eMedicine Specialties > Hematology > Stem Cells and Disorders

Myeloproliferative Disease

Haleem J Rasool, MD, FACP, Hematologist Oncologist, Department of Oncology, Franciscan Skemp Healthcare
Dale Groshek, BS, PA-C, Cancer Center, Department of Radiation Oncology, Franciscan Skemp Healthcare, La Crosse

Updated: Feb 13, 2008

Introduction

Background

Myeloproliferative diseases (MPDs) are a heterogenous group of disorders characterized by cellular proliferation of one or more hematologic cell lines in the peripheral blood, distinct from acute leukemia.

According to the French-American-British (FAB) classification, chronic myeloproliferative diseases consist of 4 diseases: chronic myelogenous leukemia (CML); polycythemia vera (PV); essential thrombocythemia (ET); and agnogenic myeloid metaplasia (AMM), which is also known as myelofibrosis (MF). In 2002, the World Health Organization (WHO) proposed an alternate classification schema for these diseases, adding chronic neutrophilic leukemia (CNL) and chronic eosinophilic leukemia (CEL)/hypereosinophilic syndrome (HES).¹ For a comparison of these classification systems, see the table below.

A related disorder, systemic mastocytosis (SM), has many features in common with the myeloproliferative diseases and is considered by some authors to belong to this group. In some patients, conditions overlap, and clear categorization may be difficult. Myeloproliferative disease may evolve into one of the other myeloproliferative conditions, transform to acute leukemia, or both.

Comparison of FAB and WHO Classifications of Chronic Myeloproliferative Diseases.

Some evidence indicates that myeloproliferative diseases arise from malignant transformation of a single stem cell. Involvement of erythropoiesis, neutrophilopoiesis, eosinophilopoiesis, basophilopoiesis, monocytopoiesis, and thrombopoiesis occurs in the chronic phase of chronic myelogenous leukemia. Some evidence also indicates that lymphocytes are derived from primordial malignant cells. This is based on observations that a single isoenzyme for glucose-6-phosphate dehydrogenase (G-6-PD) is present in some T and B lymphocytes in women with chronic myelogenous leukemia who are heterozygous for isoenzymes A and B.

See CME available on Chronic Myeloproliferative Disorders and Advances in the Treatment of Chronic Myeloid Leukemia.

Pathophysiology

Data from G-6-PD studies, cytogenetic analyses, and molecular methods have established the clonal origin of myeloproliferative diseases; this clonality potentially occurs at different stem cell levels. An attribute common to these disorders appears to be an acquired activating mutation in the gene coding for various tyrosine kinases.

In chronic myelogenous leukemia, the tyrosine kinase activity of the bcr-abl hybrid gene is increased. In polycythemia vera, essential thrombocythemia, and myelofibrosis, the prevalent genetic lesion appears to be a valine to phenylalanine substitution at amino acid position 617 (V617F) within the Janus kinase 2 (JAK2) gene.^2,3 This produces hypersensitivity to erythropoietin. At least in myelofibrosis patients the leukemic transformation is probably not related to JAK-2 (V617F) mutation status.⁴ Systemic mastocytosis has been linked with the D816 mutation of the KIT gene. The FIP1L1-PDGFR mutation has been identified in a subgroup of people with systemic mastocytosis with eosinophilia (SM-eos).

Frequency

United States

Approximately 4300 new cases of chronic myelogenous leukemia are diagnosed in the United States every year, accounting for more than half of myeloproliferative disease cases. The incidence of polycythemia vera in the United States is approximately 5-17 cases per 1 million population per year. True incidences of essential thrombocythemia and myelofibrosis are not known because epidemiological studies on these disorders are inadequate.

International

The incidence of polycythemia vera is 0.02-2.8 per 100,000 per year; Japan has the lowest incidence. Essential thrombocythemia has an incidence of 0.1-1.5 per 100,000 per year. Myelofibrosis has an international incidence of 0.4-0.9 per 100,000 per year.

Mortality/Morbidity

In the United States, 2,400 deaths every year are secondary to chronic myelogenous leukemia. Exact mortality and morbidity rates of other myeloproliferative diseases are unknown.

Race

Chronic myelogenous leukemia appears to affect all races with approximately equal frequency. The incidences of polycythemia vera, essential thrombocythemia, and myelofibrosis were tenfold higher among Ashkenazi Jews in northern Israel than in persons of Arabic descent in the region.

Sex

The female-to-male ratio is 1:1.4.

Age

Most cases encountered in clinical practice are in patients aged 40-60 years. Myeloproliferative diseases are uncommon in people younger than 20 years and are rare in childhood.

Clinical

History

• Easy fatigability
• Anorexia, weight loss
• Abdominal discomfort and early satiety secondary to splenomegaly is more common in chronic myelogenous leukemia and agnogenic myeloid metaplasia.
• Easy bruising, bleeding, and/or symptoms of thrombosis
• Swollen, painful joint(s) secondary to gouty arthritis secondary to hyperuricemia
• Priapism, tinnitus, or stupor from leukostasis
• Left upper quadrant and left shoulder pain as a consequence of splenic infarction and perisplenitis
• In many patients, abnormal blood counts are noted on a blood test performed for other reasons.

Physical

• Pallor, except in patients with polycythemia vera
• Plethora secondary to polycythemia
• Petechiae and/or ecchymosis
• Palpable spleen and/or liver
• Occasionally, syndrome of fever accompanied by painful maculopapular violaceous lesions on trunk, arms, legs, and face, which is called acute febrile neutrophilic dermatosis or Sweet syndrome

Causes

As with other malignant disorders, the precise cause of myeloproliferative disease is unknown. The etiology is complex, incompletely understood, and likely a multistep process involving more than one gene.

Differential Diagnoses

Other Problems to Be Considered

Leukemoid reaction

Workup

Laboratory Studies

• CBC counts and differential counts with microscopic examination of the peripheral smear
• Leukocyte alkaline phosphatase (LAP) score (to differentiate chronic myelogenous leukemia from other causes of leukocytosis)
• Polymerase chain reaction (PCR) or fluorescent in-situ hybridization (FISH) run on peripheral blood can detect bcr-abl gene rearrangement. This helps differentiate chronic myelogenous leukemia from other myeloproliferative diseases.
• Red blood cell mass study (true vs spurious polycythemia)
• Serum uric acid level

Imaging Studies

• Although not routinely required, a liver spleen scan may occasionally be helpful to assess the size of these organs in the diagnosis of difficult cases.

Other Tests

• Molecular test to detect bcr-abl gene when suspicious for chronic myelogenous leukemia and cytogenetically negative for Philadelphia chromosome
• PCR testing on bone marrow for JAK2 is available for suspected cases of polycythemia vera, essential thrombocythemia, or myelofibrosis.

Procedures

• Bone marrow aspiration and biopsy with cytogenetic studies are required in most, but not all, patients. Cytogenetic studies detect presence or absence of the Philadelphia chromosome and help to differentiate these disorders from myelodysplastic syndrome.

Histologic Findings

Bone marrow histology shows hypercellularity in most of these disorders. In the case of myelofibrosis, bone marrow fibrosis is demonstrated on the reticulin stain. Bone marrow fibrosis is also detected in the spent phase of chronic myelogenous leukemia and polycythemia vera.

Treatment

Medical Care

• Treatment of chronic myelogenous leukemia (CML): 
  • Hematopoietic stem cell transplantation can be considered in young patients with chronic myelogenous leukemia in chronic phase if a human leukocyte antigen (HLA)-matched donor is available.
  • Imatinib mesylate (Gleevec), a bcr-abl –specific tyrosine kinase inhibitor, is approved for use in Philadelphia chromosome–positive chronic myelogenous leukemia patients in chronic phase. In one study at 18 months, the complete response rate was 76.2% and the major cytogenetic response rate was 87.1%. Imatinib is also indicated for chronic myelogenous leukemia in blast crisis, accelerated phase, or in chronic phase after interferon alfa therapy failure. This is the treatment of choice for most patients.⁶
  • Interferon alfa, usually administered as a subcutaneous daily injection in a dose of 5 million U, produces hematologic and molecular remissions in some patients with chronic myelogenous leukemia. In these patients, evidence shows that it prolongs survival. Several patients who achieved molecular remissions have survived for more than 10 years.
  • Addition of low-dose cytosine arabinoside to interferon alfa has been reported to achieve higher remission rates.
  • Patients with chronic myelogenous leukemia who are intolerant of interferon alfa therapy can be treated with hydroxyurea.
  • Dasatinib (Sprycel) is indicated for the treatment of adults patients with chronic myeloid leukemia in chronic, accelerated, or myeloid or lymphoid blast phase who are resistant or intolerant to prior therapy including imatinib.
  • Nilotinib (Tasigna) is a kinase inhibitor indicated for the treatment of chronic phase and accelerated phase Philadelphia chromosome-positive chronic myelogenous leukemia in adult patients resistant to or intolerant to prior therapy including imatinib.
  • When the disease progresses to the blast phase, it is treated as acute leukemia, though the outcome is usually grave.
• Treatment of polycythemia vera (PV): Treatment is palliative. Young (<40 y), asymptomatic patients with polycythemia vera can be considered for therapeutic phlebotomies alone to maintain hematocrit level at less than 45%.
  • High-risk patients with systemic symptoms, history of thrombosis or bleeding, or high rate of phlebotomies or patients older than 69 years are best treated with myelosuppressive therapy in the form of hydroxyurea.⁷
  • An alternative therapy in older patients is radioactive phosphorous (32P), but this is unsuitable for younger patients because of the potential for causing secondary leukemia.
• Treatment of essential thrombocythemia (ET): Treatment of essential thrombocythemia is meant to relieve symptoms and to prevent complications because no curative modality is available at present. The aim of treatment is to maintain the platelet count within the reference range. This usually can be achieved by hydroxyurea or anagrelide.
• Treatment of myelofibrosis (MF): No curative treatment is available at the present time.
  • Asymptomatic patients can be monitored clinically until symptomatic. Hydroxyurea is useful to suppress the number of circulating cells.
  • Patients with painful, massively enlarged spleens refractory to myelosuppressive therapy are occasionally treated with radiation therapy, but they may ultimately require splenectomy.
  • A few recent reports have shown that allogeneic bone marrow transplantation may be effective in some cases.
  • Two case reports suggest that oral bisphosphonates may be beneficial in decreasing bone marrow fibrosis associated with this illness.

Surgical Care

Splenectomy is occasionally required in myelofibrosis for symptomatic relief of pain associated with the massive splenomegaly refractory to medical management.

Consultations

• Surgical consultation for permanent central venous access device placement may be required for patients in whom repeated blood draws, blood transfusions, and/or chemotherapy is anticipated.
• A radiation oncologist may need to be involved in selected cases, when splenic radiation is considered appropriate.

Diet

Massive splenomegaly is usually associated with epigastric and left upper quadrant discomfort and early satiety. Patients with these symptoms are encouraged to eat frequent, small meals rather than 3 large meals.

Activity

Individuals with myeloproliferative diseases are not encouraged to restrict their daily activities, but they are encouraged to refrain from physical activities that might expose them to abdominal trauma because massively enlarged spleens are likely to rupture, sometimes in response to minimal trauma.

Medication

The goals of pharmacotherapy are to reduce morbidity and to prevent complications.

Interferons

Interferons are naturally produced proteins with antiviral, antitumor, and immunomodulatory actions. Alpha-, beta-, and gamma-interferons may be given topically, systemically, and intralesionally.

Interferon alfa-2a and interferon alfa-2b (Roferon-A, Intron A)

Naturally produced proteins with antiviral, antitumor, and immunomodulatory actions. Alpha-, beta-, and gamma-interferons may be administered topically, systemically, and intralesionally. Interferon alfa is recommended for the initial management of low-risk CML. In low-risk CML, significant numbers of patients achieve hematological and molecular remissions. These patients have prolonged survival.

Dosing

Adult

5 million U SC qd

Pediatric

Not established

Interactions

Corticosteroids diminish effectiveness; theophylline may increase interferon alfa toxicity; cimetidine may increase antitumor effects; zidovudine and vinblastine may increase toxicity of interferon alfa

Contraindications

Documented hypersensitivity

Precautions

Pregnancy

C - Fetal risk revealed in studies in animals but not established or not studied in humans; may use if benefits outweigh risk to fetus

Precautions

Perform CBC count and serum chemistry prior to and during therapy; caution in brain metastases, severe hepatic or renal insufficiencies, seizure disorders, multiple sclerosis, or compromised CNS

Antimetabolites

Antimetabolites inhibit cell growth and proliferation.

Hydroxyurea (Hydrea)

Antineoplastic agent provides effective palliative treatment that primarily controls symptoms associated with leukocytosis, thrombocytosis, or hepatosplenomegaly due to MPD. Inhibitor of deoxynucleotide synthesis and DOC for inducing hematologic remission in CML. Less leukemogenic than alkylating agents such as busulfan, melphalan, or chlorambucil. Myelosuppressive effects last a few days to a week and are easier to control than alkylating agents. Busulfan has prolonged marrow suppression and can cause pulmonary fibrosis as well. Can be administered at higher doses in patients with extremely high WBC counts (>300,000) and adjusted accordingly as counts fall and platelet counts drop. Dose can be administered as a single daily dose or divided into 2 or 3 doses at higher dose ranges.

Dosing

Adult

500-3000 mg PO qd (20-30 mg/kg/d); titrate dose
Discontinue if WBC <2500/µL or platelet count <100,000/µL; recheck in 3 d and resume when values significantly rise toward reference ranges

Pediatric

Not established

Interactions

Coadministration with fluorouracil can increase neurotoxicity

Contraindications

Documented hypersensitivity, severe anemia or bone marrow suppression, WBC <2500/µL, platelet count <100,000/µL

Precautions

Pregnancy

C - Fetal risk revealed in studies in animals but not established or not studied in humans; may use if benefits outweigh risk to fetus

Precautions

Caution in renal impairment; closely supervise therapy; complete examination of blood, bone marrow, kidneys, and liver prior to and during therapy; perform weekly determination of hemoglobin level and total leukocyte and platelet counts; discontinue if leg ulcers develop

Anagrelide (Agrylin)

Reduces elevated platelet count in patients with essential thrombocythemia and polycythemia vera.

Dosing

Adult

0.5 mg PO qid (1 mg PO bid)

Pediatric

Not established

Interactions

None reported

Contraindications

Documented hypersensitivity

Precautions

Pregnancy

C - Fetal risk revealed in studies in animals but not established or not studied in humans; may use if benefits outweigh risk to fetus

Precautions

Initially monitor platelet count twice weekly; perform periodic hepatic and renal function tests; vasodilation, tachycardia, palpitations, and CHF may develop

Tyrosine kinase inhibitors

These agents inhibit the activity of bcr-abl tyrosine kinase, resulting in decreased proliferation and increased apoptosis in Ph-positive cell lines.

Imatinib mesylate (Gleevec)

Specifically designed to inhibit tyrosine kinase activity of the bcr-abl kinase in Ph+ leukemic CML cell lines. Used to treat newly diagnosed adult patients with CML or those in blast crisis, accelerated phase, or in chronic phase after failure to interferon alfa therapy. Also indicated to treat pediatric patients with Ph+ chronic phase CML whose disease has recurred after stem cell transplant or who have demonstrated interferon alfa resistance. Well absorbed after oral administration, with maximum concentrations achieved within 2-4 hours. Elimination is primarily in feces in form of metabolites.

Dosing

Adult

Chronic phase: 400 mg/d PO with food and large glass of water; may increase to 600 mg/d if no severe adverse effects or severe non–leukemia-related neutropenia or thrombocytopenia, disease continues to progress (any time), hematologic response is not satisfactory (after at least 3 mo treatment), or a loss of previously achieved hematologic response occurs
Accelerated phase or blast crisis: 600 mg/d PO with food and large glass of water; may increase to 800 mg/d (400 mg bid) if no severe adverse effects or severe non–leukemia-related neutropenia or thrombocytopenia, disease continues to progress (any time), hematologic response is not satisfactory (after at least 3 mo treatment), or a loss of previously achieved hematologic response occurs

Pediatric

260 mg/m²/d PO with food; may increase to 340 mg/m²/d with disease progression in absence of adverse effects

Interactions

CYP3A4 inhibitors (ketoconazole increases distribution of imatinib); CYP3A4 substrates (simvastatin increases maximum concentration of imatinib by a 2-3.5–fold factor); CYP3A4 inducers (phenytoin decreases AUC by approximately one fifth of typical AUC); likely to increase blood levels of drugs that are substrates of CYP2C9, CYP2D6, and CYP3A4/5

Contraindications

Documented hypersensitivity

Precautions

Pregnancy

X - Contraindicated; benefit does not outweigh risk

Precautions

Dose must be reduced or interrupted if edema or anemia occur, transaminases or bilirubin become elevated, or grade 3-4 neutropenia or thrombocytopenia develops; pediatric patients commonly experience musculoskeletal pain

Dasatinib (Sprycel)

Multiple tyrosine kinase inhibitor. Inhibits growth of cell lines overexpressing BCR/ABL. Orphan drug indicated for chronic myeloid leukemia (CML) in individuals resistant to or intolerant of prior therapy (eg, imatinib [Gleevec]). Has been able to overcome imatinib resistance resulting from BCR/ABL kinase domain mutations.

Dosing

Adult

70 mg PO bid; continue until disease progression or no longer tolerated
Chronic-phase CML: Escalate dose to 90 mg PO bid
Advanced-phase CML: May increase to 100 mg PO bid
Coadministration with CYP3A4 inhibitors: 20-40 mg PO qd
Coadministration with CYP3A4 inducers: May need to increase dose
If clinically viable, an alternate medication with no or minimal enzyme inhibition or induction is recommended

Pediatric

Not established

Interactions

CYP450 3A4 substrate and inhibitor; CYP3A4 inhibitors (eg, ketoconazole, itraconazole, erythromycin, clarithromycin, atazanavir, indinavir, nefazodone, nelfinavir, ritonavir, saquinavir, telithromycin) may increase serum concentrations; CYP3A4 inducers (eg, dexamethasone, phenytoin, rifampin, phenobarbital, carbamazepine, St. John's wort) may decrease serum concentrations coadministration with antacids or other drugs that decrease gastric pH (eg, H2 blockers [famotidine], proton pump inhibitors [omeprazole]) may decrease AUC and C_max; may increase plasma levels of CYP3A4 substrates (eg, alfentanil, cyclosporine, fentanyl, pimozide, quinidine, sirolimus, tacrolimus, ergot alkaloids, simvastatin)

Contraindications

None known

Precautions

Pregnancy

D - Fetal risk shown in humans; use only if benefits outweigh risk to fetus

Precautions

Adverse effects include fluid retention (including pleural effusion), bleeding, diarrhea, rash, pyrexia, infections, headache, fatigue, and nausea; frequently causes anemia, neutropenia, or thrombocytopenia; because of extensive liver metabolism, caution in patients with hepatic impairment (may need to decrease dose); swallow tab whole, do not crush or cut

Nilotinib (Tasigna)

Inhibits BCR/ABL kinase. In vitro, inhibits BCR/ABL –mediated proliferation of murine leukemic cell lines and human cell lines derived from Philadelphia chromosome–positive chronic myeloid leukemia. Under the conditions of the assays, was able to overcome imatinib resistance resulting from BCR/ABL kinase mutations in 32 of 33 mutations tested. In vivo, shown to reduce tumor size in a murine BCR/ABL xenograft model. Indicated for Philadelphia chromosome–positive chronic myeloid leukemia in adults whose disease has progressed or who cannot tolerate other therapies that include imatinib.

Dosing

Adult

400 mg PO bid 1 h ac or 2 h pc with water only; administer about 12 h apart; swallow whole (do not chew or crush)

Pediatric

Not established

Interactions

CYP3A4, CYP2C8, CYP2C9, and CYP2D6 inhibitor; CYP2B6, CYP2C8, and CYP2C9 inducer; coadministration with other drugs known to prolong QT interval (eg, class III antiarrhythmics [amiodarone, dofetilide, sotalol], tricyclic antidepressants, verapamil, erythromycin, moxifloxacin, thioridazine) increases risk of life-threatening arrhythmias and sudden death; avoid coadministration with strong CYP3A4 inhibitors (eg, grapefruit, ketoconazole, itraconazole, clarithromycin, atazanavir, indinavir, nefazodone, nelfinavir, ritonavir, saquinavir, telithromycin, voriconazole), which may increase serum levels, thereby increasing QT interval; avoid coadministration with strong CYP3A4 inducers (eg, dexamethasone, phenytoin, carbamazepine, rifampin, rifabutin, rifapentine, phenobarbital, St. John's wort)

Contraindications

Documented hypersensitivity; long QT syndrome; uncorrected hypokalemia or hypomagnesemia

Precautions

Pregnancy

D - Fetal risk shown in humans; use only if benefits outweigh risk to fetus

Precautions

May prolong QT interval, leading to life-threatening arrhythmias and possible sudden death; this risk is lowered by taking without food, avoiding grapefruit products, and confirming that potassium and magnesium levels are within normal limits; if QTc >480 milliseconds, withhold and analyze concurrent medications, serum potassium levels, and magnesium levels (reduce dose according to prescribing information); food increases bioavailability, thus administer on empty stomach to avoid elevated serum levels and toxicity; common adverse effects include myelosuppression (obtain CBC count q2wk for 2 mo, then monthly), rash, headache, nausea, and itching; may cause hepatic toxicity, edema, and pancreatitis; females of childbearing potential should use effective contraception; caution in liver impairment; withhold drug with ANC <1 X 10⁹/L, platelet count <50 X 10⁹/L, or serum lipase, amylase, bilirubin, or hepatic transaminase levels >grade 3

Follow-up

Complications

• Patients are at risk of both thrombotic and hemorrhagic events. 
  • Thrombotic and hemorrhagic events are particularly common in polycythemia vera (PV) and essential thrombocythemia (ET). Thrombosis is the cause of death in 30-40% of patients.
  • A particularly serious thrombotic event that may be associated with polycythemia vera is Budd-Chiari syndrome, which is due to hepatic venous or inferior venal caval thrombosis.
• Patients are at risk of developing secondary acute leukemia from their underlying disorder as well as their treatment.

Miscellaneous

Medicolegal Pitfalls

When suspecting polycythemia in patients with iron deficiency, replenish iron before conducting red blood cell mass studies; otherwise, some cases of true polycythemia may be missed.

Multimedia

Media file 1: Peripheral smear of a patient with chronic myelogenous leukemia (CML) shows leukocytosis with extreme left shift and basophilia.

Media file 2: Peripheral smear of a patient with chronic myelogenous leukemia (CML) in blastic phase shows several blasts.

Media file 3: Peripheral smear of a patient with essential thrombocythemia (ET) shows markedly increased number of platelets. Some of the platelets are giant (arrow).

Media file 4: Peripheral smear of a patient with agnogenic myeloid metaplasia (myelofibrosis) shows leukoerythroblastosis. This photomicrograph also shows giant platelets.

Media file 5: Photomicrograph of a peripheral smear of a patient with agnogenic myeloid metaplasia (myelofibrosis) shows findings of leukoerythroblastosis, giant platelets, and few teardrop cells.

References

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4. Mesa RA, Powell H, Lasho T, Dewald G, McClure R, Tefferi A. JAK2(V617) and leukemic transformation in myelofirbrosis with myeloid metaplasia. Leuk Res. 2006/11;30 (11):1457-60.

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14. Levine RL, Wadleigh M, Cools J. Activating mutation in the tyrosine kinase JAK2 in polycythemia vera, essential thrombocythemia, and myeloid metaplasia with myelofibrosis. Cancer Cell. Apr 2005;7(4):387-97. [Medline].

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Keywords

MPD, polycythemia vera, PV, polycythemia rubra vera, primary thrombocythemia, PT, agnogenic myeloid metaplasia, AMM, chronic myelogenous leukemia, chronic myeloid leukemia, CML, myelofibrosis, MF, acute leukemia, myelodysplastic syndrome, essential thrombocythemia, ET, Budd-Chiari syndrome, chronic idiopathic myelofibrosis, CIM, chronic neutrophilic leukemia, CNL, chronic eosinophilic leukemia, CEL, hypereosinophilic syndrome, HES

Contributor Information and Disclosures

Author

Haleem J Rasool, MD, FACP, Hematologist Oncologist, Department of Oncology, Franciscan Skemp Healthcare
Haleem J Rasool, MD, FACP is a member of the following medical societies: American College of Physicians-American Society of Internal Medicine and American Society of Hematology
Disclosure: Nothing to disclose.

Coauthor(s)

Dale Groshek, BS, PA-C, Cancer Center, Department of Radiation Oncology, Franciscan Skemp Healthcare, La Crosse
Disclosure: Nothing to disclose.

Medical Editor

Koyamangalath Krishnan, MD, FRCP, FACP, Paul Dishner Endowed Chair of Excellence in Medicine, Professor of Medicine and Chief of Hematology-Oncology, Program Director, Hematology-Oncology Fellowship, James H Quillen College of Medicine at East Tennessee State University
Koyamangalath Krishnan, MD, FRCP, FACP is a member of the following medical societies: Alpha Omega Alpha, American College of Physicians-American Society of Internal Medicine, American Society of Hematology, and Royal College of Physicians
Disclosure: Nothing to disclose.

Pharmacy Editor

Francisco Talavera, PharmD, PhD, Senior Pharmacy Editor, eMedicine
Disclosure: eMedicine Salary Employment

Managing Editor

Troy H Guthrie, Jr, MD, Director of Cancer Institute, Baptist Medical Center
Troy H Guthrie, Jr, MD is a member of the following medical societies: American Federation for Medical Research, American Medical Association, American Society of Hematology, Florida Medical Association, Medical Association of Georgia, and Southern Medical Association
Disclosure: Nothing to disclose.

CME Editor

Rajalaxmi McKenna, MD, FACP, Southwest Medical Consultants, SC, Department of Medicine, Good Samaritan Hospital, Advocate Health Systems
Rajalaxmi McKenna, MD, FACP is a member of the following medical societies: American Society of Clinical Oncology, American Society of Hematology, and International Society on Thrombosis and Haemostasis
Disclosure: Nothing to disclose.

Chief Editor

Emmanuel C Besa, MD, Professor, Department of Medicine, Division of Hematologic Malignancies, Kimmel Cancer Center, Thomas Jefferson University
Emmanuel C Besa, MD is a member of the following medical societies: American Association for Cancer Education, American College of Clinical Pharmacology, American Federation for Medical Research, American Society of Hematology, and New York Academy of Sciences
Disclosure: Nothing to disclose.

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