Immunopathology of and potential therapeutics for secondary hemophagocytic lymphohistiocytosis/macrophage activation syndrome: a translational perspective.

Secondary hemophagocytic lymphohistiocytosis/macrophage activation syndrome (sHLH/MAS) is a life-threatening immune disorder triggered by rheumatic disease, infections, malignancies, or medications. Characterized by the presence of hemophagocytic macrophages and a fulminant cytokine storm, sHLH/MAS leads to hyperferritinemia and multiorgan failure and rapidly progresses to death. The high mortality rate and the lack of specific treatments necessitate the development of a new drug. However, the complex and largely unknown immunopathologic mechanisms of sHLH/MAS, which involve dysfunction of various immune cells, diverse etiologies, and different clinical contexts make this effort challenging. This review introduces the terminology, diagnosis, and clinical features of sHLH/MAS. From a translational perspective, this review focuses on the immunopathological mechanisms linked to various etiologies, emphasizing potential drug targets, including key molecules and signaling pathways. We also discuss immunomodulatory biologics, existing drugs under clinical evaluation, and novel therapies in clinical trials. This systematic review aims to provide insights and highlight opportunities for the development of novel sHLH/MAS therapeutics.

The 4th NextGen therapies for SJIA and MAS: part 3 clinical trials in refractory SJIA: historic controls as an alternative to a withdrawal design study.

The substantial morbidity and mortality associated with refractory systemic JIA underlies the need for new treatment approaches. However, progress in this area has been limited by the difficulty of enrolling these patients in clinical trials with traditional designs, particularly in patients presenting with the life-threatening macrophage activation syndrome. At the NextGen 2022 conference, there was group consensus that using historical cohorts as a control group to avoid the need for a placebo-arm or drug withdrawal was highly desirable and might be acceptable for clinical trials in MAS to support medication efficacy and safety. However, if historic controls were used in a trial, it would be important to ensure that the historic cohort matches the study group in terms of clinical characteristics (such as disease severity and exposure to other medications), and that disease outcome in both groups is assessed using the same outcome measures. The discussions at the NextGen 2022 conference focused on the potential strategies to achieve these goals.

Macrophage activation syndrome with acute hepatitis in a patient with adult-onset immunodeficiency with anti-interferon gamma antibodies: a case report.

BACKGROUND: Macrophage activation syndrome is a rare disorder leading to unregulated immune activity manifesting with nonspecific constitutional symptoms, laboratory abnormalities, and multiorgan involvement. We report the case of a patient who presented with acute hepatitis secondary to macrophage activation syndrome diagnosed by liver biopsy and successfully treated with intravenous immune globulin, anakinra, and rituximab. CASE PRESENTATION: A 42-year-old Laotian woman with adult-onset immunodeficiency with anti-interferon gamma antibodies presented with a fever, headache, generalized myalgia, dark urine, and reduced appetite in the setting of family members at home with similar symptoms. Her laboratory workup was notable for evidence of acute hepatitis without acute liver failure. After an unrevealing comprehensive infectious and noninvasive rheumatologic workup was completed, a liver biopsy was performed ultimately revealing the diagnosis of macrophage activation syndrome. She was successfully treated with intravenous immune globulin, anakinra, and rituximab. CONCLUSION: This case highlights the importance of maintaining macrophage activation syndrome on the differential of a patient with acute hepatitis of unknown etiology in the correct clinical context and the value of a liver biopsy in making a diagnosis when noninvasive testing is unrevealing.

A rare case of coronary artery complication in a child with systemic juvenile idiopathic arthritis and macrophage activation syndrome: case report and literature review.

A rare case of coronary artery involvement in a child with Systemic Juvenile Idiopathic Arthritis (sJIA) complicated by Macrophage Activation Syndrome (MAS) is reported. The patient initially received an inaccurate diagnosis of Kawasaki Disease, sepsis, and mycoplasma infection and showed no improvement after Intravenous Immune Globulin (IVIG) treatment. Upon admission, symptoms included diffuse red rash, swelling of the limbs, lymph node enlargement, and hepatosplenomegaly. Post investigations, a diagnosis of sJIA and MAS was confirmed, and treatment involved a combination of hormones (methylprednisolone) and immunosuppressive drugs (methotrexate). The revealed widened coronary artery diameter was managed with a disease-specific treatment plan and prophylactic plus low-dose aspirin anti-coagulation therapy. Under this management, MAS was well controlled, and follow-ups showed normalization of the child's coronary artery structure and function. This case and the associated literature review underscore the importance of early recognition, diagnosis, treatment, and long-term monitoring for children presenting with sJIA and MAS complicated by coronary artery involvement.

Recent advances and evolving concepts in Still's disease.

Still's disease is a rare inflammatory syndrome that encompasses systemic juvenile idiopathic arthritis and adult-onset Still's disease, both of which can exhibit life-threatening complications, including macrophage activation syndrome (MAS), a secondary form of haemophagocytic lymphohistiocytosis. Genetic insights into Still's disease involve both HLA and non-HLA susceptibility genes, suggesting the involvement of adaptive immune cell-mediated immunity. At the same time, phenotypic evidence indicates the involvement of autoinflammatory processes. Evidence also implicates the type I interferon signature, mechanistic target of rapamycin complex 1 signalling and ferritin in the pathogenesis of Still's disease and MAS. Pathological entities associated with Still's disease include lung disease that could be associated with biologic DMARDs and with the occurrence of MAS. Historically, monophasic, recurrent and persistent Still's disease courses were recognized. Newer proposals of alternative Still's disease clusters could enable better dissection of clinical heterogeneity on the basis of immune cell profiles that could represent diverse endotypes or phases of disease activity. Therapeutically, data on IL-1 and IL-6 antagonism and Janus kinase inhibition suggest the importance of early administration in Still's disease. Furthermore, there is evidence that patients who develop MAS can be treated with IFNγ antagonism. Despite these developments, unmet needs remain that can form the basis for the design of future studies leading to improvement of disease management.

[Systemic lupus erythematosus associated macrophage activation syndrome with neuropsychiatric symptoms: A report of 2 cases].

Systemic lupus erythematosus (SLE) associated macrophage activation syndrome (MAS) is clinically severe, with a high mortality rate and rare neuropsychiatric symptoms. In the course of diagnosis and treatment, it is necessary to actively determine whether the neuropsychiatric symptoms in patients are caused by neuropsychiatric systemic lupus erythematosus (NPSLE) or macrophage activation syndrome. This paper retrospectively analyzed the clinical data of 2 cases of SLE associated MAS with neuropsychiatric lesions, Case 1: A 30-year-old female had obvious alopecia in 2019, accompanied by emaciation, fatigue and dry mouth. In March 2021, she felt weak legs and fell down, followed by fever and chills without obvious causes. After completing relevant examinations, she was diagnosed with SLE and given symptomatic treatments such as hormones and anti-infection, but the patient still had fever. The relevant examinations showed moderate anemia, elevated ferritin, elevated triglycerides, decreased NK cell activity, and a perforin positivity rate of 4.27%, which led to the diagnosis of "pre-hemophagocytic syndrome (HPS)". In May 2021, the patient showed mental trance and babble, and was diagnosed with "SLE-associated MAS"after completing relevant examinations. After treatment with methylprednisolone, anti-infection and psychotropic drugs, the patient's temperature was normal and mental symptoms improved. Case 2: A 30-year-old female patient developed butterfly erythema on both sides of the nose on her face and several erythema on her neck in June 2019, accompanied by alopecia, oral ulcers, and fever. She was diagnosed with "SLE" after completing relevant examinations, and her condition was relieved after treatment with methylprednisolone and human immunoglobulin. In October 2019, the patient showed apathy, no lethargy, and fever again, accompanied by dizziness and vomiting. The relevant examination indicated moderate anemia, decreased NK cell activity, elevated triglycerides, and elevated ferritin. The patient was considered to be diagnosed with "SLE, NPSLE, and SLE-associated MAS". After treatment with hormones, human immunoglobulin, anti-infection, rituximab (Mabthera), the patient's condition improved and was discharged from the hospital. After discharge, the patient regularly took methylprednisolone tablets (Medrol), and her psychiatric symptoms were still intermittent. In November 2019, she developed symptoms of fever, mania, and delirium, and later turned to an apathetic state, and was given methylprednisolone intravenous drip and olanzapine tablets (Zyprexa) orally. After the mental symptoms improved, she was treated with rituximab (Mabthera). Later, due to repeated infections, she was replaced with Belizumab (Benlysta), and she was recovered from her psychiatric anomalies in March 2021. Through the analysis of clinical symptoms, imaging examination, laboratory examination, treatment course and effect, it is speculated that the neuropsychiatric symptoms of case 1 are more likely to be caused by MAS, and that of case 2 is more likely to be caused by SLE. At present, there is no direct laboratory basis for the identification of the two neuropsychiatric symptoms. The etiology of neuropsychiatric symptoms can be determined by clinical manifestations, imaging manifestations, cerebrospinal fluid detection, and the patient's response to treatment. Early diagnosis is of great significance for guiding clinical treatment, monitoring the condition and judging the prognosis. The good prognosis of the two cases in this paper is closely related to the early diagnosis, treatment and intervention of the disease.

Albumin-binding recombinant human IL-18BP ameliorates macrophage activation syndrome and atopic dermatitis via direct IL-18 inactivation.

Given the clinical success of cytokine blockade in managing diverse inflammatory human conditions, this approach could be exploited for numerous refractory or uncontrolled inflammatory conditions by identifying novel targets for functional blockade. Interleukin (IL)-18, a pro-inflammatory cytokine, is relatively underestimated as a therapeutic target, despite accumulated evidence indicating the unique roles of IL-18 in acute and chronic inflammatory conditions, such as macrophage activation syndrome. Herein, we designed a new form of IL-18 blockade, i.e., APB-R3, a long-acting recombinant human IL-18BP linked to human albumin-binding Fab fragment, SL335, for extending half-life. We then explored the pharmacokinetics and pharmacodynamics of APB-R3. In addition to an extended serum half-life, APB-R3 alleviates liver inflammation and splenomegaly in a model of the macrophage activation syndrome induced in IL-18BP knockout mice. Moreover, APB-R3 substantially controlled skin inflammation in a model of atopic dermatitis. Thus, we report APB-R3 as a new potent IL-18 blocking agent that could be applied to treat IL-18-mediated inflammatory diseases.

Treatment of systemic juvenile idiopathic arthritis.

Systemic juvenile idiopathic arthritis (sJIA) is an inflammatory disease with hallmarks of severe systemic inflammation, which can be accompanied by arthritis. Contemporary scientific insights set this paediatric disorder on a continuum with its counterpart, adult-onset Still disease (AOSD). Patients with sJIA are prone to complications, including life-threatening hyperinflammation (macrophage activation syndrome (sJIA-MAS)) and sJIA-associated lung disease (sJIA-LD). Meanwhile, the treatment arsenal in sJIA has expanded markedly. State-of-the-art therapeutic approaches include biologic agents that target the IL-1 and IL-6 pathways. Beyond these, a range of novel agents are on the horizon, some of them already being used on a compassionate use basis, including JAK inhibitors and biologic agents that target IL-18, IFNγ, or IL-1ß and IL-18 simultaneously. However, sJIA, sJIA-MAS and sJIA-LD still pose challenging conundrums to rheumatologists treating paediatric and adult patients worldwide. Although national and international consensus treatment plans exist for the treatment of 'classic' sJIA, the treatment approaches for early sJIA without arthritis, and for refractory or complicated sJIA, are not well defined. Therefore, in this Review we outline current approaches for the treatment of sJIA and provide an outlook on knowledge gaps.

Anakinra and hepatotoxicity in pediatric rheumatology: a case series.

BACKGROUND: Anakinra is a recombinant interleukin-1 (IL-1) receptor antagonist used in systemic juvenile idiopathic arthritis (sJIA), refractory Kawasaki disease (KD) and cryopyrin-associated autoinflammatory syndrome (CAPS). Anakinra associated hepatotoxicity, while rare, has been described in several cases in daily practice. ​In this case series the authors describe three pediatric patients with this side effect in the setting of severe macrophage activation syndrome (MAS) in KD and sJIA. CASE PRESENTATION: The first patient was a 12-year-old boy who presented with fever, maculo-papular exanthema and polyarthralgia. Tonsillitis, distal limb induration and tender cervical lymph nodes were observed. Erythrocyte-sedimentation rate (ESR), C-reactive protein (CRP), ferritin (11,975 ng/mL), D-dimers (5,98 mg/L FEU) and soluble CD25 (3645 pg/mL) levels were elevated. Exclusion of sepsis / toxic shock syndrome warranted introduction of IV methylprednisolone and immunoglobulin (IG IV), with partial response. A MAS secondary to KD was assumed, and anakinra 2 mg/kg/day was introduced. Twenty days later he developed new-onset nausea and severe cyto-cholestasis, normalizing after 2 months of drug discontinuation. Posterior onset of polyarthritis and evanescent lead to a final diagnosis of sJIA. The second patient was a 2-year-old boy with a 10-day history of fevers, generalized rash, hepatosplenomegaly and strawberry tongue. Leucocytosis with neutrophilia and elevated CRP were observed. Initial treatment with IVIG in the setting of incomplete KD was ineffective. Mild anaemia, leukopenia and very high serum ferritin (maximum 26,128 ng/mL) ensued. Presumptive sJIA associated MAS was treated with IV methylprednisolone and anakinra 2 mg/kg/day, with prompt response. Four weeks later transaminitis was detected, and temporary anakinra suspension led to normalisation of laboratorial values. The third case related to a 4-year-old boy presenting with fever, maculopapular rash and cervical lymphadenopathy. CRP and ESR were elevated, and KD was diagnosed. IVIG and methylprednisolone were initiated with clinical worsening, warranting for anakinra introduction at 2 mg/kg/day. After three weeks, liver enzymes progressively elevated, resolving on 2 weeks of anakinra discontinuation. CONCLUSIONS: To the best of our knowledge, this is the first case series describing anakinra associated hepatotoxicity in pediatric patients with rheumatic diseases other than sJIA, bringing additional insight to therapeutic monitoring in patients undergoing this treatment.

Intravenous anakinra for the treatment of haemophagocytic lymphohistiocytosis/macrophage activation syndrome: A systematic review.

BACKGROUND: Haemophagocytic lymphohistiocytosis (HLH) or macrophage activation syndrome (MAS) has a potentially high mortality rate. Anakinra, an interleukin-1 receptor antagonist, is now recommended early in HLH/MAS, with intravenous (IV) use proposed in critically unwell patients. This systematic review establishes the literature relating to IV anakinra in secondary HLH/MAS (sHLH/MAS). METHODS: We screened Embase, PubMed, and Medline, including all reports of IV anakinra for HLH or MAS. We extracted age, HLH/MAS trigger, continuous infusion or bolus dosing, and survival. RESULTS: Twenty-nine case reports/series identified 87 patients (median age 22 years, range 22 months to 84 years), all with sHLH. Amongst identifiable triggers, 43% were systemic infection, 33% rheumatological, 9% oncological. Children had predominantly a rheumatological trigger (48%), whilst adults were more commonly infection-driven (50%). Overall, rheumatologically triggered disease showed greater survival (83.3%), particularly compared with oncological triggers (42.9%). Children had a greater survival, particularly under 10 years (83%, vs. adults, 63%). CONCLUSIONS: Despite IV anakinra recipients likely to be critically unwell, this cohort had similar disease triggers and survival compared to large historical cohorts, and enhances awareness of age and trigger-specific survival patterns. IV anakinra had a wide therapeutic dosing range and tolerability, regardless of trigger, demonstrating substantial utility in severe sHLH/MAS.

Etoposide: A rider on the cytokine storm.

For more than 40 years, the epipodophyllotoxin drug etoposide is prescribed to treat cancer. This semi-synthetic compound remains extensively used to treat advanced small-cell lung cancer and in various chemotherapy regimen for autologous stem cell transplantation, and other anticancer protocols. Etoposide is a potent topoisomerase II poison, causing double-stranded DNA breaks which lead to cell death if they are not repaired. It is also a genotoxic compound, responsible for severe side effects and secondary leukemia occasionally. Beyond its well-recognized function as an inducer of cancer cell death (a "killer on the road"), etoposide is also useful to treat immune-mediated inflammatory diseases associated with a cytokine storm syndrome. The drug is essential to the treatment of hemophagocytic lymphohistiocytosis (HLH) and the macrophage activation syndrome (MAS), in combination with a corticosteroid and other drugs. The use of etoposide to treat HLH, either familial or secondary to a viral or parasitic infection, or treatment-induced HLH and MAS is reviewed here. Etoposide dampens inflammation in HLH patients via an inhibition of the production of pro-inflammatory mediators, such as IL-6, IL-10, IL-18, IFN-γ and TNF-α, and reduction of the secretion of the alarmin HMGB1. The modulation of cytokines production by etoposide contributes to deactivate T cells and to dampen the immune stimulation associated to the cytokine storm. This review discussed the clinical benefits and mechanism of action of etoposide (a "rider on the storm") in the context of immune-mediated inflammatory diseases, notably life-threatening HLH and MAS. The question arises as to whether the two faces of etoposide action can apply to other topoisomerase II inhibitors.

Systemic lupus erythematosus associated with development of macrophage activation syndrome and disseminated aspergillosis.

PURPOSE: Macrophage activation syndrome (MAS) is a rare illness, especially in critically ill adults. The diagnosis of MAS is challenging, requiring the expertise of multiple specialists, and treatments for MAS can be associated with catastrophic complications. CLINICAL FEATURES: We describe the case of a 31-yr-old Vietnamese student who was diagnosed with cutaneous systemic lupus erythematosus (SLE) in November 2020 and was initiated on treatment with low-dose corticosteroids and hydroxychloroquine as an outpatient. Ten days later, she presented to hospital with decreased consciousness, fever, periorbital swelling, and hypotension necessitating intubation. Computed tomography angiography (CTA) and lumbar puncture did not show a stroke or central nervous system infection. Serology and clinical presentation were consistent with MAS. She was initially treated with 4.5 g pulse methylprednisolone and subsequently with the interleukin-1 receptor antagonist, anakinra, and maintenance corticosteroids because of persistently elevated inflammatory markers. Her intensive care unit stay was complicated by aspiration, airway obstruction due to fungal tracheobronchitis necessitating extracorporeal membrane oxygenation (ECMO), and ring-enhancing cerebral lesions, and, ultimately, massive hemoptysis resulting in death. CONCLUSIONS: Four features of this case merit discussion, including the: 1) infrequent association of SLE with MAS; 2) short interval between SLE diagnosis and critical illness; 3) manifestation of fungal tracheobronchitis with airway obstruction; and 4) lack of response to antifungal treatment while receiving ECMO.

RéSUMé: OBJECTIF: Le syndrome d'activation macrophagique (SAM) est une maladie rare, en particulier chez les adultes gravement malades. Le diagnostic d'un SAM est difficile à poser, nécessitant l'expertise de plusieurs spécialistes, et les traitements de ce syndrome peuvent être associés à des complications catastrophiques. CARACTéRISTIQUES CLINIQUES: Nous décrivons le cas d'une étudiante vietnamienne de 31 ans ayant reçu un diagnostic de lupus érythémateux disséminé (LED) cutané en novembre 2020; un traitement par corticostéroïdes à faible dose et hydroxychloroquine a été amorcé en ambulatoire. Dix jours plus tard, elle s'est présentée à l'hôpital avec une diminution de la conscience, de la fièvre, un gonflement périorbitaire et une hypotension nécessitant une intubation. L'angiographie par tomodensitométrie et la ponction lombaire n'ont pas révélé d'accident vasculaire cérébral ou d'infection du système nerveux central. La sérologie et la présentation clinique correspondaient à celles d'un SAM. Elle a d'abord été traitée avec 4,5 g de méthylprednisolone en injection ponctuelle, puis avec un antagoniste du récepteur à l'interleukine-1, l'anakinra et des corticostéroïdes d'entretien en raison de marqueurs inflammatoires élevés persistants. Son séjour en soins intensifs a été compliqué par une aspiration, une obstruction des voies aériennes due à une trachéobronchite fongique nécessitant une oxygénation par membrane extracorporelle (ECMO) et des lésions cérébrales avec rehaussement en anneau, et finalement une hémoptysie massive entraînant la mort. CONCLUSION: Quatre caractéristiques de ce cas méritent d'être discutées, soit: 1) l'association peu fréquente du lupus érythémateux disséminé avec un syndrome d'activation macrophagique; 2) le court intervalle entre le diagnostic de LED et la maladie grave; 3) l'apparition d'une trachéobronchite fongique avec obstruction des voies aériennes; et 4) l'absence de réponse au traitement antifongique pendant le traitement par ECMO.

Efficacy and safety of emapalumab in macrophage activation syndrome.

OBJECTIVES: Macrophage activation syndrome (MAS) is a severe, life-threatening complication of systemic juvenile idiopathic arthritis (sJIA) and adult-onset Still's disease (AOSD). The objective of this study was to confirm the adequacy of an emapalumab dosing regimen in relation to interferon-γ (IFNγ) activity by assessing efficacy and safety. The efficacy outcome was MAS remission by week 8, based on clinical and laboratory criteria. METHODS: We studied emapalumab, a human anti-IFNγ antibody, administered with background glucocorticoids, in a prospective single-arm trial involving patients who had MAS secondary to sJIA or AOSD and had previously failed high-dose glucocorticoids, with or without anakinra and/or ciclosporin. The study foresaw 4-week treatment that could be shortened or prolonged based on investigator's assessment of response. Patients entered a long-term (12 months) follow-up study. RESULTS: Fourteen patients received emapalumab. All patients completed the trial, entered the long-term follow-up and were alive at the end of follow-up. The investigated dosing regimen, based on an initial loading dose followed by maintenance doses, was appropriate, as shown by rapid neutralisation of IFNγ activity, demonstrated by a prompt decrease in serum C-X-C motif chemokine ligand 9 (CXCL9) levels. By week 8, MAS remission was achieved in 13 of the 14 patients at a median time of 25 days. Viral infections and positive viral tests were observed. CONCLUSIONS: Neutralisation of IFNγ with emapalumab was efficacious in inducing remission of MAS secondary to sJIA or AOSD in patients who had failed high-dose glucocorticoids. Screening for viral infections should be performed, particularly for cytomegalovirus. TRIAL REGISTRATION NUMBER: NCT02069899 and NCT03311854.

Treatment for macrophage activation syndrome associated with systemic juvenile idiopathic arthritis in Japan.

OBJECTIVES: To clarify how pediatric rheumatologists treat systemic juvenile idiopathic arthritis (s-JIA) associated macrophage activation syndrome (MAS) in the real world and to assess the efficacy and safety of dexamethasone palmitate (DEX-P) in the treatment of s-JIA-associated MAS. METHODS: This multicenter, retrospective study was conducted at 13 pediatric rheumatology institutes in Japan. This study included 28 patients with s-JIA-associated MAS. Clinical findings, such as treatment details and adverse events, were evaluated. RESULTS: Methylprednisolone (mPSL) pulse therapy was selected as the first-line treatment in more than half of the patients with MAS. Cyclosporine A (CsA) was used as first-line therapy in combination with corticosteroids in half of the patients with MAS. DEX-P and/or CsA were selected as the second-line therapy in 63% of patients with corticosteroid-resistant MAS. Plasma exchange was selected as the third-line therapy for DEX-P and CsA-resistant MAS. All patients improved and there were no characteristically severe adverse events associated with DEX-P. CONCLUSIONS: The first-line treatment for MAS in Japan is mPSL pulse therapy and/or CyA. DEX-P could be an effective and safe therapeutic option for patients with corticosteroid-resistant MAS.

Intravenous anakinra to curb cytokine storm in adult-onset Still's disease and in macrophage activation syndrome: A case series.

OBJECTIVE: Adult-onset Still's disease (AOSD) is an auto-inflammatory polygenic disorder, for which the diagnosis is essentially clinical. The exclusion of mimickers [such as common bacterial and viral infections, hematologic malignancies, and, more recently, severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2)] is necessary to confirm the diagnosis. Anti-interleukin (IL)-1 therapy is considered a treatment milestone for AOSD. Herein, we present a short series of newly-diagnosed AOSD or upcoming macrophage activation syndrome (MAS) cases who received intravenous (IV) anakinra, an IL-1 receptor blocker. METHODS: Four patients with newly-diagnosed AOSD or upcoming MAS were treated with IV anakinra at the Rheumatology Unit of Padova University Hospital, Italy. We obtained informed consent from the patients for use of their cases and medical images for publication purposes. RESULTS: All patients presented with AOSD or MAS during the COVID-19 pandemic, making diagnosis challenging due to similar immunological and clinical characteristics across both pathologies. All patients presented with hyperpyrexia and elevated inflammatory markers; two patients had a skin rash typically seen in AOSD. IV anakinra slowed down AOSD progression in all patients, prevented severe outcomes and mitigated the risk of multiorgan failure. All cases improved within 24hours of anakinra administration. CONCLUSION: We found that administration of anakinra in patients with newly-diagnosed AOSD and/or upcoming MAS reduced hyperinflammation and prevented life-threatening complications. The IV route appears to be preferable in the hospital setting, where comorbidities such as coagulopathies and thrombocytopenia can complicate the use of other routes of administration.