Splenectomy in chronic myeloid leukemia and myelofibrosis with myeloid metaplasia

Case report: Primary myelofibrosis presenting with portal hypertension mimicking cirrhosis

Primary myelofibrosis (PMF) is an infrequent etiology of noncirrhotic portal hypertension (PH). In clinical settings, non-cirrhotic PH is often misdiagnosed as cirrhotic PH. This case report details a patient who exhibited recurrent esophageal variceal hemorrhage and was initially misdiagnosed with cirrhosis. Initially poised for liver transplantation, the patient's liver biopsy revealed no significant cirrhosis but showed signs of extramedullary hematopoiesis (EMH). Following the accurate diagnosis of PMF, the patient underwent standard treatment, leading to an absence of recurrent gastrointestinal hemorrhage due to esophageal varices for nearly three years.

Splenic red pulp macrophages provide a niche for CML stem cells and induce therapy resistance

Disease progression and relapse of chronic myeloid leukemia (CML) are caused by therapy resistant leukemia stem cells (LSCs), and cure relies on their eradication. The microenvironment in the bone marrow (BM) is known to contribute to LSC maintenance and resistance. Although leukemic infiltration of the spleen is a hallmark of CML, it is unknown whether spleen cells form a niche that maintains LSCs. Here, we demonstrate that LSCs preferentially accumulate in the spleen and contribute to disease progression. Spleen LSCs were located in the red pulp close to red pulp macrophages (RPM) in CML patients and in a murine CML model. Pharmacologic and genetic depletion of RPM reduced LSCs and decreased their cell cycling activity in the spleen. Gene expression analysis revealed enriched stemness and decreased myeloid lineage differentiation in spleen leukemic stem and progenitor cells (LSPCs). These results demonstrate that splenic RPM form a niche that maintains CML LSCs in a quiescent state, resulting in disease progression and resistance to therapy.

The growth of K562 human leukemia cells was inhibited by therapeutic neural stem cells in cellular and xenograft mouse models

To confirm the anti-tumor effect of engineered neural stem cells (NSCs) expressing cytosine deaminase (CD) and interferon-β (IFN-β) with prodrug 5-fluorocytosine (FC), K562 chronic myeloid leukemia (CML) cells were co-cultured with the neural stem cell lines HB1.F3.CD and HB1.F3.CD.IFN-β in 5-FC containing media. A significant decrease in the viability of K562 cells was observed by the treatment of the NSC lines, HB1.F3.CD and HB1.F3.CD.IFN-β, compared with the control. A modified trans-well assay showed that engineered human NSCs significantly migrated toward K562 CML cells more than human normal lung cells. In addition, the important chemoattractant factors involved in the specific migration ability of stem cells were found to be expressed in K562 CML cells. In a xenograft mouse model, NSC treatments via subcutaneous and intravenous injections resulted in significant inhibitions of tumor mass growth and extended survival dates of the mice. Taken together, these results suggest that gene therapy using genetically engineered stem cells expressing CD and IFN-β may be effective for treating CML in these mouse models.

Indications and outcome of splenectomy in hematologic disease

Splenectomy is part of the therapeutic arsenal for benign or malignant hematological disorders that constitute the main indication for elective splenectomy. With the development of minimally invasive approaches, and in particular, laparoscopy, as well as the advent of monoclonal antibody therapy, the indications and the outcomes of splenectomy for hematologic disease have changed in recent years. Nonetheless, splenectomy has its place in hemoglobinopathies and hemolytic diseases, improves thrombocytopenia in refractory immune thrombocytopenic purpura, can reverse sequelae linked to voluminous splenomegaly secondary to myelofibrosis, or can be used for diagnostic purposes or for splenomegaly in lymphoproliferative syndromes.

The spleen microenvironment influences disease transformation in a mouse model of KITD816V-dependent myeloproliferative neoplasm

Activating mutations leading to ligand-independent signaling of the stem cell factor receptor KIT are associated with several hematopoietic malignancies. One of the most common alterations is the D816V mutation. In this study, we characterized mice, which conditionally express the humanized KIT^D816V receptor in the adult hematopoietic system to determine the pathological consequences of unrestrained KIT signaling during blood cell development. We found that KIT^D816V mutant animals acquired a myeloproliferative neoplasm similar to polycythemia vera, marked by a massive increase in red blood cells and severe splenomegaly caused by excessive extramedullary erythropoiesis. Moreover, we found mobilization of stem cells from bone marrow to the spleen. Splenectomy prior to KIT^D816V induction prevented expansion of red blood cells, but rapidly lead to a state of aplastic anemia and bone marrow fibrosis, reminiscent of post polycythemic myeloid metaplasia, the spent phase of polycythemia vera. Our results show that the extramedullary hematopoietic niche microenvironment significantly influences disease outcome in KIT^D816V mutant mice, turning this model a valuable tool for studying the interplay between functionally abnormal hematopoietic cells and their microenvironment during development of polycythemia vera-like disease and myelofibrosis.

Mayor erythropoietic response after deferasirox treatment in a transfusion-dependent anemic patient with primary myelofibrosis

Primary myelofibrosis (PMF) is a myeloproliferative neoplasm frequently complicated by transfusion dependent anemia. Both anemia and transfusion-dependence are associated with a poor outcome, at least in part because of toxic effects of iron overload (IOL). Iron-chelating therapy (ICT) is increasingly used in order to prevent IOL in this setting. Here, we describe the case of a 73-year-old man affected by PMF and severe transfusion-dependent anemia who experienced a dramatic erythroid response after being treated with deferasirox to prevent IOL.

Splenectomy in patients with myeloproliferative neoplasms: efficacy, complications and impact on survival and transformation

Splenectomy may be an effective therapeutic option for treating massive splenomegaly in patients with myeloproliferative neoplasms (MPNs). There are still limited data on its short- and long-term benefits and risks. Efficacy and short-term complications were analyzed in 94 patients with different MPNs who underwent splenectomy at M. D. Anderson Cancer Center. The long-term impact of splenectomy on overall survival (OS) and transformation free survival (TFS) was evaluated in 461 patients with myelofibrosis (MF) seen at M. D. Anderson, including 50 who underwent splenectomy during disease evolution. Splenectomy improved anemia and thrombocytopenia in 47% and 66% of patients, respectively. The most common complications were leukocytosis (76%), thrombocytosis (43%) and venous thromboembolism (16%). Post-operative mortality was 5%. Among patients with MF, splenectomy during disease evolution was associated with decreased OS (hazard ratio [HR] = 2.17, p < 0.0001) and TFS (HR = 2.17, p < 0.0001). This effect was independent of the Dynamic International Prognostic Scoring System. Splenectomy is a possible therapeutic option for patients with MF and other MPNs, and its greatest benefits are related to improvement in spleen pain and discomfort, anemia and thrombocytopenia. However, in patients with MF it appears to be associated with increased mortality.

Pregnancy in a woman with chronic neutrophilic leukemia

BACKGROUND

Chronic neutrophilic leukemia is a rare myeloproliferative disorder in women of reproductive age.

CASE

A pregnant woman with an established diagnosis of chronic neutrophilic leukemia presented at 26 weeks of gestation with splenomegaly, thrombocytopenia, leukocytosis, and anemia. Thrombocytopenia was refractory to medical treatment and, in part, was attributed to splenic sequestration. She delivered a healthy neonate at 35 weeks of gestation by repeat cesarean delivery under general anesthesia. Her preoperative platelet count was 30,000/mL and she was transfused platelets throughout the perioperative period. Her postpartum course was complicated by intraabdominal hemorrhage and severe preeclampsia. She recovered with intensive medical and surgical management.

CONCLUSION

Chronic neutrophilic leukemia poses difficult challenges during pregnancy and requires a multidisciplinary approach.

Splenectomy and partial splenectomy improve hematopoietic stem cell engraftment in hypersplenic mice

BACKGROUND

Hematopoietic stem cell (HSC) engraftment is delayed after transplantation in children with hypersplenism, increasing the morbidity and costs of care. Preliminary clinical data suggest that splenectomy before HSC transplantation may improve HSC engraftment, although this observation has not been tested in an animal model.

METHODS

We performed total splenectomy (n = 22), partial splenectomy (n = 16), or sham laparotomy (n = 21) on erythrocyte protein 4.2 knockout mice, a murine model of hereditary spherocytosis with hypersplenism. After 10 days, we lethally irradiated the mice, transplanted 3 x 10(6) allogeneic bone marrow cells, and then assessed engraftment using serial complete blood counts. Successful engraftment was defined as recovery of hemoglobin, neutrophil, or platelet counts. We compared engraftment rate using chi(2) test and time to engraftment using Student's t test analysis, with significance defined as P < .05.

RESULTS

Total splenectomy increased the rate of successful HSC engraftment and decreased the interval to HSC engraftment compared with controls. Similarly, partial splenectomy decreased the interval to HSC engraftment, with a nonsignificant trend toward improved overall rate of successful HSC engraftment.

CONCLUSION

Partial or total splenectomy before HSC transplantation improves HSC engraftment in hypersplenic mice. This model supports consideration of splenic resection in hypersplenic children requiring HSC transplantation.

Splenectomy normalizes hematocrit in murine polycythemia vera

Splenic enlargement (splenomegaly) develops in numerous disease states, although a specific pathogenic role for the spleen has rarely been described. In polycythemia vera (PV), an activating mutation in Janus kinase 2 (JAK2^V617) induces splenomegaly and an increase in hematocrit. Splenectomy is sparingly performed in patients with PV, however, due to surgical complications. Thus, the role of the spleen in the pathogenesis of human PV remains unknown. We specifically tested the role of the spleen in the pathogenesis of PV by performing either sham (SH) or splenectomy (SPL) surgeries in a murine model of JAK2^V617F-driven PV. Compared to SH-operated mice, which rapidly develop high hematocrits after JAK2^V617F transplantation, SPL mice completely fail to develop this phenotype. Disease burden (JAK2^V617) is equivalent in the bone marrow of SH and SPL mice, however, and both groups develop fibrosis and osteosclerosis. If SPL is performed after PV is established, hematocrit rapidly declines to normal even though myelofibrosis and osteosclerosis again develop independently in the bone marrow. In contrast, SPL only blunts hematocrit elevation in secondary, erythropoietin-induced polycythemia. We conclude that the spleen is required for an elevated hematocrit in murine, JAK2^V617F-driven PV, and propose that this phenotype of PV may require a specific interaction between mutant cells and the spleen.

Spleen surgery in pediatric age: seven-year unicentric experience

BACKGROUND

Either "open" and laparoscopic spleen surgery in pediatric age are well known and performed with ease in children. Yet, few data regarding follow-up and outcome are discussed in the international literature.

MATERIALS AND METHODS

Clinical notes of all patient who underwent spleen surgery in a single center between 2000 and 2007 were reviewed and a specific follow-up questionnaire was administered, aiming to evaluate pre- and postoperative data, especially considering underlying disease, cosmetic results, and quality of life after surgery.

RESULTS

Fifty-one patients underwent spleen surgery in our series, 33 of whom returned a complete follow-up questionnaire and were included in the study. Splenectomy was performed in 26 patients, whereas 7 patients underwent a partial splenectomy; 19 cases (57.6%) were approached laparoscopically. A total of 4 complications (12%) occurred in our series, none of them being intraoperative. Hospital stay resulted as significantly shorter in laparoscopic cases (5.5 +/- 2.9 vs. 8.7 +/- 4.8 days; P < 0.01), with better results in terms of cosmetics. Quality of life is strictly related to underlying disease, as well as long-term survival.

CONCLUSIONS

Whatever surgical approach is adopted, spleen surgery is safe, effective, and reproducible. When feasible, the laparoscopic approach should be preferred to the traditional open approach, as far as efficacy and safety are similar, in order to reduce hospital stay, abdominal wall traumatism, and consequently, improve postoperative pain control and cosmetic results.

Enrichment of Sca1+ hematopoietic progenitors in polycythemic mice inhibits leukemogenesis

Polycythemia vera (PV) is a myeloproliferative disorder characterized by a pronounced increase in the number of erythroid cells. However, despite this aberrant proliferation, the incidence of erythroleukemia is paradoxically rare in PV patients. In this study, we show that the progression of Friend virus-induced erythroleukemia is delayed in a mouse model of primary familial congenital polycythemia in which the wild-type Epo-receptor (EpoR) gene is replaced with a truncated human EPOR gene. Herein, we show that these mice exhibit enrichment of Sca1(+)/cKit(-) progenitors and several mature immune cells, such as dendritic cells and macrophages. In cotransplantation experiments, Sca1(+)/cKit(-) progenitors inhibit the tumorigenicity of Sca1(-)/cKit(+) erythroleukemic cells. A cell line established from Sca1(+)/cKit(-) progenitors is also capable of inhibiting leukemic proliferation in culture and in mice. This phenomenon of leukemic inhibition, also detected in the serum of PV patients, is partially attributed to increased nitric oxide secretion. In addition, the administration of erythropoietin into leukemic mice induces a polycythemia-like state associated with the expansion of Sca1(+)/cKit(-) progenitors and derivative immune cells, thereby inhibiting leukemia progression. This study indicates that a combination therapy incorporating the enrichment of Sca1(+)/cKit(-) progenitors may serve as a novel approach for the treatment of leukemia.

Angiogenesis and Anti-angiogenic Therapy in Myelofibrosis with Myeloid Metaplasia

Myelofibrosis with myeloid metaplasia (MMM) is a clonal stem cell disorder that is characterized by florid bone marrow stromal reaction including collagen fibrosis, osteosclerosis, and angiogenesis. Almost all patients with MMM display increased bone marrow microvessel density (MVD) and the extent is among the highest in hematological malignancies. This particular information has encouraged the therapeutic use of anti-angiogenic drugs in MMM. In the current review, we summarize the general concepts regarding angiogenesis, assessment of angiogenesis in hematological malignancies and then the current literature on angiogenesis and anti-angiogenic therapy in MMM.

Partial splenectomy before a hematopoietic stem cell transplantation in children

Hematopoietic stem cell (HSC) engraftment is delayed in children with hypersplenism, and splenectomy may improve HSC engraftment. However, the use of total splenectomy in children is limited because of concerns for postsplenectomy sepsis. In this study, the authors sought to assess the role of partial splenectomy for children with hypersplenism undergoing HSC transplantation.

METHODS

Five children with a variety of conditions and associated hypersplenism underwent partial splenectomy before an HSC transplantation at the authors' institution between 2000 and 2003. Primary outcome measures were rates of neutrophil and platelet engraftment. Secondary outcome measures included perioperative complications, splenic regrowth, graft-versus-host disease, and infection rate. All outcomes were compared with recipients of an HSC transplant from both age-matched nonsplenectomized children (n = 497) and hypersplenic children who underwent total splenectomy (n = 10). Outcomes were compared using Wilcoxon's rank sum test.

RESULTS

The rate of both neutrophil and platelet engraftment was faster in children who underwent either partial or total splenectomy as compared with nonsplenectomized children (mean rates of neutrophil engraftment were 26, 19, and 19 days for the nonsplenectomy, total splenectomy, and partial splenectomy groups, respectively; mean rates of platelet engraftment were 97, 37, and 45 days for the nonsplenectomy, total splenectomy, and partial splenectomy groups, respectively). Graft-versus-host disease rates were similar between the 3 groups. The mean percentage of splenic regrowth after partial splenectomy was 39%. There were no perioperative complications.

CONCLUSIONS

Partial splenectomy may be safely performed before HSC transplantation and, similar to total splenectomy, may improve the rate of HSC engraftment. Although this series has a limited number of patients, the use of partial splenectomy appears to be safe and may allow for splenic salvage to minimize the risk of postsplenectomy sepsis.

Platelet kinetics and decreased transfusion requirements after splenectomy for hematologic malignancy

OBJECTIVE

Thrombocytopenia is a significant and morbid problem in patients with hematologic malignancy, resulting in frequent platelet transfusions and significant resource consumption. We undertook this study to determine the impact of splenectomy on transfusion requirements in patients with chronic leukemia, acute leukemia, myelodysplastic syndrome, and lymphoma.

METHODS

Records of 134 patients with hematologic malignancies who underwent splenectomy were reviewed. Results are reported as mean +/- standard error of the mean.

RESULTS

Mean preoperative (preop) platelet count was 97 +/- 8 K/microL. A significant rise in platelets, compared with preop, was observed starting on postsplenectomy day 1 (141 +/- 8 K/microL, P < 0.001 versus preop) and persisted through day 7. Counts remained significantly elevated at 3 and 6 months and years 1-5. In profoundly thrombocytopenic patients (preop levels < 20 K/microL), preop count was 11 +/- 1 K/microL. A significant postsplenectomy platelet rise persisted for at least 1 year (137 +/- 52 K/microL, P < 0.05 versus preop). An increased platelet level was observed in all hematologic subgroups; in the chronic leukemias (n = 58, P < 0.01) and in lymphoma (n = 59, P < 0.001), this reached significance. Mean platelet transfusions were significantly decreased from preop (3 months preop: 8.6 +/- 2 units) compared with postsplenectomy (3 months postsplenectomy: 5.0 +/- 1 unit, P = 0.03). This decrease was even more pronounced in profoundly thrombocytopenic patients (31.6 +/- 10.6 units preop versus 8.9 +/- 4.8 units postoperative, P = 0.01).

CONCLUSIONS

In the hematologic malignancies, splenectomy produces a significant and longlasting restoration of platelet levels and a resultant decrease in platelet transfusion requirements. These beneficial effects of splenectomy hold true even for the most profoundly thrombocytopenic patients.

[Therapy-related changes of angiogenesis in Philadelphia chromosome positive chronic myelogenous leukemia]

To elucidate the effect of first-line treatment with interferon (IFN), hydroxyurea (HU) and the tyrosine kinase inhibitor imatinib (STI571) on angiogenesis, we studied bone marrow (BM) biopsies in 104 patients with chronic myelogenous leukemia (CML) and 138 patients before and after allogeneic BM transplantation (BMT). After immunostaining (CD34) and morphometric analysis in comparison with a control group, CML specimens showed an increased vascularity and conspicuous morphological abnormalities of microvessels. A close relationship between microvessels and fiber density was detectable in initial biopsies and also in repeatedly performed examinations following therapy. Monotherapy by imatinib and HU generated a significant reduction of microvessels and reticulin fibers in contrast to changes after IFN administration or combination regimens of IFN and HU. A persistence of numerical and structural anomalies of vasculature was observable even several months after BMT. These anomalies shed some light on disturbances of the stroma compartment after myeloablative therapy. The relationship between BM vascularity and fibers is probably dependent on concomitant changes of megakaryopoiesis as the source of various mediators involved in the development of myelofibrosis and neo-angiogenesis acting within a complex functional network.

Stem cell transplantation for myelofibrosis: a report from two Canadian centers

We describe the course of 25 patients with myelofibrosis (MF) due to agnogenic myeloid metaplasia (n=19) or essential thrombocytosis (n=6) who underwent allogeneic stem cell transplantation (SCT) at one of two Canadian centers. The median age at transplantation was 48.7 (IQR 45.9-50.4) years and transplantation was carried out at a median of 10.7 (IQR 5.67-26.5) months after diagnosis. Granulocyte engraftment (absolute neutrophil count >0.5 x 109/l) occurred at a median of 20 days after transplantation for splenectomized patients, compared with 27.5 days for nonsplenectomized individuals (P=0.03). Increased risk of grade II-IV acute graft-versus-host disease (P=0.04) was noted in patients transplanted after splenectomy. Patients with MF received 0.264+/-0.189 U of packed red blood cells per day over the first 180 days after transplantation, and remained dependent on red blood cell transfusions for a median of 123 (IQR 48-205) days. Complete remission of MF was documented in 33% of evaluable patients. The 1 year cumulative nonrelapse mortality was 48.3%. Median survival for this group of patients was 393 (IQR 109-1014+) days, with a projected 2-year overall survival of 41%. We conclude that allogeneic SCT offers a reasonable chance for prolonged survival in patients with advanced MF, but this occurs at the cost of considerable toxicity and nonrelapse mortality.

Substance p-fibronectin-cytokine interactions in myeloproliferative disorders with bone marrow fibrosis

Bone marrow (BM) fibrosis could occur secondarily to several clinical disorders: hematological and nonhematological. Clinical presentation of fibrosis could occur in myeloproliferative diseases, lymphoma, myelodysplastic syndrome and myeloma. The pathophysiology underlying BM fibrosis remains unclear despite intensive study, with a corresponding lack of specific therapy. This review discusses new insights in the role of substance P, cytokines and fibronectin in the development of BM fibrosis. Substance P is a neuropeptide that possesses pleiotropic properties, e.g. neurotransmission and immune/hematopoietic modulation and is linked to BM fibrosis. Cytokines and growth factors, in particular those associated with fibrogenic properties, e.g. TGF-beta, IL-1 and platelet-derived growth factor, are linked to BM fibrosis. Extracellular matrix proteins are increased in patients with BM fibrosis. Fibronectin in the sera of patients with BM fibrosis is complexed to substance P. Fibronectin appears to protect substance P from degradation by endogenous peptidases. This review describes the preliminary findings on the colocalization of substance P and fibronectin in the BM of patients with fibrosis. These data are reviewed in the context of published reports with particular focus on the relevant cytokines. A more detailed understanding of intra- and intercellular mechanisms in BM fibrosis may lead to effective therapy.

The therapy of myelofibrosis: targeting pathogenesis

Myelofibrosis with myeloid metaplasia (MMM) encompasses the diagnoses of agnogenic myeloid metaplasia (idiopathic myelofibrosis), as well as the advanced phases of polycythemia vera and essential thrombocythemia (post polycythemic and post thrombocythemia myeloid metaplasia, respectively). MMM is a clonal, hematopoietic stem cell disorder in which neither the pathogenesis, nor a broadly applicable effective therapy have been described. Clinically, these patients experience progressive marrow replacement by fibrotic tissue, ineffective hematopoiesis, problematic cytopenia's, significant hepato-splenomegaly, extramedullary hematopoiesis, profound constitutional symptoms, and a risk of blastic transformation. Historically, therapies have been targeted at palliating symptoms (i.e. splenectomy, transfusions, hydroxyurea, erythropoietin, androgens, localized radiotherapy). Stem cell transplantation appears promising, but is often toxic and not broadly applicable due to co-morbidities and age of MMM patients. Non-myeloablative approaches to conditioning may broaden the applicability of stem cell transplantation in MMM, yet results to date are preliminary. Although a definitive molecular abnormality responsible for the pathogenesis of MMM has not been described, much has been learned about the aberrant expression of pro-fibrotic cytokines and the presence of increased angiogenesis in MMM. These pathogenetic insights have led to a series of pilot clinical trials with therapeutic agents targeting aberrantly expressed cytokines (and possibly angiogenesis) including Thalidomide (alone or in combination), Etanercept, and STI-571. Amongst these later agents Thalidomide has demonstrated the most promise (palliating disease associated cytopenia's), whereas the TNF-alpha inhibitor Etanercept has aided with MMM associated constitutional symptoms. Although these later trials have been helpful in a subset of patients, no agent to date has led to solid complete responses in MMM across the spectrum of disease manifestations. Further insights into the pathogenetic mechanisms responsible for myeloproliferation (aberrant cell signaling pathways, apoptotic resistance, other) are necessary to guide selection and testing of the expanding number of novel anti-neoplastic agents in chronic myeloid disorders and MMM.

Recent publications in hematological oncology

In order to keep subscribers up-to-date with the latest developments in their field, John Wiley & Sons are providing a current awareness service in each issue of the journal. The bibliography contains newly published material in the field of hematological oncology. Each bibliography is divided into 14 sections: 1 Books, Reviews & Symposia; 2 General; Leukemias: 3 Lymphoblastic; 4 Myeloid & Myelodysplastic Syndromes; 5 Chronic; 6 Others; Lymphomas: 7 Hodgkin's; 8 Non-Hodgkin's; 9 Plasmacytomas/Multiple Myelomas; 10 Others; 11 Bone Marrow Transplantation; 12 Cytokines; 13 Diagnosis; 14 Cytogenetics. Within each section, articles are listed in alphabetical order with respect to author. If, in the preceding period, no publications are located relevant to any one of these headings, that section will be omitted.