rev bras hematol hemoter. 2015;37(1):55–57
Revista
Brasileira
de
Hematologia
e
Hemoterapia
Brazilian
Journal
of
Hematology
and
Hemotherapy
w w w . r b h h . o r g
Case
report
A
case
of
chronic
myeloid
leukemia
with
the
m-bcr
(p190)
molecular
rearrangement
identified
during
treatment
Mariana
Beatriz
Asinari
∗,
Maximiliano
Zeballos,
Sturich
Alicia,
Brenda
Nidia
Ricchi,
Ana
Lisa
Basquiera
HospitalPrivado-CentroMédicodeCórdoba,Córdoba,Argentina
a
r
t
i
c
l
e
i
n
f
o
Articlehistory: Received4March2014 Accepted6July2014
Availableonline26November2014
Introduction
Chronic myeloidleukemia (CML) isa hematological malig-nancyinwhichahighpercentageofpatientscytogenetically express the Philadelphia chromosome. This chromosome results from the reciprocal translocation, t(9;22)(q34;q11.2). Duringthisexchange,theAbelsongene(abl)onchromosome 9andthebreakpointclusterregiongene(bcr)onchromosome 22 generate the breakpoint cluster region-Abelson murine leukemia(BCR-ABL) fusiongene.Themostfrequent break-pointonchromosome22,locatedbetweenexons12and16, iscalledthemajorbreakpointclusterregion(M-bcr)andwith itscounterpartinexon2ofchromosome9resultsintheb2a2 andb3a2transcriptsthatcodefora210kDaprotein.Less fre-quently,a secondrearrangement, minorbreakpointcluster
∗ Correspondingauthorat:LaboratoryofHematologyandOncology,HospitalPrivado-CentroMédicodeCórdoba,NacionesUnidas346, 5016Córdoba,Argentina.
E-mailaddress:marianaasinari@hotmail.com(M.B.Asinari).
region(m-bcr),occursbetweenthefirstintronofthebcrgene andexon2oftheablgeneproducingthee1a2transcriptthat codesfora190kDaprotein.1–4Thisfusiontranscriptoccurs in 1–2%ofCML patientsas asole rearrangementwith the first threecases beingdescribed in1990.5–7 These patients may have aparticularclinical condition betweenCML and chronicmyelomonocyticleukemia(CMML).Thethirdtypeof transcriptise19a2whichoccursbetweenexons19and20of thebcrgeneandexon2oftheablgene.Thisiscalledthemicro breakpointclusterregion(-bcr)codingfora230kDaprotein.
Amongother unusualtranscriptsaree6a2,e2a2,e1a3,b2a3 andb3a3.1,2Theobjectiveofthisarticleistodescribeacase ofCMLwithaminorp190molecularrearrangementcausing monocytosis inperipheralblood, dysplasticchangesin the bonemarrowandlackofresponsetotreatmentwithtyrosine kinaseinhibitors.
http://dx.doi.org/10.1016/j.bjhh.2014.07.024
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revbrashematolhemoter.2 0 1 5;37(1):55–57Case
report
A65-year-oldfemale hada historyoftype2diabetes mel-litus, and a diagnosis of CML made in August 2011 at anotherinstitution.Atthetimeofdiagnosis,thepatient pre-sented splenomegaly,with a white blood cell count(WBC) of380×109/L,hemoglobin(Hb)levelof8.8g/dLandplatelet count of 560×109/L. The bone marrow aspirate showed markedgranulocytichyperplasiaandacytogenetictestof20 metaphasesexhibitedat(9;22)(q34;q11)intheentiresample. Atthat time, neither molecular biology analyses nor fluo-rescentinsituhybridization (FISH)wasperformed.Therapy withhydroxyureawasprescribed,andinSeptember2011the administrationofimatinib(400mg/day)wasbegun.InOctober 2011,theredbloodcountwasnormal,theWBCwas7.3×109/L, Hb was 9.2g/dL and platelet count was 230×109/L; atthis time,the patientreportedhairlossand edema.In Novem-ber2011,imatinibtherapywasstoppedduetopancytopenia (WBC:2×109/L).InDecember2011,thepatientwasreferred toourhospital:shewasundernotreatmentandpresented mildsplenomegaly.InJanuary2012,herWBCwas11.9×109/L withmonocytosis(49%neutrophils,2%basophils,28% lym-phocytesand 21%monocytes), Hb levelwas 11.57g/dL and plateletcountwas192×109/L.Abonemarrowaspiratewas performed.Itrevealedmarkedbonemarrowhyperplasia,and dysplasticchangesinthemyeloidaswellasintheerythroid series.
Cytogenetics showed 46,XX, t(9;22)(q34;q11) in 20 metaphases, andthe FISHanalysisconfirmed theBCR-ABL fusionin100%ofthesample.Anestedreversetranscription polymerase chain reaction (RT-PCR)4 of the bone marrow was positiveforthe m-bcr rearrangement witha381 base pair(bp)productinthesampleobtainedinJanuary2012.No bandsfortheM-bcrrearrangementwerefound.Thematerial fromthe patientand thecontrolsamplewere highquality accordingtotheamplificationproductofthe300bpablgene. Thisresult wasconfirmed bysequence analysis. A RT-PCR was performed in order to quantify the number ofcopies of the m-bcr BCR-ABL transcript. A set of primers and a TaqManprobe(Applied Biosystems)wereusedforthe e1a2 transcriptandfortheablcontrolgene;negativecontrolswere alsoincludedintheassays.8 Nanogenmolecularstandards (NanogenAdvanced Diagnostics S.p.A., Corso Torino, Italy) were employed for the calibration curve. The assays were carriedoutinanApplied7500realtimePCRsystem(Applied Biosystems Life). The BCR-ABL and ABL transcripts were analyzedinduplicate,andthenumberofBCR-ABLtranscripts wasnormalizedbytheexpressionofABL.Thecopynumber variationofthee1a2transcriptinthe patient’ssamplewas 94.4%.
Thepatientrestartedimatinib(400mg/day).Threemonths later,abonemarrowaspirateshowedbonemarrow hyperpla-siawithmildmegaloblasticchangesandabsenceofresponse accordingtocytogeneticsandFISH. Thecopy number vari-ation of the e1a2 transcript by RQ-PCR was 76.1%. These samples were analyzed to detect if the patient presented mutationsintheABLkinasedomain;allwerenegative.
The administration of imatinib was increased to 800mg/day without achieving response. In June 2012,
imatinibwas replacedbydasatinib(100mg/day)duetothe lackofresponse.Threemonthslater,anewevaluationofthe patientrevealedabettercytogeneticresponse.However,after ayearoftreatmenttheresultsofaFISHanalysisshoweda positiveBCR-ABLfusiongenein85%ofthesample.Thus,the treatmentwaschangedtonilotinib400mg/12h.Under this medication,whichisongoing,thepancytopeniapersists.
Discussion
Thecasedescribedwasreferredtoourinstitutionwitha diag-nosisofCMLandundernotreatmentduetopancytopenia.On admission,the patient’sbonemarrowwasreexaminedand thecytogeneticanalysisshowedPhiladelphiachromosomes inallofthemetaphasesanalyzed;thisresultwasconfirmed byFISH,whichrevealedaBCR-ABLfusiongenein100%ofthe sample,andbyRT-PCR,whichidentifiedanm-bcrBCR-ABL mutationwithane1a2transcriptthatencodesfora190kDa protein.Subsequently,the transcriptwasquantified by RQ-PCRandaBCR-ABL/ABLratioof94.4%wasobtained.Atthe timeofdiagnosis,mostCMLpatientshaveanM-bcrBCR-ABL molecularrearrangementcorrespondingtotheb2a2orb3a2 transcripts. Inalarge seriesofpatients withCML,the fre-quencyofthem-bcre1a2p190molecularrearrangementwas 1–2%.9,10ThecoexistenceofM-bcrandm-bcrrearrangements, apparentlyduetoalternativesplicing,hasalsobeendescribed. Theredbloodcountperformedatourinstitutionrevealed absoluteand relativemonocytosis withgranulocytic hyper-plasia and dysplasia of the bone marrow. Several authors report BCR-ABLp190 CMLcaseswith monocytosis,sharing somefeatureswithmyelodysplastic/myeloproliferative neo-plasms(MDS/MPN)duetothedifferentiationofbothlineages, granulocytesandmonocytes.Eventhoughtheuniquefeature oftheBCR-ABLp190CMLseemstobemonocytosiswithout splenomegaly,11,12thisentitycanalsopresentwithout mono-cytosis,withbasophiliaorwithsplenomegaly.Itseemsthat thereisnocharacteristicpatterninthesecases;itcanonlybe confirmedthatsomepatientspresentmonocytosisat diagno-sisorduringthecourseofthe disease,andothers,withor withoutsplenomegaly,havenomonocytosis.Inthecurrent caseitisnotexactlyknownifthepatienthadmonocytosis atthetimeofdiagnosisornot,butshedidpresentwiththis featurewhenshewasadmittedtoourinstitution.
revbrashematolhemoter.2 0 1 5;37(1):55–57
57
BCR-ABLp190CMLmayhaveuniqueclinicalandbiological features.Identifyingthesepatientsatthetimeofdiagnosis wouldallowtheoptimizationoftreatment.
Conflicts
of
interest
Theauthorsdeclarenoconflictsofinterest.
Acknowledgment
TheauthorswouldliketothankLindaFletcherforkindly help-inguswithBCR/ABLkinasedomainmutationinvestigations, notavailableinourlaboratory.
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s
1. MeloJV.ThediversityofBCR-ABLfusionproteinsandtheir relationshiptoleukemiaphenotype.Blood.
1996;88(7):2375–84.
2. MeloJV.BCR-ABLgenevariants.BaillieresClinHaematol. 1997;10(2):203–22.
3. KurzrockR,GuttermanJU,TalpazM.Themoleculargenetics ofPhiladelphiachromosome-positiveleukemias.NEnglJ Med.1988;319(15):990–8.
4. vanDongenJJ,MacintyreEA,GabertJA,DelabesseE,RossiV, SaglioG,etal.StandardizedRT-PCRanalysisoffusiongene transcriptsfromchromosomeaberrationsinacuteleukemia fordetectionofminimalresidualdisease.Reportofthe BIOMED-1ConcertedAction:investigationofminimal residualdiseaseinacuteleukemia.Leukemia. 1999;13(12):1901–28.
5.SawyersCL,TimsonL,KawasakiES,ClarkSS,WitteON, ChamplinR.Molecularrelapseinchronicmyelogenous leukemiapatientsafterbonemarrowtransplantation detectedbypolymerasechainreaction.ProcNatlAcadSciUS A.1990;87(2):563–7.
6.SelleriL,vonLindernM,HermansA,MeijerD,TorelliG, GrosveldG.Chronicmyeloidleukemiamaybeassociated withseveralbcr-ab1transcriptsincludingtheacutelymphoid leukemia-type7kbtranscript.Blood.1990;75(5):
1146–53.
7.ZaccariaA,TasslnarlA,TestoniN,LauriaF,TuraS,AlgeriR, etal.Alternativebcr/abltranscriptsinchronicmyeloid leukemia.Blood.1990;76(8):1663–8.
8.GabertJ,BeillardE,vanderVeldenVH,BiW,GrimwadeD, PallisqaardN,etal.Standardizationandqualitycontrol studiesof‘real-time’quantitativereversetranscriptase polymerasechainreactionoffusiongenetranscriptsfor residualdiseasedetectioninleukemia–aEuropeAgainst Cancerprogram.Leukemia.2003;17(12):
2318–57.
9.VermaD,KantarjianHM,JonesD,LuthraR,BorthakurG, VerstovsekS,etal.Chronicmyeloidleukemia(CML)with P190BCR-ABL:analysisofcharacteristics,outcomes,and prognosticsignificance.Blood.2009;114(11):2232–5.
10.PardananiA,TefferiA,LitzowMR,ZentC,HoganWJ,McClure RF,etal.Chronicmyeloidleukemiawithp190BCR-ABL: prevalence,morphology,tyrosinekinaseinhibitorresponse, andkinasedomainmutationanalysis.Blood.
2009;114(16):3502–3.
11.MeloJV,MyintH,GaltonDA,GoldmanJM.P190BCR-ABL chronicmyeloidleukaemia:themissinglinkwithchronic myelomonocyticleukaemia?Leukemia.1994;8(1): 208–11.
