy or autoimmune disease. Secondary haemophagocytic lymphohistiocytosis occurring in the pregnant woman represents a diagnostic challenge and carries a significant mortality. This has led to its first inclusion in the fourth Mothers and Babies: Reducing Risk through Audits and Confidential Enquiries across the United Kingdom annual maternal report in 2017. This article presents an overview of haemophagocytic lymphohistiocytosis, reviews the literature on haemophagocytic lymphohistiocytosis in pregnancy, suggests diagnostic pathways and explores the safety and efficacy of existing and potential treatment strategies for haemophagocytic lymphohistiocytosis occurring during pregnancy.

Acute Epstein‐Barr virus associated haemophagocytosis in an Asian female: What is the diagnosis?

Acute <scp>Epstein‐Barr</scp> virus associated haemophagocytosis in an Asian female: What is the diagnosis?

Neurological involvement in secondary hemophagocytic lymphohistiocytosis in children.

To describe neurological characteristics and CNS involvement on MRI in secondary hemophagocytic lymphohistiocytosis (sHLH) and differentiate it from primary hemophagocytic lymphohistiocytosis (pHLH) and acute disseminated encephalomyelitis (ADEM). Nine children with sHLH who had neurological symptoms were retrospectively included. Characteristics of brain MRI were compared to those of 15 children with pHLH and neurological involvement and 44 children with ADEM. Three children (33%) presented with isolated neurological symptoms. Neurological signs occurred within one month following Epstein-Barr virus primary infection or systemic juvenile arthritis exacerbation in 8 patients (89%). Eight children (89%) had MRI lesions. sHLH MRI lesions were distinct of those of pHLH by morphology and signal with more frequent hyposignal intensities on T1-weighted sequences (p=0.01) and well-defined and less fuzzy lesions (p=0.03). All patients survived and one patient presented severe motor and cognitive disability. Neurological symptoms of sHLH are non-specific and their outcome is favorable in most of the children. MRI at onset may help to differentiate this condition from pHLH.

CD8 + T Cells Exhibit an Exhausted Phenotype in Hemophagocytic Lymphohistiocytosis.

Hemophagocytic lymphohistiocytosis (HLH) is a hyperinflammatory syndrome mainly caused by uncontrolled activation of antigen presenting cells and CD8 T cells. CD8 T cell exhaustion is a known phenomenon in chronic viral infections and cancer. However, the role of T cell exhaustion is not yet identified in HLH in the background of persistent inflammation. So, currently, we have characterized the CD8 T cells using flow cytometry to understand the phenomenon of exhaustion in these cells in HLH. We have comprehensively evaluated lymphocyte subsets and characterized CD8 T cells using immunophenotypic markers like PD1, TIM3, LAG3, Ki67, Granzyme B, etc. in a cohort of 21 HLH patients. Effector cytokine secretion and degranulation by CD8 T cells are also studied. Our findings indicate skewed lymphocyte subsets and aberrantly activated CD8 T cells in HLH. CD8 T cells exhibit significantly increased expression of PD1, TIM3, and LAG3 prominently in primary HLH as compared to controls. PD1 + CD8 T cells express elevated levels of Granzyme B and Ki67. Moreover, CD8 T cells are hypofunctional as evidenced by significantly reduced cytokine secretion and compromised CD107a degranulation. The study has revealed that CD8 + cytotoxic T lymphocytes from HLH patients exhibited high expression of exhaustion markers with overall impaired function. To the best of our understanding, this is the first report suggesting functional exhaustion of CD8 T cells in both primary and secondary HLH. Future studies to understand the association of exhaustion with disease outcome are needed for its probable therapeutic implementation.

Epidemiological investigation of hemophagocytic lymphohistiocytosis in China

BackgroundCurrently, most research on hemophagocytic lymphohistiocytosis (HLH) have focused on etiology and therapy, leaving few epidemiological reports. The published studies of China are mainly regional investigations. We aimed to present the overall epidemiological status of HLH in China, and provide Chinese data for the international HLH epidemiological investigation.MethodsThe data of HLH cases in China in 2019 were collected and statistically analyzed.FindingsEpstein-Barr virus accounted for 44.01% of the 1445 cases in 31 regions and was the most common cause. Lymphoma-associated HLH patients were more often male (P < 0.05) while rheumatic and immune-associated HLH were more often female (P < 0.001). Primary HLH and Epstein-Barr Virus-associated HLH were predominant in children (P < 0.001) while tumor-associated HLH was predominant in adults. Lymphoma-associated HLH was positively correlated with the age of onset (P < 0.01). The diagnosis rate of 29 areas had a significant correlation with per capita Gross domestic product (P < 0.05).ConclusionThe different distribution of HLH etiology by age and gender contributes to the diagnosis of HLH by clinicians; The suboptimal diagnosis rate in regions with a high incidence of HLH in China is a result of the effect of the local economic level indicating the importance of improving the regional medical level.

Comparison of the clinical features and outcome of children with hemophagocytic lymphohistiocytosis (HLH) secondary to visceral leishmaniasis and primary HLH: a single-center study

BackgroundHemophagocytic lymphohistiocytosis (HLH) is a syndrome of excessive inflammation. We aimed to describe the clinical and laboratory findings of HLH patients secondary to Visceral leishmaniasis (VL) and their treatment outcome during a 4-year follow-up period compared to primary HLH.MethodForty children with primary HLH confirmed by genetic study and 20 children with HLH secondary to VL confirmed by a blood or bone marrow polymerase chain reaction from 2014 to 2018 in Shiraz, Fars province, Southern Iran, were enrolled.ResultsThe median age at diagnosis was 11.5 months (range 1–170), and 56.7% were male. Fever and splenomegaly were the most frequent clinical presentations. 93.3% of the subjects had an HScore > 169, which had a good correlation with HLH-2004 criteria (r = 0.371, P = 0.004). Patients with primary HLH experienced more thrombocytopenia (P = 0.012) and higher alanine transaminase (P = 0.016), while patients with VL-associated HLH had higher ferritin (P = 0.034) and erythrocyte sedimentation rate (P = 0.011). Central nervous system (CNS) involvement occurred in 38.3% of patients. The mortality rate was higher in patients with CNS disease (61% vs. 35%, P = 0.051). The 3-yr overall survival rate was 35.9%. (24% in primary HLH and 100% in VL-associated HLH, P < 0.001). In Cox regression analysis, platelet count < 100,000/ μ l (hazard ratio 4.472, 95% confidence interval 1.324–15.107, P = 0.016) correlated with increased mortality in patients with primary HLH.ConclusionVL is a potential source of secondary HLH in regions with high endemicity. Treatment of the underlying disease in VL-associated HLH is sufficient in most cases, with no need to start etoposide-based chemotherapy.

Association between genotype and clinical phenotype in children with primary hemophagocytic lymphohistiocytosis

Objective: To investigate the association between genotype and clinical phenotype in children with primary hemophagocytic lymphohistiocytosis (HLH). Methods: Clinical data of 38 children with primary HLH at Beijing Children's Hospital from November 2015 to October 2020 were analyzed retrospectively. According to whether destructive mutation site, familial HLH (FHL) or non-familial HLH, degranulation pathway and non-degranulation pathway were detected in them, these patients were divided into different groups. Clinical characteristics, laboratory tests and functional tests were analyzed in different groups. Wilcoxon test or chi-square test were used for comparison between groups. Results: Among 38 cases, there were 23 males and 15 females. The age of onset was 2.5 (0.1-13.7) years. PRF1 (13/38, 34%) and UNC13D (12/38, 32%) gene mutations had the highest detectable rate. Correlation analysis between genotypes and phenotypes suggested that patients in destructive mutation sites group (n=25) had a younger age of onset than that in non-destructive mutation sites group (n=13) (1.0 (0.1-9.0) vs. 4.0 (0.4-13.4) years, Z=-2.711, P=0.005). The incidence of central nervous system involvement and convulsion was higher in patients in familial HLH group (n=26) than that in non-familial HLH group (n=12)(62% (16/26) vs. 2/12, χ²=6.631, P=0.015; 54% (14/26) vs. 2/12, χ²=4.656, P=0.040). The levels of soluble CD25, bilirubin, interferon γ (IFN-γ) and interleukin 10 (IL-10) were higher in degranulation pathway impairment group than that in the non-degranulation pathway impairment group (38 444 (2 393-44 000) vs.15 304 (1 620-36 937) ng/L,Z=2.634,P=0.008; 23.5 (6.3-126.4) vs. 6.0 (3.6-31.0) μmol/L, Z=2.992, P=0.003; 20.7 (0-248.7) vs. 11.9 (2.6-21.0) ng/L, Z=2.156, P=0.031; 20.7 (4.3-2 500.0) vs. 11.8 (4.0-88.0) ng/L, Z=2.210, P=0.027). However, the levels of neutrophils, ferritin and lactate dehydrogenase (LDH) in degranulation pathway impairment group were lower in the non-degranulation pathway impairment group (0.5 (0.1-8.0)×109 vs. 1.0 (0.9-2.3)×109/L, Z=-3.197, P=0.001; 1 133 (78-10 452) vs. 3 048 (630-37 900) μg/L, Z=-2.407, P=0.016; 410 (188-1 254) vs. 599 (389-3 147) U/L, Z=-2.489, P=0.013). Conclusions: PRF1 and UNC13D gene mutations are most common in primary HLH. Patients with destructive gene mutations have a younger age of onset. Patients with familial HLH are more likely to have central nervous system involvement and convulsions. The levels of sCD25, bilirubin, IFN-γ and IL-10 are higher in the degranulation pathway patients.

Definition and validation of serum biomarkers for optimal differentiation of hyperferritinaemic cytokine storm conditions in children: a retrospective cohort study.

Cytokine storm syndromes are life-threatening complications that can occur in children with rheumatic conditions (macrophage activation syndrome [MAS]), inherited cytotoxicity defects (ie, primary haemophagocytic lymphohistiocytosis [HLH]), or as a result of infection or malignancies (ie, secondary HLH). To adequately steer treatment, an early and clear discrimination of these entities is essential. We aimed to define and validate serum biomarker profiles that can differentiate between primary HLH, secondary HLH (predominantly infection-associated), and MAS associated with systemic juvenile idiopathic arthritis (systemic JIA-MAS). In this multicentre, retrospective, cohort study, serum samples from patients (0-18 years) with a clinical diagnosis of primary HLH, secondary HLH, or systemic JIA-MAS were analysed by immunoassays for 55 cytokines and chemokines. Serum samples were collected from patients treated at seven clinical centres in Europe and North America. 15 serum biomarkers were validated using an independent commercial assay, and the diagnostic accuracy of the best performing biomarkers was tested in an independent validation cohort. Serum samples were collected between Dec 7, 2010, and Jan 26, 2018. In the discovery cohort of 43 patients (24 girls and 19 boys) multi-marker analyses revealed distinct serum biomarker profiles associated with primary or secondary HLH versus systemic JIA-MAS. Ten biomarkers were identified that were differentially elevated in either HLH or systemic JIA-MAS and distinguished between these clinical entities, six of which were tested in an independent validation cohort of 79 patients (34 girls and 45 boys). Serum concentrations of S100A12 and interleukin-18, as well as ratios of both S100A12 and IL-18 with chemokine (C-X-C motif) ligand (CXCL)9 and CXCL10 were identified as the most promising candidates for differential diagnostics. At initial presentation, when it is unclear whether a patient with excessive hyperferritinaemic inflammation has primary HLH, infection-associated secondary HLH, or MAS, high serum concentrations of S100A12 indicate an initial differential diagnosis of systemic JIA-MAS, thus helping to guide subsequent treatment decisions. We therefore suggest the inclusion of serum S100A12 and IL-18 in the diagnostic investigations for hyperferritinaemic syndromes; however, the definition and introduction of universially applicable cutoff values are still required. German Research Foundation, the Center for Interdisciplinary Clinical Research at University Hospital Muenster, the EU's Horizon 2020 research and innovation programme, and the Deutsche Kinderkrebsstiftung.

T Cell-Epstein-Barr Virus-Associated Hemophagocytic Lymphohistiocytosis (HLH) Occurs in Non-Asians and Is Associated with a T Cell Activation State that Is Comparable to Primary HLH.

PurposeT cell-Epstein-Barr virus–associated hemophagocytic lymphohistiocytosis (T cell-EBV-HLH) is prevalent in East Asia and has poor prognosis. Understanding of this disease is limited, and literature regarding prevalence in North America is scarce. Herein, we summarize our experience.MethodsA retrospective analysis of T cell-EBV-HLH patients admitted to Children’s Healthcare of Atlanta (GA, USA) from 2010 to 2020 was conducted. Additional immune studies were completed in a subset of patients.ResultsWe report 15 patients (10 months–19 years of age) diagnosed with T cell-EBV-HLH. Nine patients were Hispanic, and the majority did not have primary HLH (p-HLH) gene defects. Soluble interleukin-2 receptor levels in T cell-EBV-HLH were significantly higher than other forms of secondary-HLH but comparable to p-HLH, and it correlated with disease severity at presentation. Natural killer cell function was decreased in most patients despite a negative workup for p-HLH. Depending on disease severity, initial therapy included dexamethasone or dexamethasone and etoposide. Refractory patients were managed with blended regimens that included one or more of the following therapies: combination chemotherapy, alemtuzumab, emapalumab, and nivolumab. Rituximab did not appreciably decrease EBV viremia in most patients. Non-critically ill patients responded well to immunosuppressive therapy and are long-term survivors without undergoing allogeneic hematopoietic stem cell transplantation (HSCT). Alemtuzumab resulted in inflammation flare in two of the three patients. Three patients underwent allogeneic HSCT, with disease relapse noted in one. At a median follow-up of 3 years, 10 of the 15 patients are alive.ConclusionT cell-EBV-HLH occurs in the USA among the non-Asian populations, especially in those who are Hispanic.