Genomic characterization of spleens in patients with myelofibrosis

HMGA2 overexpression with specific chromosomal abnormalities predominate in CALR and ASXL1 mutated myelofibrosis

Although multiple genetic events are thought to play a role in promoting progression of the myeloproliferative neoplasms (MPN), the individual events that are associated with the development of more aggressive disease phenotypes remain poorly defined. Here, we report that novel genomic deletions at chromosome 12q14.3, as detected by a high-resolution array comparative genomic hybridization plus single nucleotide polymorphisms platform, occur in 11% of MPN patients with myelofibrosis (MF) and MPN-accelerated/blast phase (AP/BP) but was not detected in patients with polycythemia vera or essential thrombocythemia. These 12q14.3 deletions resulted in the loss of most of the non-coding region of exon 5 and MIRLET7 binding sites in the 3'UTR of the high mobility group AT hook 2 (HMGA2), which negatively regulate HMGA2 expression. These acquired 12q14.3 deletions were predominately detected in MF patients with CALR and ASXL1 co-mutations and led to a greater degree of HMGA2 transcript overexpression, independent of the presence of an ASXL1 mutation. Patients with 12q structural abnormalities involving HMGA2 exhibited a more aggressive clinical course, with a higher frequency of MPN-AP/BP evolution. These findings indicate that HMGA2 overexpression associated with genomic deletion of its 3'UTR region is a newly recognized genetic event that contributes to MPN progression.

Conventional Cytogenetic Analysis and Array CGH + SNP Identify Essential Thrombocythemia and Prefibrotic Primary Myelofibrosis Patients Who Are at Risk for Disease Progression

The Philadelphia chromosome-negative myeloproliferative neoplasms (Ph-MPNs) are a heterogeneous group of clonal hematopoietic malignancies that include polycythemia vera (PV), essential thrombocythemia (ET), and the prefibrotic form of primary myelofibrosis (prePMF). In this study, we retrospectively reviewed the karyotypes from conventional cytogenetics (CC) and array Comparative Genomic Hybridization + Single Nucleotide Polymorphism (aCGH + SNP) in patients with ET or prePMF to determine whether the combined analysis of both methodologies can identify patients who may be at a higher risk of disease progression. We performed a comprehensive genomic review on 169 patients with a clinical diagnosis of ET (154 patients) or prePMF (15 patients). Genomic alterations detected by CC or array-CGH + SNP were detected in 36% of patients. In patients who progressed, 68% had an abnormal genomic finding by either technology. There was a shorter progression-free survival (PFS) among patients who were cytogenetically abnormal or who were cytogenetically normal but had an abnormal aCGH + SNP result. Leveraging the ability to detect submicroscopic copy number alterations and regions of copy neutral-loss of heterozygosity, we identified a higher number of patients harboring genomic abnormalities than previously reported. These results underscore the importance of genomic analysis in prognostication and provide valuable information for clinical management and treatment decisions.

Splenomegaly in patients with primary or secondary myelofibrosis who are candidates for allogeneic hematopoietic cell transplantation: a Position Paper on behalf of the Chronic Malignancies Working Party of the EBMT

Splenomegaly is a hallmark of myelofibrosis, a debilitating haematological malignancy for which the only curative option is allogeneic haematopoietic cell transplantation (HCT). Considerable splenic enlargement might be associated with a higher risk of delayed engraftment and graft failure, increased non-relapse mortality, and worse overall survival after HCT as compared with patients without significantly enlarged splenomegaly. Currently, there are no standardised guidelines to assist transplantation physicians in deciding optimal management of splenomegaly before HCT. Therefore, the aim of this Position Paper is to offer a shared position statement on this issue. An international group of haematologists, transplantation physicians, gastroenterologists, surgeons, radiotherapists, and radiologists with experience in the treatment of myelofibrosis contributed to this Position Paper. The key issues addressed by this group included the assessment, prevalence, and clinical significance of splenomegaly, and the need for a therapeutic intervention before HCT for the control of splenomegaly. Specific scenarios, including splanchnic vein thrombosis and COVID-19, are also discussed. All patients with myelofibrosis must have their spleen size assessed before allogeneic HCT. Myelofibrosis patients with splenomegaly measuring 5 cm and larger, particularly when exceeding 15 cm below the left costal margin, or with splenomegaly-related symptoms, could benefit from treatment with the aim of reducing the spleen size before HCT. In the absence of, or loss of, response, patients with increasing spleen size should be evaluated for second-line options, depending on availability, patient fitness, and centre experience. Splanchnic vein thrombosis is not an absolute contraindication for HCT, but a multidisciplinary approach is warranted. Finally, prevention and treatment of COVID-19 should adhere to standard recommendations for immunocompromised patients.

How We Manage Myelofibrosis Candidates for Allogeneic Stem Cell Transplantation

Moving from indication to transplantation is a critical process in myelofibrosis. Most of guidelines specifically focus on either myelofibrosis disease or transplant procedure, and, currently, no distinct indication for the management of MF candidates to transplant is available. Nevertheless, this period of time is crucial for the transplant outcome because engraftment, non-relapse mortality, and relapse incidence are greatly dependent upon the pre-transplant management. Based on these premises, in this review, we will go through the path of identification of the MF patients suitable for a transplant, by using disease-specific prognostic scores, and the evaluation of eligibility for a transplant, based on performance, comorbidity, and other combined tools. Then, we will focus on the process of donor and conditioning regimens’ choice. The pre-transplant management of splenomegaly and constitutional symptoms, cytopenias, iron overload and transplant timing will be comprehensively discussed. The principal aim of this review is, therefore, to give a practical guidance for managing MF patients who are potential candidates for allo-HCT.

Fine-needle aspiration diagnosis of clonal extramedullary hematopoiesis in a case of myeloproliferative neoplasm

Extramedullary hematopoiesis (EMH)-the proliferation of hematopoietic progenitors outside of the bone marrow (BM) is a well-known phenomenon in myeloproliferative neoplasms (MPN). Abundant literature describes EMH at various body sites in cases of MPN, and some studies showed the presence of cytogenetic changes associated with MPN in the EMH tissues. We present a case of an 80-year-old female, with a history of MPN, presenting with mediastinal adenopathy. The transbronchial fine-needle aspiration (FNA) of the mediastinal lymph node showed EMH with atypical megakaryocytes and del(13q) demonstrated by fluorescence in situ hybridization. The subsequent BM biopsy demonstrated myelofibrosis with atypical megakaryocytes harboring the same cytogenetic abnormality. Our case highlights the capability of FNA cytology for providing accurate morphologic, immunohistochemical, and cytogenetic diagnosis of clonal EMH.

Novel findings of splenic extramedullary hematopoiesis during primary myelofibrosis, post-essential thrombocythemia, and post-polycythemia vera myelofibrosis

BCR-ABL-fusion-negative myeloproliferative neoplasms (MPNs) with myelofibrosis (MF) include primary MF, post-polycythemia vera MF and post-essential thrombocythemia MF. Clonal extramedullary hematopoiesis (EMH) can occur during MPN pathogenesis. Although histopathological bone-marrow (BM) features during clonal EMH have been investigated, those of the spleen have been poorly described. We analyzed splenectomy samples from 28 patients with MF and BM samples from 20 of them. Slides were stained with hematoxylin and eosin, reticulin, and trichrome, with immunohistochemical labeling of glycophorin A, myeloperoxidase, CD61, CD34, and CD117. We also subjected splenectomy and BM samples from six patients and spleen samples from seven patients to next-generation sequencing (NGS). Megakaryocyte-rich spleen nodules (MRSNs), seen in seven of the 28 patients, were significantly associated with megakaryocyte proliferation in the spleen (p = 0.04). We devised a grading system for spleen fibrosis (SF) and found that SF was increased in 20 of 28 patients. Notably, patients with SF were more likely to have MRSNs, suggesting that megakaryocytes might participate in SF, as previously described in BM. Comparisons of spleen and BM NGS findings of six patients' specimens revealed identical mutational status in the two organs for half of the patients. We observed additional mutations in the spleen of two patients. However, the meaning of this finding remains unknown since there was a long interval between BM and spleen samplings (68 and 82 months, respectively).

Impact of spleen size and splenectomy on outcomes of allogeneic hematopoietic cell transplantation for myelofibrosis: A retrospective analysis by the chronic malignancies working party on behalf of European society for blood and marrow transplantation (EBMT)

The role of spleen size and splenectomy for the prediction of post-allogeneic hematopoietic stem cell transplant (allo-HCT) outcome in myelofibrosis remains under debate. In EBMT registry, we identified a cohort of 1195 myelofibrosis patients transplanted between 2000-2017 after either fludarabine-busulfan or fludarabine-melphalan regimens. Overall, splenectomy was performed in 202 (16.9%) patients and its use decreased over time (28.3% in 2000-2009 vs 14.1% in 2010-2017 period). By multivariate analysis, splenectomy was associated with less NRM (HR 0.64, 95% CI 0.44-0.93, P = .018) but increased risk of relapse (HR 1.43, 95% CI 1.01-2.02, P = .042), with no significant impact on OS (HR 0.86, 95% CI 0.67-1.12, P = .274). However, in subset analysis comparing the impact of splenectomy vs specific spleen sizes, for patients with progressive disease, an improved survival was seen in splenectomised subjects compared to those patients with a palpable spleen length ≥ 15 cm (HR 0.44, 95% CI 0.28-0.69, P < .001), caused by a significant reduction in NRM (HR 0.26, 95% CI 0.14-0.49, P < .001), without significantly increased relapse risk (HR 1.47, 95% CI 0.87-2.49, P = .147). Overall, despite the possible biases typical of retrospective cohorts, this study highlights the potential detrimental effect of massive splenomegaly in transplant outcome and supports the role of splenectomy for myelofibrosis patients with progressive disease and large splenomegaly.

Myeloid, mast cell, histiocytic and dendritic cell neoplasms and proliferations involving the spleen

Splenic involvement and consequent splenomegaly are usually seen as part of systemic involvement by myeloid neoplasms as well as mast cell and histiocytic neoplasms. Primary splenic involvement by these neoplasms is rare. Splenectomy is usually not performed for establishing a diagnosis of these entities. However, in rare instances, the pathologist may need to evaluate the spleen secondary to splenic rupture or palliative splenectomy to alleviate symptoms related to splenomegaly. This review article describes the clinicopathologic features of a broad group of myeloid, mastocytic, and histiocytic proliferative and neoplastic disorders.

Advanced forms of MPNs are accompanied by chromosomal abnormalities that lead to dysregulation of TP53

The Philadelphia chromosome-negative myeloproliferative neoplasms (MPNs), including polycythemia vera (PV), essential thrombocythemia (ET), and the prefibrotic form of primary myelofibrosis (PMF), frequently progress to more overt forms of MF and a type of acute leukemia termed MPN-accelerated phase/blast phase (MPN-AP/BP). Recent evidence indicates that dysregulation of the tumor suppressor tumor protein p53 (TP53) commonly occurs in the MPNs. The proteins MDM2 and MDM4 alter the cellular levels of TP53. We investigated in 1,294 patients whether abnormalities involving chromosomes 1 and 12, which harbor the genes for MDM4 and MDM2, respectively, and chromosome 17, where the gene for TP53 is located, are associated with MPN disease progression. Gain of 1q occurred not only in individuals with MPN-BP but also in patients with PV and ET, who, with further follow-up, eventually evolve to either MF and/or MPN-BP. These gains of 1q were most prevalent in patients with a history of PV and those who possessed the JAK2V617F driver mutation. The gains of 1q were accompanied by increased transcript levels of MDM4 In contrast, 12q chromosomal abnormalities were exclusively detected in patients who presented with MF or MPN-BP, but were not accompanied by further increases in MDM2/MDM4 transcript levels. Furthermore, all patients with a loss of 17p13, which leads to a deletion of TP53, had either MF or MPN-AP/BP. These findings suggest that gain of 1q, as well as deletions of 17p, are associated with perturbations of the TP53 pathway, which contribute to MPN disease progression.