Dr MONKEZ MYOUSIF
Professor of Internal Medicine
MPNs are clonal diseases
Originating in multipotential hematopoietic progenitor cell
Characterized by independence of numerous cytokines.
Resulting in increased and abnormal myelopoiesis and
Classified according to the predominant phenotypic
expression of the myeloproliverative disease
can develop in any one of
these cell types
Normal development of blood cells
Growth Factors And Tyrosine Kinase
StatStat Proliferation and survival
A. Classic Disorders
- Philadelphia +ve :
Chronic myeloid leukemia (CML)
- Philadelphia –ve :
Polycythemia vera (PV)
Essential thrombocythemia (ET)
Chronic idiopathic myelofibrosis (CIMF)
B. Atypical Disorders
- Chronic neutrophilic leukemia
- Chronic eosinophilic leukemia
- Chronic mast cell leukemia
• CML, polycythemia, and essential thrombocythemia may
evolve into chronic myelofibrosis.
• All myeloproliferative disorders carry an increased risk of
transformation to acute myeloid leukemia (AML).
MPN have been caused by mutations
in tyrosine kinases
A. CML: Philadelphia chromosome: t(9;22),
BCR / ABL oncogene
B. PV, ET, CIMF: point mutation (V617F) of the
tyrosine kinase JAK-2 (Janus kinase 2) on
the short arm of chromosome 9 (9p), present
in patients with PV (99%), ET (50%), and
C. Chromosomal aberrations are detectable in
10–60% of cases.
JAK2 V617F is always on!!!
What does JAK2 normally do?
It is a switch that tells blood cells to grow
StatStat Proliferation and survival
Valine 617 Phenylalanine
JAK2V617F prevalence in MPN
Overproduction of one or several blood
elements with dominance of a transformed
Hypercellular marrow/marrow fibrosis.
Thrombotic and/or hemorrhagic diatheses.
Increased cell turnover → hyperuricemia
Extramedullary hematopoiesis (liver/spleen).
Transformation to acute leukemia.
Overlapping clinical features.
Curative treatment options for patients up to 75 years
of age consist of adequate conditioning protocols with
subsequent allogenic bone marrow or peripheral blood
stem cell transplantation.
Molecular inhibitors (targeted therapies), such as tyrosine
kinase inhibitors) (imatinib) .
Palliative treatment includes supportive care,
conventional chemotherapy (incl. hydroxyurea),
radiotherapy, and use of cytokines (interferon α)
A neoplastic stem cell disorder possessing
a JAK-2 mutation, which leads to
excessive production of all myeloid cell
lines, but predominantly red cells.
A. Bone Marrow
Initially hypercellular bone marrow with
distinct proliferation of all three cell lineages
with emphasis on erythropoiesis .
Further disease progression fibrosis
B. Peripheral Blood
Normochromic normocytic erythrocytosis,
Thrombocytosis in > 50% of cases.
Neutrophilia and basophilia.
The clinical course is characterized by two phases:
Initial proliferative phase with increased
“Spent phase” with increasing cytopenia, bone
marrow fibrosis, extramedullary hematopoiesis
and progressive splenomegaly
Symptoms are due to
A.Increased blood viscosity,
D.The underlying malignancy
1. Hemoglobin ≥18.5 g/dL in men, 16.5 g/dL in women
2. Presence of JAK2 V 617F
1. Hypercellular BM with panmyelosis and prominent erythroid
2. Serum erythropoietin level
3. Endogenous erythroid colony formation in vitro
Diagnosis = 2 major + 1 minor or
first major + 2 minor
A. Secondary Polycythemia
Dehydration, pulmonary / cardiac disease
Sleep apnea syndrome, smoking
Height adaptation (stay at heights of > 2,000 m)
B. Erythropoietin ↑↑
Paraneoplastic syndromes (renal cell carcinoma
cerebellar hemangioblastoma, lung cancer,
Hypervolemia with hyperviscosity and
pathologic microcirculation (pulmonary /
cerebral / renal)
Thromboembolic events / hemorrhage
Development of osteomyelo-fibrosis
Transformation to Acute Leukemia
1. Phlebotomy: One unit of blood (approximately
500 mL) is removed weekly until the hematocrit is
< 45%; the hematocrit is maintained at < 45% by
repeated phlebotomy as necessary.
2. Chemotherapy: Patients for whom
phlebotomy is problematic (because of poor
venous access) may be managed primarily
3. Allogeneic bone marrow or stem cell
transplantation in patients < 70–75 years
with severe polycythemia
4. Inhibitors of mutated JAK2
•Ten-year survival: 40–50% of patients
• Median survival: 9–12 years
Hematopoietic stem cell disease with clonal
expansion of thrombocytopoiesis and
thrombocytosis > 450,000/μl.
Median age at presentation 60–70 years
Male: female = 3:4
Incidence 1–2 cases/1,000,000/year
A. Bone Marrow
Pronounced proliferation of large mature
No signs of leukoerythroblastosis.
B. Peripheral Blood
Thrombocytosis > 450,000/μl,
A. Initially usually asymptomatic, often accidental diagnosis.
B. Symptoms due to thrombocytic complications:
Weight loss, mild fever, sweating, pruritus
Cerebral, cardiac, or peripheral arterial thrombosis
Deep vein thrombosis of the leg, pulmonary emboli
Skin symptoms: erythromelalgia (“burning feet
syndrome”), ischemic acrocyanosis, and even gangrene
CBC: thrombocytosis > 450,000/μl
Routine laboratory tests :
serum K+ often ↑↑ (pseudohyperkalemia due to K+
release from platelets).
Leukocyte alkaline phosphatase: normal / ↑ .
Platelet function test, bleeding time
Analysis of JAK-2 mutation status (V617F)
A. Sustained platelet count ≥ 450 χ 109/L
B. Bone marrow biopsy specimen showing proliferation
mainly of the megakaryocytic lineage with increased
numbers of enlarged, mature megakaryocytes
C. Not meetingWHO criteria for PV, PMF, CML, MDS, or other
D. Demonstration of JAK2V617F or other clonal marker, or in
the absence of a clonal marker, no evidence for reactive
Diagnosis requires meeting all 4 criteria.
A. Other myeloproliferative neoplasms (CML,
B. Myelodysplastic syndromes (MDS)
C. Secondary thrombocytosis
− Following splenectomy
− Chronic iron deficiency, hemolytic anemia, blood loss
− Acute-phase reaction to infection / tumors / vasculitis /
allergic reactions, etc.
2. ASA: 100 mg od
3. Chemotherapy : hydroxyurea 0.5–1.5 g/day
4. Anagrelide (dipyridamole analog)
Action: inhibits the phosphodiesterase and phospholipase A2
leading to inhibition of megakaryopoiesis and the
5. Interferon-α 3–5 × 106 IU s.c. 3 times weekly,
pegylated interferon-α 50–100/μg weekly.
Essential thrombocythemia patients have
an almost normal life expectancy.
Malignant stem cell disease with BM fibrosis
and successive suppression of hematopoietic
active bone marrow.
Median age at presentation 50–70 years:
greater incidence in men
Clonal myeloproliferation, atypical megakaryocytic hyperplasia
→ Stimulation of normal fibroblasts, collagen synthesis,
angiogenesis in response to increased PDGF.
→ Increasing reactive bone marrow fibrosis (transition of
prefibrotic to fibrotic stage)
→ Suppression of normal hematopoiesis and anemia
→ Extramedullary hematopoiesis in spleen, liver, and other
A) Initially asymptomatic, often diagnosed accidentally.
B) As bone marrow fibrosis increases and normal
General symptoms (reduced performance status, anorexia,
weight loss, fever, possibly night sweats)
Anemia, weakness, fatigue, decreased performance, pallor
leukopenia: susceptibility to infection, mucositis
Thrombocytopenia: tendency to bleed (gastrointestinal
Splenomegaly, hepatomegaly (extramedullary
Patients are almost invariably anemic at presentation.
The white blood count is variable—either low, normal, or
The platelet count is variable.
The peripheral blood smear is dramatic, with
significant poikilocytosis and
numerous teardrop forms in the red cell line.
Nucleated red blood cells are present and
the myeloid series is shifted, with immature forms including a
small percentage of promyelocytes or myeloblasts.
Platelet morphology may be bizarre, and giant degranulated
platelet forms (megakaryocyte fragments) may be seen.
The triad of teardrop poikilocytosis, leukoerythroblastic
blood, and giant abnormal platelets is highly suggestive of
The bone marrow usually cannot be aspirated (dry
tap), though early in the course of the disease it is
hypercellular, with a marked increase in
megakaryocytes. Fibrosis at this stage is detected by a
silver stain demonstrating increased reticulin fibers.
Later, biopsy reveals more severe fibrosis, with
eventual replacement of hematopoietic precursors by
There is no characteristic chromosomal abnormality.
JAK2 is mutated in ~65% of cases.
A. Other myeloproliferative syndromes (CML,
essential thrombocythemia, polycythemia vera)
B. Aplastic anemia, bone marrow metastases
C. Chronic infections (miliary tuberculosis,
Anemic patients are supported with transfusion. Anemia can
also be controlled with androgens, prednisone, thalidomide, or
First-line therapy for myelofibrosis-associated splenomegaly is
hydroxyurea, which is effective in reducing spleen size by half in
approximately 40% of patients.
Radiation therapy has a role for painful sites of extramedullary
hematopoiesis, pulmonary hypertension, or severe bone pain.
Transjugular intrahepatic portosystemic shunt might also be
considered to alleviate symptoms of portal hypertension.
The immunomodulatory medications, lenalidomide and
pomalidomide, result in control of anemia in 25% and
thrombocytopenia in ~58% of cases, without significant
reduction in splenic size.
There are several JAK2 inhibitors in development.
Ruxolitinib, a JAK2 inhibitor, has been approved by the US
Food and Drug Administration for myelofibrosis. Even though
treatment with ruxolitinib can exacerbate cytopenias, it results
in reduction of spleen size, improvement of constitutional
symptoms, and may lead to an overall survival benefit in
patients with an intermediateor high-risk disease.
The only potentially curative option for this disease is
allogeneic stem cell transplantation in selected patients.
CML is a myeloproliferative disorder
characterized by overproduction of myeloid
cells. These myeloid cells continue to
differentiate and circulate in increased
numbers in the peripheral blood.
CML is characterized by a specific chromosomal abnormality
and specific molecular abnormality. The Philadelphia
chromosome is a reciprocal translocation between the long
arms of chromosomes 9 and 22.The portion of 9q that is
translocated contains abl, a protooncogene that is the
cellular homolog of the Ableson murine leukemia virus.
The abl gene is received at a specific site on 22q, the break
point cluster (bcr). The fusion gene bcr/abl produces a novel
protein that differs from the normal transcript of the abl
gene in that it possesses tyrosine kinase activity.This
disorder is the first example of tyrosine kinase “addiction” by
Early CML (“chronic phase”) does not behave like a
Normal bone marrow function is retained, white
blood cells differentiate and, despite some
qualitative abnormalities, the neutrophils combat
However, untreated CML is inherently unstable, and
without treatment the disease progresses to an
accelerated and then acute blast phase, which is
morphologically indistinguishable from acute
Symptoms and Signs
CML is a disorder of middle age (median age at presentation is 55
Patients usually complain of fatigue, night sweats, and low-grade
fevers related to the hypermetabolic state caused by
overproduction of white blood cells.
Patients may also complain of abdominal fullness related to
Rarely, the patient will present with a clinical syndrome related to
leukostasis with blurred vision, respiratory distress, or
priapism. The white blood count in these cases is usually
< 500,000/mcL (500 × 109/L).
On examination, the spleen is enlarged
(often markedly so), and sternal tenderness
may be present as a sign of marrow
Acceleration of the disease is often
associated with fever in the absence of
infection, bone pain, and splenomegaly.
CML is characterized by an elevated white blood count; the
median white blood count at diagnosis is 150,000/mcL (150 × 109/L)
The peripheral blood is characteristic.
The myeloid series is left shifted, with mature forms dominating and
with cells usually present in proportion to their degree of maturation.
Blasts are usually < 5%.
Basophilia and eosinophilia of granulocytes may be present.
At presentation, the patient is usually not anemic.
Red blood cell morphology is normal, and nucleated red blood cells are
rarely seen.The platelet count may be normal or elevated (sometimes
to strikingly high levels).
The bone marrow is hypercellular, with left-shifted myelopoiesis.
Myeloblasts comprise < 5% of marrow cells.
The hallmark of the disease is that the bcr/abl gene is
detected by the PCR test in the peripheral blood.
A bone marrow examination is not necessary for diagnosis,
although it is useful for prognosis and for detecting other
chromosomal abnormalities in addition to the Philadelphia
With progression to the accelerated and blast phases,
progressive anemia and thrombocytopenia occur, and
the percentage of blasts in the blood and bone marrow increases.
Blast phase CML is diagnosed when blasts comprise more than
20% of bone marrow cells.
Early CML must be differentiated from the reactive
leukocytosis associated with infection. In such cases,
the white blood count is usually < 50,000/mcL (< 50 × 109/L),
splenomegaly is absent, and
the bcr/abl gene is not present.
CML must be distinguished from other
myeloproliferative disease .
The hematocrit should not be elevated,
the red blood cell morphology is normal, and
nucleated red blood cells are rare or absent.
Definitive diagnosis is made by finding the bcr/abl gene.
Normalization of the hematologic abnormalities
Suppression of the malignant, bcr/abl-expressing
The treatment of choice consists of a tyrosine kinase
inhibitor targeting the aberrantly active abl kinase.
It is expected that a hematologic complete remission, with
normalization of blood counts and splenomegaly will occur
within 3 months of treatment initiation.
Second, a major cytogenetic response should be achieved,
ideally within 3 months but certainly within 6 months.
Lastly, a major molecular response is desired within 12
months and is defined as a 3-log reduction of the bcr/abl
transcript as measured by quantitative PCR.
Patients who achieve this level of molecular response have an
excellent prognosis, with 100% of such patients remaining
free of progression at 8 years.
Imatinib mesylate was the first tyrosine kinase inhibitor
to be approved and it results in nearly universal (98%)
hematologic control of chronic phase disease at a dose of
The second-generation tyrosine kinase inhibitors,
dasatinib and nilotinib, have also been approved for use
as front-line therapy and have been shown to significantly
increase the rate of achievement of a major molecular
response compared to imatinib .
A dual bcr/abl tyrosine kinase inhibitor, bosutinib, was
approved in 2012 for patients who are resistant or
intolerant to the other tyrosine kinase inhibitors.
Patients who cannot achieve a good
molecular response to any of these agents or
progress following therapy should be
considered for treatment with allogeneic
Patients with advanced-stage disease (accelerated
phase or myeloid/lymphoid blast crisis) should be
treated with a tyrosine kinase inhibitor alone or in
combination with myelosuppressive chemotherapy.
The doses of tyrosine kinase inhibitors in that setting are
usually higher than those appropriate for chronic-phase
Since the duration of response to tyrosine kinase
inhibitors in this setting is limited, these patients should
ultimately be considered for allogeneic stem cell
Patients with good molecular responses to
tyrosine kinase inhibitor therapy have an
excellent prognosis, with essentially 100%
survival at 9 years, and it is likely that some
fraction of these patients will be cured.