[Bone marrow fibrosis in primary myelofibrosis in relation to myelodysplasia- and age-related mutations of hematopoietic cells]. / Knochenmarkfibrose bei primärer Myelofibrose in Abhängigkeit von myelodysplasie- und altersassoziierten Mutationen der Hämatopoese.

Besides histopathological findings, there are no indicators of increased risk for fibrotic progression in myeloproliferative neoplasms (MPNs). Age-related clonal hematopoiesis (ARCH) or clonal hematopoiesis of indetermined potential (CHIP) are frequent findings in the elderly and combinations with MPN driver mutations (JAK2, MPL, and CALR) have been described. To determine the impact of ARCH/CHIP-related mutations for the development of fibrosis in primary myelofibrosis (PMF), the mutational status of cases with fibrotic progression from grade 0 to grade 2/3 (n = 77) as evidenced by follow-up bone marrow biopsies (median 6.2 years) was compared to prefibrotic PMF samples without the development of fibrosis (n = 27; median follow-up 7.3 years). Frequent ARCH/CHIP-associated mutations (TET2, ASXL1, DNMT3A) demonstrable at presentation were not connected with fibrotic progression. However, mutations that are rarely found in ARCH/CHIP (SRSF2, U2AF1, SF3B1, IDH1/2, and EZH2) were present in 24.7% of cases with later development of fibrosis and not detectable in cases staying free from fibrosis (P = 0.0028). Determination of tumor mutational burden (TMB) in a subgroup of cases (n = 32) did not show significant differences (7.68 mutations/MB vs. 6.85 mutations/MB). We conclude that mutations rarely found in ARCH/CHIP provide an independent risk factor for rapid fibrotic progression (median 2.0 years) when already manifest at first presentation.

Long-term outcome of patients with newly diagnosed chronic myeloid leukemia: a randomized comparison of stem cell transplantation with drug treatment.

Tyrosine kinase inhibitors represent today's treatment of choice in chronic myeloid leukemia (CML). Allogeneic hematopoietic stem cell transplantation (HSCT) is regarded as salvage therapy. This prospective randomized CML-study IIIA recruited 669 patients with newly diagnosed CML between July 1997 and January 2004 from 143 centers. Of these, 427 patients were considered eligible for HSCT and were randomized by availability of a matched family donor between primary HSCT (group A; N=166 patients) and best available drug treatment (group B; N=261). Primary end point was long-term survival. Survival probabilities were not different between groups A and B (10-year survival: 0.76 (95% confidence interval (CI): 0.69-0.82) vs 0.69 (95% CI: 0.61-0.76)), but influenced by disease and transplant risk. Patients with a low transplant risk showed superior survival compared with patients with high- (P<0.001) and non-high-risk disease (P=0.047) in group B; after entering blast crisis, survival was not different with or without HSCT. Significantly more patients in group A were in molecular remission (56% vs 39%; P=0.005) and free of drug treatment (56% vs 6%; P<0.001). Differences in symptoms and Karnofsky score were not significant. In the era of tyrosine kinase inhibitors, HSCT remains a valid option when both disease and transplant risk are considered.

Selection for Evi1 activation in myelomonocytic leukemia induced by hyperactive signaling through wild-type NRas.

Activation of NRas signaling is frequently found in human myeloid leukemia and can be induced by activating mutations as well as by mutations in receptors or signaling molecules upstream of NRas. To study NRas-induced leukemogenesis, we retrovirally overexpressed wild-type NRas in a murine bone marrow transplantation (BMT) model in C57BL/6J mice. Overexpression of wild-type NRas caused myelomonocytic leukemias ∼3 months after BMT in the majority of mice. A subset of mice (30%) developed malignant histiocytosis similar to mice that received mutationally activated NRas(G12D)-expressing bone marrow. Aberrant Ras signaling was demonstrated in cells expressing mutationally active or wild-type NRas, as increased activation of Erk and Akt was observed in both models. However, more NRas(G12D) were found to be in the activated, GTP-bound state in comparison with wild-type NRas. Consistent with observations reported for primary human myelomonocytic leukemia cells, Stat5 activation was also detected in murine leukemic cells. Furthermore, clonal evolution was detected in NRas wild-type-induced leukemias, including expansion of clones containing activating vector insertions in known oncogenes, such as Evi1 and Prdm16. In vitro cooperation of NRas and Evi1 improved long-term expansion of primary murine bone marrow cells. Evi1-positive cells upregulated Bcl-2 and may, therefore, provide anti-apoptotic signals that collaborate with the NRas-induced proliferative effects. As activation of Evi1 has been shown to coincide with NRAS mutations in human acute myeloid leukemia, our murine model recapitulates crucial events in human leukemogenesis.

[Myeloproliferative neoplasms: histopathological and molecular pathological diagnosis]. / Myeloproliferative Neoplasien: Histopathologische und molekularpathologische Diagnostik.

Myeloproliferative neoplasms (chronic myeloproliferative disorders according to former nomenclature) comprise chronic myeloid leukemia, polycythemia vera, essential thrombocythemia, primary myelofibrosis, chronic eosinophilic leukemia, chronic neutrophilic leukemia and systemic mastocytosis. All disorders have excessive proliferation of one or more hematopoietic lineages in common and progress with different probability to blast crisis or fibrosis. A further common feature is provided by the activating mutation of tyrosin kinases and associated pathways of signal transduction (BCR-ABL, JAK2(V617F), MPL(W515L/K), KIT(D816V) and FIP1L1-PDGFRA) causative for the abnormal proliferation. With regard to diagnosis and therapy these mutations are of utmost importance because they enable the exclusion of reactive processes, contribute with varying specificity to subtyping of MPN and are at least partly sensitive to targeted therapy. The molecular mechanisms of blastic and fibrotic progression are not yet understood.

Lentiviral vectors for induction of self-differentiation and conditional ablation of dendritic cells.

Development of lentiviral vectors (LVs) in the field of immunotherapy and immune regeneration will strongly rely on biosafety of the gene transfer. We demonstrated previously the feasibility of ex vivo genetic programming of mouse bone marrow precursors with LVs encoding granulocyte macrophage colony-stimulating factor (GM-CSF) and interleukin-4 (IL-4), which induced autonomous differentiation of long-lived dendritic cells (DCs), referred to as self-differentiated myeloid-derived antigen-presenting-cells reactive against tumors (SMART-DCs). Here, LV biosafety was enhanced by using a DC-restricted and physiological promoter, the major histocompatibility complex (MHC) II promoter, and including co-expression of the herpes simplex virus-thymidine kinase (sr39HSV-TK) conditional suicide gene. Tricistronic vectors co-expressing sr39HSV-TK, GM-CSF and IL-4 transcriptionally regulated by the MHCII promoter or the ubiquitous cytomegalovirus (CMV) promoter were compared. Despite the different gene transfer effects, such as the kinetics, levels of transgene expression and persistency of integrated vector copies, both vectors induced highly viable SMART-DCs, which persisted for at least 70 days in vivo and could be ablated with the pro-drug Ganciclovir (GCV). SMART-DCs co-expressing the tyrosine-related protein 2 melanoma antigen administered subcutaneously generated antigen-specific, anti-melanoma protective and therapeutic responses in the mouse B16 melanoma model. GCV administration after immunotherapy did not abrogate DC vaccination efficacy. This demonstrates proof-of-principle of genetically programmed DCs that can be ablated pharmacologically.

Chronic idiopathic myelofibrosis: prognostic impact of myelofibrosis and clinical parameters on event-free survival in 122 patients who presented in prefibrotic and fibrotic stages. A retrospective study identifying subgroups of different prognoses by using the RECPAM method.

In chronic idiopathic myelofibrosis (CIMF) the factors predicting survival in patients who were already in the fibrotic stage have been well documented by numerous studies. Prefibrotic stages were only rarely evaluated so that the prognostic impact of myelofibrosis is currently not well known. Also predictive factors for disease-related events were not included in those studies. Thus, we evaluated the prognostic impact of myelofibrosis and other histopathological (megakaryocytes, blasts) and clinical [age, gender, splenomegaly, chemotherapy, hemoglobin (Hb), leukocyte, and platelet count] parameters in 122 patients in fibrotic and prefibrotic stages of CIMF on event-free survival. The statistical analysis was performed using the univariate log-rank test and the multivariate recursive partition and amalgamation (RECPAM) approach. In 62 patients disease-related events occurred during a mean observation period of 58 months. In univariate analysis they were associated with blast increase in the bone marrow. In RECPAM analysis a shorter event-free survival was found in anemic patients (mean: 9.3 months). In nonanemic patients older than 60 years, advanced myelofibrosis was associated with a shorter event-free mean survival of 23.2 months versus 69.3 months in less advanced cases. A slight or moderate myelofibrosis was not found to have a prognostic impact on event-free survival. The longest event-free survival was found in nonanemic patients who were younger than 60 years (mean: 185 months), regardless of the grade of myelofibrosis. Thus, we found that the most relevant prognostic parameter for event-free survival in CIMF were the Hb value, age, and grade of myelofibrosis.

[Incidence and differential diagnosis of chronic eosinophilic leukemia]. / Häufigkeit und Differenzialdiagnose der chronischen Eosinophilenleukämie.

The diagnosis of chronic eosinophilic leukemia (CEL) is based on the evidence of an autonomous, clonal proliferation of eosinophilic precursors and the exclusion of other myeloid neoplasms with eosinophilia. Histopathological evaluations of bone marrow are rare, and reliable data on the frequency of CEL do not yet exist. A total of 100 cases characterized by eosinophilia >/=1.5x10(9)/l blood for more than 6 months were evaluated. In 87 cases, the eosinophilia turned out to be secondary and a reactive genesis was likely, but not proven in 3 further cases. Idiopathic hypereosinophilic syndrome was diagnosed in three cases. The diagnosis CEL was considered in four out of a total of seven cases with a myeloid neoplasia and all four disorders showed an abnormal karyotype. However, only one of them could be classified as CEL. We conclude that CEL is a rare disease concerning only a minority of cases with chronic eosinophilia.

[The development of myelofibrosis in prefibrotic cIMF. An investigation of the progression by sequential bone marrow biopsies in 38 patients]. / Die Entwicklung der Myelofibrose bei der "präfibrotischen"cIMF. Eine Verlaufsuntersuchung durch Sequenzbiopsien des Knochenmarkes bei 38 Patienten.

Overt myelofibrosis in bone marrow biopsies as a diagnostic postulate in cIMF has been discarded only recently by the WHO. Therefore, only a few studies have been performed on the evolution of myelofibrosis in "prefibrotic" cIMF by means of sequential bone marrow biopsies. We carried out this study on 38 patients, split up into two groups, A and B according to treatment modalities, to evaluate the dynamics and frequency of myelofibrosis in both groups. Our results indicate a step-wise development of myelofibrosis from a "prefibrotic" to a "classical" cIMF, as 75-80% of the respective patients in both groups progressed to myelofibrosis. However, this evolution seems to be heterogeneous and unpredictable in individual patients, since myelofibrosis could be seen as early as less than 2 years after diagnosis in 12/38 (31.6%) patients, whereas 3 patients remained "prefibrotic" even after up to 6 years of follow-up.

Complete haematological and cytogenetic response to interferon alpha-2a of a myeloproliferative disorder with eosinophilia associated with a unique t(4;7) aberration.

A female patient with eosinophilia and cardiac symptoms was found to have a unique chromosomal aberration [t(4;7)(q11;p13)] of bone-marrow precursors. The disorder was classified as a chronic myeloproliferative syndrome with eosinophilia. Due to a significant increase in the white blood cell and eosinophil count during initial treatment with prednisone and hydroxyurea, Interferon alpha-2a was administered at a dose of 3-5 x 10(6) I.U. s.c., five times per week, and induced a long-term complete haematological and cytogenetic response. The clinical features of this case are presented and discussed in the context of the current literature.