Clonal Hematological Non-mast Cell Lineage Research Articles

KIT Inhibitor Midostaurin in Patients with Advanced Systemic Mastocytosis: Results of a Planned Interim Analysis of the Global CPKC412D2201 Trial

AbstractAbstract ▪799▪This icon denotes a clinically relevant abstract Background:Aggressive systemic mastocytosis (ASM) and mast cell leukemia (MCL) with or without an associated clonal hematologic non-mast cell lineage disease (AHNMD) are myeloproliferative neoplasms (MPN) with inadequate treatment options. The activating KIT D816V mutation occurs in ≈80% of patients (pts) with these advanced forms of SM and is central to disease pathogenesis. Midostaurin is an oral inhibitor of multiple tyrosine kinases, including wild-type and D816-mutated KIT. Promising results of an investigator-initiated trial (Gotlib et al. Blood. 2010;116:316) led to initiation of this multicenter phase 2 study (NCT00782067) of midostaurin in pts with advanced SM. Here, we report the efficacy and preliminary safety results of stage 1 of this trial. Methods:Midostaurin (100 mg BID) was administered continuously in 28-d cycles until progression or intolerable toxicity. Enrollment into an extension phase was permitted if the null hypothesis of an overall response rate (ORR) ≤ 30% was rejected per Fleming 2-stage design. Pts were required to have ≥ 1 measurable C-finding(s) (CF; eg, cytopenias, liver dysfunction) considered related to SM. The primary endpoint was ORR (major response [MR] + partial response [PR] according to Valent criteria) occurring in the first 6 cycles and maintained for ≥ 8 weeks (wk). International Working Group criteria for myelodysplastic syndrome (MDS; with slight modifications) were used to evaluate changes in transfusion dependence. Results:62 pts were enrolled in stage 1, of whom 40 (65%) were eligible for efficacy evaluation. Reasons for ineligibility included absence of measurable CF (n = 11) or CF considered unrelated to SM (n = 11). Median age of eligible pts (25 males, 63%) was 64.5 y (range: 48–80 y). 33 (83%) pts had ASM (27 with an AHNMD) and 7 (18%) had MCL (3 with an AHNMD). AHNMDs (n=30) included 10 chronic myelomonocytic leukemia (CMML), 10 MDS/MPN-unclassified (MDS/MPN-u), 4 hypereosinophilic syndrome/chronic eosinophilic leukemia (HES/CEL), and 6 other subtypes. 22 (55%) pts received at least 1 prior therapy (median: 1.5; range: 1–4). 28 (70%) pts were KIT D816V/Y–positive, 3 (8%) were KIT D816V/Y–negative, and 9 (23%) were not evaluable for mutation status. The ORR was 60% (24/40), and most responses were MRs (21/24; Table). With a median follow-up of 27 months (mo), the median duration of response and median overall survival (OS) have not been reached. Of the 7 pts with MCL, 4 (57%) achieved an MR, including 3 ongoing incomplete remissions (IR) (19+ mo in 2 pts and 32+ mo in 1 pt). The OS in MCL pts was 22.6 mo. Additionally, 3 of 4 responding ASM/MCL-HES/CEL pts exhibited resolution of blood eosinophilia (mean baseline % and absolute eosinophils: 64% and 15.6 × 109/L). Median change in serum tryptase level among the 40 pts was −61% (range: −97% to 16%), with 16 (40%) pts exhibiting a ’ 50% reduction lasting ≥ 8 wk. Median change in marrow mast cell (MC) burden in 32 evaluable pts was −41% (range: −92% to 83%), with 15/32 (47%) pts exhibiting a ≥ 50% reduction. All 62 pts received at least 1 dose of midostaurin and were included in the safety analysis. Grade 3/4 hematologic adverse events (AEs) considered drug-related were neutropenia (11%), anemia (3%), and thrombocytopenia (3%). The most common grade 3/4 drug-related non-hematologic AEs were fatigue (6%), nausea (6%), vomiting (5%), diarrhea (5%), and increased lipase (5%). As of March 15, 2012, therapy was discontinued in 26/40 pts: 7 for AEs (5 drug-related), 12 for disease progression, and 7 for other reasons. 3 of 30 pts with an AHNMD (2 CMML and 1 MDS/MPN-u) developed AML. Conclusion:In advanced SM pts, midostaurin was well tolerated and demonstrated a high rate of durable responses, including in MCL, which historically has a dire prognosis. The drug can produce significant reductions in MC burden, indicating the potential for disease modification. The stage 1 ORR was sufficient to reject the null hypothesis and permitted enrollment in the extension phase, where full accrual of 116 pts has been completed.TableOverall Response Rates and by KIT Mutation StatusResponders, %ORR (95% CI) (N = 40)60 (43.3, 75.1)MR52.5IR22.5Pure clinical response20Unspecified10PR7.5Good PR7.5Minor PR0Stable disease20Progressive disease7.5Not evaluable12.5Response by KIT D816V/Y statusKIT D816V/Y–positive (N = 28)60.7KIT D816V/Y–negative (N = 3)100Not evaluable* (N = 9)44.4** DNA not amplifiable (n = 5); missing samples (n = 4). Disclosures:Gotlib:Novartis: Membership on an entity's Board of Directors or advisory committees, Research Funding. George:Novartis: Consultancy, Membership on an entity's Board of Directors or advisory committees. Akin:Novartis: Consultancy. Sotlar:Novartis: Consultancy. Awan:Allos Therapeutics: Speakers Bureau. Morariu:Novartis: Employment. Squier:Novartis: Employment. Villeneuve:Novartis: Employment. Emery-Salbert:Novartis: Employment. Horny:Novartis: Consultancy. Valent:Novartis: Consultancy, Honoraria. Reiter:Novartis: Consultancy, Honoraria.

Delayed graft-versus-mast-cell effect on systemic mastocytosis with associated clonal haematological non-mast cell lineage disease after allogeneic transplantation

Delayed graft-versus-mast-cell effect on systemic mastocytosis with associated clonal haematological non-mast cell lineage disease after allogeneic transplantation

Targeting SHP2 phosphatase in Myeloproliferative Neoplasms

Targeting SHP2 phosphatase in Myeloproliferative Neoplasms

Systemic Mastocytosis With Associated Clonal Hematologic Nonmast Cell Lineage Disease: A Clinicopathologic Review

Systemic mastocytosis (SM) is a heterogeneous disease with 6 subtypes, including systemic mastocytosis with associated clonal hematologic nonmast cell lineage disease (SM-AHNMD). Bone marrow biopsy specimens show multifocal aggregates of mast cells with predominantly spindle-shaped morphology associated with a myeloid or, less frequently, a lymphoproliferative neoplasm defined by World Health Organization criteria. Neoplastic mast cells abnormally express CD2 and/or CD25, which may be detected by flow cytometry or immunohistochemistry. The pathogenesis of SM-AHNMD is not well understood; however, combined KIT tyrosine kinase receptor mutations and additional genetic events in myeloid stem cells may have a pathogenic role. Reactive mast cell hyperplasia, monocytic/histiocytic proliferations, SM without sufficient criteria for a diagnosis of AHNMD, atypical mast cells associated with PDGFRA rearrangements, and other tryptase-positive myeloid proliferations should be excluded. Overall, the prognosis is poor and largely related to the AHNMD. Cytoreductive therapies, splenectomy, allogeneic bone marrow transplant, and tyrosine kinase inhibitors, excluding imatinib, may have potential efficacy in the treatment of these diseases.

Systemic mastocytosis with associated acute myeloid leukemia with t (8; 21) (q22; q22)

Systemic mastocytosis with associated clonal hematological nonmast cell lineage disease (SM-AHNMD) is a subtype of mastocytosis associated commonly with myeloid neoplasms, Non-Hodgkin's lymphoma, or other hematological neoplasms. In these conditions, mastocytosis needs to be differentiated from mast cell hyperplasia or mast cell activation states. Neoplastic nature of mastocytosis is proved either by morphology, aberrant immunophenotype, or detection of point mutation at codon-816 of c-kit gene. This is a rare entity, even more so in pediatric population. Herein, we report a case of 14-year-old girl with SM associated with acute myeloid leukemia with maturation with t(8;21). Multifocal dense infiltrate of spindle-shaped mast cells on bone marrow aspirate and biopsy with coexpression of CD2 and CD25 by flow cytometric analysis proved the SM component at the time of diagnosis and persistence at post induction status also.

Mutations of the Spliceosome Complex Genes Occur In Adult Patients but Are Very Rare In Children with Myeloid Neoplasia

Abstract 2797Somatic point mutations occur frequently in adult patients with myelodysplastic syndromes (MDS) and are associated with distinct clinical features such as overall survival, genomic aberrations and clonal transformation. Recently a number of new genes had been identified which are involved in methylation and chromatin regulation (TET2, DNMT3A, ASXL1). Although mutations of these genes are present at high frequency in adult cohorts, they are very rare events in children with myeloid disease. Based on the results from a large-scale whole exome sequencing study of adult patients with myeloid neoplasia, a new group of genes involved in the formation of spliceosome complex was discovered to be recurrently somatically mutated in approximately 40% of patients with MDS and 55% of chronic myelomonocytic leukemia (CMML) cases (Yoshida, et al., unpublished data). Spliceosomes are macromolecular RNA-protein complexes that remove noncoding introns from precursor mRNA. We hypothesized that the disruption of the spliceosome complex might play a driving role in the leukemogenesis in pediatric MDS. Using targeted re-sequencing we investigated the 3 exclusive hotspots of 2 spliceosome genes that were found to be mutated in adult MDS: U2AF1 (S34), U2AF1 (Q157) and SFRS2 (P95).We analyzed a total of 339 WHO-defined pediatric cases: juvenile myelomonocytic leukemia (JMML), n=112; secondary CMML, n=12; Down syndrome-associated MDS, n=6; de novo acute myeloid leukemia (AML), n=12, MDS-related AML, n=50; refractory anemia with excess blasts (RAEB), n=52; RAEB in transformation (RAEB-T), n=11; and refractory cytopenia (RC), n=84.We found two heterozygous missense mutations: SFRS2 c.284C>T/P95L in a patient with JMML, and U2AF1 c.101C>A/S34Y in a patient with refractory cytopenia. The first patient presented with non-syndromic JMML with somatic mutation of PTPN11 c.226G>C/E76Q, normal cytogenetics, increased HbF(80%), splenomegaly, monocytosis, and was 4.5 years old at diagnosis. The patient underwent successful SCT. The analysis of buccal-swab DNA confirmed the somatic status of the SFRS2 mutation. The second patient was diagnosed at age of 17 years with systemic mastocytosis positive for c-kit D816V mutation, and with associated clonal hematological non-mast cell lineage disease: refractory cytopenia with normal cytogenetics. SCT was also performed with success on this patient. To ensure that the low rate of mutations found in our pediatric cohort was not due to technical issues, we also sequenced major mutation sites of U2AF1 and SFRS2 genes in 19 adult patients with MDS: refractory anemia (RA), n=8; RC with multilineage dysplasia (RCMD), n=3; RAEBI/II, n=5; CMML, n=3. We found 4 heterozygous changes: SFRS2 missense mutation c.284C>T/P95L in two patients with RA and RAEBII; SFRS2 deletion c.284_307/P95RfsX120 in one RA patient, and U2AF1 c.470A>C/Q157P in one RA patient. Interestingly, 3 out of 4 patients with a mutated spliceosome gene harbored a mutation of the ASXL1 gene, but none was mutated for DNMT3A.In summary, re-sequencing of 3 spliceosome gene hotspots revealed the presence of heterozygous mutations in 2/339 children and 4/19 adults with myeloid disease. The analysis of another gene-hotspot implicated in the MDS whole exome study, SF3B1 K700 is ongoing, but all pediatric cases analyzed to date were negative. The drastically reduced frequency of spliceosome mutations in pediatric compared to adult myeloid malignancies suggests a different pathogenetic mechanism in childhood disease, and fits well with previous reports that somatic mutations of non-Ras-pathway genes, such as DNMT3A, are less prevalent in pediatric cohorts. The functional impact of spliceosome mutations on leukemogenesis warrants further study. Disclosures:No relevant conflicts of interest to declare.

Systemic mastocytosis with associated clonal hematological non‐mast‐cell lineage disease: A case review

Systemic mastocytosis with associated clonal hematological non‐mast‐cell lineage disease: A case review

Variable presence of KITD816V in clonal haematological non‐mast cell lineage diseases associated with systemic mastocytosis (SM–AHNMD)

In a substantial number of patients with systemic mastocytosis (SM), an associated clonal haematological non-mast cell lineage disease (AHNMD) is detectable. Although most of these patients display KIT mutations, especially KIT(D816V), little is known about their exact frequency and their distribution in AHNMD subtypes. We examined 48 patients with SM-AHNMD for the presence of mutant KIT in the SM and AHNMD components of the disease. Mast cells and AHNMD cells were obtained from immunostained bone marrow sections by laser microdissection and examined by melting point analysis of nested-PCR products. KIT(D816V) was found in AHNMD cells in the vast majority of patients with SM-chronic myelomonocytic leukaemia (CMML, 89%). Unexpectedly, KIT(D816V) was far less frequently detectable in AHNMD cells in patients with SM-myeloproliferative neoplasm (MPN, 20%) and SM-acute myeloid leukaemia (AML, 30%). None of the patients with lymphoproliferative AHNMDs displayed KIT codon 816 mutations in AHNMD cells (0/8). In FIP1L1/PDGFRA-positive chronic eosinophilic leukaemia (CEL), neither the SM nor the CEL component of the disease exhibited the KIT mutation. Our findings demonstrate that KIT codon 816 mutations are variably present in AHNMD cells in patients with SM-AHNMD, depending on the subtype of AHNMD. The high frequency of KIT(D816V) in neoplastic mast cells and leukaemic myelomonocytic cells in SM-CMML may point to a common precursor in these patients, and may have implications for the biology of the disease and the development of KIT-targeting therapies.

Clinical and Biological Diversity of Clonal Hematological Non-Mast Cell Lineage Neoplasms Associated with Mastocytosis.

Abstract 4976 BackgroundMastocytosis has many features in common with other myeloproliferative neoplsms (MPN) and is recognized by the 2008 World Health Organization (WHO) as a major subgroup of MPNs. In 20-30% of patients with systemic mastocytosis (SM), an associated clonal hematological non mast cell lineage disease (AHNMD) is also diagnosed, and such an occurrence is recognized by WHO classification system as SM-AHNMD. The latter (AHNMD) includes predominantly myeloid neoplasms, but also rarely non-myeloid hematologic neoplasms. SM-AHMD often creates a clinicopathologic diagnostic challenge due to diverse clinical presentation and sometimes subtle morphologic findings. We reviewed the clinicopathologic features, cytogenetic and molecular findings, and clinical course of eight patients with SM-AHNMD. MethodsApproximately 30,000 bone marrow biopsy reports recorded in the institutional electronic database at Moffitt Cencer Center from January 1996 to July 2009 were reviewed. Thirty patients with SM- were identified. Diagnosis was confirmed by bone marrow (BM) histology; SM- and AHNMD-components were classified according to WHO criteria. Immunophenotypic analyses were performed on fresh samples using flow cytometry and on paraffin-embedded samples using immunohistochemistry. Molecular analyses for assessment of immunoglobulin heavy and light chain gene rearrangement and for detection of activating c-Kit D816V point mutation, as well as cytogenetic study by karyotyping and FISH analysis were performed on available skin punch biopsy and bone marrow aspirate samples. Clinical presentation, laboratory and imaging data, therapeutic regimen and clinical course were reviewed. ResultsSM was diagnosed in 30 bone marrow biopsies (0.1 %). SM-AHNMD was diagnosed in 8 patients (27% of SM) over a 13 year period. The AHNMD was MDS (3 cases: 1 refractory anemia, 2 cases of refractory anemia with ringed sideroblasts), MDS/MPN (2 cases, CMML), AML (1 case), marginal zone lymphoma (1 case) and plasma cell myeloma (1 case, IgD monoclonal). Patients ranged in age from 54 to 78 years (average 57), with a male to female ratio of 1:1. At presentation, all patients (8/8) had cytopenia; two patients (2/8) additionally had monocytosis. Cytogenetic abnormalities were identified in 3 cases (3/4) [t(8;21), t(3;5), isochromsme 14, deletion 5q, trisomy 4]. Activating c-Kit (D816V) point mutation was detected in 3 cases (3/4). In six patients (6/8), SM was diagnosed concurrently with the AHNMD and the aberrant mast cell proliferation was observed only after complete histopathologic examination. One patient (1/8) had long-standing indolent SM with cutaneous manifestation, and a second patient (1/8) suffered from recurrent “hives” for 12-15 years which was later diagnosed as cutaneous mastocytosis, prior to the development of an AHNMD. These two patients were treated with Gleevec and/or antihistamines. Upon diagnosis, all patients (8/8) were managed according to standard treatment protocols for their AHNMD. The patient with AML with t(8;21) received daunrubicin and cytarabine induction chemotherapy and intrathecal methotrexate. She achieved remission, followed by multiple relapses. ConclusionsSM-AHNMD is uncommon. AHNMD is usually myeloid, but can also be a lymphoid/plasma cell neoplasm. In the majority of our cases, mastocytosis was not clinically suspected and the patient's clinical presentation was related to the associated non-mast cell lineage neoplasm. SM-AHNMD might pose a histopathologic challenge that potentially could be missed; for the most part it is a histological diagnosis based on a combination of morphologic features and ancillary studies. Patients are managed according to the current protocols for their AHNMD. Symptoms related to mastocytosis are treated with antihistamines, as needed. Of note, unlike most patients with AML with t(8;21), the patient in our case series fared poorly with standard chemotherapy. The prognostic relevance and therapeutic implications of detecting SM associated with another hematologic malignancy and warrants further studies and remains to be clarified. DisclosuresNo relevant conflicts of interest to declare.

Cytoreductive therapy in 108 adults with systemic mastocytosis: Outcome analysis and response prediction during treatment with interferon‐alpha, hydroxyurea, imatinib mesylate or 2‐chlorodeoxyadenosine

Cytoreductive therapy in systemic mastocytosis (SM) includes several drugs whose individual merit has not been well characterized. We retrospectively studied 108 Mayo Clinic patients who met the 2008 WHO diagnostic criteria for SM and received at least one cytoreductive drug. The numbers of patients who were evaluable for response to treatment with interferon-alpha with or without prednisone (IFN-alpha), hydroxyurea (HU), imatinib mesylate (IM) or 2-chlorodeoxyadenosine (2-CdA) were 40, 26, 22, and 22, respectively. The corresponding overall (major) response rates, according to recently published consensus criteria, were 53% (18%), 19% (0%), 18% (9%), and 55% (37%). The respective overall response rates in indolent SM, aggressive SM and SM associated with another clonal hematological nonmast cell lineage disease (SM-AHNMD) were 60%, 60%, 45% for IFN-alpha, 0, 0, 21% for HU, 14%, 50%, 9% for IM and 56%, 50%, 55% for 2-CdA. The absence of mast cell mediator release symptoms in IFN-alpha-treated patients and presence of circulating immature myeloid cells in 2-CdA-treated patients predicted inferior response. TET2 mutational status did not influence treatment response. Although the major response rates with these four cytoreductive agents were still suboptimal and HU was mainly used in patients with SM-AHNMD, the current study favors 2-CdA or IFN-alpha as first-line current therapy in SM and identifies patients who are likely to respond to such therapy.

Prognostically relevant breakdown of 123 patients with systemic mastocytosis associated with other myeloid malignancies

AbstractThe prognostic heterogeneity of the World Health Organization category of “systemic mastocytosis with associated clonal hematologic nonmast cell lineage disease” (SM-AHNMD) has not been systematically validated by primary data. Among 138 consecutive cases with SM-AHNMD, 123 (89%) had associated myeloid neoplasm: 55 (45%) myeloproliferative neoplasm (SM-MPN), 36 (29%) chronic myelomonocytic leukemia, 28 (23%) myelodysplastic syndrome (SM-MDS), and 4 (3%) acute leukemia. Of the myeloid subgroups, SM-MPN displayed a 2- to 3-fold better life expectancy (P = .003), whereas leukemic transformation was more frequent in SM-MDS (29%; P = .02). The presence of eosinophilia, although prevalent (34%), was prognostically neutral, and the overall results were not affected by exclusion of FIP1L1-PDGFRA-positive cases. We conclude that it is clinically more useful to consider specific entities, such as SM-MPN, systemic mastocytosis with chronic myelomonocytic leukemia, SM-MDS, and systemic mastocytosis with-acute leukemia, rather than their broad reference as SM-AHNMD.

Spontaneous regression of aleukemic leukemia cutis harboring a NPM/RARA fusion gene in an infant with cutaneous mastosytosis

Aleukemic leukemia cutis has been rarely reported in infant leukemia. This report describes a 6-month-old boy with aleukemic leukemia cutis, which regressed without any treatments within 6 months. Interestingly, a cytogenetic analysis disclosed a leukemia clone with the karyotype of 46, XY, t(5;17)(q35;q12), which generated nucleophosmin (NPM)-retinoic acid receptor alpha fusion (RARA) fusion transcripts. The patient simultaneously had cutaneous mastocytosis, which also disappeared with the leukemia cutis. He shows no physical or laboratory abnormalities without any treatments after 12 months, although the NPM/RARA transcripts remain faintly in the bone marrow. The present case is partially compatible with systemic mastocytosis with an associated clonal hematologic non-mast cell lineage disorder, proposed by the WHO classification, and it is also suggestive of the initiation or early stage of acute promyelocytic leukemia.

Revisiting Mastocytosis in Adults: A Mayo Clinic Case Series of 342 Patients Including Information on KITD816V and JAK2V617F.

Background: Systemic mastocytosis (SM) has a varied presentation ranging from indolent forms with limited morbidity over many years to the rapidly fatal mast cell leukemia (MCL). This heterogeneity complicates clinical decision making regarding choice and timing of therapy. The aim of this study was to evaluate the prognostic value of the 2001 World Health Organization (WHO) classification of SM, and to refine risk stratification within SM sub-groups to facilitate clinical decision making. Information on KITD816V and JAK2V617F mutation analysis and clinical correlates is also provided.Methods: Patient records in the institutional electronic database from January 1976 to October 2007 were reviewed and SM patients 18 years of age or older identified; the date of diagnosis ranged from July 1964 to October 2007. Only those patients where diagnosis was confirmed by bone marrow (BM) histology were included in the analysis. KITD816V mutation analysis was performed by DNA sequencing. JAK2V617F was screened by allele-specific quantitative PCR analysis.Results: i. Clinical characteristics at presentation: A total of 342 SM patients were identified (154 female; median age at diagnosis=57 years; range 19 to 87 years). Per the 2001 WHO classification, 159 had indolent SM (ISM; median age=49 years), 41 aggressive SM (ASM; median age=65 years), 138 SM with associated clonal hematological non-mast cell lineage disease (SM-AHNMD; median age=65 years), and 4 MCL (median age=55 years) (p-value for age <0.0001). 140 (41%) patients had urticaria pigmentosa (UP) (63% with ISM; p<0.0001), 160 (47%) mast cell (MC) mediator release symptoms (69% with ISM; p<0.0001), 107 (31%) skeletal symptoms, and 142 (42%) constitutional symptoms (61% with ASM/SM-AHNMD versus 19% with ISM; p<0.0001). 123 patients (36%) had palpable splenomegaly (57% with SM-AHNMD; p<0.0001). 56 patients (16%) exhibited prominent eosinophilia (absolute eosinophil count >1500/mcl) – 31% and 22% with SM-AHNMD and ASM, respectively, versus 3% with ISM (p<0.0001); 12 of 23 patients (52%) with eosinophilia who were tested carried the FIP1L1-PDGFRA mutation. Serum tryptase (normal <11.5 ng/mL) was measured in 160 patients (47%) and almost all (96%) had an elevated level (median=64 ng/mL; range=4 to 2000 ng/mL; 33 patients had >200 ng/mL). ii. Disease course and prognostic factors After a median follow-up of 20.7 months (range=0–417), 153 deaths were recorded. 17 patients (5%) transformed to acute myeloid leukemia (AML; n=14) or MCL (n=3), most frequently with SM-AHNMD (11% versus 0% for ISM; p<0.0001). The median overall survival was 63 months (ISM=198 months, ASM=41 months; SM-AHNMD=24 months, and MCL=2 months; p<0.0001). Multivariate analysis of parameters at the time of diagnosis showed a significant and independent association between inferior survival and WHO sub-type (p<0.0001), age at diagnosis (p<0.0001), history of weight loss (p=0.01), anemia (p=0.007), thrombocytopenia (p=0.0008), hypoalbuminemia (p=0.0008), and excess BM blasts (>5%; p=0.004). A similar analysis in ISM identified anemia (p=0.04), hypoalbuminemia (P=0.002), and BM MC ≥ 30% (p=0.03) as independent predictors of inferior survival; the corresponding parameters in ASM were age at diagnosis (p=0.002) and history of weight loss (p=0.003). iii)KITD816V andJAK2V617F analysis Archived bone marrow was available in 165 patients for KITD816V and JAK2V617F analysis. By DNA sequencing, overall KITD816V detection rate was 28%: ISM 20%, ASM 29%, SM-AHNMD 33% (p=0.4). In patients with ASM (p=0.003) and SM-AHNMD (p=0.001), detection of KITD816V was associated with inferior survival. Greater than 1% (range 1–57) JAK2V617F allele burden was detected in 6 patients (4%); all belonged to SM-AHNMD including 4 with non-MC lineage myeloproliferative neoplasm.Conclusions: The current study confirms the prognostic value of the WHO subclassification of SM and identifies advanced age, weight loss, anemia, thrombocytopenia, hypoalbuminemia, and excess BM blasts as additional adverse prognostic factors. In ISM, presence of anemia, hypoalbuminemia, or BM MC ≥ 30% is associated with inferior survival. In ASM and SM-AHNMD, BM KITD816V allele burden might influence survival. JAK2V617F is rare in SM and when found, it is almost always in the context of SM-AHNMD.

Cytoreductive Therapy in Systemic Mastocytosis: Outcome Analysis and Response Prediction in 134 Consecutive Patients.

Background: Current therapy in adult systemic mastocytosis (SM) includes observation alone, topical therapy for cutaneous disease, symptomatic non-cytoreductive therapy and cytoreductive therapy. The latter involves several drugs whose individual merit in the treatment of SM has not been well characterized.Patients and Methods: Diagnosis of SM was according to the 2001 WHO criteria (World Health Organization Classification of Tumours of Hematopoietic and Lymphoid Tissues, p 1–351. Lyon, France: IARC Press; 2001). Response to cytoreductive therapy was assessed by consensus criteria (Eur J Clin Invest. 2007; 37:435). The study population was selected from a series of 342 adult SM patients referred to our institution and seen between 1964 and 2008. KITD816V mutation analysis was performed by DNA sequencing.Results: A total of 134 study patients received treatment that included at least one cytoreductive drug as either first-line (n=105) or second-line (n=29) therapy. Interferon-alpha with or without prednisone (n=58), hydroxyurea (n=43), imatinib mesylate (n=42) and 2-chlorodeoxyadenosine (n=26) were the most frequently used cytoreductive agents accounting for 120 of the 134 study cases; the remaining 14 patients received other cytoreductive drugs, none of which were effective. i. Interferon-alfa (IFN-a) with or without prednisone IFN-a with or without prednisone (24 and 34 patients, respectively) was given to 12 patients with indolent SM (ISM), 14 aggressive SM (ASM), and 32 SM with associated clonal hematological non-mast cell lineage disease (SM-AHNMD). For all 58 patients receiving therapy, complete (CR), major (MR), and partial (PR) response/regression were achieved in 3, 7, and 14 patients, respectively, for an overall response rate (ORR) of 41%. ORR in ISM, ASM, and SM-AHNMD was 50%, 43%, and 38%, respectively. Median duration of response was 12 months (range, 1–117 months). Anemia and elevated ESR were significantly associated with inferior ORR; 29% vs. 56% (p=0.04) and 14% vs. 57% (p=0.01), respectively. BM detection of KITD816V did not appear to affect response rates (p=0.4). ii. Hydroxyurea (HU) HU was given to 2 ASM, 40 SM-AHNMD and 1 mast cell leukemia (MCL) patients. The drug was used as first-line therapy in 30 patients. MR and PR were achieved in 1 and 8 SM-AHNMD patients, respectively (ORR=21%). Median duration of response was 37 months (range, 5–84 months). iii. Imatinib mesylate (IM) in patients with SM and associated eosinophilia IM was given to 22 SM patients who had associated eosinophilia (SM-eos): 2 had ISM, 2 ASM, and 18 SM-AHNMD. The drug was used as first-line therapy in 9 patients. Ten of the 22 patients with SM-eos were known to harbor the FIP1L1-PDGFRA fusion mutation and all responded to IM (ORR=100%). None of 5 FIP1L1-PDGFRA-negative SM-eos patients had a response to IM. In the remaining 7 patients with unknown mutation status, 4 patients had a response to IM (1 CR, 1 MR, and 2 PR). iv. IM in patients with SM not associated with eosinophilia IM was administered to 20 SM patients without associated eosinophilia (7 ISM, 2 ASM, 10 SM-AHNMD, and 1 MCL). Response was documented in 4 (20%) patients (1 CR, 1 MR, and 2 PR) including 1 with ISM, 2 with ASM and 1 with SM-AHNMD. Median duration of response was 19.5 months (range, 9–69 months). Two patients developed interstitial pneumonitis. v. 2-Chlorodeoxyadenosine (2-CdA) 2-CdA was given to 10 ISM, 3 ASM, and 13 SM-AHNMD patients; the drug was used as first-line therapy in 8 patients. CR, MR and PR were achieved in 1, 7, and 4 patients, respectively (ORR=46%). ORR in ISM, ASM, and SM-AHNMD was 50%, 33%, and 46%, respectively. Median duration of response was 11 months (range, 3–74 months). Presence of leukocytosis (WBC > 10 x 109/L), monocytosis (absolute monocyte count > 0.9 x 109/L) or circulating immature myeloid cells was significantly associated with inferior response; 13% vs. 61% (p=0.02); 11% vs. 69% (p=0.006) and 0% vs. 71%, (p=0.001), respectively. Response was not affected by BM detection of KITD816V (p=1.0).Conclusions: Both IFN-a and 2-CdA are reasonable treatment options, with comparable efficacy, for symptomatic SM including the subcategories of ISM, ASM and SM-AHNMD. IFN-a response was significantly better in the absence of anemia or elevated ESR. 2-CdA response was similarly better in the absence of leukocytosis, monocytosis or circulating immature myeloid cells. The therapeutic value of IM was limited to FIP1L1-PDGFRA-positive disease.

Chemotherapy and dasatinib induce long-term hematologic and molecular remission in systemic mastocytosis with acute myeloid leukemia with KIT D816V

Dasatinib has been reported to potently inhibit juxtamembrane domain mutant KIT D816V autophosphorylation and KIT-dependent activation of down stream signaling important for cell growth and survival of neoplastic cells. Additionally, dasatinib induced apoptosis in mast cell and leukemia cell lines expressing KIT D816V. Here, we present the first case report of long-term hematologic and molecular remission achieved with combined treatment with chemotherapy and dasatinib in a patient with systemic mastocytosis (SM) and acute myeloid leukemia (AML) with mutant KIT D816V expression. A 50-year-old male presented with pancytopenia, organomegaly, lymphadenopathy, and lytic bone lesions in the pelvis. The patient was found to have systemic mastocytosis (SM) and acute myelogeneous leukemia (AML) positive for KIT D816V and therefore diagnosed with SM with an associated clonal hematological non-mast cell lineage disease (SM-AHNMD). Both primary CD34+ cells containing myeloblasts and CD34− cells containing mastocytes obtained from the diagnostic BM lost viability markedly by in vitro dasatinib treatment. In addition, dasatinib diminished activity of STAT5, STAT3, AKT and ERK and attenuated the levels of c-KIT. The patient achieved a hematologic complete remission (HCR) by two induction chemotherapies with residual mastocytes. Dasatinib (70 mg PO bid, days 1–4) was added to consolidation treatments composed of four cycles of high dose cytarabine and was then continued as maintenance therapy (50 mg PO bid). Periodic bone marrow (BM) aspirate/biopsies (eight over 18 months) were performed. The patient remained in HCR, and the mastocyte burden decreased by 50%. The bone lytic lesions improved. The KIT D816Vmutation progressively decreased and became undetectable in the last three BM analyses. This result was confirmed by an independent laboratory showing a lack of c-KIT mutation in both CD34+ cells and CD34− cells in the last BM. No significant adverse effects of dasatinib occurred. Dasatinib has in vitro and in vivo efficacy in SM-AML patients with KIT D816V mutation. Along with chemotherapy, dasatinib should be considered in these patients particularly if they cannot undergo allogeneic stem cell transplantation for this poor prognostic AML.

Actualités sur la compréhension et le traitement des mastocytoses systémiques

Purpose Mast cell disorders are defined by an abnormal accumulation of tissue mast cells in one or more organ systems. Clinical symptoms in mastocytosis result from mast cells derived mediators and, less frequently, from destructive infiltration of mast cells. Systemic mastocytosis is regressive among children, whereas the disease is persistent among adults. A clonal haematological non-mast cell lineage disease can be associated. The clinical course in these patients is variable ranging from asymptomatic for years to highly aggressive and rapidly devastating. Until recently, the only treatment of this incurable disease was symptomatic. Current knowledge and key points Recent advances were done in understanding the physiopathology of this myeloproliferative syndrome which results from an activating mutation of the stem cell factor receptor: C-Kit. A somatic C-Kit mutation is usually detectable in mast cells and their progenitors. Different mutations were found and the mutation D816V is the most frequent. Their specific transduction paths were also studied. Diagnosis of systemic mastocytosis does not only rest upon pathological examination but also on molecular as well as immunological and immunochemical tools. Future prospects and projects Physiopathological advancements led to suggest new treatments in order to directly inhibit proliferative paths of masts cells such as tyrosine kinase inhibitors and rapamycin.

Systemic Mastocytosis Associated with Chronic Idiopathic Myelofibrosis: A Distinct Subtype of Systemic Mastocytosis-Associated Clonal Hematological Nonmast Cell Lineage Disorder Carrying the Activating Point Mutations KIT D816V and JAK2 V617F

In ∼20 to 30% of patients with systemic mastocytosis (SM), an associated clonal hematological nonmast cell lineage disorder (AHNMD) is diagnosed. Although SM may be considered to be closely related to the myeloproliferative disorders (MPDs), it is unknown whether JAK2^V617F+ MPD may occur as AHNMD in patients with SM. We here describe five patients with SM and co-existing chronic idiopathic myelofibrosis (SM-CIMF). In five of five patients, we detected the SM-related KIT mutation D816V, and in four of five patients, the MPD-related JAK2 mutation V617F. Surprisingly, JAK2^V617F was found not only in the AHMMD component of the disease but also in microdissected mast cells in all four JAK2^V617F-positive cases. Conversely, in two of the five patients, KIT^D816V was found not only in neoplastic mast cells but also in microdissected CD15⁺ neoplastic myeloid cells. Control experiments showed that 10 indolent SM patients without associated MPD did not carry the JAK2 mutation V617F and that 15 CIMF patients without SM did not carry the KIT mutation D816V. Altogether, these data suggest that KIT^D816V+ SM can co-exist with JAK2^V617F+ CIMF and that, in some of these SM-CIMF cases, the two mutations are present in the neoplastic cells of both disease components.

Systemic mastocytosis with plasma cell dyscrasia: Report of a case

Systemic mastocytosis (SM) comprises a heterogeneous group of disorders characterized by infiltration of bone marrow and other tissues by neoplastic mast cells. A subset of patients with SM has associated hematologic malignancy usually of myeloid origin and comprises an entity termed systemic mastocytosis with associated clonal hematological non-mast cell lineage disease (SM-AHNMD) by the current WHO classification. Reports of clonal lymphoid malignancies associated with SM are rare. We describe a patient who was simultaneously diagnosed with indolent SM and a plasma cell dyscrasia fitting the definition of monoclonal gammopathy of undetermined significance (MGUS). We also discuss the pathologic interaction between the neoplastic mast cells of SM and the lymphoid/plasma cell malignancy when these two entities coexist.

Systemic mastocytosis (SM) associated with chronic eosinophilic leukemia (SM-CEL): Detection of FIP1L1/PDGFRα, classification by WHO criteria, and response to therapy with imatinib

Based on generally accepted criteria and the WHO-classification, a subset of patients with systemic mastocytosis (SM) have (or develop) an associated clonal hematologic non-mast cell lineage disease (SM-AHNMD). We describe a case of SM with coexisting chronic eosinophilic leukemia (SM-CEL). The patient, a 51-year-old male, was first seen in 1992 with small-sized infiltrates of spindle-shaped mast cells in his marrow, and marked eosinophilia. Retrospectively, a CHIC2 deletion and the FIP1L1/PDGFRα fusion gene-product were demonstrable by FISH analysis and RT-PCR, respectively. SM-associated organopathy or mediator-related symptoms were not recorded. However, the patient developed cardiomyopathy. Therapy with interferon-alpha, hydroxyurea, and corticosteroids were without effects. By contrast, therapy with imatinib was followed by a fast and sustained response with complete and stable regression of eosinophilia, drop in eosinophil cationic protein, and decrease of serum tryptase to normal levels. This case provides further evidence for the potential of co-existence of SM with a primary eosinophilic disorder (CEL) defined by the FIP1L1/PDGFRα fusion gene. Because of the availability of a superior targeted drug (imatinib), it is of importance to screen for FIP1L1/PDGFRα in suspected CEL with or without co-existing SM.

Systemic mastocytosis with associated clonal haematological non-mast cell lineage diseases: a histopathological challenge

Aims: Although systemic mastocytosis (SM) with an associated clonal haematological non-mast cell lineage disease (SM-AHNMD) is a major subtype of SM, little is known about its frequency among myelogenous neoplasms,...