HEMATOLOGIC MALIGNANCIES Failure of terminal differentiation Failure of differentiated cells to undergo apoptosis Failure to control growth Neoplastic “stem cell” BIOLOGY

FAILURE OF TERMINAL DIFFERENTIATION Result: accumulation of rapidly dividing immature cells Example: acute leukemias, aggressive lymphomas

FAILURE TO UNDERGO APOPTOSIS Result: accumulation of relatively well- differentiated, slow-growing cells Example: chronic lymphocytic leukemia, indolent lymphomas

THE NEOPLASTIC STEM CELL Propagation of malignant clone may depend on a subset of cells with stem cell-like properties Some neoplastic stem cells retain the ability to differentiate into more than one cell type (eg, myeloproliferative/myelodysplastic disorders) Eradication of neoplastic stem cell essential to cure disease? Neoplastic stem cells may be slow-growing and resistant to treatment

Blood 2006;107:265

MYELOID NEOPLASIA Myeloproliferative disorders  Polycythemia vera  Essential thrombocytosis  Myelofibrosis/myeloid metaplasia  Chronic myelogenous leukemia Myelodysplasia Acute myelogenous leukemia

MYELOPROLIFERATIVE DISORDERS Affected cell: myeloid stem cell  All three cell lines affected; clonal hematopoiesis in most cases Differentiation: normal to mildly abnormal Kinetics: effective hematopoiesis Marrow: hypercellular, variably increased reticulin fibrosis Peripheral blood: increase in one or more cell lines in most cases  Exception: myelofibrosis

MYELOPROLIFERATIVE DISORDERS Polycythemia Vera Essential Thrombocythemia Myelofibrosis/Myeloid Metaplasia Chronic Myelogenous Leukemia

Polycythemia veraEssential thrombocythemia

Myeloid metaplasiaCML

MARROW FIBROSIS H&EReticulin stain

MYELOPROLIFERATIVE DISORDERS Diagnosis usually determined by peripheral blood counts High Hct or platelet count may cause vaso- occlusive symptoms Risk of portal vein thrombosis Splenomegaly, constitutional symptoms frequent Phlebotomy to control high Hct, hydroxyurea or other myelosuppressive Rx to control platelets, constitutional sx, etc Transition to myelofibrosis or acute leukemia possible

VASO-OCCUSION IN POLYCYTHEMIA VERA

NEJM 2004; 350:99

SPLENOMEGALY IN MYELOFIBROSIS Mayo Clin Proc 2004;79:503

JAK2 MUTATION IN CHRONIC MYELOPROLIFERATIVE DISORDERS Activation of JAK2 tyrosine kinase by cytokines initiates an important signaling pathway in myeloid cells A single point mutation of JAK2 (Val617Phe) has been identified in a high proportion (65-95%) of patients with polycythemia vera, and also in a substantial proportion of cases of essential thrombocytosis and myelofibrosis This mutation markedly increases the sensitivity of the cells to the effects of erythropoietin and other cytokine growth factors Testing for this mutation represents an important diagnostic tool This finding may lead to development new targeted therapies for myeloproliferative disorders

Mayo Clin Proc 2005;80:947

Diagnostic algorithm for polycythemia vera Mayo Clin Proc 2005;80:947

CHRONIC MYELOGENOUS LEUKEMIA Virtually all cases have t(9;22) (Ph1 chromosome) or variant translocation involving same genes bcr gene on chromosome 22 fused with abl gene on 9 Fusion gene encodes active tyrosine kinase Clonal expansion of all myeloid cell lines BIOLOGY

NEJM 2003;349:1451

CHRONIC MYELOGENOUS LEUKEMIA Blood smearMarrow biopsyBuffy coat

LEUKOSTASIS IN CML NEJM 2005;353:1044 WBC 300K

CHRONIC MYELOGENOUS LEUKEMIA Incidence 1:100,000/yr Peak incidence in 40s and 50s Leukocytosis with mixture of mature and immature forms Thrombocytosis common Splenomegaly, constitutional symptoms, eventual leukostasis Transition to acute leukemia (blast crisis) in 20%/yr  blasts may be myeloid or lymphoid  essentially 100% mortality without BMT Natural history

CHRONIC MYELOGENOUS LEUKEMIA Gleevec (imatinib) – inhibits bcr-abl protein kinase Hydroxyurea Alfa interferon Early allogeneic BMT in eligible pts (vs Gleevec Rx?) TREATMENT

NEJM 2003;349:1399

MYELODYSPLASIA Affected cell: myeloid stem cell  All cell lines affected, clonal hematopoiesis Differentiation: mildly to severely abnormal  Morphology and function may be affected Kinetics: Ineffective hematopoiesis (apoptosis of maturing cells in marrow) Marrow: variable cellularity Peripheral blood: decrease in one or more cell lines (usually anemia with or without other cytopenias)  Platelets and WBC occasionally increased Cytogenetic abnormalities frequent Risk of transition to acute leukemia high when marrow blast count > 5%

MYELODYSPLASIA Myelodysplastic disorders Refractory anemia Refractory anemia with ringed sideroblasts Refractory cytopenia with multilineage dysplasia Refractory anemia with excess blasts-1 (5-10% blasts) RAEB-2 (10-20% blasts) Mixed myeloproliferative/myelodysplastic disorders Chronic myelomonocytic leukemia Atypical CML (bcr-abl negative) WHO Classification

SURVIVAL IN MYELODYSPLASIA Overall survivalLeukemia-free survival J Clin Oncol 2005;23:7594 * Mortality of low-risk (RA) patients >70 no different from general population *

Myelodysplasia: blood smear

Myelodysplasia: blood smears with abnormal neutrophils

Myelodysplasia: marrows showing dyserythropoeisis and hypolobulated megakaryocyte

Myelodysplasia: acquired  -thalassemia with Hgb H inclusions in RBC. This is caused by somatic mutations in the  -globin gene or an associated regulatory gene, limited to the neoplastic clone Blood 2005;105:443

MDS: micromegakarycyteMDS: hypercellular marrow

MDS: ringed sideroblastCMML

RAEB – marrow blasts RAEB – circulating blast, agranular PMN

MYELODYSPLASTIC SYNDROME Myeloblast (red arrow) and abnl RBC precursor (blue arrow)

ACUTE LEUKEMIA ACUTE LEUKEMIA Biology Leukemic clone: cells unable to terminally differentiate –May be lymphoid or myeloid –AML: May arise from abnormal stem cell (eg in MDS/MPD) or de novo Accumulation of immature cells (blasts) Marrow replaced by leukemic cells Blasts accumulate in blood and other organs

ACUTE LEUKEMIA Bone marrow failure  fatigue (anemia)  infection (neutropenia)  bleeding (thrombocytopenia) Tissue infiltration  organomegaly  skin lesions  organ dysfunction  pain Pathophysiology

ACUTE LEUKEMIA Leukostasis (WBC > K)  retinopathy  encephalopathy/CNS bleeding  pneumonopathy Biochemical effects of leukemic cell products  hyperuricemia/tumor lysis syndrome  DIC  renal tubular dysfunction (lysozymuria)  lactic acidosis  hypercalcemia (rare)  spurious hypoglycemia/hypoxemia/hyperkalemia Pathophysiology (cont)

Hyperleukocytosis in AML NEJM 2003;349:767 NormalPatient (WBC 250K) 26 yo with fever, encephalopathy, retinopathy, dyspnea, lymphadenopathy

ACUTE LEUKEMIA Clinical setting Morphology Histochemistry Surface markers Cytogenetics Molecular genetics Information used in classification

ACUTE LEUKEMIA Old age, poor performance status Therapy-induced Prior myelodysplastic/myeloproliferative disorder High tumor burden Cytogenetics: Ph 1 chromosome, deletion of 5 or 7, multiple cytogenetic abnormalities Adverse prognostic features

ACUTE MYELOGENOUS LEUKEMIA Affected cell: myeloid stem cell or committed progenitor cell Differentiation: arrested at early stage, with absent or decreased maturation Kinetics: marrow replacement by immature cells, decreased normal hematopoiesis Marrow: usually markedly hyercellular with preponderance of blast forms  Hypocellular variants known Peripheral blood: variable decrease in all cell lines with or without circulating immature cells

ACUTE MYELOGENOUS LEUKEMIA 90% of adult acute leukemia: 2.2 deaths/100,000/yr Incidence rises with age Risk factors: exposure to ionizing radiation, alkylating agents and other mutagens (implicated in10-15% of all cases), certain organic solvents (benzene) Precursor diseases: myelodysplastic & myeloproliferative disorders, myeloma, aplastic anemia, Down syndrome, Klinefelter syndrome, Fanconi syndrome, Bloom syndrome Epidemiology

ACUTE MYELOGENOUS LEUKEMIAS M0 (minimal differentiation) M1 (myeloid blasts) M2 (some differentiation) M3 (promyelocytic) M4 (myelomonocytic) M5 (monocytic) M6 (erythroleukemia) M7 (megakaryoblastic leukemia) Unclassifiable (evolved from MDS, other secondary leukemias) FAB (French-American-British) classification Newer classification schemes place more emphasis on cytogenetics and less on morphology

WHO classification of AML AML with recurrent cytogenetic abnormalities –t(8;21) –inv(16) –Acute promyelocytic leukemia – t(15;17) and variants –AML with 11q23 (MLL gene) abnormalities AML with multilineage dysplasia AML/MDS, therapy-related AML not otherwise categorized –Minimally differentiated –Without maturation –With maturation –Acute myelomonocytic leukemia –Acute monoblastic and monocytic leukemia –Acute erythroid leukemia –Acute megakaryblastic leukemia –Acute basophilic leukemia –Acute panmyelosis with myelofibrosis –Myeloid sarcoma AML with ambiguous lineage –Undifferentiated AML –Bilineal AML –Biphenotypic AML

ACUTE PROMYELOCYTIC LEUKEMIA t (15;17) Translocation involves retinoic acid receptor gene High incidence of DIC/fibrinolysis All-trans retinoic acid induces remission in high proportion of cases Favorable prognosis (APML; FAB M3)

M1 M0

M2M3

M5M4

M7M6

Auer rod in AML

ACUTE LYMPHOCYTIC LEUKEMIA Morphology (FAB)  L1 (uniform)  L2 (pleomorphic)  L3 (Burkitt-type) Immunophenotypic  B-cell (Burkitt-type, 2-3% of cases)  Pre-B cell (80% )  T-lineage  Mixed lineage (lymphoid-myeloid) Classification

L1 ALLL2 ALLL3 ALL

ACUTE LYMPHOCYTIC LEUKEMIA About 3000 cases/yr in US 2/3 of cases in children (most common childhood cancer) In adults, most cases in elderly Epidemiology

ACUTE LEUKEMIA Remission induction: aggressive combination chemotherapy Post-remission  AML: consolidation (high-dose) or auto-BMT  ALL: consolidation, then maintenance (lower dose) Allogeneic bone marrow transplant in selected patients Cure rates 75%+ in childhood ALL; as high as 50% in "good risk" adults, up to 60% in BMT recipients Overall cure rates still low in adults Treatment

SURVIVAL ACCORDING TO AGE IN PATIENTS WITH FAVORABLE CYTOGENETICS TREATED FOR AML (Excluding APML) Blood 2006;107:3481

SURVIVAL ACCORDING TO AGE IN PATIENTS WITH INTERMEDIATE CYTOGENETICS TREATED FOR AML Blood 2006;107:3481

SURVIVAL ACCORDING TO AGE IN PATIENTS WITH UNFAVORABLE CYTOGENETICS TREATED FOR AML Blood 2006;107:3481

EFFECT OF AGE AND PERFORMANCE STATUS ON EARLY MORTALITY IN TREATED AML Blood 2006;107:3481