Prospective evaluation of the diagnostic value of sensitive KIT
 D816V mutation analysis of blood in adults with suspected systemic mastocytosis

Mastocytosis is a type of myeloid neoplasm characterized by the clonal, neoplastic proliferation of morphologically and immunophenotypically abnormal mast cells that infiltrate one or more organ systems. Systemic mastocytosis (SM) is a more aggressive variant of mastocytosis with extracutaneous involvement, which might be associated with multi-organ dysfunction or failure and shortened survival. Over 80% of patients with SM carry the KIT D816V mutation. However, the KIT D816V mutation serves as a weak oncogene and appears to be a late event in the pathogenesis of mastocytosis. The management of SM is highly individualized and was largely palliative for patients without a targeted form of therapy in past decades. Targeted therapy with midostaurin, a multiple kinase inhibitor that inhibits KIT, has demonstrated efficacy in patients with advanced SM. This led to the recent approval of midostaurin by the United States Food and Drug Administration and European Medicines Agency. However, the overall survival of patients treated with midostaurin remains unsatisfactory. The identification of genetic and epigenetic alterations and understanding their interactions and the molecular mechanisms involved in mastocytosis is necessary to develop rationally targeted therapeutic strategies. This review briefly summarizes recent developments in the understanding of SM pathogenesis and potential treatment strategies for patients with SM.

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PKC412 inhibits in vitro growth of neoplastic human mast cells expressing the D816V-mutated variant of KIT: comparison with AMN107, imatinib, and cladribine (2CdA) and evaluation of cooperative drug effects

Blood ◽

10.1182/blood-2005-07-3022 ◽

2006 ◽

Vol 107 (2) ◽

pp. 752-759 ◽

Cited By ~ 169

Author(s):

Karoline V. Gleixner ◽

Matthias Mayerhofer ◽

Karl J. Aichberger ◽

Sophia Derdak ◽

Karoline Sonneck ◽

...

Keyword(s):

Mast Cells ◽

Systemic Mastocytosis ◽

Drug Effects ◽

Kit Mutation ◽

Growth Inhibitory ◽

Ic50 Values ◽

Tk Inhibitors ◽

Mast Cell Leukemia ◽

Kit D816v

AbstractIn most patients with systemic mastocytosis (SM), including aggressive SM and mast cell leukemia (MCL), neoplastic cells express the oncogenic KIT mutation D816V. KIT D816V is associated with constitutive tyrosine kinase (TK) activity and thus represents an attractive drug target. However, imatinib and most other TK inhibitors fail to block the TK activity of KIT D816V. We show that the novel TK-targeting drugs PKC412 and AMN107 counteract TK activity of D816V KIT and inhibit the growth of Ba/F3 cells with doxycycline-inducible expression of KIT D816V as well as the growth of primary neoplastic mast cells and HMC-1 cells harboring this KIT mutation. PKC412 was a superior agent with median inhibitory concentration (IC50) values of 50 to 250 nM without differences seen between HMC-1 cells exhibiting or lacking KIT D816V. By contrast, AMN107 exhibited more potent effects in KIT D816V- HMC-1 cells. Corresponding results were obtained with Ba/F3 cells exhibiting wild-type or D816V-mutated KIT. The growth-inhibitory effects of PKC412 and AMN107 on HMC-1 cells were associated with induction of apoptosis and down-regulation of CD2 and CD63. PKC412 was found to cooperate with AMN107, imatinib, and cladribine (2CdA) in producing growth inhibition in HMC-1, but synergistic drug interactions were observed only in cells lacking KIT D816V. Together, PKC412 and AMN107 represent promising novel agents for targeted therapy of SM. (Blood. 2006;107: 752-759)

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Vascular Endothelial Growth Factors and Angiopoietins As New Players in Mastocytosis

10.21203/rs.3.rs-163383/v1 ◽

2021 ◽

Author(s):

Simone Marcella ◽

Angelica Petraroli ◽

Mariantonia Braile ◽

Roberta Parente ◽

Anne Lise Ferrara ◽

...

Keyword(s):

Growth Factors ◽

Mast Cells ◽

Systemic Mastocytosis ◽

Vascular Endothelial Growth Factors ◽

Vascular Endothelial ◽

Serum Concentrations ◽

Kit Receptor ◽

Clinical Variants ◽

Endothelial Growth Factors ◽

Kit D816v

Abstract Mastocytosis is a disorder characterized by the abnormal proliferation and/or accumulation of mast cells in different organs. More than 90% of patients with systemic mastocytosis have a gain-of-function mutation in codon 816 of the KIT receptor on mast cells (MCs). The symptoms of mastocytosis patients are related to the MC-derived mediators that exert local and distant effects. MCs produce angiogenic and lymphangiogenic factors, including vascular endothelial growth factors (VEGFs) and angiopoietins (ANGPTs). Serum concentrations of VEGF-A, VEGF-C, VEGF-D, ANGPT1 and ANGPT2 were determined in 64 mastocytosis patients and 64 healthy controls. Intracellular concentrations and spontaneous release of these mediators were evaluated in the mast cell lines ROSAKIT WT and ROSA KIT D816V and in human lung mast cells (HLMCs). VEGF-A, ANGPT1, ANGPT2 and VEGF-C concentrations were higher in mastocytosis patients compared to controls. The VEGF-A, ANGPT2 and VEGF-C concentrations were correlated with the symptom severity. ANGPT1 concentrations were increased in all patients compared to controls. ANGPT2 levels were correlated with severity of clinical variants and with tryptase levels. VEGF-A, ANGPT1 and VEGF-C did not differ between indolent and advanced mastocytosis. ROSAKIT WT, ROSAKIT D816V and HLMCs contained and spontaneously released VEGFs and ANGPTs. Serum concentrations of VEGFs and ANGPTs are altered in mastocytosis patients.

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Venetoclax and Decitabine Show Robust Activity in Advanced Systemic Mastocytosis

Blood ◽

10.1182/blood-2020-138826 ◽

2020 ◽

Vol 136 (Supplement 1) ◽

pp. 25-26

Author(s):

Tahani Atieh ◽

Janet Woodroof ◽

Abdulraheem Yacoub

Keyword(s):

Overall Survival ◽

Induction Chemotherapy ◽

Systemic Mastocytosis ◽

Objective Response ◽

Publicly Traded ◽

First Line ◽

Private Company ◽

Allogenic Stem Cell Transplantation ◽

Best Response ◽

Kit D816v

Systemic mastocytosis (SM) is a heterogeneous group of diseases characterized by the proliferation of abnormal mast cells in the bone marrow or other organs. 1 Activating mutations in KIT are found in the majority of patients, with the KIT D816V mutation being the most common .2 While patients with indolent systemic mastocytosis (ISM) have a life-expectancy similar to the general population, approximately 40-53% of patients with SM have an associated hematologic neoplasm (SM-AHN) with a median overall survival of 2 years. 1-3 Treatment of SM-AHN is primarily directed at the AHN as this determines overall survival, with symptomatic treatment for SM if needed.4 Midostaurin is the only approved agent for SM with KIT K816V mutation and overall response rates in SM-AHN are <60%. 5-6 No agents are approved beyond first line. We present the unique case of an 81-year-old male who presented with SM and low risk CMML (46 XY with ASXL1, KIT (p.D816V), SRSF2, TET2, RUNX1, MSH2, CBL). He received first line therapy with midostaurin 100 mg twice a day and achieved an early partial response but progressed after 7 months with increasing mastocytosis burden, rising tryptase and transformation of CMML to AML (image 1). He was subsequently treated with combination standard dose decitabine and venetoclax. The best response for the AML was CRi which was achieved after the first cycle and continues to be ongoing over 12 months since initiation of therapy. We also observed objective response of the SM disease burden on BM exams and steady decline in tryptase levels that continues to be ongoing (figure 1 and 2). Best response by IWG-MRT-ECNM is partial remission achieved after 9 months of therapy. SM-AML is rare and can be diagnosed concomitantly with SM or as a transformation of an SM-AHN. Additional mutations are often present, with the presence of ASXL1 and RUNX1 being associated with a particularly poor prognosis.7-8 Treatment for SM-AML is similar to standard AML treatment with allogenic stem cell transplantation (ASCT) being preferred in those able to tolerate it. While ASCT is the only potential cure for both diseases, SM often persists even with response of the AML.9-11 In a case report of 11 patients with SM-AML, 8 patients received induction chemotherapy with cytarabine and daunorubicin while 3 received induction with cytarabine and idarubicine. Seven patients received ASCT but five relapsed and eventually expired. None of the 3 long-term survivors had a c-KIT D816V mutation and two of them received ASCT. In 7 out of the 10 patients in CR or after ASCT, SM persisted. 9 In 2 case reports of SM-AML with D816V mutation, treatment consisted of induction and consolidation chemotherapy plus dasatinib and chemotherapy with ASCT and dasatinib. Both patients achieved HCR but again had persistent SM.10-11 The activity of hypomethylating agents (HMA) with venetoclax has not previously been reported in patients with SM-AML. Venetoclax plus either HMAs or low-dose cytarabine was approved for the treatment of AML in the elderly and those unable to tolerate induction chemotherapy in 2018. Venetoclax is an oral inhibitor of BCL-2, an antiapoptotic protein important in the pathophysiology of AML. In the initial study, the CR/Cri rate was 68% with a median time to response of 1.2 cycles. Venetoclax has also shown activity in other hematologic malignancies, including chronic lymphocytic leukemia, and non-Hodgkin's lymphoma.12 SM-AML is an aggressive disease with limited treatment options. To our knowledge, this is the first report of sustained response of both SM-AHN and AML using a HMA and venetoclax. Given the difference in response time and dynamics, this treatment combination seems to have activity in both disease clones independently. This case suggests a potential treatment option for this unmet need and demonstrates the importance of research into the utility of venetoclax in mast cell neoplasms. Disclosures Yacoub: Ardelyx: Current equity holder in publicly-traded company; Dynavax: Current equity holder in publicly-traded company; Cara Therapeutics: Current equity holder in publicly-traded company; Hylapharm: Current equity holder in private company; Incyte: Speakers Bureau; Agios: Honoraria, Speakers Bureau; Novartis: Speakers Bureau; Roche: Other: Support of parent study and funding of editorial support.

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KIT D816V mutation burden does not correlate to clinical manifestations of indolent systemic mastocytosis

Journal of Allergy and Clinical Immunology ◽

10.1016/j.jaci.2013.02.019 ◽

2013 ◽

Vol 132 (3) ◽

pp. 723-728 ◽

Cited By ~ 27

Author(s):

Sigurd Broesby-Olsen ◽

Thomas Kristensen ◽

Hanne Vestergaard ◽

Kim Brixen ◽

Michael Boe Møller ◽

...

Keyword(s):

Systemic Mastocytosis ◽

Clinical Manifestations ◽

Mutation Burden ◽

Indolent Systemic Mastocytosis ◽

Kit D816v

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A prospective evaluation of the diagnostic value of video capsule endoscopy in patients initially classified as irritable bowel syndrome

European Journal of Internal Medicine ◽

10.1016/j.ejim.2008.04.018 ◽

2009 ◽

Vol 20 (1) ◽

pp. 48-52 ◽

Cited By ~ 6

Author(s):

Bodil Ohlsson ◽

Mariette Bengtsson ◽

Jörgen Nielsen ◽

Ervin Toth

Keyword(s):

Irritable Bowel Syndrome ◽

Capsule Endoscopy ◽

Diagnostic Value ◽

Video Capsule Endoscopy ◽

Prospective Evaluation ◽

Irritable Bowel

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Recent Advances in the Molecular Biology of Systemic Mastocytosis: Implications for Diagnosis, Prognosis, and Therapy

International Journal of Molecular Sciences ◽

10.3390/ijms21113987 ◽

2020 ◽

Vol 21 (11) ◽

pp. 3987 ◽

Cited By ~ 1

Author(s):

Margherita Martelli ◽

Cecilia Monaldi ◽

Sara De Santis ◽

Samantha Bruno ◽

Manuela Mancini ◽

...

Keyword(s):

Molecular Characterization ◽

Systemic Mastocytosis ◽

Gene Mutations ◽

Scoring Systems ◽

Molecular Data ◽

Loss Of Function ◽

Prognostic Information ◽

Genetic Profiling ◽

Kit D816v

In recent years, molecular characterization and management of patients with systemic mastocytosis (SM) have greatly benefited from the application of advanced technologies. Highly sensitive and accurate assays for KIT D816V mutation detection and quantification have allowed the switch to non-invasive peripheral blood testing for patient screening; allele burden has prognostic implications and may be used to monitor therapeutic efficacy. Progress in genetic profiling of KIT, together with the use of next-generation sequencing panels for the characterization of associated gene mutations, have allowed the stratification of patients into three subgroups differing in terms of pathogenesis and prognosis: (i) patients with mast cell-restricted KIT D816V; (ii) patients with multilineage KIT D816V-involvement; (iii) patients with “multi-mutated disease”. Thanks to these findings, new prognostic scoring systems combining clinical and molecular data have been developed. Finally, non-genetic SETD2 histone methyltransferase loss of function has recently been identified in advanced SM. Assessment of SETD2 protein levels and activity might provide prognostic information and has opened new research avenues exploring alternative targeted therapeutic strategies. This review discusses how progress in recent years has rapidly complemented previous knowledge improving the molecular characterization of SM, and how this has the potential to impact on patient diagnosis and management.

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Detection of Activated STAT5 in Neoplastic Mast Cells in Patients with Systemic Mastocytosis: Role of c-kit D816V.

Blood ◽

10.1182/blood.v106.11.3515.3515 ◽

2005 ◽

Vol 106 (11) ◽

pp. 3515-3515 ◽

Cited By ~ 1

Author(s):

Karoline Sonneck ◽

Matthias Mayerhofer ◽

Karoline V. Gleixner ◽

Marc Kerenyi ◽

Maria-Theresa Krauth ◽

...

Keyword(s):

Mast Cell ◽

Mast Cells ◽

Systemic Mastocytosis ◽

Cell Leukemia ◽

Oncogenic Signaling ◽

Kit Mutation ◽

Knock Out ◽

Mast Cell Leukemia ◽

Kit D816v

Abstract Recent data suggest that activated STAT5 contributes to growth and differentiation of mast cells (MC) and that STAT5-knock out mice are MC-deficient. We have recently shown that constitutively activated STAT5 acts as a potent oncogenic signaling molecule in hematopoietic progenitor cells (Cancer Cell2005;7:87–99). In the present study, we examined the expression of activated STAT5 in neoplastic MC in systemic mastocytosis (SM) and asked whether the SM-related oncogene c-kit D816V is involved in STAT5-activation. For the immunohistochemical detection of activated tyrosine phosphorylated STAT5 (P-Y-STAT5), we used the specific monoclonal antibody AX1 (Advantex) which does not react with inactive STAT5. In all patients with SM tested (indolent SM, n=11; smouldering SM, n=2; aggressive SM, n=1; mast cell leukemia, n=1; all exhibiting c-kit D816V), MC were found to display P-Y-STAT5. Expression of activated STAT5 was also demonstrable in the c-kit D816V-positive mast cell leukemia-derived cell line HMC-1. The reactivity of HMC-1 cells with AX1 antibody was abrogated by a STAT5-specific blocking-peptide. To define the role of c-kit D816V in STAT5-activation, Ba/F3 cells with doxycycline-inducible expression of c-kit D816V (Ton.kit) were employed. In these cells, induction of c-kit D816V was followed by a massive increase in phosphorylated STAT5 as determined by a specific DNA-binding assay, whereas the total amounts of STAT5-mRNA and of the STAT5-protein showed only a slight increase or remained unchanged. In summary, these data show that neoplastic MC in SM express activated STAT5 (P-Y-STAT5), and that the transforming c-kit mutation D816V leads to persistent activation of STAT5 in these cells.

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

Blood ◽

10.1182/blood.v116.21.5052.5052 ◽

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.

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