Change In Mast Cell Bone Marrow Burden and In Serum Tryptase Level Are Not Accurate Markers of Response In Patients with Systemic Mastocytosis

Blood ◽  
2010 ◽  
Vol 116 (21) ◽  
pp. 3073-3073
Author(s):  
Alfonso QuintÁs-Cardama, ◽  
Matjaz Sever ◽  
Jorge E. Cortes ◽  
Hagop M. Kantarjian ◽  
Srdan Verstovsek
Keyword(s):  
Bone Marrow ◽  
Mast Cell ◽  
Mast Cells ◽  
Systemic Mastocytosis ◽  
Median Number ◽  
Response To Therapy ◽  
Serum Tryptase ◽  
Bone Marrow Biopsies ◽  
Tryptase Level ◽  
Bone Marrow Mast Cell

Abstract Abstract 3073 Background: Bone marrow involvement, with or without cutaneous or visceral involvement, is almost universal in patients with systemic mastocytosis (SM). The KITD816V mutation is present in most patients with SM, thus confirming its clonal nature. Patients with ASM are usually managed with cytoreductive agents such as hydroxyurea (HU), cladribine (2CDA), or interferon-alpha (IFN-α), although the activity of these therapies is limited as they do not target specifically the malignant clone. Response assessment in SM relies on symptom improvement and reduction in serum tryptase levels and visceral and/or bone marrow mast cell burden (percent mast cell involvement). We contend that the later two relatively objective metrics may not be appropriate markers of response because serum tryptase levels may vary significantly at different time-points in the same patient in the absence of intervention, do not correlate accurately with mast cell burden, and bone marrow mast cell burden determination is subject to sampling bias given the patchy infiltration observed in many cases of SM. Objectives: To assess the utility of bone marrow mast cell burden reduction and serum tryptase level reduction as criteria for response in patients with SM. Patients and Therapy: We studied a cohort of 50 patients with SM for whom at least 2 sequential bone marrow biopsies and 2 serum tryptase level determinations were available at our center. The KITD816V mutation was present in 20 (59%) of 34 assessable patients. No patient carried the JAK2V617F mutation or the FIP1L1-PDGFRA rearrangement. Patients had a diagnosis of indolent SM (ISM, n=25), aggressive SM (ASM, n=16), or SM-AHNMD (n=9). All but 1 patient received SM-directed therapy (median number of therapies 2, range 1–5), including: imatinib (n=16), dasatinib (n=23), RAD001 (n=8), denileukin diftitox (n=7). The median number of bone marrow biopsies available per patient was 4 (range, 2–14) and the median number of tryptase measurements was 6 (range, 2–18), which were obtained both on and off SM-directed therapies. Results: Four patients had a bone marrow complete response: 1 with imatinib, 2 with dasatinib, and 1 with decitabine (with SM-MDS). However none of the responders normalized their tryptase levels. We used the coefficient of variation (CV) as a normalized measure of dispersion of a probability distribution for the percentage of mast cells in bone marrow biopsies and serum tryptase levels. In this manner, the CV summarizes/describes the variation in tryptase levels and bone marrow mast cell percentage from the baseline (first recorded value) in the patients evaluated. We found that among the 49 treated patients, the percentage of bone marrow mast cells varied significantly with a CV ranging from 6 – 173% and an average of 65%. Forty-four percent of patients had a CV equal or higher to the average. Similar results were observed regarding tryptase levels, with an average CV of 19% that ranged from 0 to 96%. Thirty-six percent of patients had a CV higher than average. Conclusion: While most patients fail to respond to currently available SM-directed therapies, sequential bone marrow biopsies and tryptase level determinations exhibit remarkable variation both during and in the absence of SM-directed therapy. Therefore, it seems that single time point measurements of these values do not represent proper tools to assess accurately response to therapy. Disclosures: No relevant conflicts of interest to declare.

scholarly journals Bone marrow mast cell burden and serum tryptase level as markers of response in patients with systemic mastocytosis

2013 ◽  
Vol 54 (9) ◽  
pp. 1959-1964 ◽  
Author(s):  
Alfonso Quintás-Cardama ◽  
Matjaz Sever ◽  
Jorge Cortes ◽  
Hagop Kantarjian ◽  
Srdan Verstovsek
Keyword(s):  
Bone Marrow ◽  
Mast Cell ◽  
Systemic Mastocytosis ◽  
Serum Tryptase ◽  
Tryptase Level ◽  
Bone Marrow Mast Cell

Imatinib Mesylate in the Treatment of Systemic Mastocytosis, a Phase I/II Trial.

Blood ◽  
2004 ◽  
Vol 104 (11) ◽  
pp. 1516-1516 ◽  
Author(s):  
H.J. Droogendijk ◽  
J.C. Kluin-Nelemans ◽  
P.L.A van Daele
Keyword(s):  
Bone Marrow ◽  
Cell Proliferation ◽  
Mast Cell ◽  
Mast Cells ◽  
Imatinib Mesylate ◽  
Systemic Mastocytosis ◽  
Skin Lesions ◽  
Tissue Response ◽  
Serum Tryptase ◽  
Kit Receptor

Abstract Introduction: mastocytosis comprimes a group of diseases characterized by abnormal proliferation and accumulation of mast cells in one or more organs. A cutaneous and systemic form of mastocytosis is distinguished. Systemic mastocytosis defines the disease process in which mast cell proliferation exceeds the skin. The clinical manifestations of systemic mastocytosis depend on the tissues involved and the tissue response to the accumulation of mast cells. Although in general the disease progresses slowly, it may develop into a malignant disease. Currently there is no cure for systemic mastocytosis. Mast cells develop from pluripotent bone marrow progenitor cells that express CD34 antigen and are dispersed as precursors which undergo proliferation and maturation in different tissues. Normal mast cell development involves the action of stam cell growth factor and c-kit receptors, which are expressed by mast cells at their different developmental stages. Deregulation and/or abnormalities of the c-kit receptor are assumed to play a causal role in disordered mast-cell proliferation. In most patients a mutation in the gene for c-kit exists. One of the mutations is the D816V mutation. Aim of the study:imatinib mesylate, formerly called ST1571, is a potent inhibitor of c-kit receptor tyrosine kinase activity. In this study, we evaluate whether imatinib mesylate is safe and effective in the treatment of patients with systemic mastocytosis. Primary end-points of study are reduction in urinary N-methylhistamine excretion, serum tryptase activity, skin lesions, number of mast cells in sections of bone marrow, hepato-and/or splenomegaly and symptoms.Adverse effects on therapy are also considered. Results: up to now, 10 patients with systemic mastocytosis are treated with 400 mg of imatinib mesylate orally once daily. During the first 2 weeks of the study the patients also received 30 mg of prednisolone daily. In general imatinib mesylate is well tolerated. The first results show a 38–80% reduction in urinary N-methylhistamine excretion and 30–66% reduction in serum tryptase activity. Skin lesions diminish in two of the six patients with cutaneous mastocytosis,. Number of mast cells in sections of bone marrow are reduced in 63% (5/8) of the patients. Hepato-and/or splenomegaly is slightly decreased in two of the three patients with organomegaly. Finally 60 % of all patients experiences relief of symptoms. In eight patients the D816V mutation was found. In contrast with former studies imatinib mesylate is also effective in these patients. Further results are to be awaited. Conclusion: imatinib mesylate is safe and seems effective in the treatment of patients with systemic mastocytosis (including patients with the D816V mutation).

Kit Signaling Regulates Mitf Expression in Mastocytosis.

Blood ◽  
2006 ◽  
Vol 108 (11) ◽  
pp. 3601-3601
Author(s):  
Youl-Nam Lee ◽  
Pierre Noel ◽  
Amir Shahlaee ◽  
Melody Carter ◽  
Reuben Kapur ◽  
...  
Keyword(s):  
Bone Marrow ◽  
Mast Cell ◽  
Mast Cells ◽  
Systemic Mastocytosis ◽  
Tyrosine Kinase Receptor ◽  
Bone Marrow Biopsies ◽  
Activating Mutations ◽  
Cell Assays ◽  
Mast Cell Disease ◽  
Mitf Expression

Abstract Mastocytosis is a heterogeneous disease arising from abnormal proliferation of mast cells. Activating mutations in codon D816 of the tyrosine kinase receptor, c-kit, are found in the majority of adult patients with systemic mastocytosis, an aggressive form of the disease. Constitutive activation of the Kit signaling pathway is critical to the transformed phenotype, and thus understanding how this pathway regulates downstream events is of great importance. A number of transcription factors are also essential to mast cell development, including the Microphthalmia-associated transcription factor (Mitf). We examined Mitf expression in bone marrow biopsies from nine patients with systemic mastocytosis by immunohistochemistry; we found that Mitf is highly expressed in all cases with the D816V mutation. In contrast, Mitf is not highly expressed in non-malignant mast cells in the bone marrow from patients with aplastic anemia and leukemia, suggesting thatMitf expression is regulated by Kit-dependent signalsMitf may play a role in the transformed phenotype of mastocytosis.We show that in normal mast cells, Kit signaling markedly upregulates Mitf expression. In both normal and malignant mast cells, pharmacologic inhibitors of Kit, and the downstream kinase, PI3K, block Mitf expression. To examine whether Mitf is required for transformed phenotype from constitutive Kit signaling in mast cells, we have used a shRNA-expressing lentivirus to knockdown Mitf expression in mastocytosis cell lines. We found that silencing of Mitf markedly impaired growth in proliferation and colony forming cell assays. This work demonstrates a link between two critical factors, Kit and Mitf, in the development of malignant mast cell disease.

scholarly journals MDS with 5q deletion and rare cKIT positive mastocytosis: a diagnostic and therapeutic challenge

2019 ◽  
Vol 12 (4) ◽  
pp. e227768
Author(s):  
Daniel Steven Sanders ◽  
Thomas Fennell ◽  
Mohammad Muhsin Chisti
Keyword(s):  
Bone Marrow ◽  
Mast Cell ◽  
Case Report ◽  
Systemic Mastocytosis ◽  
Molecular Testing ◽  
Bone Marrow Biopsies ◽  
Haematological Response ◽  
Clonal Origin ◽  
Mast Cell Population ◽  
5Q Deletion

A patient with a diagnosis of myelodysplastic syndrome (MDS) with isolated 5q deletion underwent repeat bone marrow biopsy to assess haematological response after 6 months of initial lenalidomide therapy. Subsequent bone marrow biopsies revealed persistent MDS with del(5q) in addition to a small atypical mast cell population with >25% of mast cells with spindle-shaped morphology and immunohistochemistry characteristics consistent with mastocytosis. Molecular testing on the bone marrow was positive for cKIT D816V and the patient was diagnosed with systemic mastocytosis (SM) with an associated haematological neoplasm. MDS with SM is well known to be associated; however, to the best of our knowledge, only one prior case report identifies MDS with del(5q) and associated cKIT D816V positive mastocytosis. While the exact clonal origin of both chromosomal aberrations is unclear, this case illustrates the therapeutic efficacy of lenalidomide in a patient with MDS with del(5q) and rarely associated cKIT positive SM.

UK Single Instituition Experience of Mastocytosis: Guys and St Thomas' NHS Foundation Trust

Blood ◽  
2010 ◽  
Vol 116 (21) ◽  
pp. 5052-5052
Author(s):  
Nandini Sadasivam ◽  
Mufaddal Moonim ◽  
Clive Grattan ◽  
Jonathan White ◽  
Bridget Wilkins ◽  
...  
Keyword(s):  
Bone Marrow ◽  
Mast Cells ◽  
Clinical Symptoms ◽  
Systemic Mastocytosis ◽  
Symptom Control ◽  
Alpha Interferon ◽  
Treatment Needs ◽  
Self Administration ◽  
Bone Marrow Biopsies ◽  
Kit D816v

Abstract Abstract 5052 Introduction: Systemic mastocytosis(SM) is diagnosed when clonal, neoplastic mast cells are demonstrated in extracutaneous tissues. SM is a heterogeneous disorder ranging from indolent disease to aggressive multisystem involvement. We have an established mastocytosis working group in our Trust which was registered with the European Competence Network of Mastocytosis(ECNM) in 2005. We present data prospectively collected using an ECNM algorithm for the management of SM patients over 5 years. Methods: 120 cases of cutaneous mastocytosis have been discussed at 3 monthly multidisciplinary meetings with dermatology colleagues. Full blood counts, liver, bone profile and DEXA scans are reviewed with clinical symptoms and treatments. Patients with a tryptase level of >20ng/ml are offered haematology review and bone marrow investigation. In addition patients referred directly to haematology for a second opinion have their cases and bone marrows reviewed. Bone marrow samples are sent for c-kit D816V mutation analysis. Results: Classification of SM patients. 59/120 (46%) patients were offered bone marrow biopsies. Tryptase levels for these ranged from 15.1–760ng/ml (median 51.5ng/ml).4 patients declined biopsy.5/55 had normal biopsies and were c-kit negative.50 patients had SM.47/50(94%) met the WHO major criteria and 3/50(6%) minor criteria. These were subclassified-38/50(76%) had Indolent Systemic Mastocytosis(ISM);1/50 (2%) had Smouldering Systemic Mastocytosis(SSM);5/50(10%) had Aggressive Systemic Mastocytosis and 6/50(12%) had Systemic Mastocytosis with associated haematologiocal non-mast cell lineage disorder(SM-AHNMD). The bone marrow trephine disease burden was variable:ASM (range 5–100%), SSM 20%, ISM (5-45%) and AHNMD (5-100%). Tryptase levels reflected total disease bulk including cutaneous burden. C-KIT D816V mutation 44 patients with SM had samples analysed for the D816V mutation. 35 were positive (80%) and 9 negative (20%). Clinical Symptoms: 11/59 (19%) patients were asymptomatic (10 had ISM and 1 SSM).36/59 (61%) patients had urticarial symptoms needing symptomatic treatment (2 normal marrow, 2 AHNMD, 2 ASM and 30 ISM).16/59 (27%) patients had allergic symptoms ranging from mild allergies to anaphylaxis.(3 normal marrows, 13 ISM).13/59(22%) had gastrointestinal symptoms ranging from loose motions to severe colitis(1 normal marrow,1 ASM and 11 ISM). DEXA results:36/59(61%) patients had reported DEXA scans at our Trust, the rest reviewed locally. 6/36 (16%) had osteoporosis and required treatment. One 63yr old female patient has SM-AHNMD(MPD). 5 patients had ISM. 3 were females (age range 45–65yrs; tryptase levels 42.9, 49.1 and 60.5ng/ml)) and 2 male (both 45yrs: tryptase levels 31.2 and 47.8ng/ml). After 1 year of treatment with bisphophonates one of the male patients showed an improvement in his osteoporosis indices.7/36(19%) had osteopaenia reported all with a diagnosis of ISM.5 were male and 2 female (tryptase range 21.1–174ng/ml:median 40.3ng/ml).23/36(64%) patients had normal DEXA scans. Management: Treatment regimes in patients with SM are for symptom control. Antihistamines, anti-inflammatory agents, anti-leucotriene agents, mast cells stabilising agents, bisphosphonates and steroids are used. In severe anaphylactic patients self administration of adrenaline is taught. Patients with ASM have been treated with various modalities e.g. Cladrabine, Alpha Interferon, Dasatinib, Imatinib (D816V negative patients) and Midostaurine with variable partial responses.2 patients with ASM have died due to rapidly progressive disease.2 AHNMD patients have an associated MPD (1 Jak 2 postive) and are being treated with pegylated alpha interferon and venesection.2 AHNMD patients died as a result progressive acute myeloid leukaemia and Non Hodgkins Lymphoma.2 AHNMD patients (MDS/MGUS) are being monitored. Conclusions: Our data reflects the heterogeneous nature of this disorder both clinically and in the histological classification. Patients with ISM can have severe clinical manifestations and treatment needs to be tailored to the individual's symptoms. Assessment and surveillence for osteoporosis is vital for all patients. ASM patients have limited treatment options with variable and unsustained responses. Further development of evidence based novel therapies requires multicentred trials in this rare group of patients. Disclosures: Harrison: Incyte: Honoraria; Novartis: Honoraria.

Anti CD-30 Antibody-Drug Conjugate Brentuximab Vedotin (ADCETRIS®) May Be a Promising Treatment Option for Systemic Mastocytosis (SM).

Blood ◽  
2012 ◽  
Vol 120 (21) ◽  
pp. 2857-2857 ◽  
Author(s):  
Amitkumar Mehta ◽  
Vishnu V B Reddy ◽  
Uma Borate
Keyword(s):  
Mast Cell ◽  
Mast Cells ◽  
Systemic Mastocytosis ◽  
White Male ◽  
Brentuximab Vedotin ◽  
Antibody Drug Conjugate ◽  
Antimitotic Agent ◽  
Drug Conjugate ◽  
Tryptase Level ◽  
Antibody Drug

Abstract Abstract 2857 Mastocytosis is a clonal proliferation of abnormal mast cells in single or multiple organs leading to clinical syndromes ranging from a benign self-resolving cutaneous disease to the highly aggressive malignancy, mast cell leukemia (MCL). Mastocytosis is categorized under myeloproliferative neoplasms in the 2008 World Health Organization (WHO) classification of hematopoietic and lymphoid diseases. In almost all cases of SM, the bone marrow (BM) is involved by atypical mast cells. The characteristic Asp816Val (D816V) mutation in the KIT gene present in most cases gives the atypical mast cells a survival advantage that leads to treatment resistance with tyrosine kinase inhibitor (TKIs) like imatinib. According to the 2008 WHO classification, 1 major and 1 minor or 3 minor criterion are required for the diagnosis of systemic mastocytosis (Fig. 1a). Systemic Mastocytosis (SM) is subcategorized into four distinct categories in order of indolent to highly aggressive disease: Indolent Systemic Mastocytosis (ISM), SM with an associated hematologic non-MC-lineage disease (SM-AHNMD), aggressive SM (ASM) and MCL. SM with C findings categorized as ASM (Fig. 1b) is treated with cytoreductive chemotherapy such as interferon 2α or 2-chlorodeoxyadenosine (2-CdA). The overall response rate (ORR) with these agents is 40–50% with significant chemotherapy-related toxicity and short durable responses. The majority of patients with ASM and MCL relapse within a year with a very poor prognosis. The CD30 (Ki-1) antigen is expressed in the majority of ASM cases. Thus, CD30 can serve as a potential therapeutic target as well as a reliable tumor marker to follow disease status. Brentuximab vedotin is an antibody-drug conjugate compound consisting of a chimeric monoclonal antibody against CD30 linked to the antimitotic agent monomethyl auristatin E (MMAE). Here we report evidence of anti-tumor activity in two patients with CD30-positive ASM treated with brentuximab vedotin. Case #1: A 62 year old white male with significant medical history of rheumatoid arthritis, diabetes mellitus and coronary artery disease was evaluated for pancytopenia and hepatomegaly. His initial BM aspiration and biopsy revealed multifocal dense mast cell infiltrate (30–40% involvement with tryptase and CD117 positivity). His initial serum tryptase level was 276 ng/ml. He was treated with 2-CdA continuous infusion for three cycles with no significant response and substantial toxicities. He was subsequently enrolled in a clinical trial with brentuximab vedotin given every 3 weeks at 1.8 mg/kg after confirmation of CD30 positivity on BM aspirate and biopsy (Fig. 2). His peripheral blood counts started to improve after the 5thcycle and he had a durable partial response as assessed by his peripheral blood counts and BM biopsies (Fig 2). Importantly, his sequential bone marrow biopsies showed a decrease in mast cell involvement and CD30 intensity with improved normal marrow cellularity (Fig 2). His only treatment-related toxicities were grade II neuropathy and neutropenia for which his dose was reduced to 1.2 mg/kg. He is currently asymptomatic with ECOG performance status of 0 and does not require any growth factor support at Cycle 12 of this regimen. Case #2: A 79 yr old white male with significant medical history of hypertension, obstructive sleep apnea, coronary artery disease s/p CABG was referred for new diagnosis of ASM on BM biopsy (60–70% marrow involvement with 3+ mast cell density). His initial tryptase level was 224ng/ml. He was enrolled on the same clinical protocol as described above. His sequential BM biopsies revealed significant reduction in mast cell density with mild improvement in overall normal cellularity after 3 cycles of treatment. (Fig 3). Conclusion: Brentuximab vedotin is a promising targeted therapy for SM and needs to be confirmed further by a prospective multicenter clinical trial. In two patients reported here treatment is well tolerated, targets the malignant mast cells and seems to prevent disease progression in a rare disorder with few treatment options and limited response rates. Disclosures: Off Label Use: Brentuximab vedotin (ADCETRIS®) is an antibody-drug conjugate compound consisting of a chimeric monoclonal antibody against CD30 linked to the antimitotic agent monomethyl auristatin E (MMAE). It is not FDA approved for use in Mastocytosis.

Comprehensive Cytokine Profiling in Systemic Mastocytosis: Prognostic Relevance of Increased Plasma IL-2R Levels.

Blood ◽  
2012 ◽  
Vol 120 (21) ◽  
pp. 2836-2836 ◽  
Author(s):  
Animesh Pardanani ◽  
Christy Finke ◽  
Terra L Lasho ◽  
Ayalew Tefferi
Keyword(s):  
Bone Marrow ◽  
Overall Survival ◽  
Mast Cell ◽  
Median Survival ◽  
Systemic Mastocytosis ◽  
B Cell Lymphoma ◽  
World Health ◽  
Serum Tryptase ◽  
Who Criteria

Abstract Abstract 2836 Background: The clinical phenotype of systemic mastocytosis (SM) is highly variable; establishing prognosis in terms of overall survival or risk of transformation to aggressive disease for those with non-indolent and indolent disease variants, respectively, is not trivial. Similar to other clonal hemopathies, mast cell (MC) activation and/or stromal response to clonal MC expansion likely results in a dysregulated immuno cellular/cytokine profile; analysis of this aspect of SM may provide additional prognostic information within the context of well established parameters such as the World Health Organization (WHO) SM classification system. Here, we conducted a comprehensive analysis of circulating cytokines/chemokines with clinicopathologic and clinical outcome correlations in a cohort of SM patients seen at our institution. Methods: The diagnosis of SM and its subclassification were established according to WHO criteria. Inclusion in this study required availability of archived plasma, bone marrow biopsy, and cytogenetic information at the time of first referral. Follow up information including data on survival and disease progression were updated in July 2012. Concentrations of plasma cytokines were analyzed in duplicate by using Multiplex Bead-Based Luminex technology (Invitrogen, Carlsbad, CA). Results: Forty six SM patients met the above stipulated criteria; 25 (54%) were male and the median age at referral was 61 years (range 21–85). Subclassification of patients per WHO criteria was: indolent SM (ISM) 23 (50%), aggressive SM (ASM) 8 (17%) and SM with associated clonal hematological non-MC lineage disease (SM-AHNMD) 15 (33%). When the distribution of 30 cytokines was considered across the 3 SM sub groups, only interleukin (IL)-8 was significantly different (SM-AHNMD > ISM/ASM; p=0.0002). For ISM patients, increased levels of sIL-2R were associated with presence of B-findings (p=0.0046) including splenomegaly (p=0.001) and serum tryptase levels >200 ng/mL (p=0.0046), and decreased levels of IL-8 and hepatocyte growth factor (HGF) with MC mediator-release symptoms (p <0.05). Increased levels of sIL-2R (r2=0.6; p<0.0001) and RANTES (r2=0.37; p=0.0013) were correlated with bone marrow MC burden, and sIL-2R (r2=0.34; p=0.004) and MIG (r2=0.42; p=0.0012) with serum tryptase levels in ISM patients; similar findings were noted for the overall cohort. At a median follow up of 28 months (range 0–116), 20 (43%) deaths, and 3 (13%) and 1 (2%) transformations to ASM and mast cell leukemia, respectively, were recorded for the overall cohort. In univariate analysis, increased sIL-2R levels were predictive for inferior overall survival (p=0.005); this prognostic significance was maintained in multivariate analysis after adjusting for other known prognostic variables individually (i.e. WHO SM subtypes, age >65 years, hemoglobin <10 g/dL, thrombocytopenia, weight loss or hypoalbuminemia) (all p <0.05). Increased sIL-2R (>75th percentile) effectively stratified patients in the overall cohort into 2 well-delineated risk groups for overall survival (median survival 109 vs. 26 months; p=0.0004) (Figure). This sIL-2R threshold was also able to risk stratify patients within ISM (median survival not reached vs. 38 months) and non-ISM (median survival 31 vs. 5 months) categories (p <0.0001). Conclusions: The current study demonstrates s-IL2R to be a key inflammatory cytokine in SM; it is significantly correlated with a phenotype of high systemic MC burden and in this regard, is an attractive surrogate for treatment response in clinical practice, if validated. The predictive value of sIL-2R for overall survival is akin to similar observations in primary myelofibrosis and diffuse large B-cell lymphoma; in this study, it was noted to be independent of conventional measures of organopathy from MC infiltration, and thus may reflect a novel pathogenetic process in SM, mediated by dysregulated inflammatory and/or immuno cellular pathways. Disclosures: No relevant conflicts of interest to declare.

scholarly journals Cutaneous Mastocytosis in a 61-year-old Female from a Dermatological and Histopathological Perspective

2020 ◽  
pp. 01-06
Author(s):  
Erisa Kola ◽  
Jorida Memini ◽  
Ina Kola ◽  
Daniela Nakuci ◽  
John Ekladous ◽  
...  
Keyword(s):  
Bone Marrow ◽  
Mast Cell ◽  
Mast Cells ◽  
Lymph Nodes ◽  
Systemic Mastocytosis ◽  
World Health ◽  
Systemic Involvement ◽  
Cutaneous Mastocytosis ◽  
Health Organization ◽  
Cell Disorder

First described by Nettleship et al. in 1869 [1], mastocytoses are a heterogeneous group of disorders characterized by the pathologic accumulation of mast cells in various tissues [2-5]. Mastocytosis can be confined to the skin as in cutaneous mastocytosis (CM), or it can involve extracutaneous tissues such as the liver, spleen, bone marrow and lymph nodes, as in systemic mastocytosis [6]. Mastocytosis is a World Health Organization-defined clonal mast cell disorder characterized by significant clinicopathologic heterogeneity [7]. Keywords: Cutaneous mastocytosis; Systemic mastocytosis; Systemic involvement; Mast cells; Mastocytosis.

scholarly journals AK002, a Novel Humanized Monoclonal Antibody to Siglec-8, Inhibits Mast Cell Activity and Depletes Eosinophils in Ex Vivo Bone Marrow Tissue from Patients with Systemic Mastocytosis

Blood ◽  
2018 ◽  
Vol 132 (Supplement 1) ◽  
pp. 1104-1104 ◽  
Author(s):  
Bradford A Youngblood ◽  
Emily C Brock ◽  
John Leung ◽  
Alan T Chang ◽  
Christopher Bebbington ◽  
...  
Keyword(s):  
Monoclonal Antibody ◽  
Bone Marrow ◽  
Flow Cytometry ◽  
Mast Cell ◽  
Mast Cells ◽  
Ex Vivo ◽  
Systemic Mastocytosis ◽  
Cell Activity ◽  
Receptor Expression ◽  
Long Term Treatment

Abstract INTRODUCTION: Systemic Mastocytosis (SM) is a rare disease characterized by the clonal proliferation and accumulation of mast cells in the bone marrow, respiratory and gastrointestinal tracts, and organs such as the skin, liver, spleen, and brain. Common symptoms include pruritus, flushing, headache, cognitive impairment, fatigue, diarrhea, abdominal pain, hypotension and skin lesions, as well as an increased risk for osteoporosis and anaphylaxis. SM is currently managed with antihistamines, cromolyn sodium, and leukotriene blocking agents, which lack specificity and efficacy. In addition, glucocorticoids can provide temporary relief in some cases; however long-term treatment with steroids is not appropriate due to their many side effects. Siglec-8 is an inhibitory receptor selectively expressed on human mast cells and eosinophils, and therefore represents a novel target for the treatment of SM. Antibodies to Siglec-8 have been shown to inhibit mast cell activity and induce apoptosis of eosinophils. AK002 is a novel, humanized, non-fucosylated IgG1 monoclonal antibody to Siglec-8. This study evaluates the expression of Siglec-8 and ex vivo activity of AK002 on mast cells and eosinophils in bone marrow biopsies from patients with SM. METHODS: Bone marrow aspirates were obtained from patients clinically diagnosed with SM and processed to remove red blood cells. Multi-color flow cytometry was used to quantify eosinophils and mast cells and to evaluate the activation state of mast cells. The ex vivo activity of AK002 against eosinophils and mast cells was evaluated by flow cytometry. The inhibitory activity of AK002 agaist mast cells was also examined by quantifying cytokine levels in cultured bone marrow aspirate supernatants. RESULTS: All mast cells and eosinophils in bone marrow aspirates from SM patients displayed high Siglec-8 receptor expression (Figure 1). These mast cells also expressed the SM specific markers, CD25 (Figure 1) and CD30 and increased levels of cell surface degranulation markers. The expression of CD25 on mast cells significantly decreased following overnight treatment with AK002. AK002 also significantly reduced the level of mast cell-associated cytokines produced in cultured bone marrow supernatants, including IL-6, IL-8, and TNFα (Figure 2A). These changes in mast cell activity after AK002 treatment were not due to a reduction in mast cell numbers. In contrast, overnight incubation of AK002 significantly reduced the number of bone marrow eosinophils compared to an isotype control (Figure 2B). CONCLUSIONS: Bone marrow aspirates from patients with SM had activated mast cells and eosinophils that displayed robust expression of Siglec-8. AK002 demonstrated SM mast cell inhibition in ex vivo bone marrow aspirates. AK002 also had depleting effects on eosinophils, which may be valuable to SM patients with associated eosinophilia. These encouraging results could represent a novel approach for the treatment of SM. Disclosures Youngblood: Allakos, Inc.: Employment. Brock:Allakos, Inc.: Employment. Leung:Allakos, Inc.: Employment. Chang:Allakos, Inc.: Employment. Bebbington:Allakos, Inc.: Employment. Tomasevic:Allakos, Inc.: Employment.

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