Systemic mastocytosis (SM) is a heterogeneous disease characterized by the expansion of mast cells in one or more tissues, frequently characterized by the presence of
D816V mutation. The updated ...World Health Organization (WHO) classification of myeloid neoplasms recognizes SM with an associated hematological neoplasm (SM-AHN) as a new subtype among the others, which is depicted by the coexistence of SM with another hematological clonal disease. Prognosis is very different among SM patients, while its treatment, although highly personalized, is still challenging. Here we report a case of
D816V-unmutated SM associated with MDS/MPN successfully treated with imatinib.
Systemic mastocytosis (SM) results from a clonal proliferation of abnormal mast cells (MCs) in extra-cutaneous organs. It could be divided into indolent SM, smoldering SM, SM with an associated ...hematologic (non-MC lineage) neoplasm, aggressive SM, and mast cell leukemia. SM is generally associated with the presence of a gain-of-function somatic mutation in KIT at codon 816. Clinical features could be related to MC mediator release or to uncontrolled infiltration of MCs in different organs. Whereas indolent forms have a near-normal life expectancy, advanced diseases have a poor prognosis with short survival times. Indolent forms should be considered for symptom-directed therapy, while cytoreductive therapy represents the first-line treatment for advanced diseases. Since the emergence of tyrosine kinase inhibitors (TKIs), KIT inhibition has been an attractive approach. Initial reports showed that only the rare KITD816V negative cases were responsive to first-line TKI imatinib. The development of new TKIs with activity against the KITD816V mutation, such as midostaurin or avapritinib, has changed the management of this disease. This review aims to focus on the available clinical data of therapies for SM and provide insights into possible future therapeutic targets.
Systemic mastocytosis (SM) is a rare neoplasm resulting from extracutaneous infiltration of clonal mast cells (MC). The clinical features of SM are very heterogenous and treatment should be highly ...individualized. Up to 40% of all SM cases can be associated with another hematological neoplasm, most frequently myeloproliferative neoplasms. Here, we present a patient with indolent SM who subsequently developed a myeloid neoplasm with
rearrangement with complete response to low-dose imatinib. The 63-year-old patient presented with eosinophilia and elevated serum tryptase level. Bone marrow analysis revealed aberrant MCs in aggregates co-expressing CD2/CD25 and
D816V mutation (0.01%), and the
fusion gene was not identified. In the absence of 'B' and 'C' findings, we diagnosed an indolent form of SM. For 2 years after the diagnosis, the absolute eosinophil count progressively increased. Bone marrow evaluation showed myeloid hyperplasia and the
fusion gene was detected. Thus, the diagnosis of myeloid neoplasm with
rearrangement was established. The patient was treated with imatinib 100 mg daily and rapidly obtained a complete molecular remission. The clinical, biological, and therapeutic aspects of SM might be challenging, especially when another associated hematological disease is diagnosed. Little is known about the underlying molecular and immunological mechanisms that can promote one entity prevailing over the other one. Currently, the preferred concept of SM pathogenesis is a multimutated neoplasm in which
mutations represent a "phenotype modifier" toward SM. Our patient showed an evolution from
mutated indolent SM to a myeloid neoplasm with
rearrangement; when the eosinophilic component expanded, a regression of the MC counterpart was observed. In conclusion, extensive clinical monitoring associated with molecular testing is essential to better define these rare diseases and consequently their prognosis and treatment.
Systemic mastocytosis (SM) is a rare disease with a range of clinical presentations, and the vast majority of patients have a KIT D816V mutation that results in a gain of function. The ...multikinase/KIT inhibitor midostaurin inhibits the D816V mutant and has a well-established role in treating advanced SM. Even if considered the standard of therapy, some open questions remain on optimizing midostaurin management in daily practice. The current review presents the opinions of a group of experts who met to discuss routine practice using midostaurin in patients with advanced SM. The efficacy and safety of midostaurin in Phase 2 trials are overviewed, followed by practical guidance for optimal therapy management and adverse events during therapy with midostaurin. Specific guidance is given for initiating therapy and evaluating response with midostaurin as general assessment and laboratory, instrumental, pathological, and molecular exams. Special consideration is given to dose interruption, reduction, and discontinuation of therapy, as well as adverse event management and supportive therapy. Patients should be informed about possible side effects and receive practical advice to avoid or limit them and antiemetic prophylaxis so that therapy with midostaurin can continue as long as clinical benefit is observed or until unacceptable toxicity occurs. Lastly, considerations on the use of midostaurin during the ongoing Covid-19 pandemic are made. The overall scope is to provide guidance that can be useful in daily practice for clinicians using midostaurin to treat patients with advanced SM.
Management of systemic mastocytosis is an emerging challenge which requires a multidisciplinary diagnostic approach and personalized treatment strategy. Midostaurin can rapidly reduce the disease ...burden, also in cladribine refractory cases.
Management of systemic mastocytosis is an emerging challenge which requires a multidisciplinary diagnostic approach and personalized treatment strategy. Midostaurin can rapidly reduce the disease burden, also in cladribine refractory cases.
Reduced bone mass with or without fragility fractures is a common feature of mastocytosis, particularly in adult males. However, bone mineral density does not account for all the fragility fractures, ...being a part of them attributable to impairment in bone quality. Aim of this study is to assess the usefulness of DXA-derived geometry and structural indexes in the assessment of bone status in mastocytosis. Ninety-six consecutive patients (46 women and 50 men) affected by cutaneous (CM) or systemic (SM) mastocytosis were studied. Mean age (± SD) was 53.3 ± 14.23. Spine lateral X-rays for Genant's scale, DXA for lumbar (L) and femoral (F) bone mineral density (BMD), bone strain index (BSI), lumbar trabecular bone score (TBS), and hip structural analysis (HSA) were performed. Among the laboratory variables, data of serum tryptase were reported. Tryptase was higher in SM (
p
= 0.035), inversely correlated with LBMD (
r
= − 0.232;
p
= 0.022) and TBS (
r
= − 0.280;
p
= 0.005), and directly with L-BSI (
r
= 0.276;
p
= 0.006). L-BSI remained statistically significant (
p
= 0.006; adjusted
R
2
= 0.101) together with mastocytosis (SM or CM:
p
= 0.034) in the multivariate regression model with tryptase as dependent variable, being LBMD and TBS not statistically significant (
p
= 0.887, and
p
= 0.245, respectively). Tryptase increased about 22 units for each unit increase of L-BSI and about 18 units for SM against CM. L-BSI was lower (
p
= 0.012), while FN-BSI and FT-BSI were higher in women (
p
< 0.001) than in men. HSA indexes were significantly higher in men, particularly with SM. SM is a risk factor for reduced bone mass, texture and strength. Since mean L-BSI and Z-modulus of all the femoral sites are statistically higher in men than in female, it could be argued that men have a better femoral bone resistance to bending forces than women, but a worse lumbar bone resistance to compressive loads. DXA indexes of bone quality are useful in mastocytosis’ bone assessment and its clinical management.
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Introduction
Hereditary alpha-Tryptasemia (HαT) is a group of genetically defined traits that share increased copy number of TPSAB1 gene encoding for both the α- and β-alleles (Lyons et al 2018). ...Increased copy number (CN) of the α-tryptase coding sequence in TPSAB1 on one or both alleles represents the genetic base of HαT (Lyons et al 2016). HαT is characterized by mild elevation in serum tryptase levels and a variety of mast cell (MC) activation symptoms, including recurrent anaphylaxis. Prevalence in the general population is up to 5%, that increases up to 20% in systemic mastocytosis (SM); it has been suggested that HαT might be a germline variant predisposing to SM development. In SM, HαT correlated with higher incidence of mediator-related symptoms (Greiner G et al, Blood 2021). Due to its complexity, the assay for TPSAB1 CN is performed in few centers and the actual prevalence of HαT in selected subsets is still to be elucidated. To this end, we screened for HαT 2 groups of subjects, the first with MC activation symptoms and no evidence of SM, the second with diagnosis of SM according to WHO-2016.
Methods
Droplet digital PCR (ddPCR) was used to measure CN variation (CNV) in TPSAB1 by adapting standard CNV ddPCR protocol to genotype for both TPSAB1 and TPSB2 (Fig.1A). The high homology between α and β encoding isoforms and the presence of paralogous genes in a single locus makes TPSAB1 CNV detection very challenging. ddPCR was performed on genomic DNA with/without BamHI, using the PrimePCR ddPCR Copy Number reference AP3B1 (BioRad). Accuracy and precision of the ddPCR protocol was assessed by analyzing 10 samples in triplicate in 3 separate experiments. Data robustness and repeatability can be appreciated in Fig 1B.
Results
We studied 41 subjects with mediator-related symptoms and augmented basal serum tryptase (BST) (cohort 1) and 150 patients with ascertained diagnosis of mastocytosis (cohort 2). The BST threshold established for cohort 1 was equal or higher than 11 mcg/L. Median age was 64.7 yr, males 54%; median BST levels was 15.3 (range 12.3-21 mcg/L); 29% of the pts had history of anaphylaxis.
In cohort 2, 134/150 (89.3%) pts had a diagnosis of SM, whereas 13/150 (8,6%) were Cutaneous Mastocytosis (CM). Among SM patients, 113(84.3%) presented with non-advanced SM variants. Advanced forms including aggressive SM (ASM) and SM with an associated hematological neoplasm (SM-AHN) were diagnosed in 6 (4.5%) and 8 (6%) respectively. In 3 pts, SM subtype was not available. Median age was 49 yr, males 55%; 41.7% of the pts had history of anaphylaxis.
HαT was documented in 27 (65.9%) subjects in cohort 1, and 14 (9.3%) in cohort 2. In cohort 1, 3 α-tryptase (3α) copy number was observed more frequently (59.2% of HαT+ pts); conversely 3α and 2α-tryptase copy number were observed at a similar rate (42,8%) in cohort 2.
HαT+ pts in cohort 1 presented significantly higher BST (17.1 vs 12.05 mgc/L, P<0.001), as previously reported (Greiner G et al, Blood 2021); however, occurrence of mediator related symptoms was comparable to HαT wt, 72% vs 71.4% , respectively; likewise for anaphylaxis (28% in HαT+ vs 33%).
In cohort 2, BST levels were similar in HαT+ and HαT wt pts (24.6 and 24.3 mcg/L), as were anaphylaxis episodes (50% and 41%, respectively). A trend for lower MC burden in HαT+ as assessed by flow cytometry was demonstrated (% of bone marrow MC: 0.01% in HαT+ vs 0.07%) whereas no meaningful differences emerged regarding the symptom burden. In addition, a lower prevalence of KIT 816V mutation was observed in HαT+ (71.4% vs 89.5%; p=0.073).
Conclusions
In our study HαT+ was observed in around 10% of patients with SM, a prevalence lower than previously reported (Greiner et al, Blood 2021) and remarkably lower than in a selected cohort of subjects with raised BTL and history of mediator-released symptoms (66%). ddPCR represents a suitable method to investigate the presence of CNV in the α-tryptase coding sequence. Genetic testing for HαT+ should be considered in the diagnostic workout of patients presenting with anaphylaxis or MC mediator-related symptoms and no suspicion/evidence of SM. The clinical correlates of HαT in SM remain to be fully ascertained.
Supported by IMH no.GR-2016-02362631 and AIRC, Mynerva project no21267
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Elena: CELGENE: Other: funding for meeting participation; PFIZER: Membership on an entity's Board of Directors or advisory committees; NOVARTIS: Membership on an entity's Board of Directors or advisory committees; GILEAD: Membership on an entity's Board of Directors or advisory committees. Vannucchi: Novartis: Honoraria, Membership on an entity's Board of Directors or advisory committees; Incyte: Honoraria, Membership on an entity's Board of Directors or advisory committees; BMS: Honoraria, Membership on an entity's Board of Directors or advisory committees; AbbVie: Membership on an entity's Board of Directors or advisory committees.
Systemic mastocytosis (SM) is a rare disease with a range of clinical presentations, and the vast majority of patients have a KIT D816V mutation that results in gain of function. The multikinase/KIT ...inhibitor midostaurin inhibits the D816V mutant, and has a well-established role in treatment of advanced SM. Even if considered the standard of therapy, some open questions remain on how to optimize the management of midostaurin in daily practice. The current review presents the opinions of a group of experts who met to discuss routine practice with the use of midostaurin in patients with advanced SM. The efficacy and safety of midostaurin in Phase 2 trials are overviewed, followed by practical guidance for optimal management of therapy and adverse events during therapy with midostaurin. Specific guidance is given for initiating therapy and evaluating response with midostaurin in terms of general assessment and laboratory, instrumental, pathological, and molecular exams. Special consideration is given to dose interruption, reduction, and discontinuation of therapy as well as adverse event management and supportive therapy. Patients should be informed about possible side effects and receive not only practical advice to avoid or limit them, but also antiemetic prophylaxis so that therapy with midostaurin can continue as long as clinical benefit is observed or until unacceptable toxicity occurs. Lastly, considerations on the use of midostaurin during the ongoing Covid-19 pandemic are made. The overall scope is to provide guidance that can be useful in daily practice for clinicians using midostaurin to treat patients with advanced SM.
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