Acute Lymphoblastic Leukemia(1)

Document Sample
Acute Lymphoblastic Leukemia(1) Powered By Docstoc
					                   Acute Lymphoblastic Leukemia

        -- The most common malignancy in children (1/4 of all cancer, 75% of leukemia)
        -- Peak incidence between 2-5 y/o (Great Britain  U.S.  Japan)
        -- White > Black, Boy > Girl (esp. puberty)
           Other factors associated with  ALL risk : increase maternal age, higher birth
                                                      weight, paternal chemical exposure
                                                          (smoking, alcohol)

        -- Evidence for genetic factors playing a significant role in ALL :
             a) Karyotypic abnormalities in leukemic cells of ALL
             b) Association between constitutional chromosomal abnormalities and ALL
                    Trisomy 21 (Down syndrome) are 15-20X more likely to develop
                    Klinefelter’s syndrome, germline BRCA2 mutation, Beckwith-Wiedemann
                      syndrome, neurofibromatosis, Shwachman’s syndrome
                     Bloom’s syndrome, Fanconi’s anemia (AR) --- ANLL, ALL
                      Ataxia-telangiectasia (AR) --- T-ALL, B-ALL, pre-B ALL
               c) Familial leukemia
                     Siblings of ALL children have 2-4X risk than do unrelated children
               d) High incidence of leukemia in identical twins
                    Concordance rate of acute leukemia in monozygotic twins is 25%
                    Risk is highest in infancy, diminishes with age, similar to general
                      population after the age of 7 years
               e) Molecular epidemiologic evidence
                    Some important initiating events that contribute to leukemogenesis can
                      occur in utero.
                    Study of cord blood and heel-stick card shows 1/100 to 1/1000 newborn
                      have preleukemic translocations at the time of birth

      Environmental Factors : ionizing radiation and toxic chemicals
          -- The risk of leukemia is dose-related to irradiation (linear dose-response relation
             when exposure dose > 100 cGy)
          -- The type of leukemia is related to the age at exposure (Adult  AML, child  ALL)
          -- Increase risk of leukemia in children exposed to radiation in utero?
            (0.3-0.8 cGy, 5X risk in first trimester, 1.5X risk in 2nd and 3rd trimester)
     -- Neonatal ultrasound and EMF exposure does no cause childhood ALL
     -- Chronic chemical exposure has been associated with AML in adult, but no direct
       evidence exist for childhood ALL
     -- Chemotherapy /c alkylating agents has leukemogenic potential  most are ANLL

 Viral Infection :
     -- Onset age of leukemia  developing immune system  oncogenic effects of virus
     -- ALL has inverse association with hepatitis A virus? “immunologically naïve”?
     -- EBV  Burkitt’s lymphoma, L3 morphologic ALL, Hodgkin’s disease
        HTLV I & II  T-cell leukemia, hairy cell leukemia
       HIV  non-Hodgkin’s lymphoma (pre-B), mucosa-associated lymphoid tumor
              (MALT), cystic tumor of thymus, leiomyomas, leiomyosarcomas,

 Immunodeficiency :
    -- Increased risk of developing lymphoid malignancies (usually mature B-cell
       lymphoma) in children with immunodeficiency diseases or receiving
        immunosuppressive drugs
     -- Low serum immunoglobulin level in 30% of newly diagnosed ALL patients
        (Cause ? Result ?)
     -- Aberrant immune status :
            infection risk and complications
           may be a factor in leukemogenesis
           has influence in susceptibility to relapse and the development of second

 Clonal Pathogenesis :
    -- Malignant transformation of a single abnormal progenitor cell that has the capability
       to expand by indefinite self-renewal. But When?
     -- The event lead to it is complex and multifactorial, and it has been proposed to occur
        in lymphoid cells of B- or T-cell lineage or their precursor cells
     -- The causative mutation may occur years before clinical leukemia
     -- Lyphocyte precursors may be at higher risk for spontaneous mutations :
            the intrinsic, regulated, mutagenic activity occurred during immunoglobulin and
              TCR gene rearrangement
            the high rate of proliferation
     -- Identical patterns of immunoglobulin and TCR gene rearrangement in leukemic
        cells obtained at diagnosis and relapse
     -- Polyclonal disease, clonal progression, sharing a common clonal origin
     -- Cure of ALL  kill of all leukemic cells  Minimal residual disease (MRD) 
        residual cells identical to clonal cells at diagnosis? immune system has learned
       to control the proliferation of the remaining leukemic cells
       Molecular Pathogenesis :
            -- Alteration of key regulatory processes that control hematopoietic proliferation,
               differentiation and apoptosis.
            -- Mutations affect specific kinases, proteins, aberrant expression of protooncogenes or
               silencing of suppressor genes, and prevent apoptosis.

      Morphologic Classification :
        -- FAB system
Cytologic Feature         L1                               L2                        L3
Cell size                 Small cells predominate          Large, heterogeneous in   Large homogeneous
Nuclear chromatin         Homogeneous in any one case      Variable; heterogeneous   Finely stippled and
Nuclear shape             Regular; occasional clefing or   Irregular clefting and    Regular – oval to round
                          indenting                        indentation common
Nucleoli                  Not visible or small and         One or more present;      Prominent; one or more
                          inconspicuous; more vesicular    often large
Amount of cytoplasm       Scanty                           Variable; often           Moderately abundant
                                                           moderate abundant
Basophilia of cytoplasm   Slight or moderate; rarely       Variable; deep in some    Very deep
Cytoplasmic vacuolation   Variable                         Variable                  Often Prominent

            -- L1 (85%), L2(14%, common in adult), L3(1%)
            -- FAB system has prognostic value (L1>L2>L3), but no biology basis, nor apparent
               correlation with cell surface markers
            -- Morphologic variants of ALL :
                  hand-mirror cell variant (5%-23%)
                        associated with CNS disease?
                       associated with adult female whose leukemic blast display myeloid and
                         lymphoid antigens
                  azurophilic intracytoplasmic inclusions resemble the granules of myeloblast
                       2% of cases
                       the granules was shown recently to be mitochondria
            -- Cytochemical stains : periodic acid-Schiff(PAS), acid phosphatase,
                                    β-glucuronidase, acid α-naphthyl acetate esterase, peroxidase.

       Classification by Immunophenotype :
            -- In early 1970s  T-cell(20%), B-cell(1-2%), non T/non B cell (null cell) ALL
               Heterologous antisera and monoclonal antibodies  80% null cell ALL had a
                                                                   common ALL antigen CD-10
            -- 80-85% of childhood ALL is B-cell lineage
            -- More than 200 different monoclonal antibodies are now commercially available
    -- None of the monoclonal antibodies are absolutely lineage specific,
       “Lineage associated” is the preferred terminology
    -- Prognostic differences in various precursor B lineage ALL :
          earlier B lineage > mature B lineage, CD10+ > CD10-, CD34+ > CD34-
    -- Identifying gene rearrangement is helpful in confirming the lineage of ALL cells
           B-cell : Immunoglobulin gene rearrangement
                      heavy chain > κ light chain > λ light chain
           T-cell : TCR gene rearrangement
           useful markers for both MRD studies or to identify preleukemic clones present
            at the time of birth
    -- Some leukemias exhibit asynchrony of antigen expression with normal stages of
       differentiation, or manifest more than one lineage.
           immunoglobulin gene rearrangement in T-cell ALL and TCR genen
             rearrangement in B-cell ALL
          “Lineage switch”  conversion from one phenotype at diagnosis to a different
                              phenotype at relapse
          The incidence of myeloid marker expression in ALL case has been 7-25%
           (Pre-B/myeloid is more common than T-lymphocyte/myeloid)
          unknown causes  inappropriate or aberrant gene activation ?
                            clonal expansion of normal, bilineage, or multilineage
                              potential precursor ?
          High incidence of mixed-lineage phenotype in abnormal 11q23 cases, especially
           in t(4;11)(q23;q23), and in Philadelphia chromosome t(9;22)  poor prognosis

 Classification by Global Gene Expression :
    -- Microarray technology to analyze the type and amount of RNA expressed by
       leukemic cells  potential to identify new molecular markers of MRD and potential
       therapeutic targets
    -- The six most significant, prognostically important cytogenetically defined subgrougs
       can be identified by their RNA expression signals
        t(12;21), t(9;22), t(1;19), t(4;11), T-ALL, hyperdiploidy > 50 chromosomes
    -- The technique is still premature to replace older ones, and only a powerful research
       tool for now
        -- Abnormalities are detected virtually in 100% cases of ALL with methods of
            a) chromosomal banding,
            b) fluorescent in situ hybridization (FISH),
            c) spectral karyotyping (SKY)
                24 color chromosomal paints;
                reliable assignment of the chromosome origin of material in complex
            d) comparative genomic hybridization (CGH)
                detecting losses or gains of material (deletions, duplications, amplifications)
                that can be missed by both SKY and standard cytogenetic techniques
               not requiring metaphase cells or cell culture of the diagnostic material

      Ploidy :
         -- Ploidy can be determined by methods of
            a) counting modal number of chromosomes in metaphase karyotype preparation
            b) measuring DNA content by flow cytometry
                                     fluorescent content of normal diploid cell
                DNA index (DI) = ----------------------------------------------------------
                                     fluorescent content of bone marrow blasts

                     DI = 1.0  Normal diploid cells
                                 Pseudodiploid cells (cytogenetically abnormal with normal
                                                       DNA content)
                     DI > 1.0  Hyperdiploidy (Chromosome number > 46)
                     DI < 1.0  Hypodiploidy (Chromosome number < 46)
          -- Frequency of ploidy groups in childhood ALL :
              Ploidy Group                         Frequency (%)
              Near haploidy                        < 1.0
              Hypodiploidy, 30-40                  < 1.0
              Hypokiploidy, 41-45                  6.0
              Pseudodiploidy                       41.5
              Hyperdiploidy, 47-50                 15.5
              Hyperdiploidy, >50                   27.0
              Near triploidy                       < 1.0
              Near tetraploidy                     1.0
              Normal                               8.0

               Prognostic significant hyperdiploidy  DI > 1.16, (53 chromosomes)
               Childhood ALL with higher ploidy (>50 chromosomes) has the best prognosis
               Prognosis : hyperdiploidy 56-67 > 51-56 > “low hyperdiploidy” 47-50 >
               Hyperdiploidy group usually shared other favorable prognostic features :
                favorable age, low initial leukocyte count, and B-cell precursor with CALLA
          Exceptions : near-triploidy (66-73), and near-tetraploidy (82-84) which is
                        often associated with T-cell immunophenotype
    -- Trisomies
           Most common : trisomy 4, 6, 10, 14, 17, 18, 21, and X
           Combination of trisomy 4 and 10, or trisomy 10 and 17 associated with low
            risk of treatment failure; trisomy 6 also has good prognosis
           Trisomy 8 and trisomy 21 are prognostically neutral
                Chromosome 8  trisomy 8 is the most common chromosome numerical
                                     abnormality in AML, it is rare in ALL and often
                                     associated with T-cell immunophenotype
                              t(8;14)(q24;q32), and duplications of 8q24 may be
                               found in leulemic lymphoblasts
                              Chromosome 8q24 is the location of the c-myc gene,
                                which is important for cell growth and the site of
                                leukemia translocations (L3 ALL, AML, pre-B ALL)
               Chromosome 21  contains large number of oncogenic transcription
                                  factors and growth factors
                                 AML1, an oncogene on 21q22, from the runt family of
                                  Drosophila transcription factors, associated with
                                   translocations in AML [ t(8;21) AML:ETO fusion,
                                   and t(12;21) TEL:AML1 fusion ]
    -- Near-haploid ALL (24-28 chromosomes)
          The worst prognosis by ploidy
          EFS ≦ 25%

 Structural Chromosomal Abnormalities :
    -- translocation is the most common encountered structural abnormality
    -- translocations are most frequent in pseudodiploid and hypodiploid groups
    -- hundreds of translocations have been described (Table 19.1), and the t(8;14),
       t(9;22), t(4;11), and t(1;19) are associated with high rates of treatment failure
    -- t(12;21)(p13;q22)
           the most common ALL translocation (25%), good prognostic implication
           t(12;21)(p13;q22) TEL-AML1 fusion gene (TEL on 12p13, AML1 on 21q22),
             promotes the differentiation and self renewal of B-cell precursors
           favorable initial response to treatment, but not a guarantee of successful
             treatment (10% relapsed cases)
    -- t (1;19)(q23;p13)
           the second most common ALL translocation (6.5%), present in 25% of
             cytoplasmic IgM heavy chain positive (cIg+) cases of pre-B-cell ALL
           t(1;19)(q23;p13) E2A-PBX1 fusion gene (E2A on 19p, a helix-loop-helix
             transcription factor; PBX1 on 1q23 ), is a transcriptional activator
      poor prognosis on standard therapies but better outcome when therapy is
       intensified, and this has considerable heterogeneity
         t(1;19)(q23;p13) without expression of E2A-PBX1 has a good prognosis
      t(17;19)(q22;p13) E2A-HLF (hepatic leukemia transcription factor) occur in
        1% of childhood ALL, poor-prognostic group, characterized by clinical
        presentation of hypercalcemia,  DIC, a pre-B cIgM- low CD10 positivity
-- t (8;14)(q24;q32)
       identified in virtually every case of B-cell ALL FAB L3 morphology
       myc protooncogene on chromosome 8  translocated near the immunoglobulin
        heavy chain gene on chromosome 14  dysregulation of myc expression 
        uncontrolled proliferation of B cells
      two variant, t(2;8)( p12;q24) and t(8;22)(q24;q11), involving κ and λ light chain
        are less commonly
      the similarity in molecular mechanism associated with translocations in B-cell
        ALL and in Burkitt’s lymphoma supports the presumption that B-cell ALL
        represents a disseminated form of Burkitt’s lymphoma
      t(8;14)(q24;q11) involving TCR loci and myc gene  myc gene is
        overexpressed, but resulting leukemic blast display T-cell immunophenotype
-- Translocations of transcription factor genes to TCR loci may involve TCR β on
   7q34, or the TCR αδ on 14q11
      examples of such transcription factor genes included rhombotin1 and 2,
        TAL1/SCL, TAL2, HOX11, and LYL
      TAL1 :
           translocated to a TCR in approximately 5% of pediatric T-cell ALL
           partial TAL1 deletion in 25% of pediatric T-cell ALL, causes over
             expression of TAL1 protein
           not expressed in normal T cells, but critical for the formation of entire
            hemopoietic system
      HOX11:
          t(10;14)(q24;q11) and t(7;10)(q35;q24) involve translocations of HOX11
            and TCR loci
          important regulator of hemopoietic development
-- chromosome band 11q23
      associated with poor prognosis
      in 5-10% pediatric and adult ALL, in 60-70% infant leukemia, in 85%
       secondary leukemia patients who received epipodophyllotoxin therapy
      abnormalities occurred in the region of a gene variously named MLL (myeloid/
       lymphoid leukemia gene or mixed lineage leukemia), Htrx1/HRX, and ALL-1
      MLL1 protein is believed an important developmental regulator of pluripotent
       hematopoietic cells
          ALL with rearrangements involving 11q23/MLL have poorer treatment outcome
          partner genes for MLL are most common located on chromosome 4, 6, 9, 19
               t(4;11)(q21;q23) is the most common, in 5% of pediatric ALL and more
                 than 60% infant leukemias, generally occurs in B-cell precursor ALL
               t(4;11) leukemic cells manifest biphenotypic characteristics, which also is
                 noted in other 11q23 associated translocations [t(11;19)(q23;q12),
                 t(9;11)(p21;q23)]  leukemia with 11q23 rearrangement may arise from a
                                      pluripotent progenitor cell
    -- t (9;22)(q34;q11)
           the translocation with the worst prognosis in pediatric ALL
          Philadelphia chromosome (Ph), in 5% childhood ALL and 20% adult ALL
          Ph+ ALL vs. CML :
             a) translocation usually can’t be detected in multiple cell lineage in Ph+ ALL
             b) Ph chromosome is not detectable during remission in Ph+ ALL
             c) the c-abl on chromosome 9 translocated to M-bcr on chromosome 22 in
                CML, but to m-bcr in Ph+ ALL
             d) p185 bcr-abl protein in Ph+ ALL, p210 bcr-abl protein in CML
          Children with Ph+ ALL tend to be older, have higher initial leukocyte counts
           and are more likely display FAB L2 morphology. Respond poorly to therapy,
            have a lower remission induction rate, higher frequency of CNS leukemia and
            early recurrence
          even poorer prognosis with also partial or complete monosomy 7 (31%
            induction failure rate)
    -- Other structural abnormalities :
          monosomy 7 and deletions of 7q (4% pediatric ALL)
          deletion of 9p21-22 (10-30% pediatric ALL)
          t(5;14)(q31;q32) characterized by B-lineage phenotype and hypereosinophilia

 Biochemical Characterization :
    -- Terminal deoxynucleotidyl transferase (TdT)
          DNA-polymerizing enzyme that catalyzes the polymerization of
           deoxynucleoside monophosphates into a single stand DNA primer without the
           need for template instruction
          TdT activity is not present in normal lymphocyte but in normal cortical
           thymocytes and leukemic lymphoblasts of T-cell and B-cell precursor lineage
           (not in mature B-cell ALL, rarely in AML)
    -- Purine pathway enzymes
          adenosine deaminase, 5’-nucleotidase, purine nucleoside phosphorylase
          in T-cell ALL, high activity of adenosine deaminase, and decreased
            5’-nucleotidase and purine nucleoside phosphorylase activity is noted
    -- Lactate dehydrogenase (LDH)
                elevated at diagnosis, normalize during remission and increase again at relapse
          -- Glucocorticoid receptors
                the greatest numbers are seen in early B lineage ALL, T-cell ALL has lower
                  numbers, and B-cell ALL has the lowest.

      Pharmacogenetics :
         -- a relatively new field, concerns responses to specific drugs
         -- thiopurine methyltransferase (TPMT)
                an enzyme that metabolizes 6-MP into an inactive metabolite
                2 copy of wild-type TPMT  low rate of adverse consequence
                 homozygous null patients  severe toxicity
                 heterozygote patients  intermediate range of toxicities

      Cytokinetics :
         -- H-thymidine labeling indices and flow cytometry have been used to evaluate cell
          -- inverse correlation between lymphoblast proliferative capacity and prognosis
          -- high proliferative activity associated with shorter remission duration
          -- poor response to induction treatment correlated with a low RNA content which
            indicated a greater percentage of nonproliferating cells

        -- Presenting signs and symptoms reflect the impact of bone marrow infiltration and
           the extent of extramedullary disease spread
        -- Pallor, fatigue, bone pain(23%), petechiae, purpura, bleeding(48%), fever(61%)
           Lymphadenopathy(50%), hepatomegaly, splenomegaly(68%)  extramedullary
                                                                           leukemic spread
        -- T-cell ALL (15% ALL)  in older boys,
                                       high initial leukocyte counts (1/3~1/2 >100,000/cmm)
                                       mediastinal mass (50% T-cell ALL)
                                       higher incidence of CNS leukemia at diagnosis (10-15%)
          -- Childhood ALL typically presents with nonspecific symptoms and mimic other
             disease (Table 19.7)
          -- Involvement of unusual extramedullary sites (ocular, urinary bladder, pancreas)
             usually occurs in repapsed or refractory patients
          -- ALL should be taken into consideration in hypercalcemia and hypereosinophilia
            patients :
               Hypereosinophilic syndrome
                    pulmonary infiltrates, cardiomegly and congestive failure
               t(5;14) is associated with this syndrome
 Leukemia or Lymphoma ?
    -- Patient presented with features of lymphoma (anterior mediastinal mass, massive
        lymphadenopathy) may have bone marrow involvement
     -- ALL and non-Hodgkin’s lymphoma are closely related disorders :
           malignant T cells of lymphoblastic lymphoma are similar to those of T-cell ALL
           malignant B cells of Burkitt’s lymphoma are similar to those of B-cell ALL
               shares the same immunologic and molecular features
               B-cell ALL is considered to be disseminated form of Burkitt’s lymphoma

 Hematologic Abnormalities at Presentation
     -- The degree of leukocyte count elevation at diagnosis is one of the single most
        important predictor of prognosis in ALL
     -- Initial pancytopenia is rare in ALL and must differentiated with aplastic anemia
     -- Definitive establishment of diagnosis  bone marrow aspiration
            >5% lymphoblasts in bone marrow is highly suggestive of leukemia, but a
             minimum of 25% blast cells is required before the diagnosis is confirmed

 Other Abnormal Laboratory Findings
    -- Reflects the leukemic cell burden, the extent of extramedullary spread, the excessive
        proliferation and destruction of leukemic cells
     -- Uric acid
           increased anabolism and catabolism of purines
           complication : uric acid nephropathy, renal failure
           management : hydration, alkalinization, xanthine oxidase inhibitor
     -- Calcium, potassium and phosphate
           abnormalities are more frequent in bulky extramedullary disease and high initial
             leukocyte counts
           Hypercalcemia may results form leukemic infiltration of bone or release of
            parahormone-like substance from lymphoblast
     -- LDH
           leukemic cell lysis, ineffective hematopoiesis, liver involvement
     -- Others : anterior mediastinal mass, skeletal changes (periosteal elevation,
                 subperiosteal cortical thickening, osteolytic lesion, osteoporosis),
                 coagulation abnormalities

 Patterns of Spread
     -- The most common sites of extramedullary spread are the CNS, testes, liver, kidneys,
        nodes, and spleen. Others including skin, ocular anterior chamber, pleural,
        pericardial spaces and ovary.
     -- Central Nervous System Leukemia :
           Definitions of CNS disease based on CSF findings
                  Status          CSF findings
                  CNS-1           No lymphoblasts
                  CNS-2           <5 WBCs/μL with definable blasts on cytocentrifuge exam
                  CNS-3           >5 WBCs/μL with blast cells (or cranial nerve palsy)

                TdT determination is an additional means for confirming the diagnosis
                “bloody” taps or contamination of CSF with peripheral blood elements may
                  pose a serious risk of later CNS disease and relapse
                Most frequent cranial nerve involvement is the 3rd, 4th, 6th, 7th cranial nerve
          -- Testicular Leukemia :
                Clinical demonstrable testicular disease at diagnosis is rare, but 25% has occult
                 testicular disease
                Overt testicular involvement usually appears as painless testicular enlargement
                “Isolated” testicular relapse  blood-testes barrier ?  leukemia cells also
                 demonstrated in liver, spleen and lymph nodes
                Risk factors increase testicular relapse :
                    high initial WBC > 20000/cmm, T-cell disease, prominent lymphadenopathy,
                    splenomegaly, thrombocytopenia < 30000/cmm

        -- Factors Associated with Prognosis for Patients with ALL
            Initial white blood cell count          Hemoglobin level
            Sex                                     Race
            Rapidity of leukemic cytoreduction      Platelet count
            Cytogenetics / Ploidy                   Serum immunoglobulin
            Immunologic subtype                     Myeloid antigen expression on leukemic cells
            FAB morphology                          Nutritional status
            Mediastinal mass
            Organomegaly and lymphadenopathy

      Leukocyte Count and Age
         -- leukocyte count > 50000/cmm has poorer prognosis (T-cell ALL, infant t(4;11))
         -- younger(<2y) and older(>10y) patients have an inferior prognosis
            The worst prognosis is for infants <1y at diagnosis (EFS <10-20%)
         -- high CNS relapse rate in infants
         -- infancy ALL usually express HLA-DR antigen, are CD10 negative and do not
            express mature B-cell antigens. t(4;11) is common and rearrangement of
            11q23/MLL indicates poor prognosis

      Cytogenetic Factors
         -- Hyperdiploid lymphoblasts accumulate increased amounts of MTX and MTX
            polyglutamates, and higher basal apoptotic rates compared with lower ploidy
      Sex -- girls have a better prognosis than boys
              (risk of testicular relapse, higher T-cell disease incidence in boys)

     Race -- poorer outcome for black than for white (esp. in 1-9y age group)
     Leukemic Cell Burden -- hepatosplenomegaly and lymphadenopathy
     Response to Treatment
        -- patients who do not achieve a complete remission within the usual 4 to 6 week
           induction period have a high rate of relapse and shortened survival
        -- residual leukemia demonstrable in bone marrow on day 14 of induction is an
           independent predictor of inferior outcome
        -- MRD levels that are undetectable or at least less than 10-4 at the end of a standard
           induction are associated with the best prognosis

     Nutritional Status – undernutrition is a predictor of treatment failure and has less
                           tolerance for chemotherapy
     Other Prognostic Factors
        -- low serum IgG is associated with induction failure
         -- low IgG / M / A is correlated with a poor chance of EFS


Lingjuan Ma Lingjuan Ma