Hemophagocytic lymphohistiocytosis: pathogenesis and treatment

FDA Approval Summary: Ciltacabtagene Autoleucel for Relapsed or Refractory Multiple Myeloma

In February 2022, the FDA approved ciltacabtagene autoleucel, a chimeric antigen receptor (CAR) T-cell therapy targeting the B-cell maturation antigen, for adult patients with relapsed/refractory multiple myeloma after ≥4 lines of therapy, including an immunomodulatory agent, a proteasome inhibitor, and an anti-CD38 monoclonal antibody. Approval was based on overall response rate (ORR), complete response (CR) rate, and duration of response (DoR) in 97 adult patients in a single-arm, open-label, multicenter phase 2 trial (CARTITUDE-1 [NCT03548207]). Patients received a single infusion of ciltacabtagene autoleucel, preceded by lymphodepleting chemotherapy. Of the 97 patients evaluable, ORR was 97.9% [95% confidence interval (CI), 92.7-99.7] with a stringent CR rate of 78.4% (95% CI, 68.8-86.1). After median follow-up of 18 months, the median DoR was 21.8 months (95% CI, 21.8-not estimable [NE]) in responders (PR or better) and NE (95% CI, 21.8 months-NE) in patients who achieved stringent CR. Serious adverse reactions occurred in 55% of the 97 patients evaluated for safety. Grade 3 or higher cytokine release syndrome (CRS) and neurologic toxicities occurred in 5% and 11% of the patients, respectively, leading to a Risk Evaluation and Mitigation Strategy. Neurologic toxicities included immune effector cell-associated neurologic syndrome, typically seen with CAR-T products, parkinsonism, peripheral neuropathy, cranial nerve palsies, and Guillain-Barré syndrome. One fatal case of hemophagocytic lymphohistiocytosis/macrophage activation syndrome occurred. Prolonged and recurrent grade 3 or 4 cytopenias occurred; a single patient required hematopoietic stem-cell rescue.

Nephrotoxicity in Bispecific Antibodies Recipients: Focus on T-Cell-Engaging Bispecific Antibodies

Recently, bispecific antibodies (BsAbs) are evolving the landscape of cancer treatment and have significantly improved the outcomes of relapsed or refractory cancer patients. As increasing BsAbs entered clinical practice, specific toxicities have emerged, and renal side-effects have been described. However, there are a lack of studies analyzing the nephrotoxicity in the anti-cancer BsAbs recipients systematically. In this review, we demonstrate the etiologies, mechanisms, other risk factors and treatment options of kidney injury in the BsAbs recipients to provide a more comprehensive insight into the nephrotoxicity post-BsAbs therapy. Significantly, due to the limited clinical trial data on each subject, we mainly conclude the related etiologies, mechanisms, and risk factors of nephrotoxicity that occur in T-cell-engaging BsAbs recipients. Nephrotoxicity associated with non-T-cell BsAbs may be associated with adverse nephrotoxicity of related monoclonal antibodies to two specific antigens. The aim of this paper is to provide nephrologists and oncologists with theoretical knowledge to provide better medical management for recipients who receive BsAbs, especially T-cell-engaging BsAbs treatment.

Clinical Presentations, Diagnosis, and Genetic Features of Hemophagocytic Lymphohistiocytosis: A Single Institutional Experience With the Saudi Population

Background Hemophagocytic lymphohistiocytosis (HLH) is an uncommon, potentially fatal condition caused by high immune activation. The present study aimed to identify the clinical manifestations, geographic distribution, and associated pathogenic genetic mutations of HLH in Saudi Arabia. Method A retrospective cross-sectional study was conducted at King Fahad Medical City (KFMC), with a total of 59 patients diagnosed with HLH in the period between 2006 and 2018. All genetic results and clinical and biochemical data were retrieved and statistically analyzed using IBM SPSS Statistics for Windows, Version 25 (Released 2017; IBM Corp., Armonk, New York, United States). Results The results revealed that 48 patients (81.4%) had 15 pathogenic mutations of primary HLH whereas 8 (13.6%) patients had no genetic mutation. The most common variant mutation identified was c.1430C>T of the STXBP2 gene (42.4% of total patients), followed by c.1122G>A of the PRF1 gene (10.2% of patients), which demonstrated a distinctive geographic and tribal association. Patients with RAB27A mutation tend to present at an older age than the others with a median age of presentation of 5.5 months vs 2 months for patients with PRF1 mutations. No significant differences in clinical features were observed among the various groups. Conclusion This study highlights the incidence of genetic mutations among the Saudi population with HLH. The STXBP2 is the most common mutation followed by PRF1 mutations, many mutation variants are associated with a distinctive tribal and geographic association.

Population Pharmacokinetics of the Anti-Interferon-Gamma Monoclonal Antibody Emapalumab: An Updated Analysis

INTRODUCTION

Emapalumab is a fully human monoclonal antibody that targets free and receptor-bound interferon-gamma (IFNγ), neutralizing its biological activity. IFNγ levels differ by orders of magnitude between patients with primary hemophagocytic lymphohistiocytosis (HLH) and macrophage activation syndrome (MAS; a form of secondary HLH) in systemic juvenile idiopathic arthritis (sJIA). Therefore, this study aimed to develop a population pharmacokinetic model for emapalumab across a patient population with a wide range of total (free and emapalumab-bound) IFNγ levels using observations from patients with primary HLH or MAS in sJIA in clinical trials.

METHODS

Pharmacokinetic data were pooled (n = 58; 2709 observations) from studies enrolling patients administered emapalumab for primary HLH or MAS in sJIA. Patients with primary HLH were administered emapalumab 1 mg/kg (potentially increasing to 3, 6, and up to 10 mg/kg based on clinical response) every 3 days. Patients with MAS in sJIA were administered emapalumab 6 mg/kg, followed by 3 mg/kg every 3 days until day 15 and twice weekly until day 28. An earlier population PK model was re-parameterized using this data.

RESULTS

The final model for emapalumab comprised a 2-compartment model with first-order elimination. Emapalumab clearance remains constant when the total IFNγ concentration (free and emapalumab-bound) is < ~ 10,000 pg/ml but increases proportionally to total IFNγ concentration above this threshold. Emapalumab clearance was estimated to be 0.00218, 0.00308, 0.00623 and 0.01718 l/h at total serum IFNγ concentrations of 103, 104, 105 and 106 pg/ml, respectively, with corresponding terminal half-lives of 19.2, 13.8, 7.18 and 3.12 days for a 1-year-old patient weighing 10 kg with primary HLH. The median terminal half-life for emapalumab in patients with MAS in sJIA was estimated to be 24.0 (range, 6.13-32.4) days, which is similar to observations in healthy volunteers.

CONCLUSIONS

Emapalumab pharmacokinetics in patients with primary HLH and MAS in sJIA were described by a two-compartment model with fixed allometric exponents and an age-related effect. Differences in total IFNγ levels between patients with primary HLH and MAS may affect emapalumab pharmacokinetics, suggesting that each indication may require different dosing to rapidly control hyperinflammation.

TRIAL REGISTRATION

Clinicaltrials.gov identifiers: NCT01818492, NCT03311854 and NCT02069899.

Haemophagocytic lymphohistiocytosis caused by GATA2 deficiency: a report on three patients

BACKGROUND

Haemophagocytic lymphohistiocytosis (HLH) is a syndrome that occurs in patients with severe systemic hyperinflammation. GATA binding protein 2 (GATA2) is a transcription factor and key component in haematopoiesis and stem cell biology.

CASE PRESENTATION

Three patients with HLH, one with Mycobacterium avium infection, one with Epstein-Barr virus (EBV) infection, and one with Mycobacterium kansasii infection, were all subsequently found to have a defect in the GATA2 gene through genetic testing.

CONCLUSIONS

GATA2 deficiency syndrome should be considered in patients with myelodysplastic syndrome, nontuberculous mycobacterium infection and HLH. In addition, the GATA2 gene variant may be a genetic defect that could be the cause of the primary HLH. However, further studies are needed to confirm the role of GATA2 pathogenic variants in the pathogenesis of HLH.

Tuberculosis-Associated Hemophagocytic Lymphohistiocytosis: Diagnostic Challenges and Determinants of Outcome

Background

Tuberculosis (TB) can induce secondary hemophagocytic lymphohistiocytosis (HLH), a severe inflammatory syndrome with high mortality. We integrated all published reports of adult HIV-negative TB-associated HLH (TB-HLH) to define clinical characteristics, diagnostic strategies, and therapeutic approaches associated with improved survival.

Methods

PubMed, Embase, and Global Index Medicus were searched for eligible records. TB-HLH cases were categorized into (1) patients with a confirmed TB diagnosis receiving antituberculosis treatment while developing HLH and (2) patients presenting with HLH of unknown cause later diagnosed with TB. We used a logistic regression model to define clinical and diagnostic parameters associated with survival.

Results

We identified 115 individual cases, 45 (39.1%) from countries with low TB incidence (<10/100 000 per year). When compared with patients with HLH and known TB (n = 21), patients with HLH of unknown cause (n = 94) more often had extrapulmonary TB (66.7% vs 88.3%), while the opposite was true for pulmonary disease (91.5% vs 59.6%). Overall, Mycobacterium tuberculosis was identified in the bone marrow in 78.4% of patients for whom examination was reported (n = 74). Only 10.5% (4/38) of patients tested had a positive result upon a tuberculin skin test or interferon-γ release assay. In-hospital mortality was 28.1% (27/96) in those treated for TB and 100% (18/18) in those who did not receive antituberculosis treatment (P < .001).

Conclusions

Tuberculosis should be considered a cause of unexplained HLH. TB-HLH is likely underreported, and the diagnostic workup of patients with HLH should include bone marrow investigations for evidence of Mycobacerium tuberculosis. Prompt initiation of antituberculosis treatment likely improves survival in TB-HLH.

Neonatal hemophagocytic lymphohistiocytosis: A meta-analysis of 205 cases

BACKGROUND

Neonatal hemophagocytic lymphohistiocytosis (nHLH), defined as HLH that presents in the first month of life, is clinically devastating. There have been few large descriptive studies of nHLH.

OBJECTIVES

The objective of this study was to perform a meta-analysis of published cases of nHLH.

METHODS

A comprehensive literature database search was performed. Cases of HLH were eligible for inclusion if clinical analysis was performed at age ≤30 days. Up to 70 variables were extracted from each case.

RESULTS

A total of 544 studies were assessed for eligibility, and 205 cases of nHLH from 142 articles were included. The median age of symptom onset was day of life 3 (interquartile range [IQR]: 0-11, n = 141). Median age at diagnosis was day of life 15 (IQR: 6-27, n = 87). Causes of HLH included familial HLH (48%, n = 99/205), infection (26%, n = 53/205), unknown (17%, n = 35/205), macrophage activation syndrome/rheumatologic (2.9%, n = 4/205), primary immune deficiency (2.0%, n = 5/205), inborn errors of metabolism (2.4%, n = 5/205), and malignancy (2.0%, n = 4/205). Fever was absent in 19% (n = 28/147) of all neonates and 39% (n = 15/38) of preterm neonates. Bicytopenia was absent in 26% (n = 47/183) of patients. Central nervous system (CNS) manifestations were reported in 63% of cases (n = 64/102). Liver injury (68%, n = 91/134) and/or liver failure (24%, n = 32/134) were common. Flow cytometry was performed in 22% (n = 45/205) of cases. Many patients (63%, n = 121/193) died within the period of reporting. Discernable values for HLH diagnostic criteria were reported between 30% and 83% of the time.

CONCLUSIONS

Evaluation of nHLH requires rapid testing for a wide range of differential diagnoses. HLH diagnostic criteria such as fever and bicytopenia may not occur as frequently in the neonatal population as in older pediatric populations. Neurologic and hepatic manifestations frequently occur in the neonatal population. Current reports of nHLH suggest a high mortality rate. Future publications containing data on nHLH should improve reporting quality by reporting all clinically relevant data.

Hemophagocytic lymphohistiocytosis after solid organ transplantation: A challenge for clinicians

Hemophagocytic lymphohistiocytosis (HLH) is a rare inflammatory disorder with a high mortality rate and a wide range of symptoms. Solid organ transplantation, which provides patients with a unique immunosuppressive state, is a less common predisposing factor for HLH. HLH after solid organ transplantation (HLH-SOT) is very rare and fatal. It is hard to diagnose and treat and extremely understudied. The use of immunosuppressants makes the situation of HLH-SOT more complex. This review summarizes the existing literature on HLH after solid organ transplantation and describes its triggers and symptoms, focusing on its diagnosis and treatment. We performed a literature search of case reports, case series, letters to the editor, and clinical quizzes describing patients with HLH after solid organ transplantation (HLH-SOT). We provide recommendations on the diagnosis protocol and treatment strategy based on the existing evidence.

Drug-induced secondary haemophagocytic lymphohistiocytosis in hairy cell leukaemia

Haemophagocytic lymphohistiocytosis (HLH) is a rare, aggressive, excess immune activation syndrome. Diagnosis can be challenging due to its several clinical mimics including sepsis. There are multiple aetiologies of HLH; in adults, it is most commonly triggered by infection, malignancy, drugs and autoimmune processes. Failure to rapidly diagnose and treat this condition can be fatal. The management of HLH includes identifying and removing the trigger, supportive management and immunosuppression. Identifying the trigger is essential to inform the most appropriate type of immunosuppression. Here, we report a case of likely drug-induced HLH in a patient recently treated for hairy cell leukaemia. The culprit drug was thought to be co-trimoxazole and this case report highlights a very rare complication of this commonly used drug. We discuss our management approach with steroid monotherapy and withdrawal of co-trimoxazole.

Molecular Mutations in Histiocytosis: A Comprehensive Survey of Genetic Alterations

Histiocytosis represents a group of uncommon disorders characterized by the abnormal accumulation of specialized immune cells, such as macrophages, dendritic cells, or monocyte-derived cells, in various tissues and organs. Over 100 distinct subtypes have been documented, each displaying a broad spectrum of clinical presentations and histological characteristics. Till today, histiocytosis has been addressed through a combination of chemotherapy, radiotherapy, and surgery, with varying responses from individual patients. Due to its atypical symptoms, it has been prone to misdiagnosis. Advances in our understanding of the cellular and molecular aspects of these conditions are paving the way for improved diagnostic methods and targeted therapies. Researchers have extensively investigated various mutations in patient samples. However, no paper has yet provided a comprehensive summary of the collective analysis of mutations and pathways. Hence, this paper consolidates research efforts that specifically concentrate on gene mutations identified in patient samples of different subtypes of histiocytosis. These insights are essential for developing targeted therapies and improving diagnosis. Further, it provides potential insights to enhance the development of more effective therapeutic approaches for rare diseases.

Precise CRISPR-Cas9 gene repair in autologous memory T cells to treat familial hemophagocytic lymphohistiocytosis

Familial hemophagocytic lymphohistiocytosis (FHL) is an inherited, often fatal immune deficiency characterized by severe systemic hyperinflammation. Although allogeneic bone marrow transplantation can be curative, more effective therapies are urgently needed. FHL is caused by inactivating mutations in proteins that regulate cellular immunity. Here, we used an adeno-associated virus-based CRISPR-Cas9 system with an inhibitor of nonhomologous end joining to repair such mutations in potentially long-lived T cells ex vivo. Repaired CD8 memory T cells efficiently cured lethal hyperinflammation in a mouse model of Epstein-Barr virus-triggered FHL2, a subtype caused by perforin-1 (Prf1) deficiency. Furthermore, repair of PRF1 and Munc13-4 (UNC13D)-whose deficiency causes the FHL subtype FHL3-in mutant memory T cells from two critically ill patients with FHL restored T cell cytotoxicity. These results provide a starting point for the treatment of genetic T cell immune dysregulation syndromes with repaired autologous T cells.

Murine Models of Secondary Cytokine Storm Syndromes

Hemophagocytic lymphohistiocytosis (HLH) comprises a broad spectrum of life-threatening cytokine storm syndromes, classified into primary (genetic) or secondary (acquired) HLH. The latter occurs in a variety of medical conditions, including infections, malignancies, autoimmune and autoinflammatory diseases, acquired immunodeficiency, and metabolic disorders. Despite recent advances in the field, the pathogenesis of secondary HLH remains incompletely understood. Considering the heterogeneity of triggering factors and underlying diseases in secondary HLH, a large diversity of animal models has been developed to explore pivotal disease mechanisms. To date, over 20 animal models have been described that each recapitulates certain aspects of secondary HLH. This review provides a comprehensive overview of the existing models, highlighting relevant findings, discussing the involvement of different cell types and cytokines in disease development and progression, and considering points of interest toward future therapeutic strategies.

Etoposide Therapy of Cytokine Storm Syndromes

Etoposide has revolutionized the treatment of primary as well as secondary hemophagocytic lymphohistiocytosis (HLH), and it is, together with corticosteroids, the most widely used therapy for HLH. In the early 1980s, long-term survival in primary HLH was <5% but with the etoposide-/dexamethasone-based protocols HLH-94 and HLH-2004, in combination with stem cell transplantation, 5-year survival increased dramatically to around 60% in primary HLH, and based on analyses from the HLH-2004 study, there is likely room for further improvement. Biologically, etoposide administration results in potent selective deletion of activated T cells as well as efficient suppression of inflammatory cytokine production. Moreover, etoposide has also been reported to promote programmed cell death (apoptosis) rather than proinflammatory lytic cell death (pyroptosis), conceivably ameliorating subsequent systemic inflammation, i.e., a treatment very suitable for cytokine storm syndromes (CSS). The combination of etoposide and corticosteroids may also be beneficial in cases of severe or refractory secondary HLH (sHLH) with imminent organ failure, such as infection-associated HLH caused by Epstein-Barr virus (EBV) or malignancy-triggered HLH. In CSS associated with rheumatic diseases (macrophage activation syndrome, MAS or MAS-HLH), etoposide is currently used as second- or third-line therapy. Recent studies suggest that etoposide perhaps should be part of an aggressive therapeutic intervention for patients with severe refractory or relapsing MAS, in particular if there is CNS involvement. Importantly, awareness of sHLH must be further increased since treatment of sHLH is often delayed, thereby missing the window of opportunity for a timely, effective, and potentially life-saving HLH-directed treatment.

Inflamed-HLH, MAS, or something else?

Hemophagocytic lymphohistiocytosis (HLH) is a syndrome of excessive and maladaptive inflammation. Primary HLH is most frequently encountered in young children, and, without timely recognition and therapy, can lead to multiorgan failure and death. It is most often diagnosed using the HLH-2004 criteria and by identifying pathological mutations. However, the HLH-2004 criteria are not specific for HLH, and patients can easily fulfill these diagnostic criteria in other proinflammatory states in which HLH-therapy would not be indicated, including hematologic malignancies, infections, and rheumatologic disease. Therefore, great care must be taken to ensure that the specific disease associated with features of HLH is accurately recognized, as consequences of improper treatment can be catastrophic. We propose a diagnostic pathway for patients for whom HLH is on the differential (visual abstract). Importantly, in situations in which the initial diagnostic workup is equivocal or unrevealing, reevaluation for occult malignancy, infection, or rheumatologic disease would be prudent, as occult presentations may be missed on primary evaluation. Temporizing medications can be used in critically ill patients while awaiting secondary evaluation. By using this framework, clinicians will be able to more reliably discern primary HLH from other pro-inflammatory states and thus provide timely, appropriate disease-specific therapy.

Clinical characteristics, treatment, and management of pembrolizumab induced hemophagocytic lymphohistiocytosis

BACKGROUND

Hemophagocytic lymphohistiocytosis (HLH) is a rare and fatal adverse reaction to pembrolizumab. The clinical characteristics of pembrolizumab induced HLH are unknown. Exploring the clinical features of pembrolizumab induced HLH is crucial for the treatment and prevention of immune checkpoint inhibitor-induced HLH.

METHODS

The literature related to pembrolizumab induced HLH was collected for retrospective analysis by searching the Chinese and English databases from inception until August 31, 2023.

RESULTS

A total of 24 patients were included, including 17 men (70.8%) with a median age of 61 years (41,80). The time between the last infusion and the start of HLH ranged from 2 to 46 days, with a median time of 14 days. Fever (100%) was the most common symptom, accompanied by splenomegaly (14 cases, 58.3%) and hepatomegaly (6 cases, 25.0%). Laboratory examination revealed revealed anemia (18 cases, 75.0%), leukopenia (12 cases, 50.0%), thrombocytopenia (20 cases, 83.3%), hypertriglyceridemia (11 cases, 45.8%), hypofibrinogenemia (11 cases, 45.8%). decreased natural killer cell function (7 cases, 29.2%), and elevated soluble CD25(15 cases, 62.5%). All patients developed hyperferriinemia, with a median of 30,808 ng/mL (range 1303 ~ 100,000). Bone marrow biopsy showed hemophagocytosis (15 cases, 62.5%). After discontinuation of pembrolizumab and treatment with steroids, etoposide, intravenous immunoglobulin, cytokine blocking, and immunosuppression, 17 patients recovered or improved, and 5 patients eventually died.

CONCLUSION

HLH should be suspected when unexplained fever, cytopenia, splenomegaly, and elevated aminotransferase occur in patients using pembrolizumab. Screening for risk factors before treatment with pembrolizumab may be necessary to prevent HLH.

A rare case of orbital inflammation complicated by hemophagocytic lymphohistiocytosis

We report a rare case of orbital inflammation complicating hemophagocytic lymphohistiocytosis (HLH) patient. HLH is a rare, life-threatening disorder characterized by uncontrolled activation of cytotoxic T lymphocytes, natural killer cells, and macrophages. A 37-year-old man known to have HLH, presented with a left periorbital swelling that was unsuccessfully treated as an orbital cellulitis, with intravenous antibiotics. A computed tomography (CT) scan of the orbits revealed inflammatory changes with no orbital collection or paranasal sinus disease. An orbital biopsy demonstrated lymphoplasmacytic infiltrations admixed with histiocytes. The patient deteriorated and was admitted to the intensive care unit. Ensuing blood results supported a diagnosis of HLH, and the patient responded well to subsequent immunosuppression. This case report highlights the importance of re-considering the diagnosis of orbital cellulitis in treatment resistant cases, particularly in the absence of sinus disease. To our knowledge, this is the third case of orbital inflammation associated with HLH patients.

Glomerular lipidosis as a feature of renal-limited macrophage activation syndrome in a transplanted kidney: a case report

BACKGROUND

Glomerular lipidosis is a rare histological feature presenting the extensive glomerular accumulation of lipids with or without histiocytic infiltration, which develops under various conditions. Among its various etiologies, macrophage activation syndrome (MAS) is a condition reported to be associated with histiocytic glomerular lipidosis. Here we describe the first case of glomerular lipidosis observed in a renal allograft that histologically mimicked histiocytic glomerulopathy owing to MAS.

CASE PRESENTATION

A 42-year-old man underwent successful living-donor kidney transplantation. However, middle-grade proteinuria and increased serum triglyceride levels indicative of type V hyperlipidemia developed rapidly thereafter. An allograft biopsy performed 6 months after the transplantation showed extensive glomerular infiltration of CD68+ foam cells (histiocytes) intermingled with many CD3+ T-cells (predominantly CD8+ cells). Furthermore, frequent contact between glomerular T-cells and histiocytes, and the existence of activated CD8+ cells (CD8+, HLA-DR+ cells) were observed by double immunostaining. There was no clinicopathological data suggesting lipoprotein glomerulopathy or lecithin cholesterol acyltransferase deficiency, both of which are well-known causes of glomerular lipidosis. The histological findings were relatively similar to those of histiocytic glomerulopathy caused by MAS. As systemic manifestations of MAS, such as fever, pancytopenia, coagulation abnormalities, hyperferritinemia, increased liver enzyme levels, hepatosplenomegaly, and lymphadenopathy were minimal, this patient was clinicopathologically diagnosed as having renal-limited MAS. Although optimal treatment strategies for MAS in kidney transplant patients remains unclear, we strengthened lipid-lowering therapy using pemafibrate, without modifying the amount of immunosuppressants. Serum triglyceride levels were normalized with this treatment; however, the patient's extensive proteinuria and renal dysfunction did not improve. Biopsy analysis at 1 year after the transplantation demonstrated the disappearance of glomerular foamy changes, but the number of glomerular infiltrating cells remained similar.

CONCLUSION

To our knowledge, this is the first reported case of glomerular lipidosis in a transplanted kidney. Increased interaction-activation of histiocytes (macrophages) and CD8+ T-cells, the key pathogenic feature of MAS, was observed in the glomeruli of this patient, who did not demonstrate overt systemic manifestations, suggesting a pathological condition of renal-limited MAS. The clinical effects of triglyceride-lowering therapy were limited, suggesting that hypertriglyceridemia was not the cause of but rather may be a consequence of renal-limited MAS.

Hemophagocytic lymphohistiocytosis with a hemizygous PRF1 c.674G>A mutation

Hemophagocytic lymphohistiocytosis(HLH) is a rare highly-fatal disease presenting with fever, hepatosplenomegaly, and pancytopenia and has a poor prognosis. Homozygous or semi-zygous or complex heterozygous variants can cause familial HLH and heterozygous carriers are frequently seen in secondary HLH. A 42-year-old male patient was admitted to the hospital for persistent fever, fatigue, and splenomegaly. Investigations revealed hypertriglyceridemia, hyperlactatemia dehydrogenaseemia, hyperferritinemia, and elevated levels of soluble cluster of differentiation 25. We found a heterozygous mutation of PRF1: c.674G>A (p.R225Q) through next-generation sequencing technology of hemophagocytic-lymphohistiocytosis-related genes. After a brief remission with dexamethasone and etoposide-based therapy, the disease relapsed quickly, and an allogeneic hematopoietic stem cell transplant was performed to achieve complete remission. To date, the patient's condition was in complete remission. Our study detected a rare missense mutation in the PRF1 gene in a patient with HLH disease and the c.674G>A mutation may be rated as a possible pathogenic variant.

Lethal immunotoxicity in high-dose systemic AAV therapy

High-dose systemic gene therapy with adeno-associated virus (AAV) is in clinical trials to treat various inherited diseases. Despite remarkable success in spinal muscular atrophy and promising results in other diseases, fatality has been observed due to liver, kidney, heart, or lung failure. Innate and adaptive immune responses to the vector play a critical role in the toxicity. Host factors also contribute to patient death. This mini-review summarizes clinical findings and calls for concerted efforts from all stakeholders to better understand the mechanisms underlying lethality in AAV gene therapy and to develop effective strategies to prevent/treat high-dose systemic AAV-gene-therapy-induced immunotoxicity.

Panniculitic primary cutaneous gamma delta T-cell lymphoma with concomitant features of autoimmune disease emphasizing a pathophysiologic continuum of lupus profundus with the panniculitic T cell lymphomas

Certain T-cell lymphomas exhibit unique homing properties of the neoplastic lymphocytes for the subcutaneous fat. There are two primary forms of subcutaneous panniculitic lymphomas of T-cell origin. One falls under the designation of primary cutaneous gamma-delta T-cell lymphomas (PGD-TCL) whereby there is dominant involvement of the fat defininng a panniculitic form of PGD-TCL. The neoplastic cells are of the gamma-delta subset and are either double negative for CD4 and CD8 and/or can express CD8. They often have an aggressive clinical course. The other form of panniculitic T-cell lymphoma falls under the designation of subcutaneous panniculitis-like T-cell lymphoma (SPTCL). It represents a subcutaneous lymphoma derived from CD8+ T cells of the alpha-beta subset and typically has an indolent course. These two forms of panniculitic T-cell lymphoma exhibit overlapping histologic features with lupus profundus (LP), a putative form of panniculitic T-cell dyscrasia. We present three cases of PGD-TCL of the fat in the setting of lupus erythematosus (LE) (two cases) and dermatomyositis (DM) (one case), respectively. There were concurrent features of LE and DM in their lymphoma biopsies in two cases while a prior biopsy in one was interpreted as LP. In this latter case, the LP diagnosis presaged the diagnosis of panniculitic PGD-TCL by three years. One patient diagnosed with panniculitic PGD-TCL had hemophagocytic syndrome after developing a lupus-like complex including certain supportive serologies such as antibodies to double-stranded DNA following initiation of statin therapy. The second patient presented with PGD-TCL and concomitant features of anti-nuclear matrix 2 (NXP2) DM. The third patient presented in 2003 with LP and overlying skin features of acute LE, initially responding to Plaquenil, and then four years later was diagnosed with PGD-TCL heralded by Plaquenil treatment resistance. Two of the patients died of their lymphoma. All biopsies showed a characteristic histopathology of PGD-TCL. In two cases, the PGD-TCL was associated with overlying LE-cutaneous findings; another case had skin changes of lymphocyte-rich DM. In two cases, the MXA stain was strikingly positive, the surrogate type I interferon marker that is typically upregulated in biopsies of LE and DM. There are eight prior reported cases describing SPTCL with concomitant cutaneous changes of LE. In six cases there was an established history of LE, including LP responding initially to Plaquenil, similar to one of our cases. In the context of SPTCL or panniculitic PGD-TCL, panniculitic T-cell lymphomas can be associated with concomitant clinical and histologic features of LE or DM, including an upregulated type I interferon signature. Identifying histologic features associated with either of these prototypic autoimmune conditions should not be considered exclusionary to diagnosing any panniculitic T-cell lymphoma. A clinical, histomorphologic, and pathophysiologic continuum exists with LP, SPTCL and panniculitic PGD-TCL.

Hemophagocytic lymphohistiocytosis secondary to unrecognized Bartonella henselae infection: a case report

BACKGROUND

Bartonella henselae is a species of intracellular bacteria transmitted to humans through animal bites and scratches contaminated with the feces of arthropod vectors, and are most commonly associated with cat exposure although transmission from other mammals has been reported. Bartonella henselae infection has a spectrum of clinical manifestations and has rarely been reported as cause of hemophagocytic lymphohistiocytosis (HLH) in immunocompromised hosts.

CASE PRESENTATION

We present a report of Bartonella henselae infection progressing to HLH in an immunocompetent patient. The patient initially presented with regional lymphadenopathy but the diagnosis was not suspected as the patient reported no exposure to cats. On further history, he did report a scratch from a dog prior to development of symptoms. The patient was treated with methylprednisolone, intravenous immunoglobulin and anakinra for the HLH and three months of Doxycycline for Bartonella infection, with complete resolution of symptoms.

CONCLUSIONS

Although commonly associated with cat exposure, Bartonella henselae transmission can occur after exposure to other animals and vectors including dogs and clinicians need to maintain an index of suspicion for timely diagnosis. Bartonella henselae is associated with a spectrum of clinical manifestations which can include disseminated infection with severe complications such as hemophagocytic lymphohistiocytosis. Prompt initiation of Bartonella treatment is essential when thought to be the trigger for hemophagocytic lymphohistiocytosis although the optimal treatment regimen is unclear.

Hemophagocytic lymphohistiocytosis secondary to histoplasmosis: A case report in a patient with AIDS and recent SARS-CoV-2 infection and minireview

Here, we describe the case of a naïve HIV late presenter female African patient with progressive disseminated histoplasmosis and a severe life-threatening clinical picture in a non-endemic area. She had not visited Africa in the past decade. She developed a reactive hemophagocytic lymphohistiocytosis and an acute psychiatric disorder. Histoplasmosis was diagnosed after two bone marrow biopsies. Therapy with liposomal amphotericin B resulted in rapid and progressive improvements in blood examinations and clinical conditions, including the disappearance of psychiatric disorders. The characteristics of our case were compared with those of all other cases of hemophagocytic syndrome secondary to histoplasmosis in HIV-positive patients reported in PubMed. In conclusion, clinicians outside endemic areas should evaluate histoplasmosis as a cause of severe clinical picture, especially in a patient with a travel history to an endemic area, even after many years, considering the possible reactivation of latent infection.

Sepsis in Immunocompromised Host and a Hematologic Complication

CASE PRESENTATION

A 43-year-old Puerto Rican man with a kidney transplant presented to the ED with 2 weeks of flu-like symptoms, nausea, and vomiting. He had plasma exchange therapy 2 months before for acute transplant rejection and has been tolerating a heightened immunosuppressive regimen. CT scans characterized opacities as possibly early tree-in-bud opacities (Fig 1A). Patient remained stable throughout hospital stay with an unremarkable workup and was discharged with doxycycline for nonspecific pneumonia.

Secondary Hemophagocytic Lymphohistiocytosis Due to Typhoid Fever

Hemophagocytic lymphohistiocytosis (HLH) is a potentially fatal hyper-inflammatory state that is caused by a highly activated but ineffective immune system. It can be primary or secondary to triggers like infections, malignancies, and autoimmune conditions. The authors present the case of a young male with a fever and abdominal pain due to typhoid. He continued to have a high-spiking fever and developed dyspnea, requiring oxygen therapy despite being treated with appropriate antibiotics. Laboratory evaluation revealed cytopenias and deranged liver function tests, and abdominal imaging revealed hepatosplenomegaly. These clinical and laboratory findings raised suspicion of HLH secondary to typhoid fever. Further investigations were suggestive of hyperferritinemia and hypofibrinogenemia, and bone marrow aspirates showed hemophagocytes. The patient was treated with immunosuppression (dexamethasone) and antibiotics and showed remarkable recovery. Hemophagocytic lymphohistiocytosis should be suspected in patients with tropical infections like enteric fever, tuberculosis, malaria, dengue, etc. that worsen despite appropriate treatment, as late diagnosis is associated with greater mortality.

Prognostic Factors and Long-term Outcomes in 41 Children With Primary Hemophagocytic Lymphohistiocytosis: Report of a Single-center Experience and Review of the Literature

Hemophagocytic lymphohistiocytosis (HLH) is a rare life-threatening hyperinflammatory syndrome with diverse clinical manifestations leading to major diagnostic and therapeutic difficulties. This study aimed to evaluate clinical manifestations, prognostic factors, and long-term outcomes in children with primary HLH. Forty-one patients diagnosed with primary HLH were retrospectively evaluated for patient characteristics, HLH gene mutations, clinical and laboratory manifestations, prognostic factors, and long-term outcomes. The median age of the patients at the time of diagnosis was 3 months (minimum to maximum: 1 to 144 mo). There were 23 patients who had HLH mutation analysis performed, 10 patients with PRF1 mutation, 6 with STX11 mutation, and 7 with UNC13D mutation. Thirteen patients (31.7%) had central nervous system involvement. No correlation was found between overall survival and central nervous system involvement. The estimated 5-year overall survival for the patient who had hematopoietic stem cell transplantation was 9.4 times better than the patients who did not receive hematopoietic stem cell transplantation (81.3% vs 16.7%; P = 0.001). Median serum sodium and blood urea nitrogen levels were significantly higher in deceased HLH patients compared with surviving HLH patients ( P = 0.043, and P = 0.017, respectively). Primary HLH has a poor outcome with high mortality, which necessitates well-designed and international clinical trials to improve diagnosis, therapy, and long-term outcomes.

Immunodeficiency with susceptibility to lymphoma with complex genotype affecting energy metabolism (FBP1, ACAD9) and vesicle trafficking (RAB27A)

Introduction

Inborn errors of immunity (IEI) are characterized by a dysfunction of the immune system leading to increased susceptibility to infections, impaired immune regulation and cancer. We present a unique consanguineous family with a history of Hodgkin lymphoma, impaired EBV control and a late onset hemophagocytic lymphohistiocytosis (HLH).

Methods and results

Overall, family members presented with variable impairment of NK cell and cytotoxic T cell degranulation and cytotoxicity. Exome sequencing identified homozygous variants in RAB27A, FBP1 (Fructose-1,6-bisphosphatase 1) and ACAD9 (Acyl-CoA dehydrogenase family member 9). Variants in RAB27A lead to Griscelli syndrome type 2, hypopigmentation and HLH predisposition.

Discussion

Lymphoma is frequently seen in patients with hypomorphic mutations of genes predisposing to HLH. We hypothesize that the variants in FBP1 and ACAD9 might aggravate the clinical and immune phenotype, influence serial killing and lytic granule polarization by CD8 T cells. Understanding of the interplay between the multiple variants identified by whole exome sequencing (WES) is essential for correct interpretation of the immune phenotype and important for critical treatment decisions.

Hemophagocytic lymphohistiocytosis as a rare complication of dengue haemorrhagic fever: a case report

BACKGROUND

Haemophagocytic lymphohistiocytosis (HLH) is an uncommon systemic inflammatory syndrome that can happen secondary to numerous conditions. It rarely occurs due to dengue infection causing significant mortality and morbidity even with appropriate treatment. The outcome is further poor if the diagnosis of HLH is delayed or left untreated. Therefore, a high degree of clinical suspicion is paramount in diagnosing HLH.

CASE PRESENTATION

A 17-year-old Sinhalese boy was admitted to a tertiary care hospital in Sri Lanka with a 4-day history of fever, headache, nausea, vomiting, and diarrhea. He was hemodynamically stable, and the serological investigation confirmed a dengue infection. On the fifth day of fever, he entered the critical phase of dengue infection, confirmed by ultrasound evidence of plasma leaking. However, he had ongoing high fever spikes during the critical phase, and even after the critical phase was over, the fever spikes continued. Simultaneously, hepatosplenomegaly was noticed, and he showed persistent thrombocytopenia, neutropenia, and anemia despite the resolution of the critical phase. Further, the workup revealed a serum ferritin level of > 3000 ng/mL triglyceride level of 314 mg/dL, and the bone marrow biopsy revealed an increased haemophagocytic activity. Secondary HLH was diagnosed on the basis of criteria used in the HLH-2004 trial and successfully managed with intravenous dexamethasone 10 mg/body surface area/day for the first 2 weeks, followed by a tapering regimen over 8 weeks.

CONCLUSION

This case emphasizes the need to consider HLH as a potential complication when persistent fever and cytopenias are present after recovering from dengue fever, particularly in patients with unusual clinical features like hepatosplenomegaly. Early recognition and prompt treatment with appropriate immunosuppressive therapy, such as intravenous dexamethasone, can lead to a successful response and good prognosis.

Secondary hemophagocytic lymphohistiocytosis associated with heat stroke: A case report and review of literature

RATIONALE

Hemophagocytic lymphohistiocytosis (HLH) is a syndrome with potentially fatal consequences that results from an excessive immune response caused by malfunctioning natural killer cells and cytotoxic T lymphocytes. Secondary HLH, which is the predominant type in adults, is associated with various medical conditions, including infections, malignancies, and autoimmune diseases. Secondary HLH associated with heat stroke has not been reported.

PATIENT CONCERNS

A 74-year-old male was admitted to the emergency department after being unconscious in a 42°C hot public bath. The patient was witnessed to be in the water for more than 4 hours. The patient's condition was complicated by rhabdomyolysis and septic shock, which were managed with mechanical ventilation, vasoactive agents, and continuous renal replacement therapy. The patient also showed evidence of diffuse cerebral dysfunction.

DIAGNOSES

While the patient's condition initially improved, the patient developed a fever, anemia, thrombocytopenia, and an acute rise in total bilirubin, which, we suspected, was caused by HLH. Further investigations revealed elevated serum ferritin and soluble interleukin-2 receptor levels.

INTERVENTIONS

The patient received 2 cycles of serial therapeutic plasma exchange to lower the endotoxin burden. To manage HLH, high-dose glucocorticoid therapy was done.

OUTCOMES

Despite the best efforts, the patient did not recover and expired from progressive hepatic failure.

LESSONS

We report a novel case of secondary HLH associated with heat stroke. Diagnosing secondary HLH can be difficult since clinical manifestations of the underlying disease and HLH may present simultaneously. Early diagnosis and prompt initiation of treatment is required to improve the prognosis of the disease.

Hemophagocytic Syndrome and COVID-19: A Comprehensive Review

Hemophagocytic lymphohistiocytosis (HLH), a hyperinflammatory hyperferritinemic syndrome, is triggered by various etiologies and diseases and can lead to multiorgan dysfunction and death. There are two types of HLH: primary and secondary. Primary HLH (pHLH) is caused by a genetic mutation resulting in dysfunction in cytotoxic T lymphocytes (CTLs), natural killer (NK) cells, hyperactivated immune cells, and hypercytokinemia. In secondary HLH (sHLH), an underlying etiology is the cause of the disease. Infections, malignancy, and autoimmune diseases are well-known triggers for sHLH. Infectious triggers for sHLH are most frequently viruses, where different mechanisms, including dysregulated CTLs and NK cell activity and persistent immune system stimulation, have been reported. Similarly, in severe coronavirus disease 2019 (COVID-19) patients, a hyperinflammatory mechanism leading to hypercytokinemia and hyperferritinemia has been demonstrated. A similar dysfunction in CTLs and NK cells, persistent immune system stimulation with increased cytokines production, and severe end-organ damage have been reported. Therefore, a significant overlap is present between the clinical and laboratory features seen in COVID-19 and sHLH. However, SARS-CoV-2, similar to other viruses, can trigger sHLH. Hence, a diagnostic approach is needed in severe COVID-19 patients presenting with multiorgan failure, in whom sHLH should be considered.

Flea-Borne Typhus Causing Hemophagocytic Lymphohistiocytosis: An Autopsy Case

Infection with members of the order Rickettsiales (the genera Rickettsia, Anaplasma, Orientia, and Ehrlichia) is known to cause hemophagocytic lymphohistiocytosis (HLH). The literature is scant on flea-borne typhus (FBT) being implicated in this process. We present a case of autopsy-proven HLH caused by FBT in a 71-year-old diabetic female who was initially suspected of having diabetic ketoacidosis who rapidly suffered decompensated multi-organ failure. Although she was suspected of having FBT and HLH pre-mortem, due to her rapid progression to multi-organ failure, she was transitioned to comfort care by her family five days after admission. A literature search yielded five other cases of HLH secondary to FBT, which are analyzed in this review. The literature on HLH occurring with infection due to other members of the order Rickettsiales is also surveyed.

Traffic jam within lymphocytes: A clinician's perspective

With the discovery of novel diseases and pathways, as well as a new outlook on certain existing diseases, cellular trafficking disorders attract a great deal of interest and focus. Understanding the function of genes and their products in protein and lipid synthesis, cargo sorting, packaging, and delivery has allowed us to appreciate the intricate pathophysiology of these biological processes at the molecular level and the multi-system disease manifestations of these disorders. This article focuses primarily on lymphocyte intracellular trafficking diseases from a clinician's perspective. Familial hemophagocytic lymphohistiocytosis is the prototypical disease of abnormal vesicular transport in the lymphocytes. In this review, we highlight other mechanisms involved in cellular trafficking, including membrane contact sites, autophagy, and abnormalities of cytoskeletal structures affecting the immune cell function, based on a newer classification system, along with management aspects of these conditions.

Hemophagocytic Lymphohistiocytosis in Adults: A Retrospective Study in a Belgian Teaching Hospital

Introduction

Hemophagocytic lymphohistiocytosis (HLH) is a life-threatening disease, which can be primary (due to genetic mutation) or secondary to malignancy, infection and rheumatologic diseases. Data concerning Belgian patients with adult HLH are lacking.

Methods

This retrospective study was performed in a teaching hospital in Belgium. All cases of adult HLH, from December 2010 to April 2022, were reviewed. Patients with more than five HLH-2004 criteria and/or HScore >80% were included in the study. The objective of our study was to describe clinical and biological characteristics of patients with HLH and attempt to look for variables associated with mortality.

Results

Fifty-two patients were included in the final analysis. Mean age (SD) of patients was 48 (18) years old, and 29 patients were of male gender (56%). The underlying diseases associated with HLH were malignancy (M-HLH) in 22 patients, infection related HLH in 20 patients, rheumatologic disease related HLH in 7 patients, idiopathic in 2 patients and secondary to pregnancy in 1 patient. Overall mortality, mortality at 30 days and 90 days were 24/52 (46%), 13/52 (25%) and 4/52 (10%), respectively. In univariate analysis, malignancy, male sex, age and disseminated intravascular coagulation (DIC) were associated with mortality (p < 0.05). In multivariate analysis, only age was significantly associated with mortality (odds ratio, 1.053; 95% confidence interval, 1.016–1.092; p 0.005).

Conclusion

In our study, the most frequent triggers were malignancy and infectious agent followed by rheumatologic disease. Risk factors for mortality were age, male sex, malignancy and DIC, but only age remained significant in multivariate analysis. Treatment guidelines are mainly based on pediatric patients, and it is important for physician to describe adult patients’ outcome to better understand this disease and adapt treatment.

COVID-19, Endothelium and the Cardiometabolic Patient: A Possible Role for Capillary Leak Syndrome

Capillary leak syndrome is an under-diagnosed condition leading to serious hypoalbuminemia with diffuse edema, pulmonary edema, severe hypotension, and possibly death. Sepsis leading to hemophagocytic lymphohistiocytosis (HLH) is a major risk factor; however, capillary hyper-permeability is the core underlying pathophysiological mechanism. Endothelial dysfunction plays a major role in cardiometabolic disease through insulin resistance, lipotoxicity, and, eventually, oxidative stress and chronic inflammation. We review the literature concerning the aforementioned mechanisms as well-established risk factors for adverse COVID-19 outcomes. We especially focus on data regarding the underlying endothelial effects of SARS-CoV-2 infection, including direct damage and increased vascular leakage through a hyper-inflammatory cascade and diminished nitric oxide bioavailability. Interestingly, an increased incidence of hypoalbuminemia has been observed in patients with severe COVID-19, especially those with underlying cardiometabolic disease. Importantly, low albumin levels present a strong, positive association with poor disease outcomes. Therefore, in this review article, we highlight the important role of cardiovascular risk factors on endothelium integrity and the possible link of endothelial damage in the hypoalbuminemia-associated adverse prognosis of COVID-19 patients.

Macrophage activation syndrome in adults: Characteristics, outcomes, and therapeutic effectiveness of etoposide-based regimen

Objectives

To describe the clinical characteristics and outcomes of adult macrophage activation syndrome (MAS) patients and to provide experience for the treatment.

Methods

Adult patients with MAS admitted to Beijing Friendship Hospital from December 2014 to September 2021 were enrolled in this study. Clinical data of patients were collected and analyzed.

Results

A total of 118 adult MAS patients entered this study. MAS was the first manifestation in 43 (36.4%) patients, while 75 (63.6%) developed MAS after the diagnosis of autoimmune disease (AID) with a median diagnostic interval of 2 (0.5–359) months. Eighty-two patients were initially treated with glucocorticoid-based regimen; the overall response (OR) rate at the 2-week posttreatment was 37.8%. Forty-five patients switched to etoposide-based regimen, and the OR rate was 84.4%. Thirty-six patients were initially treated with etoposide-based regimen, and the OR rate at the 2-week posttreatment was 80.6%. Serum IL-18 (P = 0.021), IFN-γ (P = 0.013), IP-10 (P = 0.001), IL-10 (P = 0.041), IL-1RA (P < 0.001), and TNF-α (P = 0.020) levels of patients were significantly decreased in the remission phase than in the active phase. Levels of SDF-1α (P = 0.018) and IL-7 (P = 0.022) were higher in refractory patients, while the GRO-α level had a strong tendency toward statistical significance (P = 0.050). The probability of overall survival (OS) at 3, 6, and 36 months after HLH diagnosis were 89.8%, 89.0%, and 87.9%, retrospectively. The active MAS status at the 2-week post initial treatment [P = 0.009, HR = 15.281, 95% CI, (0.1.972, 118.430)] and baseline neutrophil count (Neu) <1.5 × 10⁹/l [P = 0.017, HR = 3.678, 95% CI, (1.267, 10.672)] were negative prognostic factors.

Conclusion

MAS typically occurs within 2 months after the onset of autoimmune disease in adults. SDF-1α, IL-7, and GRO-α could be used to predict refractory MAS. The etoposide-based regimen is effective and tolerable for adult MAS.

MIS-C and Visceral Leishmaniasis Co-occurence: Has the Clinic of Other Diseases Masked in the Pandemia?

At the end of 2019, the newly detected severe acute respiratory syndrome-coronavirus (COVID)-2 in China spread rapidly and caused a global epidemic. It has been observed that the virus, which is the cause of COVID-2019 and can cause severe acute respiratory failure, later causes a hyperinflammatory picture and causes a clinical picture similar to Kawasaki disease. Fever, cardiac involvement and rash are the most common findings in this picture, which is called multisystem inflammatory syndrome (MIS-C). Although its pathophysiology is not fully known yet, the most common cause is thought to be post-infection immune dysregulation. Visceral leishmaniasis (VL) is a zoonosis in which Leishmania infantum and rarely Leishmania donovani are the agents and can cause a similar clinical picture. In this text; we discussed a patient who was followed up with a diagnosis of COVID-associated MIS-C, but without an adequate response in his clinic with MIS-C treatment, and was diagnosed with VL with further examinations. To our knowledge, this is the first MIS-C and VL co-occurence in the literature.

Anakinra for the treatment of adult secondary HLH: a retrospective experience

Anti-cytokine therapies have been gaining attention as a means of improving outcomes in adult secondary HLH (asHLH), which currently has poor outcomes when treated with standard etoposide-based therapies. Anakinra is an interleukin-1 antagonist that is increasingly being used in the management of asHLH. Here is described a multi-hospital series of 16 adult patients with secondary HLH treated with anakinra. Provoking factors of secondary HLH included hematologic malignancy (n = 7, 44%), bacterial infection (n = 7, 44%), viral infection (n = 5, 31%), rheumatologic disorder (n = 4, 25%), and unknown (n = 1, 6%). Five patients remained alive at time of last follow-up (OS = 31%). Median OS was 1.7 months from initiation of anakinra (range 0.2–59). OS among patients with rheumatologic causes of secondary HLH was 75%, whereas only 17% of patients with other provoking factors survived (p = 0.0293). Anakinra was well tolerated, with only 1 patient experiencing associated toxicity (grade 3 liver injury). Anakinra may be useful in the management of asHLH provoked by rheumatologic conditions, although its benefit in asHLH provoked by other factors may be limited.

A Case of Macrophage Activation Syndrome Manifesting as the Initial Presentation of Systemic Lupus Erythematosus

Macrophage activation syndrome (MAS) is a potentially fatal complication of an autoimmune rheumatologic disease characterized by overwhelming inflammation, multiorgan failure, and high mortality if untreated. We report a rare case of a 56-year-old man who presented with fever for three weeks and had a constellation of clinical features and laboratory findings, meeting the diagnostic criteria for systemic lupus erythematosus (SLE) and SLE-associated MAS. He was treated with high dose intravenous corticosteroid and hydroxychloroquine, resulting in resolution of fever and dramatic clinical improvement.

Inflammation in pediatric epilepsies: Update on clinical features and treatment options

The role of inflammation is increasingly recognized in triggering or sustaining epileptic activity. In the last decades, increasing research has provided definite evidence to support the link between immunity, inflammatory process, and epilepsy. Neuro- and systemic inflammation play a pivotal role in driving epileptogenesis through different pathogenetic mechanisms: the activation of innate immunity in glia, neurons, and microvasculature, the brain mediated by blood-brain barrier (BBB) impairment, and the imbalance of pro- and anti-inflammatory molecules produced by both arms of immunity. More recently, research has focused on the adverse effects of maternal or early-life immune activation and cytokine imbalance on fetal neurodevelopment and postnatal epilepsy. A complex crosstalk between the immune and nervous system, and a crucial interplay of genetic, epigenetic, and environmental factors may influence structures and functions of the developing brain. A better understanding of the inflammatory process in promoting epilepsy implies that targeting specific pathways may be effective in seizure control. Multiple targets have been identified so far, and several antiseizure interventions are obtained by inhibiting inflammatory signaling or protecting/restoring BBB. All this evidence has changed the field of epilepsy research and neuropharmacology. Further developments and new treatments will rapidly emerge to improve seizure management in inflammation-related epilepsies. This article is part of the Special Issue "Severe Infantile Epilepsies".

FDA Approval Summary: Idecabtagene Vicleucel for Relapsed or Refractory Multiple Myeloma

In March 2021, the FDA approved idecabtagene vicleucel, a chimeric antigen receptor T-cell therapy targeting the B-cell maturation antigen (BCMA), for adult patients with relapsed/refractory multiple myeloma (RRMM) after ≥4 lines of therapy including an immunomodulatory agent, a proteasome inhibitor, and an anti-CD38 mAb. Approval was based on overall response rate (ORR), complete response (CR) rate, and duration of response (DOR) in 100 adult patients with RRMM treated with idecabtagene vicleucel in a single-arm trial. Patients received a single infusion of idecabtagene vicleucel, preceded by lymphodepleting chemotherapy with cyclophosphamide and fludarabine. Of the 100 patients in the efficacy evaluable population, ORR was 72% [95% confidence interval (CI), 62-81] with stringent CR rate of 28% (95% CI, 19-38). After median follow-up of 10.7 months, median DOR was 11 months (95% CI, 10.3-11.4) in responders (partial response or better) and 19 months [95% CI, 11.4 months, not estimable (NE)] in patients who achieved stringent CR. Serious adverse reactions occurred in 67% of 127 patients evaluated for safety. Grade 3 or higher cytokine release syndrome and neurologic toxicities occurred in 9% and 4%, respectively, leading to a Risk Evaluation and Mitigation Strategy. Hemophagocytic lymphohistiocytosis/macrophage activation syndrome occurred in 4%, with two fatalities. Prolonged cytopenia requiring hematopoietic rescue occurred in 2% (3/127), with two fatalities.

Mechanistic Insights in Hemophagocytic Lymphohistiocytosis: Subsequent Acute Hepatic Failure in a Multiple Myeloma Patient following Therapy with Ixazomib-Lenalidomide-Dexamethasone

Hemophagocytic lymphohistiocytosis (HLH) is a rare, elusive, and life-threatening condition that is characterized by the pathologic and uncontrolled secondary activation of the cytotoxic T-cells, natural killer cells (NK-cells), and macrophages of the innate immune system. This condition can develop in sporadic or familial contexts associated with hematological malignancies, as a paraneoplastic syndrome, or linked to an infection related to immune system deficiency. This leads to the systemic inflammation responsible for the overall clinical manifestations. Diagnosis should be thorough, and treatment should be initiated as soon as possible. In the current manuscript, we focus on classifying the HLH spectrum, describing the pathophysiology and the tools needed to search for and correctly identify HLH, and the current therapeutic opportunities. We also present the first case of a multiple myeloma patient that developed HLH following therapy with the ixazomib-lenalidomide-dexamethasone protocol.

Concomitant Hemophagocytic Lymphohistiocytosis and Cytomegalovirus Disease: A Case Based Systemic Review

Background

Hemophagocytic lymphohistiocytosis (HLH) is an immune mediated life-threatening condition. It is driven by an overactivation of the immune system and causes inflammatory tissue damage potentially leading to organ failure and death. Primary HLH is caused by genetic mutations, while secondary HLH is triggered by external factors. Viral infections are a well-known cause of secondary HLH. Cytomegalovirus (CMV) is a virus in the herpes family known to cause HLH in rare cases.

Methods

We report a recent case of CMV-induced HLH, followed by a systematic review of described cases of this rare disease entity, through a structured search in the medical database PubMed. All articles were assessed on a predetermined set of inclusion criteria.

Results

A total of 74 patients (age > 18 years) with CMV-related HLH were identified, 29 men, 42 women, and three patients with unspecified gender. Median age was 37.5 years (range 18-80). Sixty-six patients (88%) had one or more comorbid conditions and 22 patients (30%) had inflammatory bowel disease (IBD), the most frequent comorbidity. Forty patients (54%) received some form of immunomodulating treatment prior to HLH development. The general treatment approach was in general dual, consisting of antiviral treatment and specific immunomodulating HLH treatment approaches. Treatment outcome was at 77% survival, while 23% had fatal outcome.

Conclusion

The findings highlight the importance of early diagnostic work up and treatment intervention. Ability to recognize the characteristic clinical traits and perform specific HLH diagnostic workup are key factors to ensure targeted diagnostic work and treatment intervention for this patient group.

Efficacy and safety of allogeneic hematopoietic stem cell transplant in adults with hemophagocytic lymphohistiocytosis: a systematic review of literature

Hemophagocytic lymphohistiocytosis (HLH) is a rare but life-threatening disorder of the immune system. While familial HLH is usually seen in children, secondary HLH is more common in adults. Secondary HLH is associated with a wide variety of underlying conditions including infections, malignancy and autoimmune disorders. While HLH 94/04 protocol-based chemotherapy can be used for initial treatment, allogeneic hematopoietic stem cell transplant (allo-HSCT) remains the only potentially curative treatment modality for this disorder. In this systematic review, we analyzed available literature on the role of allo-HSCT in adolescent and adult patients using PubMed, Cochrane, Embase and ClinicalTrials.gov. A total of 11 retrospective studies evaluated the role of allo-HSCT for HLH. Allo-HSCT, when compared to non-HSCT approach, appears to be associated with reasonable efficacy and acceptable safety for adolescent and adult patients with HLH.

A Review of Hemophagocytic Lymphohistiocytosis in Patients With HIV

We provide an elaborate review of cases published between January 2005 and April 2021 on hemophagocytic lymphohistiocytosis (HLH) in HIV patients. Seventy articles describing 81 adult patients (age ≥19 years) were included. The median age was 40 years, and 78% were males. Only 65% were known to have HIV before presentation. CD4 count was ≥200 cells/mm3 in 23%, and HIV viral load was <200 copies/mL in 41%. The lack of meticulous reporting of ≥5 of 8 criteria for HLH diagnosis was evident in a third of cases. At least 1 infectious agent-other than HIV-was believed to trigger HLH in 78% of patients. The most common were Epstein-Barr virus (26%), human herpesvirus 8 (21%), and Histoplasma capsulatum (17%). Sixty percent survived. Among those, 93% received treatment for identified secondary trigger(s), while 51% received HLH-directed therapy. There was significant heterogeneity in the treatment regimens used for HLH.

Treatment Strategies for Central Nervous System Effects in Primary and Secondary Haemophagocytic Lymphohistiocytosis in Children

Purpose of Review

This review presents an appraisal of current therapeutic options for the treatment of central nervous system haemophagocytic lymphohistiocytosis (CNS-HLH) in the context of systemic disease, as well as when CNS features occur in isolation. We present the reader with a diagnostic approach to CNS-HLH and commonly used treatment protocols. We discuss and evaluate newer treatments on the horizon.

Recent Findings

Mortality is high in patients who do not undergo HSCT, and while larger studies are required to establish benefit in many treatments, a number of new treatments are currently being evaluated. Alemtuzumab is being used as a first-line treatment for CNS-HLH in a phase I/II multicentre prospective clinical trial as an alternative to traditional HLH-1994 and 2004 protocols. It has also been used successfully as a second-line agent for the treatment of isolated CNS-HLH that is refractory to standard treatment. Ruxolitinib and emapalumab are new immunotherapies that block the Janus kinase—Signal Transducer and Activator of Transcription (JAK-STAT) pathway that have shown efficacy in refractory HLH, including for CNS-HLH disease.

Summary

Treatment of CNS-HLH often requires HLH-94 or 2004 protocols followed by haematopoietic stem cell transplantation (HSCT) to maintain remission, although relapse can occur, particularly with reduced intensity conditioning if donor chimerism falls. CNS features have been shown to improve or stabilise following HSCT in CNS-HLH in the context of systemic disease and in isolated CNS-HLH. Encouraging reports of early cohort studies suggest alemtuzumab and the Janus kinase (JAK) inhibitor ruxolitinib offer potential salvage therapy for relapsed and refractory CNS-HLH. Newer immunotherapies such as tocilizumab and natalizumab have been shown to be beneficial in sporadic cases. CNS-HLH due to primary gene defects may be amenable to gene therapy in the future.