Use of Next Generation Sequencing to Define the Origin of Primary Myelofibrosis

Primary myelofibrosis (PMF) is a chronic myeloproliferative neoplasm (MPN) characterized by progressive bone marrow sclerosis, extra-medullary hematopoiesis, and possible transformation to acute leukemia. In the last decade, the molecular pathogenesis of the disease has been largely uncovered. Particularly, genetic and genomic studies have provided evidence of deregulated oncogenes in PMF as well as in other MPNs. However, the mechanisms through which transformation to either the myeloid or lymphoid blastic phase remain obscure. Particularly, it is still debated whether the disease has origins in a multi-potent hematopoietic stem cells or instead in a commissioned myeloid progenitor. In this study, we aimed to shed light upon this issue by using next generation sequencing (NGS) to study both myeloid and lymphoid cells as well as matched non-neoplastic DNA of PMF patients. Whole exome sequencing revealed that most somatic mutations were the same between myeloid and lymphoid cells, such findings being confirmed by Sanger sequencing. Particularly, we found 126/146 SNVs to be the e same (including JAK2V617F), indicating that most genetic events likely to contribute to disease pathogenesis occurred in a non-commissioned precursor. In contrast, only 9/27 InDels were similar, suggesting that this type of lesion contributed instead to disease progression, occurring at more differentiated stages, or maybe just represented “passenger” lesions, not contributing at all to disease pathogenesis. In conclusion, we showed for the first time that genetic lesions characteristic of PMF occur at an early stage of hematopoietic stem cell differentiation, this being in line with the possible transformation of the disease in either myeloid or lymphoid acute leukemia.

Philadelphia-positive acute lymphoblastic leukemia in a case of MPL p.(W515L) variant essential thrombocythemia: case report and literature review

Acute lymphoblastic leukemia (ALL) arising in preexisting myeloproliferative neoplasms (MPN) is rare with historical cases unable to differentiate between concomitant malignancies or leukemic transformation. Here, we report a case of patient with Philadelphia positive B lymphoblastic leukemia (Ph+ALL) who developed from MPL-mutated essential thrombocythemia (ET) 13 years after initial presentation. Molecular studies showed the discrepancy between the high percentage of lymphocyte blasts (91%) and the low MPL p.(W515L) variant allele frequency (2.59%) at diagnosis in the bone marrow, indicating that the Ph+ALL clone did not originate from the ET clone carrying the MPL p.(W515L) variant. After the treatment of a new tyrosine kinase inhibitor flumatinib and prednisolone, cytogenetic and molecular remission had been achieved rapidly and followed by the recovery of original ET manifestation. Although relapsed eventually, this is still a very rare case of simultaneous presence of two cytogenetics abnormalities and evolution of MPL p.(W515L) variant ET to Ph+ALL and may provide evidence to illustrate the clonal relationship of MPN and post-MPN ALL.

Paroxysmal Nocturnal Hemoglobinuria in the Context of a Myeloproliferative Neoplasm: A Case Report and Review of the Literature

Paroxysmal nocturnal hemoglobinuria (PNH) is characterized by intravascular hemolytic anemia and thrombosis and is notoriously associated with aplastic anemia and myelodysplastic syndromes. Rarer associations include myeloproliferative neoplasms (MPNs), which are also burdened by increased thrombotic tendency. The therapeutic management of this rare combination has not been defined so far. Here, we describe a 62-year-old man who developed a highly hemolytic PNH more than 10 years after the diagnosis of MPN. The patient started eculizumab, obtaining good control of intravascular hemolysis but without amelioration of transfusion-dependent anemia. Moreover, we performed a review of the literature regarding the clinical and pathogenetic significance of the association of PNH and MPN. The prevalence of PNH clones in MPN patients is about 10%, mostly in association with JAK2V617F-positive myelofibrosis. Thrombotic events were a common clinical presentation (35% of subjects), sometimes refractory to combined treatment with cytoreductive agents, anticoagulants, and complement inhibitors. The latter showed only partial effectiveness in controlling hemolytic anemia and, due to the paucity of data, should be taken in consideration after a careful risk/benefit evaluation in this peculiar setting.

Clinical and prognostic significance of small paroxysmal nocturnal hemoglobinuria clones in myelodysplastic syndrome and aplastic anemia

In this large single-centre study, we report high prevalence (25%) of, small (<10%) and very small (<1%), paroxysmal nocturnal hemoglobinuria (PNH) clones by high-sensitive cytometry among 3085 patients tested. Given PNH association with bone marrow failures, we analyzed 869 myelodysplastic syndromes (MDS) and 531 aplastic anemia (AA) within the cohort. PNH clones were more frequent and larger in AA vs. MDS (p = 0.04). PNH clone, irrespective of size, was a good predictor of response to immunosuppressive therapy (IST) and to stem cell transplant (HSCT) (in MDS: 84% if PNH+ vs. 44.7% if PNH-, p = 0.01 for IST, and 71% if PNH+ vs. 56.6% if PNH- for HSCT; in AA: 78 vs. 50% for IST, p < 0.0001, and 97 vs. 77%, p = 0.01 for HSCT). PNH positivity had a favorable impact on disease progression (0.6% vs. 4.9% IPSS-progression in MDS, p < 0.005; and 2.1 vs. 6.9% progression to MDS in AA, p = 0.01), leukemic evolution (6.8 vs. 12.7%, p = 0.01 in MDS), and overall survival [73% (95% CI 68-77) vs. 51% (48-54), p < 0.0001], with a relative HR for mortality of 2.37 (95% CI 1.8-3.1; p < 0.0001) in PNH negative cases, both in univariate and multivariable analysis. Our data suggest systematic PNH testing in AA/MDS, as it might allow better prediction/prognostication and consequent clinical/laboratory follow-up timing.

Coexistence of Primary Myelofibrosis and Paroxysmal Nocturnal Hemoglobinuria Clone with JAK2 V617F, U2AF1 and SETBP1 Mutations: A Case Report and Brief Review of Literature

Primary myelofibrosis (PMF) and paroxysmal nocturnal hemoglobinuria (PNH) are very rare diseases, respectively, and it is uncommon to have both diseases together. Mutational profiling using next-generation sequencing in PMF and PNH detected additional mutations associated with myeloid neoplasms, suggesting a step-wise clonal evolution. We present here a very rare case with PMF and PNH with JAK2 V617F, U2AF1 and SETBP1 mutations at the time of diagnosis. The combination of these two diseases and three genetic mutations is difficult to interpret at once. (i.e., the sequence of these two clonal diseases or the time points of acquiring these mutations). Our report suggests that when diagnosing or treating patients with PMF, it is necessary to keep in mind that PNH may be present at the same time or sometimes new. The genetic mutations simultaneously found in this patient require further research to elucidate the clinical significance and their genetic associations fully.

Acute lymphoblastic leukemia secondary to myeloproliferative neoplasms or after lenalidomide exposure

Philadelphia‐negative (Ph⁻) myeloproliferative neoplasms (MPN) do rarely transform to acute lymphoblastic leukemia (ALL). While causality is difficult to establish, a few cases of ALL arising after exposure to lenalidomide for registered indications (multiple myeloma, myelodysplastic syndrome with 5q deletion) have been described in the literature.

Acute Lymphoblastic Leukemia Arising in CALR Mutated Essential Thrombocythemia

The development of acute lymphoblastic leukemia in an existing myeloproliferative neoplasm is rare with historical cases unable to differentiate between concomitant malignancies or leukemic transformation. Molecular studies of coexisting JAK2 V617F-positive myeloproliferative neoplasms and mature B cell malignancies indicate distinct disease entities arising in myeloid and lymphoid committed hematopoietic progenitor cells, respectively. Mutations of CALR in essential thrombocythemia appear to be associated with a distinct phenotype and a lower risk of thrombosis yet their impact on disease progression is less well defined. The as yet undescribed scenario of pro-B cell acute lymphoblastic leukemia arising in CALR mutated essential thrombocythemia is presented. Intensive treatment for the leukemia allowed for expansion of the original CALR mutated clone. Whether CALR mutations in myeloproliferative neoplasms predispose to the acquisition of additional malignancies, particularly lymphoproliferative disorders, is not yet known.

Acute Myeloid Leukemia Evolving from JAK 2-Positive Primary Myelofibrosis and Concomitant CD5-Negative Mantle Cell Lymphoma: A Case Report and Review of the Literature

Primary myelofibrosis (formerly known as chronic idiopathic myelofibrosis), has the lowest incidence amongst the chronic myeloproliferative neoplasms and is characterized by a rather short median survival and a risk of progression to acute myeloid leukemia (AML) noted in a small subset of the cases, usually as a terminal event. As observed with other chronic myeloproliferative neoplasms, the bone marrow biopsy may harbor small lymphoid aggregates, often assumed reactive in nature. In our paper, we present a 70-year-old Caucasian male who was diagnosed with primary myelofibrosis, and after 8 years of followup and therapy developed an AML. The small lymphoid aggregates noted in his bone marrow were neoplastic in nature and represented bone marrow involvement by a CD5-negative mantle cell lymphoma (MCL) that presented without any associated lymphadenopathy. We reviewed the English medical literature to identify a single case report of simultaneous association of AML and a MCL in the bone marrow. The unusual association presented here suggests an increase in observer awareness to apparently benign lymphoid aggregates in chronic myeloproliferative neoplasms.