Splenic irradiation in myelofibrosis with myeloid metaplasia: a review

Myelofibrosis: Genetic Characteristics and the Emerging Therapeutic Landscape

Primary myelofibrosis (PMF) is one of three myeloproliferative neoplasms (MPN) that are morphologically and molecularly inter-related, the other two being polycythemia vera (PV) and essential thrombocythemia (ET). MPNs are characterized by JAK-STAT-activating JAK2, CALR, or MPL mutations that give rise to stem cell-derived clonal myeloproliferation, which is prone to leukemic and, in case of PV and ET, fibrotic transformation. Abnormal megakaryocyte proliferation is accompanied by bone marrow fibrosis and characterizes PMF, while the clinical phenotype is pathogenetically linked to ineffective hematopoiesis and aberrant cytokine expression. Among MPN-associated driver mutations, type 1-like CALR mutation has been associated with favorable prognosis in PMF, while ASXL1, SRSF2, U2AF1-Q157, EZH2, CBL, and K/NRAS mutations have been shown to be prognostically detrimental. Such information has enabled development of exclusively genetic (GIPSS) and clinically integrated (MIPSSv2) prognostic models that facilitate individualized treatment decisions. Allogeneic stem cell transplantation remains the only treatment modality in MF with the potential to prolong survival, whereas drug therapy, including JAK2 inhibitors, is directed mostly at the inflammatory component of the disease and is therefore palliative in nature. Similarly, disease-modifying activity remains elusive for currently available investigational drugs, while their additional value in symptom management awaits controlled confirmation. There is a need for genetic characterization of clinical observations followed by in vitro and in vivo preclinical studies that will hopefully identify therapies that target the malignant clone in MF to improve patient outcomes.

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.

Management of challenging myelofibrosis after JAK inhibitor failure and/or progression

The myeloproliferative neoplasms (MPNs) encompass a heterogenous set of diseases that have variable survival, but in the setting of treatment refractory and progressive disease, prognosis has been characteristically poor. JAK inhibition with ruxolitinib or fedratinib therapy has become the first line treatment for symptomatic or intermediate to high risk myelofibrosis. However, after three years of ruxolitinib therapy, approximately half of all patients with myelofibrosis will likely have stopped treatment. JAK inhibition failure represents a mixture of etiologies, including drug intolerance, suboptimal dosing, drug resistance, or progression of disease. JAK inhibition failure and accelerated/blast phase have now become the primary clinical challenges in the treatment of myelofibrosis and high risk polycythemia vera, and no phase III trials or clear treatment guidelines exist to guide management strategies in this setting. On the other hand, this represents an exciting time in treatment of JAK inhibitor failure and accelerated phase MPNs due to the advent of recently approved drugs as well as new targeted agents currently under investigation. In this article, we review the management options for these challenging clinical scenarios. We discuss the options for JAK inhibitor dose optimization and overcoming resistance by utilizing combinations of JAK inhibition, primarily ruxolitinib, with alternative commercially available therapies. For patients who have progressed, we discuss recent data regarding targeted therapy options approved for AML that represent potentially efficacious options in the progressive MPN setting. We also discuss the new clinical agents under development in MF and accelerated MPNs that may offer new therapeutic options in the years to come.

Managing myelofibrosis (MF) that "blasts" through: advancements in the treatment of relapsed/refractory and blast-phase MF

Myelofibrosis (MF) is the most aggressive form of Philadelphia chromosome-negative myeloproliferative neoplasm, and it is complicated by severe symptom burden, thrombotic events, infections, cytopenias, and transformation to acute myeloid leukemia (AML). Ruxolitinib, the first-line therapy for symptomatic or intermediate- and high-prognostic risk MF, has improved overall survival for this population. However, approximately one-half of MF patients will discontinue ruxolitinib by the first few years of therapy due to a spectrum of resistance, intolerance, relapse, or progression to blast phase disease. Danazol, erythropoietin-stimulating agents, and spleen-directed therapies can be useful in the ruxolitinib-resistant setting. In the ruxolitinib-refractory or -intolerant setting, commercial and novel therapies, either alone or in combination with ruxolitinib, have shown clinical utility. For blast-phase MF, the recent advancements in available AML therapies have increased the options with targeted and more tolerable therapies. In this article, we will discuss our paradigm for the management of relapsed/refractory and blast-phase MF in the context of therapeutic advancements in both AML and MF.

Treatment of symptomatic splenomegaly with low doses of radiotherapy: Retrospective analysis and review of the literature

OBJECTIVES

To evaluate the effectiveness of low doses of radiation therapy for symptomatic splenomegaly in malignant and benign diseases.

PATIENTS AND METHODS

5 patients with symptomatic splenomegaly were treated with low doses of radiation in our centre (January 2008-December 2016). 4/5 patients had malignant neoplasia (acute myeloid leukemia, non Hogdkin lymphoma and prolymphocytic B cell leukemia) and splenomegaly was caused by extramedullary hematopoiesis. 1/5 patient had benign disease (HBV liver cirrhosis) and splenomegaly was caused by vascular ectasia. Median age was 73 years (range 61-86 years). There were 4 females and 1 male. These patients had exclusively splenic pain or abdominal discomfort in 20%, exclusively cytopenias 40% and both 40%. Patients needed radiation therapy for symptomatic control. Dose per fraction was 0.5 Gy every two days; total dose initially prescribed 10 Gy. IGRT were performed in all patients to ensure an appropriate position and to adapt the treatment volume to the changes in the spleen volume along the treatment. Median craneocaudal length size of the spleen was more than 26 cm (range 15.2-34.9 cm).

RESULTS

Median radiation doses were 4.85 Gy (range 2.5-10). Median craneocaudal spleen size reduction was 4.6 cm (0-8 cm). Splenic pain and abdominal disturbances improved in all patients. Median increase of haemoglobin and platelets levels was 1.6 mg/dl and 27.950 cells respectively in the first week after the end of radiotherapy.One patient had to interrupt her treatment due to grade II neutropenia. No other toxicities were described. With a median follow-up of 39 months (16-89 months), only one recurrence was described at 24 months and consisted of thrombocytopenia. The patient received a second course of radiotherapy with excellent response.

CONCLUSION

Low doses of radiation therapy for treatment of symptomatic splenomegaly were effective, with a low rate of side effects. Splenic pain and abdominal discomfort completely improved and cytopenias rised to secure levels.

Primary myelofibrosis: current therapeutic options

Primary myelofibrosis is a Philadelphia-negative myeloproliferative neoplasm characterized by clonal myeloid expansion, followed by progressive fibrous connective tissue deposition in the bone marrow, resulting in bone marrow failure. Clonal evolution can also occur, with an increased risk of transformation to acute myeloid leukemia. In addition, disabling constitutional symptoms secondary to the high circulating levels of proinflammatory cytokines and hepatosplenomegaly frequently impair quality of life. Herein the main current treatment options for primary myelofibrosis patients are discussed, contemplating disease-modifying therapeutics in addition to palliative measures, in an individualized patient-based approach.

Ruxolitinib for the treatment of primary myelofibrosis

PURPOSE

The pharmacology, pharmacokinetics, pharmacogenomics, clinical efficacy, and safety profile of ruxolitinib for the treatment of primary myelofibrosis are reviewed.

SUMMARY

Ruxolitinib, an oral tyrosine kinase inhibitor that targets the Janus-associated kinases (JAKs) 1 and 2, has been recently approved for the treatment of patients with intermediate- or high-risk myelofibrosis. Unlike previous treatment options for patients with myelofibrosis, ruxolitinib offers a targeted therapy option for these patients who often suffer with severe and debilitating symptoms associated with the disease process. After oral administration, ruxolitinib is rapidly absorbed and can be given without regard to meals. Ruxolitinib is primarily metabolized by the cytochrome P-450 (CYP) 3A4 isoenzyme system; therefore, if concomitant use with a strong CYP3A4 inhibitor is unavoidable, an initial dosage reduction is warranted. Two Phase III randomized trials comparing ruxolitinib to either placebo or best available therapy found a rapid and sustained response in the reduction of spleen size and improvements in constitutional symptoms and quality of life, with one study demonstrating an improvement in overall survival. The most commonly reported serious adverse effects of ruxolitinib are anemia and thrombocytopenia. Ruxolitinib is administered as an oral tablet given twice daily, with the initial starting dosage based on the baseline platelet count. Dosage reductions are based on the development of thrombocytopenia.

CONCLUSION

By directly targeting both JAK1 and JAK2 through small-molecule inhibition, ruxolitinib elicits a reduction in splenomegaly and disease-related symptoms in patients with intermediate- or high-risk myelofibrosis while maintaining an acceptable toxicity profile and a low treatment-discontinuation rate.

Treatment and management of myelofibrosis in the era of JAK inhibitors

Myelofibrosis (MF) can present as a primary disorder or evolve from polycythemia vera (PV) or essential thrombocythemia (ET) to post-PV MF or post-ET MF, respectively. MF is characterized by bone marrow fibrosis, splenomegaly, leukoerythroblastosis, extramedullary hematopoiesis, and a collection of debilitating symptoms. Until recently, the therapeutic options for patients with MF consisted of allogeneic hematopoietic stem cell transplant (alloHSCT), the use of cytoreductive agents (ie, hydroxyurea), splenectomy and splenic irradiation for treatment of splenomegaly, and management of anemia with transfusions, erythropoiesis-stimulating agents (ESAs), androgens, and immunomodulatory agents. However, with increased understanding of the pathogenesis of MF resulting from dysregulated Janus kinase (JAK) signaling, new targeted JAK inhibitor therapies, such as ruxolitinib, are now available. The purpose of this article is to review the clinical features of MF, discuss the use and future of JAK inhibitors, reassess when and how to use conventional MF treatments in the context of JAK inhibitors, and provide a perspective on the future of MF treatment.

Update on the treatment of Ph-negative myeloproliferative neoplasms

SUMMARY Myeloproliferative neoplasms (MPNs) that do not harbor the BCR–ABL rearrangement include polycythemia vera (PV), essential thrombocythemia (ET) and primary myelofibrosis. All of these diseases are characterized by an increased risk of vascular complications and by the propensity to evolve into acute leukemia. The JAK2V617F mutation determines a gain of function in the gene encoding JAK2 and is the most frequent molecular abnormality in MPNs, with an estimated prevalence of more than 95% in PV and 50% in ET and primary myelofibrosis. Molecular markers, together with marrow histology and cytogenetic data, are increasingly relevant for MPN diagnosis, and their prognostic value is under evaluation. In PV and ET, the use of aspirin, hydroxyurea and phlebotomy remain the mainstay of treatment. In myelofibrosis, conventional therapy (androgens, steroids, chemotherapy and splenectomy) has still only palliative effects. The only potentially curative approach is allogeneic stem cell transplantation, but treatment-related mortality remains high. In the last 2 years, the JAK–STAT pathway has become the target of selective tyrosine kinase inhibitors, which might represent a promising therapeutic option. Their role in future therapy, as single agents and/or in combinatorial approaches, is yet to be determined.

Effects of spleen status on early outcomes after hematopoietic cell transplantation

To assess the impact of spleen status on engraftment, and early morbidity and mortality after allogeneic hematopoietic cell transplantation (HCT), we analyzed 9,683 myeloablative allograft recipients from 1990 to 2006; 472 had prior splenectomy (SP), 300 splenic irradiation (SI), 1,471 with splenomegaly (SM), and 7,440 with normal spleen (NS). Median times to neutrophil engraftment (NE) and platelet engraftment (PE) were 15 vs 18 days and 22 vs 24 days for the SP and NS groups, respectively (P<0.001). Hematopoietic recovery at day +100 was not different across all groups, however the odds ratio of days +14 and +21 NE and day +28 PE were 3.26, 2.25 and 1.28 for SP, and 0.56, 0.55, and 0.82 for SM groups compared to NS (P<0.001), respectively. Among patients with SM, use of peripheral blood grafts improved NE at day +21, and CD34+ cell dose >5.7 × 10(6)/kg improved PE at day+28. After adjusting variables by Cox regression, the incidence of GVHD and OS were not different among groups. SM is associated with delayed engraftment, whereas SP prior to HCT facilitates early engraftment without having an impact on survival.

Philadelphia-negative chronic myeloproliferative neoplasms

Chronic myeloproliferative diseases without the Philadelphia chromosome marker (Ph-), although first described 60 years ago, only became the subject of interest after the turn of the millennium. In 2001, the World Health Organization (WHO) defined the classification of this group of diseases and in 2008 they were renamed myeloproliferative neoplasms based on morphological, cytogenetic and molecular features. In 2005, the identification of a recurrent molecular abnormality characterized by a gain of function with a mutation in the gene encoding Janus kinase 2 (JAK2) paved the way for greater knowledge of the pathophysiology of myeloproliferative neoplasms. The JAK2 mutation is found in 90-98% of polycythemia vera and in about 50% essential thrombocytosis and primary myelofibrosis. In addition to the JAK2 mutation, other mutations involving TET2 (ten-eleven translocation), LNK (a membrane-bound adaptor protein); IDH1/2 (isocitrate dehydrogenase 1/2 enzyme); ASXL1 (additional sex combs-like 1) genes were found in myeloproliferative neoplasms thus showing the importance of identifying molecular genetic alterations to confirm diagnosis, guide treatment and improve our understanding of the biology of these diseases. Currently, polycythemia vera, essential thrombocytosis, myelofibrosis, chronic neutrophilic leukemia, chronic eosinophilic leukemia and mastocytosis are included in this group of myeloproliferative neoplasms, but are considered different situations with individualized diagnostic methods and treatment. This review updates pathogenic aspects, molecular genetic alterations, the fundamental criteria for diagnosis and the best approach for each of these entities.

Danazol therapy combined with intermittent application of chemotherapy induces lasting remission in myeloproliferative disorder (MPD): an alternative for the elderly with advanced MPD

There is no good alternative therapy available for elderly patients with advanced myeloproliferative disorders (MPD) who failed on conventional therapies and are not candidates for bone marrow transplant. We report here an effective therapy that induced exceptionally long-lasting remissions and improved quality of life. Eighteen elderly patients (mean age: 70·6 years) (16 myelofibrosis and 2 thrombocythemia) who had failed on conventional therapies were treated. Danazol was administered daily at 200-800 mg throughout the study. Chemotherapy was applied intermittently as needed to reduce spleen size and blood counts. Busulfan (2-4 mg/day) was used most often and 6-mercaptopurine (6-MP) (50-100 mg/day) and/or cytarabine (100-200 mg/m(2)) if the white blood cell (WBC) count rose rapidly. When MPD stabilized, chemotherapy was discontinued and dosage of danazol was reduced. Therapy was well tolerated. Overall, 61% of patients responded with unexpectedly long-lasting remissions and improved quality of life. Three (17%) had excellent (E) response, defined by normalization of blood counts and non-palpable spleen, while eight (44%) had good (G) response, defined by rise of Hct by ≥7% and ≥50% reduction of spleen. Mean duration of remission was 45 months (10-78 months) in E responders and 11 months in G responders (2-22 months). This regimen offers a safe and effective alternative for advanced MPD in the elderly.

Radiotherapy of splenomegaly : a palliative treatment option for a benign phenomenon in malignant diseases

PURPOSE

Since the 20(th) century, radiotherapy (RT) has been used for treatment of symptomatic splenomegaly (SM). SM occurs in association with hematologic disorders. The purpose of this analysis was to determine the indication, treatment concepts, and efficiency of RT.

MATERIAL AND METHODS

Clinical features, treatment concepts, and outcome data during the past 20 years were analyzed. Endpoints were pain relief, symptomatic and hematological response, and treatment-related side effects.

RESULTS

From 1989-2009, a total of 122 patients received 246 RT courses because of symptomatic SM. Overall 31 patients had chronic myelogenous leukemia (CML), 37 had chronic lymphocytic leukemia (CLL), 23 had osteomyelofibrosis (OMF), 17 had polycythemia vera (PV), 5 had acute myelogenous leukemia, 4 had idiopathic thrombocytopenic purpura (ITP), 3 had non-Hodgkin lymphoma (NHL), and 2 had multiple myeloma (MM). Patients were treated with (60)Co gamma rays or 5-15MV photons. The fraction size ranged from 10-200 cGy and the total dose per treatment course from 30-1600 cGy. Significant pain relief was achieved for 74.8% of the RT courses given for splenic pain. At least 50% regression was attained for 77% of the RT courses given for SM. 36 patients died within 2 months due to the terminal nature of their disease. Of the RT courses applied for cytopenia, 73.6% achieved a significant improvement of hematological parameters and reduction of transfusion need. Notable hematologic toxicities were reported < EORTC/RTOG II°.

CONCLUSION

The present analysis documents the efficacy of RT. In addition, RT as a palliative treatment option for symptomatic SM should not be forgotten.

How I treat myelofibrosis

It is currently assumed that myelofibrosis (MF) originates from acquired mutations that target the hematopoietic stem cell and induce dysregulation of kinase signaling, clonal myeloproliferation, and abnormal cytokine expression. These pathogenetic processes are interdependent and also individually contributory to disease phenotype-bone marrow stromal changes, extramedullary hematopoiesis, ineffective erythropoiesis, and constitutional symptoms. Molecular pathogenesis of MF is poorly understood despite a growing list of resident somatic mutations that are either functionally linked to Janus kinase (JAK)-signal transducer and activator of transcription hyperactivation (eg JAK2, MPL, and LNK mutations) or possibly involved in epigenetic dysregulation of transcription (TET2, ASXL1, or EZH2 mutations). Current prognostication in primary MF is based on the Dynamic International Prognostic Scoring System-plus model, which uses 8 independent predictors of inferior survival to classify patients into low, intermediate 1, intermediate 2, and high-risk disease groups; corresponding median survivals are estimated at 15.4, 6.5, 2.9, and 1.3 years. Such information is used to plan a risk-adapted treatment strategy for the individual patient, which might include observation alone, conventional or investigational (eg, JAK inhibitors, pomalidomide) drug therapy, allogenic stem cell transplantation with reduced- or conventional-intensity conditioning, splenectomy, or radiotherapy. I discuss these treatment approaches in the context of who should get what and when.

Tachykinins and Hematopoiesis

Originally discovered in the 1930s, tachykinins have been a subject of renewed interest. Antagonists to the tachykinin receptors have shown potential in the treatment of a variety of maladies including neurodegenerative disorders, heart disease, pain perception and malignancies. Tachykinins have been the subject of intense studies due to their impact on hematopoiesis that has significant effects on endothelial tissue and vascular conditions. Hematopoiesis relies on a relatively small subset of bone marrow-resident hematopoietic stem cells. This review discusses the network developed by cytokines and the tachykinins to regulate hematopoiesis. An understanding of tachykinin effect on normal hematopoietic functions and their involvement in hematological disorders could lead to new treatments for bone marrow disorders such as fibrosis, leukemia and anemia.

Peripheral blood complete remission after splenic irradiation in mantle-cell lymphoma with 11q22-23 deletion and ATM inactivation

Mantle Cell Lymphoma (MCL) is a well-known histological and clinical subtype of B-cell non-Hodgkin's Lymphomas. It is usually characterized by an aggressive disease course, presenting with advanced stage disease at diagnosis and with low response rates to therapy. However few cases of indolent course MCL have been described. We herein report a case of MCL with splenomegaly and peripheral blood involvement as main clinical features. The patient underwent moderate dose splenic radiation therapy and achieved spleen downsizing and peripheral blood complete remission. Splenic irradiation has been extensively used in the past as palliative treatment in several lymphoproliferative disorders and a systemic effect and sometimes peripheral blood complete remissions have been observed. Mainly advocated mechanisms responsible for this phenomenon are considered direct radiation-induced apoptotic cell death, immune modulation via proportional changes of lymphocyte subsets due to known differences in intrinsic radiosensitivity and a radiation-induced cytokine release. The peculiar intrinsic radiosensitivity pattern of lymphoid cells could probably be explained by well-defined individual genetic and molecular features. In this context, among NHLs, MCL subtype has the highest rate of ATM (Ataxia Teleangiectasia Mutated) inactivation. While the ATM gene is thought to play a key-role in detecting radiation-induced DNA damage (expecially Double Strand Breaks), recent in vitro data support the hypothesis that ATM loss may actually contribute to the radiosensitivity of MCL cells. ATM status was retrospectively investigated in our patient, with the tool of Fluorescence In Situ Hybridization, showing a complete inactivation of a single ATM allele secondary to the deletion of chromosomal region 11q22-23. The presence of this kind of cytogenetic aberration may be regarded in the future as a potential predictive marker of radiation response.

New approaches in the treatment of myelofibrosis

Myelofibrosis with myeloid metaplasia (MMM) is a chronic clonal neoangiogenesis disorder characterized by bone marrow fibrosis and neoangiogensis with extramedullary hematopoiesis. Identification of prognostic factors associated with MMM have not impacted the treatment of the disease, which continues to be palliative with the exception of allogeneic stem cell transplantation (SCT) for potential long-term disease-free survival in selected patients. Additional insights into the pathophysiology of MMM have resulted in the use of novel therapeutic strategies in the treatment of this disease. The rationale for the investigation of these agents in MMM and the status of clinical trials with various modalities such as angiogenesis inhibitors (e.g., thalidomide), tyrosine kinase inhibitors (e.g., imatinib mesylate), farnesyl transferase inhibitors (e.g., R115777), and other agents are reviewed, in addition to the potential roles of autologous and allogeneic SCT.

Palliative irradiation of the spleen

We analyzed the efficacy of splenic irradiation in a population of patients with hematologic diseases. The records of the Radiation Oncology Division, Naval Medical Center San Diego were retrospectively reviewed for all patients treated with splenic irradiation (SI) between January 1, 1990 and March 1, 2001. The charts of 17 patients were identified: 5 patients had chronic myelogenous leukemia, 4 had chronic lymphocytic leukemia, 4 had idiopathic myelofibrosis, 2 had polycythemia vera, and 1 patient each had idiopathic thrombocytopenic purpura and acute myelogenous leukemia. Patient ages ranged from 37 to 88 years. Sixteen of 17 suffered from symptomatic splenomegaly. Twenty-six courses of splenic irradiation were delivered to these 17 patients. Treatment courses generally consisted of two fractions of 50 cGy in the first week, two fractions of 75 cGy the second week, and two fractions of 100 cGy the third week. Blood counts were checked prior to each treatment. Seven of the 17 patients died 1 month or less after SI due to the terminal nature of their disease. Twenty-two of 25 treatment courses for splenomegaly resulted in decreased pain and symptoms. Five patients required two treatment courses for splenomegaly, and one patient required five treatment courses. Three of four patients treated for thrombocytopenia demonstrated improvement, but only one was evaluable for more than 2 weeks due to disease-related mortality. Three of five patients treated for leukocytosis had significant improvement. In general, patients suffered few significant complications from this palliative intervention. Splenic irradiation can effectively palliate symptomatic splenomegaly in patients for whom splenectomy is not an option. Retreatment is possible. Splenic irradiation is less effective in the treatment of thrombocytopenia or leukocytosis.

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.

Radiation therapy for symptomatic hepatomegaly in myelofibrosis with myeloid metaplasia

OBJECTIVE

To describe the experience with liver irradiation in advanced cases of myelofibrosis with myeloid metaplasia (MMM).

METHODS

Over a 20-yr period, 14 patients with MMM were treated with a total of 25 courses of liver, abdominal, or abdominal and pelvic irradiation for symptomatic hepatomegaly with (5 patients) or without (9 patients) ascites. All 14 patients had advanced disease and 11 (79%) had previous splenectomy. The median radiation therapy (RT) dose per course was 150 cGy (range 50-1000) administered at a median of six fractions. Four patients received two to six courses.

RESULTS

Twelve of the 14 patients (86%) had a transient (median 3 months) subjective response from RT. However, in only 35% of these was there a transient (median 3 months) decrease in palpable liver size. Four of the five patients with ascites experienced a short-term response from RT. Eight of the 13 patients suitable for evaluation (62%) had treatment-associated cytopenia, often in the form of anemia and/or thrombocytopenia. At last follow-up, 10 patients (71%) had died after a median of 7 months (range 0.1-23) and 4 were alive at 3, 20, 33, and 57 months after RT.

CONCLUSIONS

Low-dose abdominal RT for symptomatic hepatomegaly or ascites associated with advanced-stage MMM is myelosuppressive and provides only temporary and mainly subjective and short-lived relief.

Safety and efficacy of splenic irradiation in the treatment of patients with idiopathic myelofibrosis: a report on 15 patients

Splenic irradiation in idiopathic myelofibrosis (IMF) has often been use d in selected situations when other therapies were unefficient or contraindicated. This could improve quality of life of patients, but literature remains rare in this field. We have assessed the impact of splenic irradiation in 15 patients with IMF. All of them were no longer responsive to usual treatments, and they presented at least one of the following features: constitutional symptoms, splenic pain, large splenic size, and anemia requiring >2 units of red blood cell transfusion per month. The planned schedule of radiotherapy consisted in daily fractions of 0.4-1 Gy. The median dose of radiotherapy per treatment was 9.8 Gy (range, 0.6-30.5). The overall response rate was 59% with a median duration of 10 months (range, 1-19). Splenic irradiation was more effective on constitutional symptoms, splenic pain, and spleen size. The best responses were noted when full doses of radiotherapy could be delivered, and when patients were previously fewly transfused. Splenic irradiation effectively palliates IMF-related symptoms, and constitute an alternative therapy for patients refractory to usual treatments.