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Chronic M yeloid Leukemia

Chronic M yeloid Leukemia. Amer Rassam, M.D. Learning Objectives. Myeloproliferative disorders (MPDs) Molecular genetics of chronic myeloid leukemia Clinical manifestations and diagnosis of chronic myeloid leukemia Overview of the treatment of chronic myeloid leukemia

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Chronic M yeloid Leukemia

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  1. Chronic Myeloid Leukemia Amer Rassam, M.D.

  2. Learning Objectives • Myeloproliferative disorders (MPDs) • Molecular genetics of chronic myeloid leukemia • Clinical manifestations and diagnosis of chronic myeloid leukemia • Overview of the treatment of chronic myeloid leukemia • Initial treatment of chronic myeloid leukemia in chronic phase

  3. Learning Objectives • Explain how to define and identify a relapse • Treatment of CML in chronic phase after failure of initial therapy • Clinical use of tyrosine kinase inhibitors for chronic myeloid leukemia • Treatment of CML in accelerated phase and blast crisis • Prognosis

  4. Myeloproliferative Disorders • Chronic Myeloid Leukemia (CML) • Polycythemia Vera (PCV) • Essential Thrombocythemia (ET) • Primary Myelofibrosis (PMF)

  5. Myeloproliferative Disorders • Clonal disorders of hematopoiesis that arise in hematopoietic stem or early progenitor cell. • Characterized by the dysregulated production of particular lineage of mature myeloid cells with fairly normal maturation. • Exhibit a variable tendency to progress to acute leukemia • Share abnormalities of hemostasis and thrombosis • Overlap between the clinical features

  6. Introduction • CML is a clonal myeloproliferative neoplasm • Dysregulated production and uncontrolled proliferation of mature and maturing granulocyte with fairly normal differentiation • Fusion of 2 genes: BCR (or chromosome 22) and ABL1 (on chromosome 9), resulting in BCR-ABL1 fusion gene • Final result: Abnormal chromosome 22 called Philadelphia (Ph) chromosome • Final product: BCR-ABL1 fusion protein, a dysregulated tyrosine kinase

  7. Introduction • Uncontrolled production of mature and maturing granulocytes • Predominantly neutrophils, but also basophils and eosinophils • Triphasic or biphasic clinical course • Chronic phase, accelerated phase, blast crisis

  8. Phases of CML (before Imatinib) Advanced phases Chronic phase Median duration5–6 years Accelerated phase Median duration6–9 months Blast crisis Median survival3–6 months

  9. Epidemiology • Annual incidence: 1 to 2 cases per 100,000 • 15% – 20% of all adult leukemias • Incidence increases significantly with age • Median age: ~ 55 years • Prevalence increasing due to current therapy • Most patients present in CP, 85% • Majority of CML-related deaths due to progression to AP/BC • 50% of CML patients are asymptomatic at diagnosis • Risk factors • Exposure to ionizing radiation, the only known

  10. Molecular Genetics of CML • The Philadelphia chromosome was originally detected by workers in Philadelphia. • The first genetic abnormality to be associated with a human cancer. • The result of a balanced translocation between chromosomes 9 and 22. • Derivative chromosome 22 is significantly smaller • Ph chromosome is present in hematopoietic cells from patients with CML. • Therefore, the Ph chromosome is acquired and NOT inherited through the germline.

  11. Molecular Genetics of CML • The development of chronic phase CML appears to be a direct result of the BCR-ABL1 activity, which promotes its development by allowing: • Uncontrolled proliferation of transformed cells • Discordant maturation • Escape from apoptosis • Altered interaction with the cellular Matrix • The progression of CML from chronic phase to accelerated face or blast crisis is a complex, multistep process (may be related to GMP). • Also, it appears to involve the constitutive expression of the BCR-ABL1 tyrosine kinase.

  12. BCR ABL Ph ABL BCR 9q+ Molecular Genetics of CML { q11 BCR 22 { ABL q34 9

  13. Exons Introns CML Breakpoints ALL Breakpoints Ph chromosome and bcr-abl gene Chromosome 9 Chromosome 22 9 q+ 2-11 c-bcr 1 9 c-abl Ph (or 22q-) 22 2-11 p210Bcr-Abl 2-11 bcr p190Bcr-Abl bcr-abl abl FUSION PROTEINWITH TYROSINEKINASE ACTIVITY bcr-abl gene structure t(9;22) translocation

  14. Philadelphia chromosome t(9;22)(q34;q11) 22q- = Philadelphia chromosome

  15. Clinical Manifestations • Asymptomatic in 20-50% of patients • Fatigue 34%, weight loss 20%, excessive sweating 15%, abdominal fullness 15%, bleeding episodes 21% (platelet dysfunction). • Abdominal pain in the LUQ (enlarged spleen) • Tenderness over the lower sternum. • Acute gouty arthritis • Findings: Splenomegaly, anemia, WBC > 100,000, platelet count > 600,000

  16. Peripheral Blood Pathology • Leukocytosis (median of 100,000) • Differentiation shows virtually all cells of neutrophilic series • Blasts < 2% • Myelocytes more than metamyelocytes (a classic finding in CML) • Neutrophils cytochemistry is abnormal – low LAP score • Basophilia in 90% of cases • Thrombocytosis. If low platelets – consider an other

  17. CML Peripheral Blood Smear

  18. CML Peripheral Blood Smear

  19. Bone Marrow Pathology • Granulocytic maturation pattern same as in the peripheral blood • Increased reticulin fibrosis and vascularity • Erythroid islands are reduced in number and size • Dwarf megakaryocytes • Pseudo-Gaucher’s cells and Sea Blue histiocytes (markers of increased cell turnover) • Iron-laden macrophages are reduced or absent

  20. Pseudo-Gaucher cells

  21. Pseudo-Gaucher cells

  22. Sea Blue Histiocyctes

  23. CML – Bone Marrow

  24. Diagnosis of CML • Typical findings in the blood and bone marrow • Requires the detection of the Ph chromosomal or its product, the BCR-ABL1 fusion mRNA and the BCR-ABL1 protein. • Conventional cytogenetic analysis (karyotyping) – The first method • Florence and in situ hybridization (FISH) analysis • RT-PCR (The BEST) • Southern blot techniques – rarely used • Western Blotting – low sensitivity and labor intensive

  25. BCR-ABL (FISH)

  26. RT-PCR for BCR-ABL Target sequence • Qualitative RT-PCR allow for the diagnosis of CML • Quantitative RT-PCR is used to quantify the amount of disease • Allows for the identification of cryptic BCR-ABL translocations • Does not require a bone marrow aspirate for optimal results 1 Denaturation: Heat briefly to separate DNA strands 2 Annealing: Cool to allow primersto form hydrogen bond with ends of target sequence Cycle 1 yields 2 molecules Primers 3 Extension: DNA polymerase adds nucleotides to the 3” end of each primer New nucleo-tides Cycle 2 yields 4 molecules Cycle 3 yields 8 molecules; 2 molecules (in white boxes) match target sequence

  27. Most CML patients are diagnosed in the chronic phase Chronic phase Blastic phase

  28. Differential Diagnosis • Leukemoid reaction • Juvenile myelomonocytic leukemia (JMML) • Chronic myelomonocytic leukemia (CMML) • Atypical CML • Chronic eosinophilic leukemia • Chronic neutrophilic leukemia • Other myeloproliferative neoplasms • Other Ph chromosome positive malignancies

  29. Accelerated Phase CML • 10-19% blasts in the peripheral blood or bone marrow • Peripheral blood basophils ≥20% • Platelets < 100,000/microL, unrelated to therapy • Platelets > 1,000,000/microL, unresponsive to therapy • Progressive splenomegaly and increasing WBC, unresponsive to therapy • Cytogenic evolution

  30. Blastic Phase CML Blast crisis is generally refractory to treatment, occurs approximately 3-5 years after the diagnosis of CML and 18 months after the onset of accelerated face • Blasts in the peripheral blood ≥20% or in the bone marrow ≥30% • Large foci or clusters of blasts on the bone marrow biopsy • Presence of extramedullary blastic infiltrate (e.g., myeloid sarcoma, also known as granulocytic sarcoma or chloroma)

  31. Blast Phase CML – Bone Marrow

  32. Blast Phase CML – Bone Marrow

  33. Clinical Debate What is the optimal frontline therapy for CML?

  34. Principles of CML treatment • Relieve symptoms of hyperleukocytosis, splenomegaly and thrombocytosis. • Hydration • Chemotherapy (Busulfan, hydroxyurea) • Control and prolonging the chronic phase (non-curative) • Tyrosine kinase inhibitors • Alpha-interferon + chemotherapy • Chemotherapy (hydroxyurea)

  35. Treatment Options Treatment decisions for patients with CML are complex, due to the variety of available options, many of which are conflicting. • Potential cure with allogeneic hematopoietic stem cell transplantation • Disease control without cure using tyrosine kinase inhibitors (TKIs) • Palliative therapy with cytotoxic agents

  36. Factors influencing choice of therapy • Phase of CML • Availability of a donor for allogeneic stem cell transplant • Patient age • Presence of medical co-morbidities • Response to treatment with TKIs

  37. Crossover IRIS Study Design: Imatinib Mesylate Versus IFN- + ara-C 1106 patients enrolled from June 2000 to January 2001 Imatinib Mesylate IF: · Loss of MCR or CHR · Increasing WBC count S R · Intolerance of treatment · at 12 months* Failure to achieve MCR · Failure to achieve CHR at 12 months* · Request to discontinue IFN-* a IFN- + ara-C Progression · Increasing WBC count S = screening.R = randomization. · Loss of MCR or CHR · Accelerated phase or blast crisis · Death

  38. Hematologic Responses 100 96% 90 Imatinib mesylate 80 70 60 67% % Responding 50 IFN- + ara-C 40 30 20 10 0 0 3 6 9 12 15 18 21 Months Since Randomization

  39. Cytogenic Responses 100 90 83% 80 Imatinib mesylate 70 60 % Responding 50 40 30 20% 20 IFN- + ara-C 10 0 0 3 6 9 12 15 18 21 Months Since Randomization

  40. Overall Survival on First-Line Imatinib (IRIS Study)

  41. Resistance to Imatinib occurs predominantly during advanced phase CML Chronic Phase Blast Crisis Relapse • Advanced stage cancers are characterized by multiple genetic changes • Patients in advanced phase often relapse with the development of chemotherapy resistance • Some patients in blast crisis CML respond to Imatinib but then tends to relapse Bone marrow to peripheral blood Hematopoietic differentiation Ph-negative Ph+ blasts Ph+ Ph+ Imatinib mesylate- resistant blasts

  42. Initial Treatment Tyrosine kinase inhibitors are for first-line therapy in chronic phase CML • Imatinib (Gleevec) • Dasatinib (Sprycel) • Nilotinib (Tasigna) All 3 agents are considered to be (category 1) based on the NCCN guidelines and recommendations. Second-generation TKIs (dasatinib or nilotinib) produce faster and deeper response than imatinib

  43. Treatment of CML after failure of initial therapy No randomized trials have directly compared the efficacy of second-generation TKIs in patients with chronic phase CML who experience failure of an initial TKIs • A trial of another TKI. • Dasatinib preferred in patients with pancreatitis, elevated bilirubin or hyperglycemia • Dasatinib crosses the blood brain barrier and would therefore be preferred in patients with CNS involvement • Nilotinib might be chosen for patients with a history of pleural or pericardial effusion or disease • Dasatinib and Nilotinib can result in QT prolongation

  44. Other Options • Bosutinib – toxicity is a limiting factor • Ponatinib – toxicity is a limiting factor • Increase the dose of Imatinib • Omacetaxine mepesuccinate – SQ Injection • Approved by the FDA for patients resistant or intolerant to 2 or more TKIs • Hematopoietic cell transplant – the only cure • Clinical trials

  45. Other Options Patients who are ineligible for HCT but have either a contraindication to a second-generation TKI or have failed to respond to treatment with available TKI • Interferon alfa plus cytarabine • Hydroxyurea • Busulfan

  46. Response Criteria • Hematologic response • Cytogenic response • Molecular response

  47. Resistance to treatment • Primary resistance – patient fails to achieve a desired response to initial treatment • Secondary resistance – patient with an initial response to a TKI ultimately relapses

  48. Loss of Response Patients should be re-evaluated with a bone marrow biopsy with cytogenetics, and BCR-ABL kinase mutation analysis • T315I mutation • Resistant to all TKIs, except Ponatinib • Patient should be evaluated for SCT • Y253H, E255k/V and F359V/C/I mutations • Resistant to Imatinib and Nilotinib but sensitive to Dasatinib • F317L/V/I/C, V299L and T315A mutations • Sensitive to Nilotinib but with intermediate sensitivity to Imatinib and Dasatinib

  49. Mechanisms of action TKIs • They block the initiation of bcr-abl pathway • Many TKIs also affect other signaling pathways • Dasatinib and Bosutinib inhibit both Bcr-Abl and Src kinases. • Nilotinib inhibits Bcr-Abl, c-kit and platelet derived growth factor receptor (PDGFR) • These differences in targeted pathways may be responsible for their varied clinical effects in tumors

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