ALBERT

Description: Castleman disease (CD) describes a heterogeneous group of hematologic disorders that share characteristic lymph node histopathology. Patients of all ages present with either a solitary enlarged lymph node (unicentric CD) or multicentric lymphadenopathy (MCD) with systemic inflammation, cytopenias, and life-threatening multiple organ dysfunction resulting from a cytokine storm often driven by interleukin 6 (IL-6). Uncontrolled human herpesvirus-8 (HHV-8) infection causes approximately 50% of MCD cases, whereas the etiology is unknown in the remaining HHV-8-negative/idiopathic MCD cases (iMCD). The limited understanding of etiology, cell types, and signaling pathways involved in iMCD has slowed development of treatments and contributed to historically poor patient outcomes. Here, recent progress for diagnosing iMCD, characterizing etio-pathogenesis, and advancing treatments are reviewed. Several clinicopathological analyses provided the evidence base for the first-ever diagnostic criteria and revealed distinct clinical subtypes: thrombocytopenia, anasarca, fever, reticulin fibrosis/renal dysfunction, organomegaly (iMCD-TAFRO) or iMCD-not otherwise specified (iMCD-NOS), which are both observed all over the world. In 2014, the anti-IL-6 therapy siltuximab became the first iMCD treatment approved by the US Food and Drug Administration, on the basis of a 34% durable response rate; consensus guidelines recommend it as front-line therapy. Recent cytokine and proteomic profiling has revealed normal IL-6 levels in many patients with iMCD and potential alternative driver cytokines. Candidate novel genomic alterations, dysregulated cell types, and signaling pathways have also been identified as candidate therapeutic targets. RNA sequencing for viral transcripts did not reveal novel viruses, HHV-8, or other viruses pathologically associated with iMCD. Despite progress, iMCD remains poorly understood. Further efforts to elucidate etiology, pathogenesis, and treatment approaches, particularly for siltuximab-refractory patients, are needed.

Description: Multicentric Castleman's disease (MCD) describes a heterogeneous group of disorders involving proliferation of morphologically benign lymphocytes due to excessive proinflammatory hypercytokinemia, most notably of interleukin-6. Patients demonstrate intense episodes of systemic inflammatory symptoms, polyclonal lymphocyte and plasma cell proliferation, autoimmune manifestations, and organ system impairment. Human herpes virus-8 (HHV-8) drives the hypercytokinemia in all HIV-positive patients and some HIV-negative patients. There is also a group of HIV-negative and HHV-8-negative patients with unknown etiology and pathophysiology, which we propose referring to as idiopathic MCD (iMCD). Here, we synthesize what is known about iMCD pathogenesis, present a new subclassification system, and propose a model of iMCD pathogenesis. MCD should be subdivided into HHV-8-associated MCD and HHV-8-negative MCD or iMCD. The lymphocyte proliferation, histopathology, and systemic features in iMCD are secondary to hypercytokinemia, which can occur with several other diseases. We propose that 1 or more of the following 3 candidate processes may drive iMCD hypercytokinemia: systemic inflammatory disease mechanisms via autoantibodies or inflammatory gene mutations, paraneoplastic syndrome mechanisms via ectopic cytokine secretion, and/or a non-HHV-8 virus. Urgent priorities include elucidating the process driving iMCD hypercytokinemia, identifying the hypercytokine-secreting cell, developing consensus criteria for diagnosis, and building a patient registry to track cases.

Description: Key Points HIV-negative UCD and iMCD are heterogeneous at the clinical, immunophenotypic, and pathologic levels. Complete surgical resection is the primary option of treatment of UCD, while siltuximab is more effective for iMCD than rituximab.

Description: Idiopathic multicentric Castleman disease (iMCD) is a rare lymphoproliferative disorder. The anti–interleukin 6 (IL-6) therapy siltuximab is not available everywhere, and is not effective for over one-half of patients. Alternative treatment approaches are urgently needed. In the first iMCD clinical trial directed against a target other than IL-6 signaling, we investigated a thalidomide-cyclophosphamide-prednisone (TCP) regimen in newly diagnosed iMCD patients. This single-center, single-arm, phase 2 study enrolled 25 newly diagnosed iMCD patients between June 2015 and June 2018. The TCP regimen (thalidomide 100 mg daily for 2 years; oral cyclophosphamide 300 mg/m2 weekly for 1 year; prednisone 1 mg/kg twice a week for 1 year) was administered for 2 years or until treatment failure. The primary end point was durable tumor and symptomatic response for at least 24 weeks. Twelve patients (48%) achieved the primary end point with no relapse, 3 patients (12%) demonstrated stable disease, and 10 patients (40%) were evaluated as treatment failure. Even when considering all patients, there were significant (P 〈 .05) improvements in median symptom score, IL-6 level, hemoglobin, erythrocyte sedimentation rate, albumin, and immunoglobulin G. Among responders, the median levels of all evaluated parameters significantly improved, to the normal range, after treatment. The regimen was well tolerated. One patient died of pulmonary infection and 1 patient had a grade 3 adverse event (rash); 2 patients died following disease progression. Estimated 1-year progression-free survival and overall survival were 60% and 88%, respectively. The TCP regimen is an effective and safe treatment of newly diagnosed iMCD patients, particularly when siltuximab is unavailable. This trial was registered at www.clinicaltrials.gov as #NCT03043105.

Description: Background: Multicentric Castleman disease (MCD) describes a heterogeneous group of poorly-understood diseases involving proinflammatory hypercytokinemia that ultimately results in systemic inflammatory symptoms, generalized lymphadenopathy, multiple organ system dysfunction, and even death. HHV-8 is responsible for driving MCD in immunosuppressed patients (HHV-8-associated MCD). There is also a cohort of HHV-8-negative MCD cases, referred to as idiopathic MCD (iMCD), in which the etiology remains unknown. No formal diagnostic criteria exist for iMCD, and knowledge is limited to small case series and case reports. Objectives: We conducted a systematic literature review to describe demographic, clinical, and laboratory features of iMCD as well as the treatments currently used in practice. Methods: PubMed was queried using a comprehensive list of terms to identify all published cases of HHV-8-negative MCD. Criteria for study inclusion were as follows: (1) Pathology-confirmed Castleman disease in multiple lymph nodes; (2) Exclusion of another cause of Castleman-like histopathology, such as SLE or POEMS syndrome; (3) Negative testing for HHV-8 via PCR of blood, PCR of lymph node tissue, serum serologies, and/or IHC for LANA-1; (4) Written in English and published from January 1995 to July 2013; and (5) Availability of specified minimum data elements. HIV-positive cases were excluded. Inclusion criteria were confirmed by three independent investigators, who also extracted data into a standardized database. Case report authors were contacted to gather additional data in a standardized case report form. Results: 3,428 articles were identified on PubMed. Initial evaluation for exclusion criteria yielded 1,951 MCD cases; 629 patients were HIV-positive (32%). Of the 999 HIV-negative and 323 HIV-unknown MCD cases, 626 were HHV-8 negative (32% of total MCD), 517 were HHV-8-unknown (26%), and 179 were HHV-8-positive (9%).129 cases of HHV-8-negative MCD met all inclusion criteria and were included in the final analysis. 58% were male and median age was 50 years (range: 2-80). Frequently reported clinical features included: fever (51/64), enlarged liver and/or spleen (45/60), pleural effusion (29/38), edema (26/36), and weight loss (21/29). There were 43 plasmacytic, 26 mixed, and 23 hyaline vascular cases out of 108 cases that reported histopathological subtype. The most commonly reported laboratory abnormalities included elevated CRP (70/79), anemia (76/90), hypergammaglobulinemia (63/82), hypoalbuminemia (57/63), elevated IL-6 (57/63), and positive ANA (14/38). Of cases with abnormal platelet levels, 28 had thrombocytopenia and 14 had thrombocytosis. There were 19 reported cases with elevated soluble IL-2R levels and 15 with elevated VEGF. 27 patients were diagnosed with a malignancy before (5), concurrently with (12), or after (10) diagnosis. Most commonly employed first line therapies included corticosteroid monotherapy (36%), combinations of cytotoxic chemotherapies (36%) that included regimens with cytoxan (17%) and rituxan (12%), and anti-IL-6 therapies, such as siltuximab and tocilizumab, without a cytotoxic agent (10%). Thalidomide, bortezomib, anakinra, and IVIG were used less frequently. Patients experienced no response (21%), partial response (42%), and complete response (37%) to first-line therapies. Failure (relapse, death, additional treatment) of first line therapy occurred in 41% of patients, and median time to treatment failure was 6 months. Overall, 22% of patients died by the time of most recent follow up (median: 28 months) with median length of survival among fatal cases being 26 months (range: 1-120). The most common causes of death were septic shock, multi-organ failure, including renal and cardiac, pulmonary complications, and malignancy. Conclusion: This study identified a significant proportion of MCD patients who are HIV-negative and HHV-8-negative (iMCD). 45% of patients did not demonstrate the plasmacytic variant alone, which has been classically associated with MCD. It is striking that 22% of patients died by the time of most recent follow up, which had a median length of 26 months. Despite the many limitations of analyzing case reports, this study provides the most comprehensive data on HHV-8-negative MCD to date. A global natural history study and Castleman disease registry are urgently needed to gather more extensive data on MCD. Disclosures Fajgenbaum: Janssen Pharmaceuticals: Membership on an entity's Board of Directors or advisory committees. Off Label Use: Cyclophosphamide, rituximab, tocilizumab, thalidomide, bortezomib, anakinra, and intravenous immunoglobulin will be presented as drugs used in HHV-8-negative MCD. It is very important to inventory the treatments that a physician has available when conventional therapies do not work, which is frequent in MCD. At the time that this data set was assembled, there were no FDA approved therapies for this orphan disease. van Rhee:Janssen: Consultancy, Membership on an entity's Board of Directors or advisory committees.

Description: Idiopathic multicentric Castleman disease (iMCD) is a rare hematologic illness involving episodic disease flares with polyclonal cytokine-induced lymphoproliferation, systemic inflammation, and life-threatening multi-organ dysfunction. iMCD is further classified by clinical features and the most severe cases of iMCD often fall into the thrombocytopenia, anasarca, fever/elevated C-reactive protein, reticulin myelofibrosis, renal dysfunction, and organomegaly (TAFRO) clinical subtype. A cytokine storm involving interleukin(IL)-6 drives disease pathogenesis in a subset of patients, however only 34% of patients were found to respond to anti-IL-6 therapy with siltuximab in its registrational clinical trial. The identification of next generation therapeutics for iMCD-TAFRO patients has been challenging as the etiology, pathological cell types, and signaling pathways involved in iMCD-TAFRO are largely unknown. In this study, we aimed to identify cellular drivers and pathophysiological mechanisms of iMCD-TAFRO through the use of an unbiased multi-omics approach. We obtained paired bulk peripheral blood mononuclear cells (PBMCs) from a cohort of ten iMCD-TAFRO patients isolated during disease flare and clinical remission. These paired PBMC samples were utilized for flow cytometry to assess immune cell frequency and phenotype between iMCD-TAFRO flare and remission as well as between flare and age/sex matched healthy donors (n = 10). Three paired iMCD-TAFRO samples were also selected for transcriptional profiling using single-cell RNA sequencing (scRNAseq). We observed phenotypic differences across the T cell, monocyte, and NK cell compartments. We observed a significant increase in the frequency of CD8 T cells within the T cell compartment as well as an increased frequency of granzyme B and perforin expressing CD8 T cells in iMCD-TAFRO flare compared to healthy donors. We also observed a significant increase in the frequency of CD56+ NK cells within the NK cell compartment and a significant increase in the frequency of CD14+ monocytes within the monocyte compartment during iMCD-TAFRO flare compared to healthy donors. Together, these data suggest activation and involvement of CD8 T cell, NK cell, and monocyte subsets during iMCD-TAFRO flare. We next utilized Gene Set Enrichment Analysis (GSEA) of our single-cell transcriptomics dataset to ask whether circulating immune cell frequencies display enrichment of the 50 Hallmark gene sets during flare compared to remission across three iMCD-TAFRO patients. We found significant enrichment (FDR 〈 0.01) of genes within the Interferon Alpha Response gene set in circulating non-naïve CD8 T cells, classical monocytes, nonclassical monocytes, NK cells, and dendritic cells. These data suggest that a number of circulating immune cell populations may be responding to Type I interferon (IFN-I) during iMCD-TAFRO flare. In addition, our group has recently reported mTORC1 activation in iMCD and has characterized in three iMCD-TAFRO patients a clinical response following mTOR inhibition with sirolimus. Within our scRNAseq dataset, we identified mTORC1 signaling to be enriched only in circulating classical and nonclassical monocytes during flare. Having observed enrichment of both the Interferon Alpha Response Gene set and the mTORC1 signaling gene set in circulating monocytes, we then asked whether the relative expression of IFN-I response genes and mTORC1 signaling genes are correlated within circulating classical and nonclassical monocytes. Indeed, we observed a significant positive correlation between the average relative expression of mTORC1 signaling genes and IFN-I Response genes across classical, but not nonclassical, monocytes from all three iMCD-TAFRO patients (all R2 ≥0.6, p

Description: Introduction: Castleman disease (CD) is an uncommon lymphoproliferative disorder of unclear etiology. CD is broadly subclassified into unicentric (UCD) and multicentric (MCD) disease based on based on clinical, radiological, laboratory and histomorphological findings. UCD presents with minimal symptoms, is restricted to a single lymph node station, and excision is usually curative. Multicentric CD, in contrast, presents with systemic inflammatory symptoms, multicentric lymphadenopathy, and vital organ dysfunction. MCD is further subclassified into Human Herpesvirus-8(HHV-8)-associated MCD and HHV-8-negative/idiopathic MCD (iMCD), the etiology of which is poorly understood. Histologically, UCD frequently shows a hyaline vascular pattern with atretic follicles, thickened mantle zones and increased interfollicular vascularity with hyalinization. iMCD frequently shows increased interfollicular plasma cells and hyperplastic follicles. iMCD is also characterized by a systemic hypercytokinemia that includes IL-6, VEGF, IL-2, TNF-α, IL-10 and CXCL13. However, the cell(s) involved in initiating and amplifying the cytokine network are unclear. We combined histomorphology and cytokine in situ hybridization to identify the hypercytokine-producing cells in lymph nodes from CD patients. In addition, T and B lymphocytes play important roles in initiating and amplifying the cytokine response and their clonality has not been well-studied in CD. Here, we performed deep sequencing of the immunoglobulin heavy chain and T cell receptor gene loci. Methods: Lymph node biopsies from patients with UCD and iMCD were identified from the pathology archives of the Children's Hospital of Philadelphia. 17 UCD cases and 8 HHV8-negative iMCD cases were examined. Reactive lymph nodes (N=10) with plasmacytosis and/or other CD-like features served as controls. Cytokine expression was determined by RNA in situ hybridization (RNAscope) on formalin fixed paraffin embedded tissue. IL-6, IL-6R, VEGF, IL-10, TNF-α, IL-1β, IL-2, and IL-8 RNA expression patterns were analyzed in conjunction with histomorphological features. Expression was manually quantified with a semi-quantitative grading scale (0-4) per manufacturer recommendations and statistical analysis was performed using the Chi-square test. Fresh frozen lymph node tissue was utilized for deep sequencing of the TCR Vβ and IgH gene loci. VDJ usage, clonal frequency and CDR3 sequence was determined and compared between subtypes of CD and reactive lymph node controls. Results: Lymph nodes from patients with iMCD express significantly higher levels of VEGF compared to patients with UCD and controls (75% vs. 29% vs. 0%; p=0.014). Atretic follicles and interfollicular regions were the source of increased VEGF expression. Potential cell types responsible for the increased VEGF production in these regions are follicular dendritic cells in the atretic follicles and plasma cells in the interfollicular areas. IL-6 expression was also significantly higher in iMCD cases compared to UCD and controls (75% vs. 25% vs. 20%, p=0.026) in a subset of cells within the interfollicular regions. This cellular source of the excess IL-6 in the interfollicular region may be endothelial cells. Thus, follicular dendritic cells in the germinal centers and endothelial cells, T cells, and plasma cells in the interfollicular spaces are potential sources for increased VEGF and IL-6. IL-6R, IL-10, TNF-α, IL-1β, IL-2, and IL-8 showed no significant differences between the various subtypes of CD. Deep sequencing of the TCRα gene loci revealed mildly expanded clonal T-cell populations (5% of total sequences) in a subset of iMCD cases (2/6) and UCD cases (1/9) compared to controls (0/15). B cell populations were polyclonal in both subtypes of CD and in reactive lymph nodes. Conclusion: The findings suggest that cells in the interfollicular region and atretic follicles in the lymph nodes are a potential source of the systemic hypercytokinemia in iMCD. The locations and patterns of cytokine expression implicate follicular dendritic cells, endothelial cells, and plasma cells specifically as potential hypercytokine-producing cells. Additionally, T cells in CD show oligoclonality in some cases and may play an important role in initiating or amplifying the immune response in CD. Disclosures Fajgenbaum: Janssen Pharmaceuticals, Inc.: Research Funding.

Description: Castleman disease (CD) describes a group of heterogeneous diseases defined by shared characteristic lymph node histopathology and is classified based on the number of regions of enlarged lymph nodes. Multicentric CD (MCD) involves multiple regions of lymphadenopathy as well as systemic inflammation, cytopenias, and vital organ dysfunction due to a cytokine storm that often includes interleukin-6. In ~50% of patients, the pathogenic driver is Kaposi sarcoma-associated/human herpesvirus-8 (HHV-8) in the context of immunosuppression. In contrast, the etiologic driver in HHV8-negative MCD (idiopathic or iMCD) is unknown. To date, most research has focused on descriptive characterization of the enlarged lymph nodes, and the pathological cell types driving iMCD pathogenesis remain unidentified. Given that lymphoid cells circulate through the blood and lymph nodes, are able to produce high levels of cytokines upon activation, and are the primary cell types responsible for the enlarged lymph nodes in iMCD and other related diseases, we first performed a detailed immunophenotyping of peripheral blood mononuclear cells (PBMCs) obtained from iMCD patients in remission (n=16), iMCD patients during disease flare (n=6) and healthy donors (HD) (n=15). PBMCs were isolated by density gradient and either stained immediately or cryopreserved for future analyses. A HD sample was drawn at the same time as each experimental sample and processed and analyzed in parallel. Our initial hypothesis was that analysis of iMCD flare PBMCs would reveal an abnormal myeloid or lymphocyte subset. Thus, we stained and analyzed PBMCs for standard lineage markers: CD11b, CD15, CD19, CD3, CD56 and CD14. However, we observed no gross differences in population frequencies during either remission or flare compared to HD. Additionally, no differences in the proportions of natural killer T cells (CD3+CD56+), or CD4+ or CD8+ lymphocytes were observed. However, more refined examinations of the lymphocyte sub-sets based upon activation status revealed an increased proportion of activated memory (CD62LlowHLA-DR+) CD8+ cells during iMCD flare compared to HD and iMCD patients in remission and a decreased proportion of naïve (CD62L+CD45RA+) CD8+ cells compared to HD (p

Description: Human herpesvirus-8(HHV-8)-negative/idiopathic multicentric Castleman disease (iMCD) is a rare and poorly understood disorder diagnosed in ~1,000 individuals in the USA each year. It involves polyclonal lymphoproliferation, constitutional symptoms, systemic inflammation and an uncontrollable cytokine storm resulting in life-threatening multi-organ failure. Diagnosis and treatment can be difficult due to limited etiological understanding and heterogeneous presentation - clinical, laboratory, and histopathological abnormalities overlap with infectious, autoimmune and oncological diseases. iMCD symptoms and disease progression are largely believed to be driven by interleukin-6 (IL-6). However, approximately 66% of iMCD patients did not respond to anti-IL-6 therapy, siltuximab, the only FDA-approved iMCD therapy, in its phase II study (NCT01024036). Few treatment options exist for anti-IL-6 refractory patients because alternative driver cytokines and signaling pathways are not known. Herein we report the largest study to-date of iMCD serum proteomes with correlative anti-IL6 response data from 92 iMCD patients in disease flare (n=75 of which were collected as part of NCT01024036), in order to: (1) molecularly define iMCD, (2) identify predictors of response to anti-IL6 therapy, and (3) gain insights into the pathogenesis of iMCD. Proteomes of HHV8-positive MCD (n=20), Hodgkin lymphoma (n=20), rheumatoid arthritis (n=20) and healthy individuals (n=44) were also analyzed. Of the ~1,300 analytes measured using SomaLogic SOMAscan, 1,178 passed QC and were included in analyses. Each analyte was log2 transformed and capped at the 2.5th and 97.5th percentiles. Clinical and laboratory data collected at the time of sample draw were used to calculate disease activity following a modified CHAP scale: C-reactive protein, hemoglobin and albumin; missing performance status. Response to siltuximab was determined in NCT01024036. Data analysis was performed using the Medidata Rave Omics machine learning platform and R v3.4.4. Clustering of baseline proteomic data for iMCD patients identified six clusters that ranged in size from seven to 27 subjects. No associations with race, site, sex, age, or batch were found. Analytes identified among the strongest differentiators include cytokines, chemokines and inflammatory molecules. Interestingly, the largest cluster was associated with response to siltuximab (p

Description: Castleman disease (CD) describes a group of heterogeneous hematologic disorders with characteristic histopathological features. CD can present with unicentric or multicentric (MCD) regions of lymph node enlargement. Some cases of MCD are caused by human herpesvirus-8 (HHV-8), whereas others are HHV-8–negative/idiopathic (iMCD). Treatment of iMCD is challenging, and outcomes can be poor because no uniform treatment guidelines exist, few systematic studies have been conducted, and no agreed upon response criteria have been described. The purpose of this paper is to establish consensus, evidence-based treatment guidelines based on the severity of iMCD to improve outcomes. An international Working Group of 42 experts from 10 countries was convened by the Castleman Disease Collaborative Network to establish consensus guidelines for the management of iMCD based on published literature, review of treatment effectiveness for 344 cases, and expert opinion. The anti–interleukin-6 monoclonal antibody siltuximab (or tocilizumab, if siltuximab is not available) with or without corticosteroids is the preferred first-line therapy for iMCD. In the most severe cases, adjuvant combination chemotherapy is recommended. Additional agents are recommended, tailored by disease severity, as second- and third-line therapies for treatment failures. Response criteria were formulated to facilitate the evaluation of treatment failure or success. These guidelines should help treating physicians to stratify patients based on disease severity in order to select the best available therapeutic option. An international registry for patients with CD (ACCELERATE, #NCT02817997) was established in October 2016 to collect patient outcomes to increase the evidence base for selection of therapies in the future.