The diagnosis of systemic mastocytosis (SM) is based on various clinical, dermatological, serological, and hematological findings but essentially relies on histological evidence of an abnormal ...increase in tissue-localized mast cells (MCs). The extra-cutaneous organ most frequently affected is the bone marrow (BM), and therefore, histological examination of trephine biopsy specimens of the iliac crest is mandatory on suspicion of SM. At microscopic examination, neoplastic MCs show aberrant morphology, usually with prominent spindling. Immunohistochemistry is a useful tool in the diagnosis of SM because mast cell (MC) infiltrates may be slight and scarce, in a mixed background of lymphohistiocytic cells, eosinophils, and plasma cells. Moreover, neoplastic MCs exhibit an aberrant phenotype. Recent evidence, largely derived from molecular genetics, has enhanced the diagnostic capability of SM, also providing the basis for adequate prognostic and therapeutic evaluation. The cases herein reported illustrate the variable clinical manifestations and disease course of SM, focusing on diagnostic and therapeutic challenges. In accordance with the World Health Organization (WHO) classification and the International Consensus Classification (ICC) systems, our findings emphasize the importance of an integrated diagnostic approach for SM, with proper application of diverse assessment methodologies in order to improve SM classification and treatment effectiveness.
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Introduction: Myelofibrosis (MF), whether primary (PMF) or secondary (SMF) to polycythemia vera or essential thrombocytemia, is characterized by a complex and partially undeciphered molecular ...architecture. Besides mutations in driver genes (JAK2, CALR, MPL), somatic mutations in selected myeloid-associated genes have been shown to impact prognosis of MF patients (pts). Among these, ASXL1 mutations (ASXL1MTs) are associated with poor outcomes in myeloid malignancies including PMF, where they are included in the category of “high molecular risk” (HMR) mutations along with EZH2MTs, IDH1/2MTs, and SRSF2MTs (Vannucchi AM, Leukemia 2013). However, a recent study (Luque Paz D, Blood Adv 2021) questioned the value of ASXL1MTs in MF. The current study aimed at further characterizing the prognostic role of ASXL1MTs in MF.
Methods: After IRB approval, pts with WHO-defined MF were included in the study. Mutational analysis by targeted NGS was performed as previously described (Guglielmelli P, JCO 2017). All deposited variants were manually curated to assess pathogenicity. In this study, we also used the molecular model proposed by Luque Paz et al. that identifies 4 genetic groups: TP53MT; High-risk (≥1 mutation in EZH2, CBL, U2AF1, SRSF2, IDH1/2); ASXL1MT-only; and “Others”.
Results: A total of 525 pts were included in the study, including 331 (63%) PMF and 194 (37%) SMF. Median age at diagnosis was 89 (18-90) years, 314 (60%) were male. The median follow-up time was 80 (98% CI, 68-90) months. Overall, 324 (62%) pts were JAK2MT, 126 (24%) CALRMT, 24 (5%) MPLMT, 40 (8%) triple negative (TN), and 11 (2%) double mutated. Among non-driver genes, ASXL1MTs were found in 158 (30%) pts, EZH2MTs in 45 (9%), SRSF2MTs in 37 (7%), NRASMTs in 30 (6%) U2AF1MTs in 27 (5%), TP53MTs and CBLMTs in 25 (5%) each, IDH1/2MTs in 18 (3%), and KRASMTs in 15 (3%). Pts in the HMR category were 125 (38%) in PMF and 63 (32%) in SMF.
According to the above model, distribution of pts was as follows: TP53MT n=25 (5%), High-risk n=137 (26%), ASXL1MT-only n=64 (12%), and Others n=299 (57%). Pts in the TP53MT and ASXL1MT-only groups were more likely to be diagnosed with SMF compared to pts in the High-risk and Others groups (44% and 48% vs 28% and 38%, respectively). In addition, the High-risk group was enriched in TN pts (16%), while CALRMTs were more common in the ASXL1MT-only and Others compared to the TP53MT and High-risk groups (25% and 27% vs 12% and 18%, respectively).
In univariate analysis, the TP53MT and High-risk groups were associated with the worst overall survival (OS), with median values of 38 (14-110) and 55 (45-85) months (P=.0039), respectively (Fig 1A). Albeit remarkably better, the OS of pts in the ASXL1MT-only group was inferior compared to pts in the Others group (median 124 91-156 vs 193 142-NR months; P=.0118) (Fig 1A).
We then analyzed separately PMF and SMF cohorts. In the former, the TP53MT and High-risk groups remained associated with the worst OS (median 58 20-126 vs 55 36-85 months), although with no significant difference, likely due to the low frequency (4%) of TP53MTs mutations in PMF (Fig 1B). Concurrently, the negative prognostic impact of the ASXL1MT-only group was confirmed in comparison to the Others group (median 103 78-NR vs 320 178-NR months; P=.0170). In pts with SMF, while the TP53MT group (6%) had by far the worst OS (median 13 6-NR months), the OS of the ASXL1MT-only group (median 141 56-171 months) was comparable to that of the Others group (median 131 106-NR months; P=.5188) and not different from the High-risk group (median 58 45-174 months; P=.3606) (Fig 1C). In a further analysis including only pts in the High-risk group, ASXL1MTs were found in 62% and 63% of patients with PMF and SMF, respectively. In survival analysis, the presence of ASXL1MTs was associated with an increased risk of death only in PMF (median OS 47 31-73 vs 102 34-317 months; P=.0240), unlike in SMF (median OS 90 47-174 vs 25 16-338 months; P=.3296) (Fig 1D-E).
Conclusion: In the current study, we critically re-addressed the prognostic impact of ASXL1MTs by applying a genetic model recently developed by Luque Paz et al. to our cohort of molecularly annotated, WHO-defined MF pts. Overall, our results confirm that ASXL1MTs -even in the absence of other co-occurring high-risk mutations- harbor a negative prognostic impact mainly in PMF. These findings also reinforce the idea that PMF and SMF represent two different biological entities.
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Vannucchi: Incyte: Honoraria, Membership on an entity's Board of Directors or advisory committees; Novartis: 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.
A score to predict the association between unexplained osteoporosis and an underlying systemic Mastocytosis (SM) is lacking.
This study aimed at identifying criteria able to predict the diagnosis of ...SM without skin involvement and provide an indication for bone marrow (BM) assessment.
We included 139 adult patients with unexplained osteoporosis and suspected SM. After BM evaluation, 63 patients (45.3 %) were diagnosed with SM, while the remaining 76 patients (54.7 %) negative for clonal mast cell (MC) disorders, constituted our control group. Univariate and multivariate analysis identified three independent predictive factors: age (<54 years: +1 point, >64 years: −1 point), serum basal tryptase (sBT) levels >19 ng/mL (+2 points) and vertebral fractures (+2 points).
These variables were used to build the OSTEO-score, able to predict the diagnosis of SM before BM assessment with a sensitivity of 73.5 % and a specificity of 67.1 %. Patients with a score < 3 had a lower probability of having SM compared to patients with a score ≥ 3 (28.5 % and 71.4 %, respectively, p < 0.0001). When sBT levels were corrected for the presence of hereditary alpha-tryptasemia (HαT) using the BST calculater (https://bst-calculater.niaid.nih.gov/) recently published 1,2, the sensitivity of ΗαT-adjusted OSTEO-score increased to 87.8 %, and the specificity reached 76.1 %. Also, the positive predictive value of a score ≥ 3 increased to 85.2 %.
Further studies are needed to validate these results and characterize the role of tryptase genotyping in patients with unexplained osteoporosis in reducing the risk of misdiagnosing patients with SM. Our proposed scoring model allows the identification of patients with the highest probability of having SM, avoiding unnecessary BM studies.
•A predictive score for mastocytosis in severe osteoporosis cases is lacking.•Bone marrow assessment in unexplained osteoporosis should not rely solely on elevated basal tryptase levels.•The application of a predictive score would avoid unnecessary bone marrow studies.
Background: CEBPA-mutated acute myeloid leukemia (AML) is a separate entity in the updated WHO and ICC classifications. Previously identified by double mutations, the clinical profile and favorable ...outcome were correlated with in-frame mutations in bZIP domain. Beyond mutations recurrent in myeloid neoplasms (involving TET2, FLT3, NRAS), CEBPA-mutated AML is enriched in gene mutations (i.e., GATA2, CSF3R, WT1) rarely observed in CEBPA-wild type AML. No conclusive findings have been drawn for the prognostic impact of additional mutations. Of note, somatic GATA2 mutations have been associated with invasive fungal infections in myeloid neoplasms. Although overall correlating with favorable prognosis, an unexpectedly high rate of treatment-related mortality (TRM) in CR has been described in a large multicenter study on intensively treated CEBPA-mutated patients (pts) (Schlenk et al Blood 2013;122(9):1576). Aims: The aim of our study was to correlate baseline and treatment characteristics with the outcome and hematological toxicity in an intensively treated cohort of CEBPA-bZIP mutated AML pts. Methods: Pts entering the study had a diagnosis of CEBPA-bZIP AML confirmed according to 2022 WHO and ICC criteria. Pts were characterized by next-Generation deep amplicon sequencing with Ion Torrent platform (ThermoFisher Scientific) covering a panel of 40 genes. Sequence alignment and filtering were performed by NextGENe version 2.4.2.1 (SoftGenetics). The first two chemotherapy cycles were categorized according to the delivery of an anthracycline (ANTHRAC) and cytarabine (ARA-C) at high dose (HDAC). The study was approved by the local institutional review board. Results: From 2004 to 2023, 49 pts with CEBPA-bZIP mutated AML met the inclusion criteria at project study sites (Firenze, Bergamo). Their features are detailed in Table 1. CR rate was achieved in 45 of 49 pts (91.8%), with a DFS and OS of 74.3% and 82.4% at 5 y, respectively. Based on NGS, at least one additional mutation was identified in 18 (36.7%) pts (NGS+), the majority of them involving GATA2 (n=14, 28.6%). As per treatment, 44 pts received at least two cycles, of which no (n=2, 4.6%), one (n=14, 31.8%), or two (n=28, 63.6%) ANTHRAC-containing cycles. As regarded HDAC, 19 (43.2%), 17 (38.6%) and 8 (18.2%) pts received no, one or two HDAC-containing cycles, respectively. No significant differences emerged for DFS or OS between NGS+ and NGS- groups (P=0.33 and 0.52, respectively). To gain insight into potential causes of toxicity during CR, we focused on hematopoietic recovery after induction and consolidation. NGS+ pts showed slower neutrophil (ANC) recovery (median, 22 days to >500/uL after induction and 25 days after consolidation) compared to NGS- group (19 days, P=0.018; 18 days P=0.058, respectively). Such effect was enhanced by treatment with ANTHRAC-containing cycles: NGS+ pts receiving two cycles required significantly longer time to recover from first consolidation cycle, both for ANC (30 days) and platelet count (34 days) vs 22 (P=0.012) and 27 (P=.010) days, respectively, of other categories (Figure 1). A proportion of 45.5% (5/11) NGS+/ANTHRAC-2 pts could not complete the planned chemotherapy program due to hematological toxicity compared to 19.3% (6/31, P=0.09) in other categories. No significant prolongation of recovery was observed for HDAC. Conclusions: CEBPA-bZIP mutated AML is featured by high response rate and favorable outcome. Delayed hematopoietic recovery was observed in pts bearing additional mutations (especially GATA2) when treated with anthracyclines in first two cycles. Our findings suggest the cumulative dosage of anthracyclines should be limited in CEBPA-mutated/NGS+ patients to spare hematological toxicity on turn impairing the therapeutic plan.
Systemic mastocytosis (SM) encompasses a heterogeneous group of clonal disorders characterized by abnormal expansion of mast cells (MCs). Beyond KIT and other genes recurrently mutated in myeloid ...neoplasms, several genetic variants have been described as predisposing to the development of the disease and influencing its clinical phenotype. Increased copy number variants of the TPSAB1 gene were identified as a cause of nonclonal elevated tryptasemia and defined as hereditary α-tryptasemia (HαT). Moreover, HαT is enriched in patients with SM, where it can affect the incidence of mediator-related symptoms.
In a multicenter data set of 444 patients with MC disorders, we aimed to investigate the clinical correlates of germline TPSAB1 copy number gains.
Droplet digital PCR was performed in all cases to ascertain the presence of HαT. Clinical history along with blood values and bone marrow examination were analyzed.
We confirmed a higher incidence of HαT+ cases (n = 59, 13.3%) in patients diagnosed with mastocytosis with respect to the general population (approximately 5%). HαT+ patients were characterized by a lower MC-associated disease burden and higher levels of tryptase. Several disease variables were coherent with this pattern, from bone marrow MC infiltration to MC-related histopathologic traits, which also accounted for a significantly higher incidence of clonal MC activation syndrome in HαT+ (10.2%) compared to HαT− (3.4%, P = .029) patients. We also confirmed that HαT+ carriers had a significantly higher frequency of anaphylaxis, without relevant differences for other clinical manifestations.
These findings on a large patient series support and extend previous data, and suggest that knowledge of HαT status may be useful for personalized management of patients with SM.
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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.
Transformation from chronic (CP) to blast phase (BP) in myeloproliferative neoplasm (MPN) remains poorly characterized, and no specific mutation pattern has been highlighted. BP-MPN represents an ...unmet need, due to its refractoriness to treatment and dismal outcome. Taking advantage of the granularity provided by single-cell sequencing (SCS), we analyzed paired samples of CP and BP in 10 patients to map clonal trajectories and interrogate target copy number variants (CNVs). Already at diagnosis, MPN present as oligoclonal diseases with varying ratio of mutated and wild-type cells, including cases where normal hematopoiesis was entirely surmised by mutated clones. BP originated from increasing clonal complexity, either on top or independent of a driver mutation, through acquisition of novel mutations as well as accumulation of clones harboring multiple mutations, that were detected at CP by SCS but were missed by bulk sequencing. There were progressive copy-number imbalances from CP to BP, that configured distinct clonal profiles and identified recurrences in genes including NF1, TET2, and BCOR, suggesting an additional level of complexity and contribution to leukemic transformation. EZH2 emerged as the gene most frequently affected by single nucleotide and CNVs, that might result in EZH2/PRC2-mediated transcriptional deregulation, as supported by combined scATAC-seq and snRNA-seq analysis of the leukemic clone in a representative case. Overall, findings provided insights into the pathogenesis of MPN-BP, identified CNVs as a hitherto poorly characterized mechanism and point to EZH2 dysregulation as target. Serial assessment of clonal dynamics might potentially allow early detection of impending disease transformation, with therapeutic implications.
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