1. The Chronic Myeloproliferative Disorders
Dr.Mahmoodzadeh
Hemathologist-Oncologist

2. The Chronic Myeloproliferative Disorders
Polycythemia vera (PV)
Essential thrombocytosis (ET)
Primary myelofibrosis (PMF)
All 3 are clonal stem cell disorders in which there is:
“Overproduction” of 1 or more of the formed elements of the blood
Splenomegaly due to extramedullary hematopoiesis
Myelofibrosis
Transformation to acute leukemia at variable but low rates
The 3 disorders were recently reclassified by the WHO as myeloproliferative neoplasms

3. The Revised WHO Classification of the Chronic MPDs
MYELOPROLIFERATIVE NEOPLASMS
Chronic myeloid leukemia, BCR-ABL1-positive
Chronic neutrophilic leukemia
Polycythemia vera
Essential thrombocytosis
Primary myelofibrosis
Chronic eosinophilic leukemia, not otherwise specified
Mastocytosis
Myeloproliferative neoplasms, unclassifiable

4. Rationale for Classifying PV, ET, and PMF Separately From the Myeloproliferative Neoplasms
These 3 disorders share in common mutations in the JAK2 and MPL genes
There is an inherent (germline) patient proclivity to JAK2 and MPL mutations
Constitutive signal transduction in these disorders occurs through normal signaling pathways
Phenotypic mimicry and clinical overlap occur between these 3 disorders but not between them and the other MPNs
Targeted therapy has been developed for PV, ET, and PMF

5. The Phenotypic Mimicry of the Chronic Myeloproliferative Disorders
Essential Thrombocytosis
“Isolated Thrombocytosis”
Primary Myelofibrosis
Acute
Leukemia
Polycythemia Vera
“All pathways lead to polycythemia vera”

6. Cytokine Receptors Utilizing Janus Family Kinases.

7. Granulocyte-Monocyte
Hematopoietic Stem Cell Hierarchy
Pluripotent
Hematopoietic
Stem Cell
Common
Hematopoietic
Stem Cell
T Lymphocytes
B Lymphocytes
Erythroid Progenitors
Granulocyte-Monocyte
Progenitors
Megakaryocytic
Progenitors
JAK2V617F
Polycythemia vera is the ultimate consequence of the JAK2V617F mutation

8. *Some of these patients have JAK2 exon 12 mutations
JAK2V617F Expression in the Chronic Myeloproliferative Disorders PV
PMF ET
JAK2V617F+
92%
42%
45%
JAK2V617F–
8%*
58%
55%
*Some of these patients have JAK2 exon 12 mutations

9. Effect of JAK2V617F Expression on Clinical PhenotypePV ET
PMF
Age -
Older
Hemoglobin
Higher (+/+)
Higher
Fewer transfusions
Leukocyte count
Thrombosis
More (venous)
Pruritus
More (+/+) +
Transformation
Fibrosis (+/+)
Survival
Longer(?)

10. JAK2V617F Is Not the Initiating Mutation in the 3 MPDs
Hematopoietic stem cells do not require JAK2 for their survival or proliferation
JAK2V617F is not present in some patients with familial polycythemia vera
JAK2V617F can arise as a secondary event in clones expressing a cytogenetic abnormality or another mutation
Leukemic transformation in patients with JAK2V617F-positive MPD can occur in a JAK2V617F-negative type cell
BUT: JAK2 is the major final common signaling pathway in all chronic MPDs and, therefore, whether mutated or not, is an appropriate therapeutic target

11. Polycythemia Vera
Polycythemia vera is a chronic myeloproliferative disorder in which there is overproduction of morphologically normal red blood cells, white blood cells, and platelets in the absence of a definable stimulus
Erythrocytosis is the feature that distinguishes polycythemia vera from the other 2 chronic myeloproliferative disorders
There is currently no specific clonal diagnostic marker for polycythemia vera

12. Causes of Absolute Erythrocytosis Causes of Relative Erythrocytosis
Hypoxia
Carbon monoxide intoxication (tobacco abuse, environmental)
High-affinity hemoglobins
High altitude
Pulmonary disease
Right-to-left shunts
Sleep apnea syndrome
Neurologic disease
Renal Disease
Renal artery stenosis
Focal sclerosing or membranous glomerulonephritis
Renal transplantation
Tumors
Hypernephroma
Hepatoma
Cerebellar hemangioblastoma
Uterine fibromyoma
Adrenal tumors
Meningioma
Pheochromocytoma
Drugs
Androgenic steroids
Recombinant erythropoietin
Familial (with normal hemoglobin function; Chuvash; EPO receptor mutations; 2,3 BPG deficiency)
Polycythemia vera
JAK2V617F
JAK2 exon 12 mutations
Causes of Relative Erythrocytosis
Loss of Fluid From the Vascular Space
Emesis
Diarrhea
Diuretics
Sweating
Polyuria
Hypodipsia
Hypoalbuminemia
Capillary leak syndromes,
burns
Peritonitis
Chronic Plasma Volume Contraction
Hypoxia from any cause
Androgen therapy
Recombinant erythropoietin therapy
Hypertension
Tobacco use
Pheochromocytoma
Ethanol abuse
Sleep apnea
Only ~5 % of patients with absolute erythrocytosis are likely to have polycythemia vera

13. Proposed Revised WHO Criteria for Polycythemia Vera
Major criteria
1. Hemoglobin > 18.5 g/dL in men, 16.5 g/dL in women or other evidence of increased red blood cell volume*
2. Presence of JAK2617V > F or other functionally similar mutation such as JAK2 exon 12 mutation
Minor criteria
1. Bone marrow biopsy showing hypercellularity for age with trilineage growth (panmyelosis) with prominent erythroid, granulocytic, and megakaryocytic proliferation
2. Serum erythropoietin level below the reference range for normal
3. Endogenous erythroid colony formation in vitro
Diagnosis requires the presence of both major criteria and 1 minor criterion or the presence of the first major criterion together with 2 minor criteria.
*Hemoglobin or hematocrit greater than 99th percentile of method-specific reference range for age, sex, altitude of residence or hemoglobin greater than 17 g/dL in men, 15 g/dL in women if associated with a documented and sustained increase of at least 2 g/dL from an individual’s baseline value that cannot be attributed to correction of iron deficiency, or elevated red blood cell mass greater than 25% above mean normal predicted value. .

14. Diagnostic Criteria A1 Raised red cell mass A2 Normal O2 sats and EPO
A3 Palpable spleen
A4 No BCR-ABL fusion
B1 Thrombocytosis >400 x 109/L
B2 Neutrophilia >10 x 109/L
B3 Radiological splenomegaly
B4 Endogenous erythroid colonies
A1+A2+either another A or two B establishes PV

15. Red cell mass and plasma volume measurements
Algorithm for the Diagnosis of Polycythemia Vera
Elevated hemoglobin or hematocrit
Red cell mass and plasma volume measurements
Elevated red cell mass
Both normal
O2 saturation
Normal red cell mass
Decreased plasma volume
> 93%
< 93%
JAK2V617F
Hypoxic erythrocytosis
Tobacco use
Androgens
Diuretics
Pheochromocytoma + –
Polycythemia vera
Serum erythropoietin level
Normal or low
Polycythemia vera
EPO-receptor mutation
Renal disease
Tumors
High-affinity hemoglobins
Elevated
Renal disease
Tumors
VHL mutation
High-affinity hemoglobins ..

16. Essential Thrombocytosis
Also known as essential thrombocythemia, hemorrhagic thrombocytosis, idiopathic thrombocytosis, or primary thrombocytosis
Disorder of unknown etiology
Principal clinical feature is the overproduction of platelets in the absence of a definable cause
No specific diagnostic marker

17. Causes of Thrombocytosis
Tissue inflammation
Collagen vascular disease, inflammatory bowel disease
Malignancy
Infection
Myeloproliferative disorders
Polycythemia vera, primary myelofibrosis, essential thrombocytosis, chronic myelogenous leukemia
Myelodysplastic disorders
5q-syndrome, idiopathic refractory sideroblastic anemia
Postsplenectomy or hyposplenism
Hemorrhage
Iron deficiency anemia
Surgery
Rebound
Correction of vitamin B12 or folate deficiency, post-ethanol abuse
Hemolysis
Familial
Thrombopoietin overproduction, constitutive Mpl activation, K39N

18. Diagnostic criteria for ET
Platelet count >600 x 109/L for at least 2 months
Megakaryocytic hyperplasia on bone marrow aspiration and biopsy
No cause for reactive thrombocytosis
Absence of the Philadelphia chromosome
Normal red blood cell (RBC) mass or a HCT <0.48
Presence of stainable iron in a bone marrow aspiration
No evidence of myelofibrosis
No evidence of MDS

22. Therapy of ET based on the risk of thrombosis

23. Diagnostic Criteria for Essential Thrombocytosis
Persistent thrombocytosis more than 400 x 109/L in the absence of a reactive cause*
Absence of iron deficiency (normal serum ferritin for sex)
JAK2V617F assay (peripheral blood; expression establishes the presence of an MPD but not its type; absence does not exclude an MPD)
Hemoglobin less than 16 g/dL in a man or less than 14 g/dL in a woman (hematocrit < 47% in a man or < 44% in a woman) in the absence of splenomegaly; otherwise, red blood cell mass and plasma volume determinations are mandatory if a JAK2V617F assay is positive
Negative Bcr-Abl FISH (peripheral blood) if a JAK2V617F assay is negative
If there is anemia, macrocytosis, or leukopenia, or evidence of extramedullary hematopoiesis (ie, circulating nucleated erythrocytes, immature myelocytes, or splenomegaly), a bone marrow examination (including flow cytometry and cytogenetics) is mandatory regardless of JAK2V617F expression status

24. Primary Myelofibrosis
Also known as agnogenic myeloid metaplasia, idiopathic myelofibrosis, myelofibrosis and myeloid metaplasia, or primary osteomyelofibrosis
Clonal stem cell disorder involving a pluripotent hematopoietic stem cell resulting in disordered blood cell production, marrow fibrosis, and extramedullary hematopoiesis, most prominently involving the spleen, with eventual bone marrow failure or transformation to acute leukemia in some patients

25. Causes of Myelofibrosis
Malignant
Acute leukemia (lymphocytic, myelogenous, megakaryocytic)
Chronic myelogenous leukemia
Hairy cell leukemia
Hodgkin disease
Primary myelofibrosis
Lymphoma
Multiple myeloma
Myelodysplasia
Metastatic carcinoma
Polycythemia vera
Systemic mastocytosis
Non-Malignant
HIV infection
Hyperparathyroidism
Renal osteodystrophy
Systemic lupus erythematosus
Tuberculosis
Vitamin D deficiency
Thorium dioxide exposure
Gray platelet syndrome
Thrombopoietin receptor agonists

26. Diagnostic Criteria for Primary Myelofibrosis
Leukoerythroblastic blood picture
Increased marrow reticulin in the absence of an infiltrative or granulomatous process
Splenomegaly
JAK2V617F assay (peripheral blood; expression establishes the presence of an MPD but not its type; PV is always a consideration; absence does not exclude an MPD)
Increased circulating CD34+ cells (> 15 x 106/L) and no increase in marrow CD34+ cells by in situ immunohistochemistry
Characteristic cytogenetic abnormalities (peripheral blood: del(13q), 9p, del(20q), del(12p), partial trisomy 1q, trisomy 8, and trisomy 9)
Absence of Bcr-Abl, AML, or MDS cytogenetic abnormalities by FISH (peripheral blood)

27. The Consequences of Polycythemia Vera
Cause
Thrombosis, systemic hypertension, hemorrhage
Elevated red blood cell mass, decreased von Willebrand factor multimers
Organomegaly, pulmonary hypertension
Extramedullary hematopoiesis or elevated red blood cell mass
Pruritus, acid-peptic disease
Inflammatory mediators
Erythromelalgia
Thrombocytosis
Hyperuricemia, gout, renal stones
Increased cell turnover
Myelofibrosis
Reaction to the neoplastic clone
Acute leukemia
Therapy-induced or clonal evolution (“Richter syndrome”)

28. The Challenges of Treating Polycythemia Vera
In a study of 1213 patients with PV, cancer-free survival and survival analyses for death or major thrombosis were better among patients who did not receive chemotherapy[a]
In a prospective, controlled clinical trial of 292 patients with PV, hydroxyurea did not prevent thrombosis or myelofibrosis[b]
Hydroxyurea therapy was associated with a late (> 10 years) risk for transformation to acute leukemia[b,c]
In a study of 40 patients with PV, pegylated interferon alfa-1a induced complete hematologic and molecular responses with low toxicity[d]

29. The Complications of Polycythemia Vera and Their Management
Erythrocytosis
Phlebotomy; (new JAK2 inhibitors)
Pruritus
Antihistamines; (new JAK2 inhibitors); pegylated interferon; psoralens and ultraviolet-A light ; hydroxyurea
Erythromelalgia; ocular migraine
Aspirin; anagrelide; (new JAK2 inhibitors); pegylated interferon; hydroxyurea
Thrombosis (arterial; venous)
Phlebotomy; aspirin; coumadin; hydroxyurea (transient ischemic attack only)
Thrombocytosis
(new JAK2 inhibitors); anagrelide; pegylated interferon; hydroxyurea
Hemorrhage
Epsilon aminocaproic acid
Leukocytosis
(new JAK2 inhibitors); pegylated interferon; hydroxyurea
Hyperuricemia
Allopurinol (uric acid ~10 mg %)
Splenomegaly
(new JAK2 inhibitors); pegylated interferon; thalidomide; hydroxyurea; imatinib; splenectomy

30. Effect of a JAK2 Inhibitor in 34 Patients With Established PV (Phase 2 trial data)
97% achieved durable hematocrit control in the absence of phlebotomy
59% achieved a durable reduction in splenomegaly of at least 50%
88% achieved a reduction in leukocytosis to ≤ 15 x 109/L
92% achieved a reduction in platelet count to ≤ 600 x 109/L
59% achieved a complete phenotypic remission
92% had durable relief from pruritus in 1 month
The reduction in JAK2V617F allele burden was modest
There were 3 grade 3 adverse events: 2 thrombocytopenia and 1 neutropenia
The nonresponder rate was 3%

31. Complications of Essential Thrombocytosis
Microvascular ischemia
migraine
erythromelalgia
transient ischemic attacks
Macrovascular thrombosis
stroke
acute coronary syndrome
peripheral arterial occlusion
digital gangrene
deep venous thrombosis
Hemorrhage due to acquired von Willebrand disease
Transformation to acute leukemia

32. Treatment Is Not Always Required for Patients With ET
Thrombosis and hemorrhage are infrequent in patients with low-risk ET and the thrombosis rate was not different than normal[a,b]
Thrombosis in patients with ET reaches a plateau after 9 years[a]
Cytoreduction did not change the complication rate of extreme thrombocytosis[c]
The transformation of ET to high risk does not have an impact on overall survival[a]

33. Management of Thrombocytosis in Essential Thrombocytosis
Asymptomatic thrombocytosis requires no therapy in the absence of a thrombotic (prior thrombosis, tobacco use) or significant hemorrhagic diathesis
Platelet counts ≥ 1000 x 109/L can be associated with reduced von Willebrand factor, high molecular-weight multimers, and ristocetin cofactor activity
Hemorrhage associated with thrombocytosis can be controlled with epsilon aminocaproic acid
Aspirin is the treatment of choice for erythromelalgia unless ristocetin cofactor activity is reduced
For platelet count reduction, particularly in patients under age 60, anagrelide or interferon, if tolerated, are preferable to hydroxyurea. The new JAK2 inhibitors may prove preferable to the above drugs
It is not necessary to lower the platelet count to normal but only to a level that alleviates symptoms

34. Effects of a JAK2 Inhibitor in 39 Patients With Established Thrombocytosis (Phase 2 trial data)
49% normalized their platelet count within 2 weeks
82% maintained a platelet count ≤ 600 x 109/L for 9.8 months
93% with a platelet count ≥ 1000 x 109/L achieved a > 50% reduction
75% had complete resolution of splenomegaly
49% had a complete phenotypic remission
Reduction in the JAK2V617F allele burden was modest
There were 2 grade 3 adverse events involving leukopenia
The nonresponder rate was 8%

35. Complications of Primary Myelofibrosis
Anemia
Hypoproliferative due to folate or iron deficiency, inflammation, autoimmune hemolysis, hemodilution, or impaired stem cell function
Thrombocytopenia
Splenic sequestration, impaired stem cell function
Incapacitating splenomegaly and splenic infarction
Portal hypertension
Pulmonary hypertension
Organ compromise due to extramedullary hematopoiesis
Obstructive uropathy
Intestinal obstruction
Ascites
Pleural effusions
Hepatic failure
Fibrous tumors
Spinal or cranial compression
Bone pain due to periostitis or increased intramedullary vascularity
Bone marrow failure with pancytopenia
Acute leukemia

36. Management of Primary Myelofibrosis
Low-risk patients under age 45 should be considered for marrow transplantation if a matched sibling donor is available
High-risk patients up to age 65 may benefit from reduced-intensity conditioning marrow transplantation[a]
Symptomatic anemia may respond to corticosteroids, recombinant erythropoietin, folate, danazol, or low-dose thalidomide, or possibly targeted JAK2 inhibition[b]
Constitutional symptoms respond to targeted JAK2 inhibition[c]
Splenomegaly may respond to targeted JAK2 inhibition, low-dose interferon, low-dose thalidomide and prednisone, or hydroxyurea[c]
Splenic irradiation is only palliative and temporary and is associated with severe neutropenia and infection
Splenectomy is only palliative and can lead to exuberant hepatic extramedullary hematopoiesis or splanchnic vein thrombosis
a. Rondelli D, et al. Blood. 2005;105:4115.
b. Mesa RA, et al. Blood. 2003;101:2534.
c. Verstovsek S, et al. N Engl J Med. 2010;363:1117.

37. Summary
The chronic MPDs — PV, ET, and PMF — are distinct disease entities that share many clinical features (phenotypic mimicry) due to unregulated JAK2 signaling or a similar signaling abnormality
Because these disorders differ with respect to their natural history and survival, diagnosis must be accurate to ensure that therapy is appropriate
Treatment of these 3 disorders should be tailored to fit their clinical manifestations
PV is the most common of the 3 MPDs because it is the ultimate expression of the JAK2V617F mutation
All chemotherapeutic agents are leukemogenic in the MPDs and should be avoided whenever possible, which may now be possible with the new JAK2 inhibitors
JAK2 inhibitors will be very useful for safely reducing splenomegaly, controlling blood counts, and alleviating constitutional symptoms, but will not eradicate these disorders
Pegylated interferon or reduced-intensity conditioning bone marrow transplantation offer the possibility of complete molecular remission