Biological therapies for hemophagocytic lymphohistiocytosis: current knowledge and future perspectives

INTRODUCTION

Hemophagocytic lymphohistiocytosis (HLH) is a hyperinflammatory syndrome with a dismal prognosis. The underlying causes of HLH are diverse. However, the overabundance of cytokines was shared by all forms of HLH. Cytokine-targeted biotherapies have been increasingly used in HLH treatment.

AREAS COVERED

In this review, we aim to provide an overview of biological treatment options for HLH.

EXPERT OPINION

Biological therapies offer alternative treatment options for patients with refractory/relapsed HLH or who are intolerant to conventional chemotherapies. As a complement to traditional treatment, biological agents improve response rates, maintain more protracted periods of remission, and reduce treatment related toxicity. A combination of biological agents may be a promising direction for HLH treatment. However, they may induce HLH to deteriorate and even trigger HLH.

Immune Effector Cell-Associated Hemophagocytic Lymphohistiocytosis-Like Syndrome

T cell-mediated hyperinflammatory responses, such as cytokine release syndrome (CRS) and immune effector cell-associated neurotoxicity syndrome (ICANS), are now well-established toxicities of chimeric antigen receptor (CAR) T cell therapy. As the field of CAR T cells advances, however, there is increasing recognition that hemophagocytic lymphohistiocytosis (HLH)-like toxicities following CAR T cell infusion are occurring broadly across patient populations and CAR T cell constructs. Importantly, these HLH-like toxicities are often not as directly associated with CRS and/or its severity as initially described. This emergent toxicity, however ill-defined, is associated with life-threatening complications, creating an urgent need for improved identification and optimal management. With the goal of improving patient outcomes and formulating a framework to characterize and study this HLH-like syndrome, we established an American Society for Transplantation and Cellular Therapy panel composed of experts in primary and secondary HLH, pediatric and adult HLH, infectious disease, rheumatology and hematology, oncology, and cellular therapy. Through this effort, we provide an overview of the underlying biology of classical primary and secondary HLH, explore its relationship with similar manifestations following CAR T cell infusions, and propose the term "immune effector cell-associated HLH-like syndrome (IEC-HS)" to describe this emergent toxicity. We also delineate a framework for identifying IEC-HS and put forward a grading schema that can be used to assess severity and facilitate cross-trial comparisons. Additionally, given the critical need to optimize outcomes for patients experiencing IEC-HS, we provide insight into potential treatment approaches and strategies to optimize supportive care and delineate alternate etiologies that should be considered in a patient presenting with IEC-HS. By collectively defining IEC-HS as a hyperinflammatory toxicity, we can now embark on further study of the pathophysiology underlying this toxicity profile and make strides toward a more comprehensive assessment and treatment approach.

Hemophagocytic lymphohistiocytosis after autologous stem cell transplantation in angioimmunoblastic T-cell lymphoma: A case report

BACKGROUND

Angioimmunoblastic T-cell lymphoma (AITL), a unique subtype of peripheral T-cell lymphoma, has relatively poor outcomes. High-dose chemotherapy with autologous stem cell transplantation (ASCT) can achieve complete remission and improve outcomes. Unfortunately, subsequent T-cell lymphoma-triggered hemophagocytic lymphohistiocytosis (HLH) has a worse prognosis than B-cell lymphoma-triggered HLH.

CASE SUMMARY

We here report a 50-year-old woman with AITL who achieved a favorable outcome after developing HLH 2 mo after receiving high-dose chemotherapy/ ASCT. The patient was initially admitted to our hospital because of multiple enlarged lymph nodes. The final pathologic diagnosis, made on biopsy of a left axillary lymph node was AITL (Stage IV, Group A). Four cycles of the following chemotherapy regimen were administered: Cyclophosphamide 1.3 g, doxorubicin 86 mg, and vincristine 2 mg on day 1; prednisone 100 mg on days 1-5; and lenalidomide 25 mg on days 1-14. The interval between each cycle was 21 d. The patient received a conditioning regimen (busulfan, cyclophosphamide, and etoposide) followed by peripheral blood stem cell infusion. Unfortunately, she developed sustained fever and a low platelet count 17 d after ACST, leading to a diagnosis of HLH after ASCT. During treatment, she experienced thrombocytopenia and Pneumocystis carinii pneumonia. The patient was successfully treated with etoposide and glucocorticoids.

CONCLUSION

It is possible that development of HLH is related to immune reconstitution after ASCT.

Epstein-Barr virus-induced infection-associated hemophagocytic lymphohistiocytosis with acute liver injury: A case report

BACKGROUND

Hemophagocytic lymphohistiocytosis (HLH) is a severe hyperinflammatory reaction, which is rare and life-threatening. According to the pathogen, HLH is divided into genetic and acquired. The most common form of acquired HLH is infection-associated HLH, of which Herpes viruses, particularly Epstein-Barr virus (EBV), are the leading infectious triggers. However, it is difficult to distinguish between simple infection with EBV and EBV-induced infection-associated HLH since both can destroy the whole-body system, particularly the liver, thereby increasing the difficulty of diagnosis and treatment.

CASE SUMMARY

This paper elaborates a case about EBV-induced infection-associated HLH and acute liver injury, aiming to propose clinical guides for the early detection and treatment of patients with EBV-induced infection-associated HLH. The patient was categorized as acquired hemophagocytic syndrome in adults. After the ganciclovir antiviral treatment combined with meropenem antibacterial therapy and methylprednisolone inhibition to inflammatory response, gamma globulin enhanced immunotherapy, the patient recovered.

CONCLUSION

From the diagnosis and treatment of this patient, attention should be paid to routine EBV detection and a further comprehensive understanding of the disease as well as early recognition and early initiation are keys to patients’ survival.

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.

The emerging role of anti-PD-1 antibody-based regimens in the treatment of extranodal NK/T-cell lymphoma-associated hemophagocytic lymphohistiocytosis

PURPOSE

Anti-PD-1 antibody (anti-PD-1 mAb) showed favorable outcomes in some patients with relapsed/refractory (r/r) extranodal NK/T-cell lymphoma (ENKTL). However, the role of anti-PD-1 antibody in NK/T-cell lymphoma-associated hemophagocytic lymphohistiocytosis (NK/T-LAHS) remains unclear. Here, we evaluated the efficacy and toxicity of anti-PD-1 antibody-based treatment in NK/T-LAHS patients.

METHODS

The clinical data of 98 patients diagnosed with NK/T-LAHS at Sun Yat-sen University Cancer Center and the First Affiliated Hospital of Guangdong Pharmaceutical University from May 2014 to November 2021 were retrospectively analyzed. All patients received anti-HLH [HLH-2004 (etoposide, dexamethasone, cyclosporine A) or DEP-based (liposomal doxorubicin, etoposide, methylprednisolone)] regimen and sequential anti-ENKTL chemotherapy (ChT) combined with anti-PD-1 antibody or not.

RESULTS

The overall response rate (ORR) of the anti-PD-1 mAb plus ChT regimens was higher than that of the ChT regimens (73.3% vs. 45.5%, P = 0.041). The toxicity of the anti-PD-1 mAb plus ChT regimens was tolerable. Except for higher rate of neutropenia, no significant difference in adverse events (AEs) was observed between the two groups. When the optimal response to anti-ENKTL was achieved, the median EBV DNA levels in patients who received anti-PD-1 mAb plus ChT were significantly lower than patients who received ChT only (878 copies/mL vs. 18,600 copies/mL, P = 0.001). With a median follow-up of 26.6 months (range 0-65.9 months), the median overall survival (mOS) was 3.5 months (95% CI：2.3-4.7 months). Patients treated with anti-PD-1 mAb plus ChT experienced a longer mOS than those who received ChT only [5.2 months (95% CI: 2.5-7.8 months) vs. 1.5 months (95% CI: 0.5-2.6 months), P = 0.002]. Cox multivariate analysis found that anti-PD-1 mAb was an independent prognostic factor for all NK/T-LAHS patients.

CONCLUSION

In conclusion, anti-PD-1 mAb combined with ChT regimens seemed to be associated with prolonged survival in NK/T-LAHS patients and may represent a potentially promising treatment strategy for this population.

A Diagnostic Dilemma: Adult-Onset Still's Disease With Secondary Hemophagocytic Lymphohistiocytosis/Macrophage Activation Syndrome?

Adult-onset Still's disease (AOSD) is a rare autoinflammatory condition. It is a diagnosis of exclusion by ruling out all related infectious, inflammatory, autoimmune, and malignant diseases. We present a case of a 23-year-old Caucasian male who presented with fever, night sweats, joint pain, weight loss, and diarrhea. The initial presentation delayed the diagnosis. Upon further investigation, we formulated the diagnosis of AOSD. In sporadic cases, AOSD with secondary hemophagocytic lymphohistiocytosis (HLH), also known as macrophage activation syndrome (MAS), is a devastating disorder of uncontrolled immune activation characterized by clinical and laboratory evidence of extreme inflammation. In case of suspected secondary complications, timely involvement of a multidisciplinary team and starting of appropriate medications is necessary.

Solid organ graft-versus-host disease in a recipient of a COVID-19 positive liver graft

A 66-year-old male with end-stage liver disease (ESLD) secondary to non-alcoholic fatty liver disease (NAFLD), complicated by hepatocellular carcinoma (HCC), underwent deceased donor liver transplantation from a Coronavirus disease 2019 (COVID-19) positive donor. He presented a month later with fever, diarrhea and pancytopenia which led to hospitalization. The hospital course was notable for respiratory failure, attributed to invasive aspergillosis, as well as a diffuse rash. A bone marrow biopsy revealed hypocellular marrow without specific findings. In the following days, laboratory parameters raised concern for secondary hemophagocytic lymphohistiocytosis (HLH). Clinical concern also grew for solid organ transplant graft-versus-host-disease (SOT-GVHD) based on repeat marrow biopsy with elevated donor-derived CD3+ T cells on chimerism. After, a multidisciplinary discussion, the patient was started on ruxolitinib, in addition to high dose steroids, to address both SOT-GVHD and secondary HLH. Patient developed symptoms concerning for hemorrhagic stroke and was transitioned to comfort care. Although GVHD has been studied extensively in hematopoietic stem cell transplant (HSCT) patients, it is a rare entity in SOT with a lack of guidelines for management. Additionally, whether COVID-19 may play a role in development of SOT-GVDH has not been explored.

Serum sCD25/ferritin ratio combined with MCP-1 is a valid predictor for identifying LAHS with HLH as the first manifestation

PURPOSE

Lymphoma-associated haemophagocytic syndrome (LAHS) is a group of malignant diseases with rapid progression and a high mortality rate. Our study aimed to discover the significance of serum sCD25/ferritin ratio as well as cytokines in assisting the diagnosis of LAHS.

METHODS

We retrospectively analyzed the clinical data of 82 patients with LAHS with hemophagocytic lymphohistiocytosis (HLH) as the first manifestation and divided them into B-LAHS group and T/NK-LAHS group according to lymphoma pathological diagnosis for comparison. And patients with LAHS were divided into responding group, non-responding group according to the assessment of efficacy after receiving DEP/L-DEP induction therapy for 2 weeks to compare possible valuable indicators.

RESULTS

Serum sCD25/ferritin ratio and MCP-1 levels were significantly different between B-LAHS and T/NK-LAHS groups (P = 0.001, P = 0.022). An sCD25/ferritin ratio > 7.8 tended to suggest a diagnosis of B-LAHS (AUC = 0.71, 95% CI: 0.596-0.823), and the sCD25/ferritin ratio had better predictive value when combined with MCP-1 (AUC = 0.81, 95% CI: 0.699-0.922). The sCD25/ferritin ratio was also significantly different between the two groups responding or not responding to induction therapy (P = 0.002), yielding an optimal cutoff value of 11.48. An sCD25/ferritin ratio > 11.48 tended to suggest that the patient's LAHS was responsive to induction therapy.

CONCLUSION

Our study reveals that serum sCD25/ferritin ratio combined with MCP-1 is a valid predictor for identifying LAHS with HLH as the first manifestation and may assist in predicting whether the lymphoma is of B-cell or T/NK-cell origin. The sCD25/ferritin ratio can also be used to predict the early response of LAHS after induction therapy.

The Clinical Significance and Prognostic Role of Whole-Blood Epstein-Barr Virus DNA in Lymphoma-Associated Hemophagocytic Lymphohistiocytosis

PURPOSE

To evaluate the role of circulating Epstein-Barr virus (EBV) DNA in lymphoma-associated hemophagocytic lymphohistiocytosis (HLH).

METHODS

We conducted a retrospective cohort study to explore the clinical and prognostic significance of EBV DNA in lymphoma-associated HLH. We included adult patients with combined diagnoses of lymphoma and HLH from January 2010 and November 2022 by retrieving the medical record system.

RESULTS

A total of 281 patients with lymphoma-associated HLH were identified. Elevated whole-blood EBV DNA was observed in 54.4% (153/281) of patients, and the median copy number was significantly higher in the T/NK-cell malignancies (199,500, interquartile range, 30,000-1,390,000) than that in the B-cell non-Hodgkin lymphoma (5520, interquartile range, 1240-28,400, P < 0.001). The optimum cutoff for predicting survival was 16,100 copies/mL. Compared to the patients with EBV DNA ≤ 16,100 copies/mL, those with EBV DNA > 16,100 copies/mL were younger and had more T/NK-cell malignancies, lower levels of neutrophils and fibrinogen, and higher levels of hemoglobin, alanine aminotransferase, aspartate aminotransferase, lactic dehydrogenase, and β₂-microglobulin. A higher load of EBV DNA (> 16,100 copies/mL), thrombocytopenia (< 100 × 10⁹/L), neutropenia (< 1 × 10⁹/L), hypofibrinogenemia (≤ 1.5 g/L), and elevated levels of creatinine (> 133 μmol/L) were independent adverse predictors of 60-day overall survival and overall survival. A prognostic index based on EBV DNA and the other four factors was established to categorize the patients into four groups with significantly different outcomes.

CONCLUSION

Our study identified high EBV load as a risk factor for lymphoma-associated HLH and established a prognostic index to predict outcomes.

Hemophagocytic lymphohistiocytosis in inflammatory bowel disease: a nationwide analysis

Hemophagocytic lymphohistiocytosis (HLH) is a rare but life-threatening immune dysregulation disease. Patients with inflammatory bowel disease (IBD) can become profoundly immunocompromised due to immunosuppressive therapy, hence increasing the risk of viral infections that can trigger HLH. However, data on the association between IBD and HLH remains limited. We used data from the National Inpatient Sample (2012-2019) utilizing International Classification of Diseases (ICD)-9 or ICD-10 codes to identify individuals with IBD, either Crohn's disease (CD) or ulcerative colitis (UC), and HLH. The primary outcome was to compare the prevalence of HLH among patients with IBD with those without IBD. Secondary outcomes included in-hospital mortality, mean hospital length of stay, and description of HLH-associated triggers in IBD patients. A total of 513,322 hospitalizations included a diagnosis of IBD, 188,297 had UC and 325,025 had CD. Compared to the general population, patients with IBD were older (median age of 52 vs. 49 years, p < 0.05), more likely to be male, and of Asian/Pacific Islander descent, and had a higher median household income. There was also a higher prevalence of liver disease, autoimmune diseases, tobacco abuse, and hypothyroidism (all had p-value of < 0.001) in IBD patients. There were 94 hospitalizations identified with a diagnosis of HLH in IBD patients. Compared to patients without IBD, patients with IBD had increased odds of developing HLH (0.02% vs 0.01%, p-value < 0.001). After adjusting for various demographic characteristics, co-morbidities, and HLH-related conditions, IBD was an independent predictor for developing HLH (adjusted OR, 2.3; 95% CI, 1.847-2.866, p-value of < 0.001). There was no statistical difference between CD and UC in the odds of developing HLH. Compared to IBD patients without HLH, patients with IBD and HLH had a lower mean age at diagnosis (38 vs 52, p-value of < 0.001), higher in-hospital mortality (14.9% vs 1.5%, p-value of < 0.001), and longer mean hospital length of stay (days) (17 vs 5.4, p-value of < 0.001). Prevalence of different HLH-associated illnesses was identified in HLH patient's discharge data. Lymphoma was the most common associated malignancy (18.1%) and cytomegalovirus infection was the most common associated infection (16.0%). Our population-based study suggests that IBD is independently associated with developing HLH. Early recognition of IBD patients presenting with features suggestive of HLH is warranted to aide early diagnosis and aggressive treatment.

Nationwide analysis of adult hospitalizations with hemophagocytic lymphohistiocytosis and systemic lupus erythematosus

INTRODUCTION

Hemophagocytic lymphohistiocytosis (HLH) is a well-recognized complication of systemic lupus erythematosus (SLE). This study aims to characterize HLH with and without SLE in the US adult inpatient population.

METHODS

We performed a retrospective study of HLH with and without SLE from the 2016-2019 National Inpatient Sample (NIS) database. We described the demographic characteristics of HLH with and without SLE. Multivariable analysis was performed to calculate odds ratios (OR) for in-hospital death.

RESULTS

A total of 8690 hospitalizations had HLH. Of those 605 (7%) had SLE, and 8085 (93%) did not have SLE. Relative to the non-SLE group, the SLE group was younger, had more females, less whites, more African Americans, more Hispanics, and more Asian/Pacific Islanders. Over 60% of HLH with or without SLE had a concurrent infection. Sixty (9.9%) of HLH hospitalizations with SLE died compared to 1735 (21.5%) of those without SLE. Among HLH hospitalizations, multivariable analysis showed that age (OR 1.02; 95% C.I. 1.016-1.031), Charlson Comorbidity Index (OR 1.15; 95% C.I. 1.091-1.213), infections (OR 3.35; 95% C.I. 2.467-4.557), and leukemia/lymphoma (OR 1.46; 95% C.I. 1.112-1.905) had higher odds of in-hospital death. SLE did not increase the odds of death.

CONCLUSIONS

Inpatients with both HLH and SLE were younger, had a higher proportion of racial/ethnic minorities, and were predominately female. One out of every 10 hospitalizations for HLH ended in death but SLE itself was not an independent risk factor for death. Concurrent infection was the variable most associated with HLH death. Key Points • HLH and SLE group were younger and had higher proportions of female and racial/ethnic minorities. • SLE was not an independent risk factor for death in HLH patients.

Serum cytokine pattern in children with hemophagocytic lymphohistiocytosis

This study aimed to compare the serum levels of 34 cytokines of children with hemophagocytic lymphohistiocytosis (HLH) and explored the specific cytokine pattern of HLH subtypes and the relationship between cytokine levels and prognosis. This retrospective study assessed the clinical data and cytokine levels of newly diagnosed children with HLH in Beijing Children's Hospital, Capital Medical University, from January 2017 to December 2021. A total of 101 children were enrolled in the study. The levels of IFN-γ and IL-18 increased in more than 90% of patients, and MIP-1α, SDF-1α, IP-10, IL-6, IL-8, IL-10, IL-1 RA, and TNF-α increased at different levels in more than 50% of patients. The levels of IL-10 in EBV-HLH increased significantly, followed by IFN-γ and IL-18, while IL-10 and IFN-γ in CAEBV-HLH had a slight increase. Except for IL-10, the levels of IL-6, Eotaxin, IL-13, IL-18, IFN-γ, and MIP-1β in Rh-HLH increased significantly. F-HLH had significantly high IL-10 levels and a slight increase in IL-13. We showed that various cytokines could assist in differentiating HLH subtypes with ROC curve analysis. When IL-10/IL-6 was 1.37, the sensitivity and specificity of diagnosing EBV-HLH were higher than 80% (AUC = 0.837, p < 0.001). The effect of cytokine ratio on classifying HLH subtypes (17/22, 77.3%) was more significant than the single cytokine (5/22, 22.7%). The 3-year overall survival (OS) rate of children with F-HLH was the lowest during the follow-up. The 3-year OS of patients with EBV-HLH and CAEBV-HLH was significantly higher than that with F-HLH (88.1% ± 5.0% vs. 94.1% ± 5.7% vs. 57.1% ± 14.6%, p = 0.017). Cox proportional hazards model revealed that elevated GM-CSF and MCP-1, as well as CNS involvement, were independent risk factors for poor outcomes for patients with HLH. Various cytokines play important roles in HLH. Different subtypes of HLH have their specific cytokines pattern, and the ratio of cytokines may be more significant in differentiating HLH subtypes than the single one. Elevated GM-CSF and MCP-1 could be useful biomarkers for a poor prognosis for patients with HLH.

Mouse models of systemic juvenile idiopathic arthritis and macrophage activation syndrome

Macrophage activation syndrome (MAS) is a life-threatening complication of pediatric rheumatic diseases, occurring most commonly in children with systemic juvenile idiopathic arthritis (SJIA). Despite several classes of currently available treatment options for SJIA, including biologic agents targeting IL-1 or IL-6, there remain severe cases suffering from refractory disease and recurrent MAS. The phenotype of MAS is similar to hemophagocytic lymphohistiocytosis (HLH), but the underlying pathophysiology of MAS complicating SJIA or other disorders has not been fully clarified. These facts make it challenging to develop and utilize animal models to study MAS. To date, there is no "perfect" model replicating MAS, but several models do demonstrate aspects of SJIA and/or MAS. In this review, we examine the proposed animal models of SJIA and MAS, focusing on how they reflect these disorders, what we have learned from the models, and potential future research questions. As we better understand the key features of each, animal models can be powerful tools to further define the pathophysiology of SJIA and MAS, and develop new treatment targets and strategies.

A case of hemophagocytic lymphohistiocytosis with a significant response to baricitinib: a first report with review of literature

Hemophagocytic lymphohistiocytosis (HLH) is a febrile disease with hyperinflammation characterized by activated macrophages with phagocytosis. The treatment strategy of secondary HLH has not been clearly established. Because of the high mortality rate and poor prognosis of HLH, alternative treatment strategies have been sought in treatment-resistant cases. Recently, there have been several reports that ruxolitinib, a Janus kinase (JAK) 1/JAK2 inhibitor, was effective against secondary HLH. Since the pathogenesis of HLH involves the overproduction of cytokines and JAK transmits a variety of cytokine signals, JAK inhibitors are thought to be effective in HLH. We herein report a case of HLH that was refractory to glucocorticoids, cyclosporine, and etoposide but responded to baricitinib. In the field of rheumatology, treatment-resistant cases of secondary HLH remain unmet needs. This is the first report to show that baricitinib was effective in a case of HLH. The accumulation of more cases in the future may prove that baricitinib is a potent agent for treating HLH.

An unforeseen reality: Hemophagocytic lymphohistiocytosis following alemtuzumab treatment for a multiple sclerosis

Alemtuzumab is a humanized monoclonal antibody indicated for treatment of highly active relapsing-remitting multiple sclerosis (HA-RRMS). It binds to CD52 antigen and produces a rapid and prolonged lymphocyte depletion followed by a different pattern of T and B cell repopulation. Among others, its adverse events are autoimmune diseases.In this article, we present a patient with HA-RRMS, who was subsequently treated with alemtuzumab and afterwards developed hemophagocytic lymphohistiocytosis (HLH). Albeit rarely, HLH can be triggered by alemtuzumab treatment.HLH can favourably respond to prompt immunosuppressant therapy.Multidisciplinary approach by a team consisting of a neurology, hematology and rheumatology specialist is needed to treat this potentially lethal condition.

Miliary tuberculosis-associated hemophagocytic lymphohistiocytosis with a high level of soluble interleukin-2 receptor successfully treated with concomitant recombinant thrombomodulin: A case report

Hemophagocytic lymphohistiocytosis (HLH) is a fatal disease characterized by a highly inflammatory state due to the abnormal activation of T lymphocytes and macrophages. Miliary tuberculosis (MTB) is a rare cause of HLH and its clinical appearances occasionally resembles that of intravascular lymphoma (IVL). A 76-year-old woman presented with persistent fever and fatigue. Abnormal laboratory findings showing thrombocytopenia (13,000/μL), hypofibrinogenemia (101 mg/dL), hyperferritinemia (2,312 ng/mL), and markedly elevated soluble interleukin-2 receptor (sIL-2R) level (32,200 U/mL), in addition, hemophagocytosis in the bone marrow (BM) smear, were suggestive of IVL-associated HLH. The pathology of the BM biopsy specimen showed granuloma with non-caseous necrosis, and culture tests using sputum, gastric fluid, urine, and peripheral and bone marrow blood revealed the presence of Mycobacterium tuberculosis, leading to the final diagnosis of MTB-associated HLH. Anti-TB medications and corticosteroids were administered, but thrombocytopenia, hypofibrinogenemia, and hyperferritinemia persisted. Concomitant use of recombinant thrombomodulin (rTM) enabled regression of clinical status. In this case, BM biopsy served as the diagnosis of MTB-associated HLH, although IVL-associated HLH is initially suspected by an extremely high level of sIL-2R. Furthermore, this case report informs that using rTM could improve the outcomes of MTB-associated HLH.

The clinical and immunological characteristics in fatal severe fever with thrombocytopenia syndrome virus (SFTSV) infection

OBJECTIVE

This study aimed to make a comprehensive evaluation of peripheral immune profiles for further understanding the immunopathogenesis of severe fever with thrombocytopenia syndrome (SFTS).

METHODS

Forty-seven patients with SFTS virus infection were included, of which 24 were deceased. The percentages, absolute numbers, phenotype of lymphocyte subsets were detected by flow cytometry.

RESULTS

In patients with SFTS, the numbers of CD3+T, CD4+T, CD8+T and NKT cells were decreased compared with healthy controls (HCs), accompanied with highly active and exhausted phenotypes for T cells, and overproliferating plasmablasts. High inflammatory status, dysregulation of coagulation and host immune response were more obvious in deceased patients than that of survivors. Higher levels of PCT, IL-6, IL-10, TNF-α, APTT, TT and the occurrence of hemophagocytic lymphohistiocytosis were poor prognostic indicators of SFTS.

CONCLUSIONS

The evaluation of immunological markers in combination with laboratory tests has critical value for selecting prognostic markers and potential treatment target.

Granulomatous inflammation and hypogammaglobulinemia: Clinical conundrum of familial hemophagocytic lymphohistiocytosis type 5

Familial hemophagocytic lymphohistiocytosis (HLH) is an inherited disorder characterized by systemic hyperinflammation caused by an uncontrolled immune response mediated by T-lymphocytes, natural killer (NK) cells, and macrophages. Most children with familial HLH present within first 2 years of life and can have fatal disease unless hematopoietic stem cell transplant (HSCT) is performed (1). However, few patients may have late presentation and prolonged survival. With increasing awareness and facilities to identify HLH these disorders are being identified beyond infancy (2-4). Clinical and laboratory features are often similar to other primary immune deficiency diseases and pose diagnostic challenges (4-6). We report two patients who presented beyond the first decade of life with HLH, granulomatous inflammation, hypogammaglobulinemia, reduced B cells and were diagnosed to have familial HLH type 5 due to defect in STXBP2 gene.

Severe COVID-19-associated hyperinflammatory syndrome versus classic hemophagocytic lymphohistiocytosis: similarities, differences, and the way forward

The hyperinflammatory immune response in severe COVID-19 infection shares features with secondary hemophagocytic lymphohistiocytosis (sHLH) in the form of fever, cytopenia, elevated inflammatory markers, and high mortality. There are contrasting opinions regarding utility of HLH 2004 or HScore in the diagnosis of severe COVID-19-related hyperinflammatory syndrome (COVID-HIS). This was a retrospective study of 47 patients of severe COVID-19 infection, suspected to have COVID-HIS and 22 patients of sHLH to other illnesses, to evaluate the diagnostic utility and limitations of HLH 2004 and/or HScore in context to COVID-HIS and to also evaluate the utility of Temple criteria for predicting severity and outcome in COVID-HIS. Clinical findings, hematological, and biochemical parameters along with the predictor of mortality were compared between two groups. Only 6.4% (3/47) of cases fulfilled ≥5/8 HLH 2004 criteria and only 40.52% (19/47) of patients showed HScore >169 in COVID-HIS group. 65.9% (31/47) satisfied the Temple criteria in COVID-HIS as compared with 40.9% (9/22) in the non-COVID group (p = 0.04). Serum ferritin (p = 0.02), lactate dehydrogenase (p = 0.02), direct bilirubin (p = 0.02), and C-reactive protein (p = 0.03) were associated with mortality in COVID-HIS. Both HScore and HLH-2004 criteria perform poorly for identifying COVID-HIS. Presence of bone marrow hemophagocytosis may help to identify about one-third of COVID-HIS missed by the Temple Criteria.

Angioimmunoblastic T-cell lymphoma induced hemophagocytic lymphohistiocytosis and disseminated intravascular coagulopathy: A case report

BACKGROUND

Angioimmunoblastic T-cell lymphoma (AITL) is a subtype of peripheral T-cell lymphoma, with heterogenous clinical manifestations and poor prognosis. Here, we report a case of AITL induced hemophagocytic lymphohistiocytosis (HLH) and disseminated intravascular coagulopathy (DIC).

CASE SUMMARY

An 83-year-old man presented with fever and purpura of both lower limbs for one month. Groin lymph node puncture and flow cytometry indicated a diagnosis of AITL. Bone marrow examination and other laboratory related indexes indicated DIC and HLH. The patient rapidly succumbed to gastrointestinal bleeding and septic shock.

CONCLUSION

This is the first reported case of AITL induced HLH and DIC. AITL is more aggressive in older adults. In addition to male gender, mediastinal lymphadenopathy, anaemia, and sustained high level of neutrophil-to-lymphocyte ratio may indicate a greater risk of death. Early diagnosis, early detection of severe complications, and prompt and effective treatment are vital.

Unusual presentation of systemic lupus erythematosus as hemophagocytic lymphohistiocytosis in a female patient: A case report

BACKGROUND

Hemophagocytic lymphohistiocytosis (HLH) is a rare life-threatening disorder, often resulting in the immune-mediated injury of multiple organ systems, including primary HLH and secondary HLH (sHLH). Among them, sHLH results from infections, malignant, or autoimmune conditions, which have quite poor outcomes even with aggressive management and are more common in adults.

CASE SUMMARY

We report a rare case of a 36-year-old female manifested with sHLH on background with systemic lupus erythematosus (SLE). During hospitalization, the patient was characterized by recurrent high-grade fever, petechiae and ecchymoses of abdominal skin, and pulmonary infection. Whole exon gene sequencing revealed decreased activity of natural killer cells. She received systematic treatment with Methylprednisolone, Etoposide, and anti-infective drugs. Intravenous immunoglobulin and plasmapheresis were applied when the condition was extremely acute and progressive. The patient recovered and did not present any relapse of the HLH for one year of follow-up.

CONCLUSION

The case showed sHLH, thrombotic microvascular, and infection in the whole course of the disease, which was rarely reported by now. The treatment of the patient emphasizes that early recognition and treatment of sHLH in SLE patients was of utmost importance to improve the prognosis and survival rate of patients.

Population pharmacokinetics of ruxolitinib in children with hemophagocytic lymphohistiocytosis: focus on the drug-drug interactions

PURPOSE

The optimal dose regimen of ruxolitinib (RUX) in children with hemophagocytic lymphohistiocytosis (HLH) remains to be determined. The aim was to develop and verify a population pharmacokinetic (PPK) model, and then provide references for the optimization of dose regimen of RUX in children with HLH.

METHODS

A total of 189 RUX concentrations from 32 children were included. The PPK model was established using the nonlinear mixed-effects model approach. Predictive performance and stability of the final PPK model were evaluated. The exposure of RUX in different clinical scenarios was simulated through Monte Carlo simulations.

RESULTS

A one-compartment model with first-order absorption and linear elimination was identified to describe the disposition of RUX. The absorption rate constant (K_a) in the final PPK model was 1.05 h^-1, and the apparent clearance (CL/F) and volume of distribution (V/F) were 9.80 L/h and 30.6 L, respectively. Coadministration with triazoles (TZS) and azithromycin (AZM) resulted in approximately 31.0% and 32.4% reductions in the CL/F of RUX, respectively. Multiple evaluation procedures showed satisfactory predictive performance and stability of the final model. Monte Carlo simulations showed that the exposure of RUX was significantly affected by the coadministration with TZS and/or AZM under different clinical scenarios.

CONCLUSION

For the first time, a PPK model of RUX in children with HLH was developed and evaluated. The coadministration with TZS and/or AZM were found to reduce the clearance of RUX in children. These findings could provide new insights for the precise treatment of RUX in children with HLH.

The biology of VSIG4: Implications for the treatment of immune-mediated inflammatory diseases and cancer

V-set and immunoglobulin domain containing 4 (VSIG4), a type I transmembrane receptor exclusively expressed in a subset of tissue-resident macrophages, plays a pivotal role in clearing C3-opsonized pathogens and their byproducts from the circulation. VSIG4 maintains immune homeostasis by suppressing the activation of complement pathways or T cells and inducing regulatory T-cell differentiation, thereby inhibiting the development of immune-mediated inflammatory diseases but enhancing cancer progression. Consequently, VSIG4 exhibits a potential therapeutic effect for immune-mediated inflammatory diseases, but also is regarded as a novel target of immune checkpoint inhibition in cancer therapy. Recently, soluble VSIG4, the extracellular domain of VSIG4, shed from the surface of macrophages, has been found to be a biomarker to define macrophage activation-related diseases. This review mainly summarizes recent new findings of VSIG4 in macrophage phagocytosis and immune homeostasis, and discusses its potential diagnostic and therapeutic usage in infection, inflammation, and cancer.