Virome capture sequencing does not identify active viral infection in unicentric and idiopathic multicentric Castleman disease

Characterizing the heterogeneity of Castleman disease and oligocentric subtype: findings from the ACCELERATE registry

ABSTRACT

Castleman disease (CD) describes a group of rare lymphoproliferative disorders that exhibit a wide range of symptomatology and degree of lymphadenopathy, particularly across the 2 forms of CD with unknown etiology, unicentric CD (UCD), and human herpesvirus-8-negative/idiopathic multicentric CD (iMCD). Whereas UCD cases typically present with localized lymphadenopathy and mild symptoms, iMCD involves multicentric lymphadenopathy and cytokine storm-driven symptoms with 3 recognized clinical phenotypes. Increasingly, there are anecdotal reports of cases that do not fit into this framework, but these cases have not been systematically described. Herein, we use the ACCELERATE natural history registry to characterize the spectrum of CD based on disease features, symptomatology, and severity. Our results characterize a cohort of 179 CD cases, which were reviewed and confirmed by an expert panel of clinicians and hematopathologists. We show that patients with CD present on a continuous spectrum of clinical phenotypes, and we describe oligocentric CD (OligoCD), an intermediate phenotype that does not fit the criteria for UCD or iMCD. These cases tend to have "oligocentric" lymphadenopathy (median [interquartile range] regions of lymphadenopathy, 3.0 [2.0-4.0]) in a regional pattern and exhibit a mild clinical phenotype that is more similar to UCD than iMCD. We also show that patients with OligoCD are inconsistently categorized as UCD vs iMCD, highlighting the need for this characterization. Future data collected through ACCELERATE may further elucidate the natural history and risk profile of these patients.

Common connective tissue disorder and anti-cytokine autoantibodies are enriched in idiopathic multicentric castleman disease patients

Introduction

Idiopathic Multicentric Castleman Disease (iMCD) is a polyclonal lymphoproliferative disorder involving cytokine storms that can lead to organ failure and death. The cause of iMCD is unknown, but some clinical evidence suggests an autoimmune etiology. For example, connective tissue disorders (CTDs) and iMCD share many clinical features, and autoantibodies have been anecdotally reported in individual iMCD patients. This study investigates whether common autoantibodies are shared across iMCD patients.

Methods

We assembled custom bead-based protein arrays consisting of 52 autoantigens traditionally associated with CTDs and 38 full-length cytokines and screened serum samples from 101 iMCD patients for IgG autoantibodies. We also screened samples with a 1,103-plex array of recombinant human protein fragments to identify additional autoantibody targets. Finally, we performed receptor blocking assays on select samples with anti-cytokine autoantibodies (ACAs) identified by array.

Results

We found that an increased proportion of iMCD patients (47%) tested positive for at least one CTD-associated autoantibody compared to healthy controls (HC) (17%). Commonly detected CTD-associated autoantibodies were associated with myositis and overlap syndromes as well as systemic lupus erythematosus (SLE) and Sjögren's Syndrome (SS). ACAs were also detected in a greater proportion of iMCD patients (38%) compared to HC (10%), while the protein fragment array identified a variety of other autoantibody targets. One iMCD sample tested positive for receptor blocking against interferon-ω (IFNω).

Discussion

IgG autoantibodies binding autoantigens associated with common CTDs and cytokines are elevated in iMCD patients compared to HC, suggesting that autoimmunity may be involved in iMCD pathogenesis.

Epstein-Barr virus-encoded RNA-positive lymphocytes in bone marrow and lymph nodes in an autopsy case of TAFRO syndrome

A 55-year-old man was admitted to the hospital with vomiting, diarrhoea, and chest pain. Upon examination, he exhibited signs of increased inflammatory response, acute kidney injury, and thrombocytopenia, leading to a diagnosis of TAFRO syndrome, which was supported by the clinical evidence of generalised lymphadenopathy, pleural effusion, and hepatosplenomegaly. Despite receiving intensive multimodal immunosuppressive therapy, including glucocorticoid pulse therapy (methylprednisolone 1000 mg/day), tocilizumab, and cyclosporine in the intensive care unit, the patient showed minimal response and succumbed to the disease on the seventh day of hospitalisation. Histopathological analysis of the lymph nodes revealed idiopathic multicentric Castleman disease-like features, and Epstein-Barr virus-encoded RNA (EBER) in situ hybridisation identified multiple EBER-positive cells. These findings highlight the elusive pathogenic mechanism of TAFRO syndrome and the potential resistance of some patients to standard treatments such as tocilizumab. The presence of EBER-positive cells in lymph nodes or bone marrow may serve as an indicator of disease severity and treatment resistance. Therefore, histopathological detection of EBER-positive cells may help predict responsiveness to conventional treatments, disease severity, and prognosis in patients with TAFRO syndrome.

No evidence for active viral infection in unicentric and idiopathic multicentric Castleman disease by Viral-Track analysis

Castleman disease (CD) is a rare hematologic disorder characterized by pathologic lymph node changes and a range of symptoms due to excessive cytokine production. While uncontrolled infection with human herpesvirus-8 (HHV-8) is responsible for the cytokine storm in a portion of multicentric CD (HHV-8-associated MCD) cases, the etiology of unicentric CD (UCD) and HHV-8-negative/idiopathic MCD (iMCD) is unknown. Several hypotheses have been proposed regarding the pathogenesis of UCD and iMCD, including occult infection given the precedent established by HHV-8 infection. To investigate potential active infections in UCD and iMCD, we implemented Viral-Track, a computational method that identifies viral mRNA sequences from next-generation sequencing data. We applied Viral-Track to short sequencing reads from a cohort of UCD (n = 22), iMCD (n = 19), and controls (n = 86). While viral sequences for several unusual viruses were identified in individual CD patients,  sequences for the same virus were not found across multiple CD patients or they were not specific to CD samples and were also found in non-CD samples. These results suggest that active viral infection is unlikely to be a pathological driver of UCD or iMCD.

A rare presentation of unicentric Castleman's disease in the thigh: A case report and review of literature

BACKGROUND

Castleman's disease (CD) is a rare lymphoproliferative, emulating both benign and malignant diseases. The diagnosis of CD is formulated upon the combination of clinical and laboratory criteria and ultimately confirmed by histopathological assessment. Due to its rarity, CD presents a challenge in treatment selection, with available options encompassing surgery, chemotherapy, and autologous stem cell transplantation. However, studies suggest that surgical resection of the lesion is the most effective treatment modality, especially for unicentric CD (UCD).

CASE SUMMARY

Here, we describe the case of a 25-year-old woman who presented with painless left thigh swelling for 10 wk. She had been following a low-fat diet to lose weight and had normal laboratory results. Magnetic resonance imaging revealed a well-circumscribed, demarcated cystic lesion located in the left inguinal region with eccentrically positioned signal void vascular structures, measuring 4.3 cm × 3 cm × 3.2 cm, likely of lymphoid origin. The patient underwent surgical resection, and the final histopathology showed a vascular proliferation and hyalinization of the vessel walls, along with atretic germinal centers traversed by penetrating vessels, consistent with CD. The patient was discharged home one day after the procedure in good condition, with a follow-up appointment scheduled in our outpatient clinic.

CONCLUSION

Although surgical resection is the mainstay for UCD, a multidisciplinary approach is needed due the lack of specific diagnostic features and treatments.

Increase in Vascular Endothelial Growth Factor (VEGF) Expression and the Pathogenesis of iMCD-TAFRO

TAFRO (thrombocytopenia (T), anasarca (A), fever (F), reticulin fibrosis (F/R), renal failure (R), and organomegaly (O)) is a heterogeneous clinical subtype of idiopathic multicentric Castleman disease (iMCD) associated with a significantly poorer prognosis than other subtypes of iMCD. TAFRO symptomatology can also be seen in pathological contexts outside of iMCD, but it is unclear if those cases should be considered representative of a different disease entity or simply a severe presentation of other infectious, malignant, and rheumatological diseases. While interleukin-6 (IL-6) is an established driver of iMCD-TAFRO pathogenesis in a subset of patients, the etiology is unknown. Recent case reports and literature reviews on TAFRO patients suggest that vascular endothelial growth factor (VEGF), and the interplay of VEGF and IL-6 in concert, rather than IL-6 as a single cytokine, may be drivers for iMCD-TAFRO pathophysiology, especially renal injury. In this review, we discuss the possible role of VEGF in the pathophysiology and clinical manifestations of iMCD-TAFRO. In particular, VEGF may be involved in iMCD-TAFRO pathology through its ability to activate RAS/RAF/MEK/ERK and PI3K/AKT/mTOR signaling pathways. Further elucidating a role for the VEGF-IL-6 axis and additional disease drivers may shed light on therapeutic options for the treatment of TAFRO patients who do not respond to, or otherwise relapse following, treatment with IL-6 targeting drugs. This review investigates the potential role of VEGF in the pathophysiology of iMCD-TAFRO and the potential for targeting related signaling pathways in the future.

TAFRO Syndrome and COVID-19

TAFRO syndrome is a systemic inflammatory disease characterized by thrombocytopenia and anasarca. It results from hyperinflammation and produces severe cytokine storms. Severe acute respiratory syndrome coronavirus 2, which led to the coronavirus disease 2019 (COVID-19) pandemic, also causes cytokine storms. COVID-19 was reported to be associated with various immune-related manifestations, including multisystem inflammatory syndrome, hemophagocytic syndrome, vasculitis, and immune thrombocytopenia. Although the pathogenesis and complications of COVID-19 have not been fully elucidated, the pathogeneses of excessive immunoreaction after COVID-19 and TAFRO syndrome both involve cytokine storms. Since the COVID-19 pandemic, there have been a few case reports about the onset of TAFRO syndrome after COVID-19 or COVID-19 vaccination. Castleman disease also presents with excessive cytokine production. We reviewed the literature about the association between TAFRO syndrome or Castleman disease and COVID-19 or vaccination against it. While the similarities and differences between the pathogeneses of TAFRO syndrome and COVID-19 have not been investigated previously, the cytokines and genetic factors associated with TAFRO syndrome and COVID-19 were reviewed by examining case reports. Investigation of TAFRO-like manifestations after COVID-19 or vaccination against COVID-19 may contribute to understanding the pathogenesis of TAFRO syndrome.

Hybrid-Capture Target Enrichment in Human Pathogens: Identification, Evolution, Biosurveillance, and Genomic Epidemiology

High-throughput sequencing (HTS) has revolutionised the field of pathogen genomics, enabling the direct recovery of pathogen genomes from clinical and environmental samples. However, pathogen nucleic acids are often overwhelmed by those of the host, requiring deep metagenomic sequencing to recover sufficient sequences for downstream analyses (e.g., identification and genome characterisation). To circumvent this, hybrid-capture target enrichment (HC) is able to enrich pathogen nucleic acids across multiple scales of divergences and taxa, depending on the panel used. In this review, we outline the applications of HC in human pathogens-bacteria, fungi, parasites and viruses-including identification, genomic epidemiology, antimicrobial resistance genotyping, and evolution. Importantly, we explored the applicability of HC to clinical metagenomics, which ultimately requires more work before it is a reliable and accurate tool for clinical diagnosis. Relatedly, the utility of HC was exemplified by COVID-19, which was used as a case study to illustrate the maturity of HC for recovering pathogen sequences. As we unravel the origins of COVID-19, zoonoses remain more relevant than ever. Therefore, the role of HC in biosurveillance studies is also highlighted in this review, which is critical in preparing us for the next pandemic. We also found that while HC is a popular tool to study viruses, it remains underutilised in parasites and fungi and, to a lesser extent, bacteria. Finally, weevaluated the future of HC with respect to bait design in the eukaryotic groups and the prospect of combining HC with long-read HTS.

Idiopathic multicentric Castleman disease: An update in diagnosis and treatment advances

Idiopathic multicentric Castleman disease (iMCD) is a rare disease, and it is likely underdiagnosed because of the heterogeneity of clinical manifestations and laboratory findings. While the disease leads to significant morbidity and mortality, its causes are not yet fully elucidated. There have been significant advances in diagnosis and treatment of iMCD in the past decade, including the approval of the anti-IL-6 antibody siltuximab. In this review, we provide an update of the many new developments and publications surrounding iMCD.

The Cytokine Storm of Multicentric Castleman Disease

As described throughout this book, different triggers can elicit a variety of different cytokine storm disorders that share overlapping clinical features (Fig. 31.1). Even within a particular cytokine storm disorder, multiple different triggers can elicit the syndrome. Like HLH, multicentric Castleman disease (MCD) serves as a great example of this as it can be caused by a viral infection, neoplastic cell population, or an unknown cause. Furthermore, the idiopathic subtype of MCD (iMCD) provides one of the first examples of a cytokine storm disorder that could be abrogated with targeted neutralization of a single cytokine when inhibition with the anti-interleukin-6 (IL-6) receptor monoclonal antibody tocilizumab was shown to effectively treat iMCD in the 1990s. Of course, this "iMCD treatment," tocilizumab, has been used in a variety of cytokine storm settings over the last 30+ years.

Analysis of characteristics of four patients with adrenal unicentric Castleman disease

Background

Castleman Disease (CD) is a group of diseases with characteristic lymph node histopathology, characterized by marked enlargement of deep or superficial lymph nodes. Adrenal CD is rarely reported, and an accurate preoperative diagnosis of adrenal CD is difficult.

Method

We report four cases of CD in the adrenal gland confirmed by pathology and review the characteristics of this rare disease, highlighting the necessity of diagnostic evaluation and follow-up of the patients.

Results

All of the patients sought medical advice because of adrenal incidentalomas. No significant abnormalities were presented in the biochemistry or endocrine systems. The imaging suggested a moderate-to-large mass with uneven moderate contrast enhancement of the adrenal region, similar to a pheochromocytoma. All cases were misdiagnosed as pheochromocytomas before operation and finally confirmed by histopathology. Three cases were pathologically diagnosed as hyaline vascular CD, and one case was diagnosed as plasma cell CD. All the patients are alive without recurrence after a median follow-up of 8 years.

Conclusion

The adrenal CD should be considered after excluding pheochromocytoma and malignancy in the adrenal region. The long-term prognosis of patients with complete resection of the mass is excellent.

[Castleman disease]

The term "Castleman disease" covers a variety of entities that have very different clinical, biological, pathological and physiopathological features. In this issue, we review the characteristics of the unicentric Castleman disease, of the HHV8 associated multicentric Castleman disease and the idiopathic multicentric Castleman disease associated or not with TAFRO syndrome ("thrombocytopenia, anasarca, fever, reticulin myelofibrosis and/or renal insufficiency, organomegaly"). We detail the differential diagnostics of these entities.

Diagnostics différentiels de la maladie de Castleman

Clinicians are sometimes confronted with the diagnostic difficulties of the idiopathic form of Castleman's Disease (iMCD). As this review reports with demonstrative clinical cases, iMCD can mimic various serious systemic pathologies such as certain autoimmune diseases, Still's disease, POEMS syndrome, and malignant lymphoproliferations, sharing a very similar histology and identical symptoms. To make a diagnosis of iMCD, the clinician must eliminate all the pathologies mentioned above, but he must first think of it and evoke this diagnosis of rare disease before the first symptoms but also know how to evoke this diagnosis again even after several years of evolution of a disease like those mentioned above whose evolution is not favorable. © 2022 Published by Elsevier Masson SAS on behalf of Société nationale française de médecine interne (SNFMI).

The disease course of Castleman disease patients with fatal outcomes in the ACCELERATE registry

Castleman disease (CD) describes a group of rare, potentially fatal lymphoproliferative disorders. To determine factors associated with mortality in CD, we analysed data from deceased patients in the ACCELERATE registry and compared them with matched controls. We analysed demographic, treatment and laboratory data from all deceased CD patients, matched controls and a subgroup of idiopathic multicentric Castleman disease (iMCD) patients. Of the 140 patients in ACCELERATE with a confirmed CD diagnosis, 10 had died. There were 72 patients with confirmed iMCD; six were deceased. The deceased CD cohort had more hospitalisations per year, higher overall hospitalisations and more days hospitalised per month, and received more treatment regimens per year than the matched‐control group. Analysis of laboratory values showed a significantly decreased absolute lymphocyte count at months 3 and 6 in the deceased cohort compared with controls. Among iMCD patients, there was a higher proportion of iMCD‐TAFRO (thrombocytopenia, anasarca, fever, reticulin myelofibrosis, renal dysfunction and organomegaly) cases in the deceased group. The deceased iMCD group had significantly lower immunoglobulin M, international normalised ratio and platelet count. These data demonstrate that there may be differences between patients who have fatal and non‐fatal outcomes, and provide preliminary suggestions for parameters to evaluate further.

Leg-type form of idiopathic multicentric Castleman disease associated with severe lower extremity chronic venous/lymphatic disease

Idiopathic multicentric Castleman disease (iMCD) is a lymphoproliferative disease of unknown etiology. Deciphering mechanisms involved in CD pathogenesis may help improving patients' care. Six cases of stereotyped sub-diaphragmatic iMCD affecting lower limb-draining areas and associated with severe and often ulcerative lower extremity chronic dermatological condition were identified in our cohort. Pathological examination revealed mixed or plasma-cell type MCD. In three patients, shotgun metagenomics failed to identify any pathogen in involved lymph nodes. Antibiotics had a suspensive effect while rituximab and tocilizumab failed to improve the condition. This novel entity requires a specific approach and exclusion of potentially harmful immunomodulation.

Castleman disease

Castleman disease (CD), a heterogeneous group of disorders that share morphological features, is divided into unicentric CD and multicentric CD (MCD) according to the clinical presentation and disease course. Unicentric CD involves a solitary enlarged lymph node and mild symptoms and excision surgery is often curative. MCD includes a form associated with Kaposi sarcoma herpesvirus (KSHV) (also known as human herpesvirus 8) and a KSHV-negative idiopathic form (iMCD). iMCD can present in association with severe syndromes such as TAFRO (thrombocytopenia, ascites, fever, reticulin fibrosis and organomegaly) or POEMS (polyneuropathy, organomegaly, endocrinopathy, monoclonal plasma cell disorder and skin changes). KSHV-MCD often occurs in the setting of HIV infection or another cause of immune deficiency. The interplay between KSHV and HIV elevates the risk for the development of KSHV-induced disorders, including KSHV-MCD, KSHV-lymphoproliferation, KSHV inflammatory cytokine syndrome, primary effusion lymphoma and Kaposi sarcoma. A CD diagnosis requires a multidimensional approach, including clinical presentation and imaging, pathological features, and molecular virology. B cell-directed monoclonal antibody therapy is the standard of care in KSHV-MCD, and anti-IL-6 therapy is the recommended first-line therapy and only treatment of iMCD approved by the US FDA and EMA.

Novel somatic alterations in unicentric and idiopathic multicentric Castleman disease

OBJECTIVES

Castleman disease (CD) is a heterogeneous group of disorders involving systemic inflammation and lymphoproliferation. Recently, clonal mutations have been identified in unicentric CD (UCD) and idiopathic multicentric CD (iMCD), suggesting a potential underlying neoplastic process.

METHODS

Patients with UCD or iMCD with next generation sequencing (NGS) data on tissue DNA and/or circulating tumor DNA (ctDNA) were included.

RESULTS

Five patients were included, 4 with iMCD and 1 with UCD. Four patients (80%) were women; median age was 40 years. Three of five patients (60%) had ≥1 clonal mutation detected on biopsy among the genes included in the panel. One patient with iMCD had a 14q32-1p35 rearrangement and a der(1)dup(1)(q42q21)del(1)(q42) (1q21 being IL-6R locus) on karyotype. This patient also had a NF1 K2459fs alteration on ctDNA (0.3%). Another patient with iMCD had a KDM5C Q836* mutation, and one patient with UCD had a TNS3-ALK fusion but no ALK expression by immunohistochemistry.

CONCLUSIONS

We report 4 novel somatic alterations found in patients with UCD or iMCD. The 1q21 locus contains IL-6R, and duplication of this locus may increase IL-6 expression. These findings suggest that a clonal process may be responsible for the inflammatory phenotype in some patients with UCD and iMCD.

[Multicentric Castleman's disease combined with polyserositis and POEMS syndrome: case report and review article]

Castleman disease (CD) is a very rare disorder characterised by hyperplasia of the lymphoid tissue. The aetiology varies considerably and includes autoimmunological, infectious, autoinflammatory and paraneoplastic diseases (e.g. MGUS with POEMS syndrome). What they all have in common is usually a dysregulation/overproduction of certain cytokines and growth factors (including interleukin 6 and VEGF). The sum of these changes sometimes causes very heterogeneous symptoms and thus often makes early diagnosis difficult. The prognosis of unrecognised and untreated disease is very serious and has an average 5‑year survival rate of 55-77%. The present paper describes the case of a 79-year-old patient with refractory polyserositis who was correctly diagnosed after > 8 years.

International evidence-based consensus diagnostic and treatment guidelines for unicentric Castleman disease

Castleman disease (CD) includes a group of rare and heterogeneous disorders with characteristic lymph node histopathological abnormalities. CD can occur in a single lymph node station, which is referred to as unicentric CD (UCD). CD can also involve multicentric lymphadenopathy and inflammatory symptoms (multicentric CD [MCD]). MCD includes human herpesvirus-8 (HHV-8)-associated MCD, POEMS-associated MCD, and HHV-8-/idiopathic MCD (iMCD). The first-ever diagnostic and treatment guidelines were recently developed for iMCD by an international expert consortium convened by the Castleman Disease Collaborative Network (CDCN). The focus of this report is to establish similar guidelines for the management of UCD. To this purpose, an international working group of 42 experts from 10 countries was convened to establish consensus recommendations based on review of treatment in published cases of UCD, the CDCN ACCELERATE registry, and expert opinion. Complete surgical resection is often curative and is therefore the preferred first-line therapy, if possible. The management of unresectable UCD is more challenging. Existing evidence supports that asymptomatic unresectable UCD may be observed. The anti-interleukin-6 monoclonal antibody siltuximab should be considered for unresectable UCD patients with an inflammatory syndrome. Unresectable UCD that is symptomatic as a result of compression of vital neighboring structures may be rendered amenable to resection by medical therapy (eg, rituximab, steroids), radiotherapy, or embolization. Further research is needed in UCD patients with persisting constitutional symptoms despite complete excision and normal laboratory markers. We hope that these guidelines will improve outcomes in UCD and help treating physicians decide the best therapeutic approach for their patients.

Clinical Analysis of Castleman's Disease of the Lacrimal Gland

Objective

To explore the clinical manifestations, imaging characteristics, and pathological characteristics of Castleman's disease of the lacrimal gland, enhance the knowledge of the disease, and improve the level of its diagnosis and treatment.

Methods

In the retrospective study, the data of 5 patients diagnosed with Castleman's disease of the lacrimal gland in Tianjin Medical University Eye Hospital from 2014 to 2018 were analyzed, and the relevant literature was reviewed.

Results

All the 5 patients were confirmed by pathological examination. Clinical manifestations were characterized by mass occupying lesions in the lacrimal gland area, without obvious pain, accompanied by eyelid swelling and ptosis, as well as space-occupying symptoms. Imaging examination showed that there was a soft tissue mass in the enlarged lacrimal gland area, and the mass was rich in blood flows while showing no obvious specificity, which could invade the surrounding muscles. All patients underwent surgical resection. Pathological results showed that 1 case was of the hyaline-vascular type, 3 cases were of the plasma cell type, and 1 case showed malignant transformation to plasma cell tumor.

Conclusion

Castleman's disease of the lacrimal gland is a rare orbital lymphoproliferative disease lacking specificity in clinical manifestations and imaging examination. As there are difficulties in differentiating the disease from orbital inflammatory pseudotumor and orbital lymphoma, its diagnosis still depends on pathological examination. The disease is mainly treated with surgical resection, and the pathological type is determined postoperatively.

Insufficient evidence exists to use histopathologic subtype to guide treatment of idiopathic multicentric Castleman disease

Idiopathic multicentric Castleman disease (iMCD) is a rare immunologic disorder characterized by systemic inflammation, multicentric lymphadenopathy, and organ dysfunction. Enlarged lymph nodes demonstrate a spectrum of characteristic but variable histopathologic features historically categorized into hyaline vascular (HV) (or hypervascular [HyperV] more recently), plasmacytic, or "mixed." Though the etiology is unknown, a pro-inflammatory cytokine storm, often involving interleukin-6 (IL-6), contributes to pathogenesis. Anti-IL-6 therapy with siltuximab is the only FDA- or EMA-approved treatment based on efficacy and safety in multiple studies. Importantly, no patients considered to have HV histopathology achieved the primary endpoint in the Phase II study. NCCN currently recommends siltuximab first-line for iMCD, except for patients considered to have HV histopathology. We investigated whether histopathologic subtype should guide siltuximab treatment decisions. Secondary analyses of clinical trial and real-world data revealed similar clinical benefit across histopathologic subtypes. Notably, only 18 of 79 patients in the Phase II study were consistently classified into histopathologic subtype by three independent review panels, demonstrating limited reliability to guide treatment decisions. Real-world data further demonstrate siltuximab's effectiveness in patients considered to have HV (or HyperV). Though histopathology is a critical component for diagnosis, there is insufficient evidence to guide treatment based solely on lymph node histopathologic subtype.

Five biopsies, one diagnosis: challenges in idiopathic multicentric Castleman disease

A previously healthy 29-year-old man initially presented to the hospital with pleuritic chest pain and shortness of breath. Over the next 2 months he developed ongoing fevers and night sweats with recurrent exudative pleural effusions and ascites. He had an extensive infectious and autoimmune workup that was unremarkable. He had an initial lymph node biopsy that showed reactive changes only. He had an acute kidney injury and his renal biopsy revealed thrombotic microangiopathy. His liver biopsy showed non-specific inflammatory changes. His bone marrow biopsy showed megakaryocyte hyperplasia and fibrosis, which raised suspicion for the thrombocytopenia, ascites, reticulin fibrosis, renal dysfunction and organomegaly syndrome subtype of multicentric Castleman disease. This prompted a repeat lymph node biopsy, showing changes consistent with mixed type Castleman disease that fit with his clinical picture. He was initiated on steroids and siltuximab with significant clinical improvement.

Overview of Castleman disease

Castleman disease (CD) describes a group of at least 4 disorders that share a spectrum of characteristic histopathological features but have a wide range of etiologies, presentations, treatments, and outcomes. CD includes unicentric CD (UCD) and multicentric CD (MCD), the latter of which is divided into idiopathic MCD (iMCD), human herpes virus-8 (HHV8)-associated MCD (HHV8-MCD), and polyneuropathy, organomegaly, endocrinopathy, monoclonal plasma cell disorder, skin changes (POEMS)-associated MCD (POEMS-MCD). iMCD can be further subclassified into iMCD-thrombocytopenia, ascites, reticulin fibrosis, renal dysfunction, organomegaly (iMCD-TAFRO) or iMCD-not otherwise specified (iMCD-NOS). Advances in diagnosis, classification, pathogenesis, and therapy are substantial since the original description of UCD by Benjamin Castleman in 1954. The advent of effective retroviral therapy and use of rituximab in HHV8-MCD have improved outcomes in HHV8-MCD. Anti-interleukin-6-directed therapies are highly effective in many iMCD patients, but additional therapies are required for refractory cases. Much of the recent progress has been coordinated by the Castleman Disease Collaborative Network (CDCN), and further progress will be made by continued engagement of physicians, scientists, and patients. Progress can also be facilitated by encouraging patients to self-enroll in the CDCN's ACCELERATE natural history registry (#NCT02817997; www.CDCN.org/ACCELERATE).

Identifying and targeting pathogenic PI3K/AKT/mTOR signaling in IL-6-blockade-refractory idiopathic multicentric Castleman disease

BACKGROUND

Idiopathic multicentric Castleman disease (iMCD) is a hematologic illness involving cytokine-induced lymphoproliferation, systemic inflammation, cytopenias, and life-threatening multi-organ dysfunction. The molecular underpinnings of interleukin-6(IL-6)-blockade refractory patients remain unknown; no targeted therapies exist. In this study, we searched for therapeutic targets in IL-6-blockade refractory iMCD patients with the thrombocytopenia, anasarca, fever/elevated C-reactive protein, reticulin myelofibrosis, renal dysfunction, organomegaly (TAFRO) clinical subtype.

METHODS

We analyzed tissues and blood samples from three IL-6-blockade refractory iMCD-TAFRO patients. Cytokine panels, quantitative serum proteomics, flow cytometry of PBMCs, and pathway analyses were employed to identify novel therapeutic targets. To confirm elevated mTOR signaling, a candidate therapeutic target from the above assays, immunohistochemistry was performed for phosphorylated S6, a read-out of mTOR activation, in three iMCD lymph node tissue samples and controls. Proteomic, immunophenotypic, and clinical response assessments were performed to quantify the effects of administration of the mTOR inhibitor, sirolimus.

RESULTS

Studies of three IL-6-blockade refractory iMCD cases revealed increased CD8+ T cell activation, VEGF-A, and PI3K/Akt/mTOR pathway activity. Administration of sirolimus significantly attenuated CD8+ T cell activation and decreased VEGF-A levels. Sirolimus induced clinical benefit responses in all three patients with durable and ongoing remissions of 66, 19, and 19 months.

CONCLUSION

This precision medicine approach identifies PI3K/Akt/mTOR signaling as the first pharmacologically-targetable pathogenic process in IL-6-blockade refractory iMCD. Prospective evaluation of sirolimus in treatment-refractory iMCD is planned (NCT03933904).

FUNDING

Castleman's Awareness & Research Effort/Castleman Disease Collaborative Network, Penn Center for Precision Medicine, University Research Foundation, Intramural NIH funding, and National Heart Lung and Blood Institute.