MYELOPROLIFERATIVE DISORDERS EVOLVING CONCEPTS

ANTONIO PARREIRAIPOFG - LISBOA

MPD- PV

- ET

- MF

MDS- RA

- RARS

- RAEB – I

- RAEB - II

CMML

CML

AML

Neoplastic Myeloid disorders

1950

Myeloproliferative disorders - MPD

● Neoplastic (clonal) disorders of hematopoietic stem cells

● Dysregulated proliferation of one / several cell lineages

● Thrombotic and hemorrhagic complications● Fibrosis is frequent● Progression to AML may occur

• Red cells - Polycythemia Rubra Vera – PV

• White cells - Chronic Myeloid Leukemia – CML

• Platelets- Essential Thrombocytemia – ET

• Stroma - Idiopathic Myelofibrosis - IM

Myeloproliferative disorders - MPD

Chronic Myeloid Leukemia15-20% of adult leukemia (1.6/100000)

Increased WBC

Nowell & Ungeford. J Nat Cancer Inst, 1960

David Hungeford

1973. Rowley J. Nature. 1973 Jun 1;243(5405):290-3.

CML was the first human malignancy shown to be ‘due’ to acquisition CML was the first human malignancy shown to be ‘due’ to acquisition

of a fusion protein with activated tyrosine kinase activityof a fusion protein with activated tyrosine kinase activity

ALTERED ADHESION

APTOPTOSIS INHIBITION

MITOGENIC ACTIVATION -

PROLIFERATION

“Blast” crisis(acute leukemia – AML, ALL)

Diag 1 2 3 4 5

Chronic phase

Acceleratedphase

Death

Chronic Myeloid Leukemia – clinical evolution

years

Clonal evolution

Ren R. NATURE REVIEWS | CANCER VOLUME 5 | MARCH 2005

1960 1973 1986 1996 2001

t(9;22)# Ph

Imatinib in vitro

Imatinib therapy

Clinical examination and morphology

Cytogenetics

PCR/interphase cytogenetics

Bcr-Abl

Morphology Molecular lesion Pathophysiology Rational treatment

50 years

New TK inhibitors

46,XY,t(9;22)(q34;q11)

IRIS Trial Results: Cumulative Best Responseat 12 and 60 Months

Adapted from: Druker B et al. ASCO 2006. Abstract 6506.

% r

esp

on

din

g

Months since randomisation to imatinib

57 y ♀ pt, Ph+ CML in chronic phase

BCR-ABL Real-time quantitative PCR follow-up

0,001

0,01

0,1

1

10

100

0 6 18 24 26 29 38 41 45 48 50

Months from diagnosis

% B

CR

-AB

L t

ran

scri

pts

GLIVEC 400 mg

GLIVEC 600 mg

E255V DASATINIB 140 mg/day

IPOFG 2006

Adapted from Campbell and Green, NEJM, 2006;355,2452

Historical perspective of Ph-negative Myeloproliferative Disorders

1892- First description of PV

1951 – PV, ET, IM linked as related disorders

1974 - Identification of EPO-independent erythroid colonies

1976 – Stem-cell origin of PV

1983-2003 – Dysregulated tyrosine kinases described in CML, CMML, Chronic eosinophilic leukemia and mastocytosis

2002 – Mitotic recombination of chromosome 9p as common lesion in PV

2001-2004 – EPO independent growth in PV dependent on JAK-STAT signaling

2005 – Description of JAK2 V617F mutation.

Campbell P and Green A. N Engl J Med 2006;355:2452-2466

Laboratory Features of Polycythemia Vera, Essential Thrombocythemia, and Idiopathic Myelofibrosis

Polycythemia

● True / Absolute– Primary Polycythemia– Secondary polycythemia

● Epo dependent– Hypoxia dependent– Hypoxia independent

● Epo independent– Apparent / Relative

● Reduction in plasma volume

Absolute increase in RBCs, leukocytosis, trhombocytosis

● 2-3 / 100.000● Median age of

presentation – 55-70; M/F: 1.2

● Plethora, generalized pruritus, unusual thrombosis, gout

● Splenomegaly

Polycythemia Rubra Vera - PV

● A1 – raised red cell mass

● A2 - Normal O2 sat and low EPO

● A3 – palpable spleen

● A4 – No BCR-ABL fusion

● B1 – Thrombocytosis > 400

● B2 – Neutrophilia > 10

● B3 – Radiological splenomegaly

● B4 – Endogenous erythroid colonies

● A1+A2+ either one A or two B

Diag criteria

Essential Thrombocythemia - ET

Clonal MPD

Platelets persistently > 600

Lack of positive diagn criteria

2.5 / 100.000

M/F: 2:1

Median age diagn: 60

Transformation

Headache, lightheadness

Syncope

Erythromelalgia (burning hands and feet wih erythema)

Transient visual disturbancies

Thrombosis and haemorrhage

Idiopathic myelofibrosis - IM

Normocytic anemia, poikilocytosis

● Low WBC / Platelets● Hepatosplenomegaly● Extramedulllary

hematopoesis ● BM fibrosis● Rare, M/F: 2:1● Median age diagn: 60● Transformation

agnogenic myeloid metaplasia or

myelofibrosis with myeloid metaplasia

JAK2 V617F MUTATION

•The mutation leads to the constitutive activation of the JAK2 tyrosine kinase

• JAK2 protein is a cytoplasmic tyrosine kinase

AAT TAT GGA GTA TGT GTC TGT GGA GAC GAG

wild type

mutant

617 codon

valine

phenylalanine

AAT TAT GGA GTA TGT TTC TGT GGA GAC GAG

•A single point mutation (G T) in the JH2 pseudokinase domain of the JAK2 gene results in a valine to phenylalanine substitution at amino acid 617 (V617F).

• Two independent studies in 2005 demonstrated that a significant proportion of patients with PV, ET and IM have acquired this somatic mutation (Baxter et al, Lancet 2005, Levine et al, Cancer Cell 2005).

Campbell P and Green A. N Engl J Med 2006;355:2452-2466

Campbell P and Green A. N Engl J Med 2006;355:2452-2466

Role of JAK2 in Pathway Signaling and Erythropoietin Binding, Stem-Cell Differentiation, and Development of Homozygosity for the V617F Mutation

Kralovics R et al. N Engl J Med 2005;352:1779-1790

Possible Roles of the JAK2 V617F Mutation in Myeloproliferative Diseases

Incidence of JAK2 V617F mutation in MPD

Polycythemia Vera 90 - 95% 25 - 30%

Essential Thrombocytemia 35 – 50% 1 – 3 %

Idiopathic Myelofibrosis 50 – 60% 10 – 29%

JAK2 homozygosityJAK2 mutation

Ross and Wernig, Hematology 2006

Campbell P and Green A. N Engl J Med 2006;355:2452-2466

Classification of the Myeloproliferative Disorders on the Basis of Molecular Pathogenetic Characteristics

JAK2 exon 12 mutations

Scott et al, 2007

Diagnostic algorithm for suspected PV in routin clinical practice – Tefferi, ASH 2006

Diagnostic criteria of MPD JAK2 V617F +(proposed by Campbell and Green, 2006)

JAK2+ Polycythemia (Diagn if both criteria)

A1 High hematocrit (>52% M; >48% F) or increased red cell mass (>25% predicted value)

A2 Mutation in JAK2

JAK2+ Thrombocytemia (Diagn if both criteria)

A1 Platelet count > 450x10e9/L

A2 Mutation in JAK2

A3 No other myeloid cancer, especially JAK2 PV, IM or MDS

JAK2+ Myelofibrosis Diagn if A1 and A2 and any two of B criteria)

A1 Reticulin grade 3 or higher

A2 Mutation in JAK2

B1 Palpable spenomegaly

B2 Otherwise unexplained anemia

B3 Teardrop cells on peripheral blood smear

B4 Leucoerythroblastic blood film

B5 Systemic symptoms

B6 Histological evidence of extramedullary hematopoiesis