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Leukemia Research 35 (2011) e131– e133

Contents lists available at ScienceDirect

Leukemia Research

jo ur nal homep age: www.elsev ier .com/ locate / leukres

etter to the Editor

UP214-ABL1 positive T-cell acute lymphoblastic leukemiaatient shows an initial favorable response to imatinib therapyost relapse

. Introduction

Recent studies have shown the presence of the NUP214-ABL1usion gene in 6% of cases of T-cell acute lymphoblastic leukemiaT-ALL) [1,2]. This fusion gene was originally observed on ampli-ed episomes formed by extrachromosomal circularization of the00 kb DNA sequence located between the NUP214 and the ABL1enes on chromosome 9q34 [1]. More recently, intrachromosomalmplification of the fusion, seen as homogenously staining regionshsr), has been reported, but only rarely [2,3].

Like the BCR-ABL1 fusion gene seen in cases of chronic myeloideukemia (CML), the NUP214-ABL1 fusion gene encodes a con-titutively activated tyrosine kinase. Given that tyrosine kinasenhibitors (TKIs) are able to suppress the constitutive kinase activityf ABL1, they may potentially be used in the treatment of patientsith NUP214-ABL1 positive T-ALL. A recent study has shown thatUP214-ABL1 positive human T-ALL cell lines are sensitive to theKIs imatinib, nilotinib and dasatinib [4]. However, to date onlywo case studies describing NUP214-ABL1 positive T-ALL patientsreated with TKIs have been reported, with mixed results [5,6].ere, we report a patient with intrachromosomal insertion of a sin-le copy of the NUP214-ABL1 fusion sequence who initially showed

favorable response to imatinib therapy post-relapse.

. Case study

The patient, a 41-year old male, presented with lethargy (4/52eeks), sore throat, a dry cough, myalgias and lower hip and backain. On examination he was found afebrile and hemodynami-aly stable, with a mild to moderate splenomegally. Laboratoryndings at diagnosis included a hemoglobin level of 146 g/L, ahite blood cell count of 361 × 109/L with 78% lymphoblasts,

nd a platelet count of 70 × 109/L. Immunophenotyping of bonearrow revealed a blast cell population positive for cytoplasmic

D3, CD38 and CD7 expression, with weak CD34 and cytoplas-ic CD79a expression, which established a diagnosis of T-cell

cute lymphoblastic leukemia. Conventional cytogenetics revealed karyotype of 46,XY,?inv(3)(p23q2?7)[20]. Metaphase fluores-ence in situ hybridisation with the LSI BCR-ABL dual fusionrobe (Vysis) was performed, and an extra ABL1 signal wasetected at 4q21 in addition to the ABL1 signals at 9q34 (Fig. 1a).his inserted fragment was apparently not amplified, and was

bserved in 89% of interphase nuclei. No extrachromosomal ABL1ybridisation signals were observed. RT-PCR and sequencing anal-sis (Fig. 1b) revealed a fusion between NUP214 exon 32 andBL1 exon 2 (primers NUP21432F 5′-GCTCTGGAGGAGGAAGTGTG-′ [4] and ABL1R 5′-GGTTGGGGTCATTTTCACTG-3′ [4]). Single

145-2126/$ – see front matter. Crown Copyright © 2011 Published by Elsevier Ltd. All rioi:10.1016/j.leukres.2011.03.025

nucleotide polymorphism (SNP) microarray analysis using the Illu-mina HumanCytoSNP-12 BeadChip showed gain of an extra copyof the region between ABL1 and NUP214, corresponding to thegenomic sequence of a single episome (Fig. 1c).

The patient initially received HyperCVAD induction chemother-apy, and attained a cytogenetic remission after two cycles oftreatment. He received a sibling allograft five months afterdiagnosis, but relapsed three months later. Conventional cyto-genetics showed a karyotype containing the original?inv(3)abnormality, along with multiple additional chromosomal abnor-malities, indicating relapse with cytogenetic evolution (Karyotype:46,XY,inv(1)(p3?6.1q12),?inv(3)(p23q2?7), add(11)(q2?5)[2]/46,XY,add(1)(p34),-3,?inv(3)(p23q2?7),add(5)(p15),add(6)(p23),add(7)(q11.2),-9,-12, +2∼4mar[cp7]/46,XY[8].nuc ish(ABL1x3),(BCRx2)[92/100]). FISH analysis revealed an extra ABL1 sig-nal in 92% of interphase nuclei. The patient was subsequentlytreated with a combination of imatinib (600 mg daily), vin-cristine and prednisolone, and a quick hematologic remissionwas attained. Qualitative RT-PCR for the NUP214-ABL1 tran-script in peripheral blood was used to monitor the patient’sresponse to imatinib therapy. A qualitative decrease in NUP214-ABL1 transcript levels was detected over the first five monthsof treatment, and the patient remained in hematologicalremission over this period. However, an increase in tran-script levels was observed at six months (Fig. 1d), and thepatient relapsed hematologically and cytogenetically shortlyafter (Karyotype: 47∼48,XY,t(1;7) (q22;q11.2),-3,add(5)(p15),add(6)(p23), +8,-9,-12,i(12)(p10), del(17)(p13),-20, +3mar[cp10]/46,XY[10]). The patient died two months post second relapse.

3. Discussion

Here we have demonstrated a 41 year old male T-ALL patientwith intrachromosomal insertion of a single NUP214-ABL1 fusionsequence who initially showed a favorable response to imatinibtherapy post relapse. It is interesting to note that this patientachieved a second complete remission (CR) that was twice theduration of remission post-allograft. The unusually long durationof disease control in this setting is in keeping with a favorableresponse to imatinib, although it is impossible to establish the rela-tive contribution of this agent in combination with vincristine andprednisolone. This positive response is in contrast to that describedby Stergianou et al. [5], who reported no bone marrow responsein a 42 year old male T-ALL patient with episomal amplificationof NUP214-ABL1 after treatment with 400 mg imatinib daily postrelapse [5]. The initial favorable response in the current case study

may possibly be accounted for by the prescription of a higherdosage of imatinib (600 mg/day), as is prescribed for CML in blastcrisis.

The second generation TKI dasatinib has been demonstrated toshow significantly higher antiproliferative activity against human

ghts reserved.

e132 Letter to the Editor / Leukemia Research 35 (2011) e131– e133

Fig. 1. (a) FISH performed on a de-colorized G-banded metaphase using the LSI BCR-ABL dual fusion probe (Vysis). An extra ABL1 signal was detected at chromosome 4q21.(b) Sequencing analysis detected an in-frame fusion between exon 32 of NUP214 and exon 2 of ABL1. (c) SNP array analysis showed genetic gain of the region between ABL1a me. (da as dei situ hp

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nd NUP214 on chromosome 9q34, corresponding to the sequence of a single episo control for RNA quality. A qualitative decrease in NUP214-ABL1 transcript levels wn transcript levels was observed from six months onwards. FISH, fluorescence inhosphoribosyltransferase.

UP214-ABL1 positive T-cell lines than imatinib in vitro [4]. Addi-ionally, in one published case study, a 21 year old male T-ALLatient with episomal NUP214-ABL1 amplification was treated suc-essfully with upfront dasatinib monotherapy, achieving completeytogenetic remission within three weeks [6]. In the current casetudy, the NUP214-ABL1 transcript was identified in the patientetrospectively (post first relapse), and the patient was prescribedmatinib based solely on the observation of an extra ABL1 signal byISH. Although the response to imatinib was initially encouraging,

complete molecular remission was not attained, and the patientelapsed six months after treatment. The patient did not receiveasatinib, though compassionate use was approved very shortlyrior to death.

The insertion of one single episomal NUP214-ABL1 sequencento chromosome 4q21 in our patient is unusual, as there appearso be a lack of genomic amplification. One study described a 28 yearld male patient who displayed an insertion of a single episomet 14q12 as the sole anomaly in 33% of metaphases [2]. However,his patient also showed intrachromosomal amplification as hsr in

further 5% of cells, and episomal amplification in <1% of cells.o apparent amplification could be identified in our patient, and

he insertion of a single NUP214-ABL1 fusion sequence at 4q21as seen as the sole abnormality in 89% of interphase nuclei atiagnosis.

A possible model for the formation, amplification, and optionaleintegration of NUP214-ABL1 fusion sequences has been proposed

) Qualitative RT-PCR detection of NUP214-ABL1 transcripts. HPRT was amplified astected over the first five months of treatment with imatinib. However, an increaseybridisation. SNP, single nucleotide polymorphism. HPRT, hypoxanthine-guanine

whereby reinsertion may serve to increase the stability of the fusionthrough cycles of cell division [2]. In this model, several episomalsequences may reintegrate as small hsr, or a single episome mayreintegrate within the vicinity of a highly active promotor, increas-ing the rate of transcription without genomic amplification. Thelatter appears to be the case in our patient, and with further stud-ies, we hope to test this hypothesis by mapping the site of theNUP214-ABL1 insertion.

In conclusion, the case study described here provides furtherclinical information regarding the efficacy of imatinib treatmentin NUP214-ABL1 positive T-ALL. It also highlights the importanceof early detection of this fusion, in order to facilitate the upfronttreatment of these patients with tyrosine kinase inhibitors in com-bination with chemotherapy, which appears to be a promisingtreatment strategy.

Conflict of interest statement

The authors declare no conflict of interest.

Acknowledgements

We would like to acknowledge the Department of Molecu-lar Genetics, PathWest Laboratory Medicine, QEII Medical Centre,Perth, Australia for performing the SNP array studies.

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Letter to the Editor / Leukem

Contributions. S.C. prepared manuscript, performed molecularaboratory work; J.O. proposed research project, performed cyto-enetics and FISH studies; G.R. provided input regarding moleculartudies; J.C. provided care to the case study subject and alluthors provided direction for research and approved final versionubmitted.

eferences

1] Graux C, Cools J, Melotte C, Quentmeier H, Ferrando A, Levine R, et al. Fusion ofNUP214 to ABL1 on amplified episomes in T-cell acute lymphoblastic leukemia.Nat Genet 2004;36:1084–9.

2] Graux C, Stevens-Kroef M, Lafage M, Dastugue N, Harrison CJ, MugneretF, et al. Heterogeneous patterns of amplification of the NUP214-ABL1fusion gene in T-cell acute lymphoblastic leukemia. Leukemia 2009;23:125–33.

3] Ballerini P, Busson M, Fasola S, van den Akker J, Lapillione H, Romana SP,et al. NUP214-ABL1 amplification in t(5;14)/HOX11L2-positive ALL presentwith several forms and may have a prognostic significance. Leukemia 2005;19:468–70.

4] Quintas-Cardama A, Tong W, Manshouri T, Vega F, Lennon PA, Cools J, et al.Activity of tyrosine kinase inhibitors against human NUP214-ABL1-positive Tcell malignancies. Leukemia 2008;22:1117–24.

5] Stergianou K, Fox C, Russell NH. Fusion of NUP214 to ABL1 on amplified episomesin T-ALL – implications for treatment. Leukemia 2005;19:1680–1.

6] Deenik W, Beverloo HB, van der Poel-van de Luytgaarde SC, Wattel MM, vanEsser JW, Valk PJ, et al. Rapid complete cytogenetic remission after upfrontdasatinib monotherapy in a patient with a NUP214-ABL1-positive T-cell acutelymphoblastic leukemia. Leukemia 2009;23:627–9.

earch 35 (2011) e131– e133 e133

Sarah Clarke ∗

Department of Hematology, PathWest LaboratoryMedicine WA, Royal Perth Hospital, GPO Box X2213,

Perth 6847, WA, Australia

John O’ReillyGiuliana Romeo

Department of Hematology, PathWest LaboratoryMedicine WA, Royal Perth Hospital, Perth, WA,

AustraliaSchool of Pathology and Laboratory Medicine,

University of Western Australia, Nedlands, WA,Australia

Julian CooneyDepartment of Hematology, Royal Perth Hospital,

Perth, WA, Australia

∗ Corresponding author. Tel.: +61 8 9224 2407;fax: +61 8 9224 3449.

E-mail address: Sarah.Clarke@health.wa.gov.au(S. Clarke)

8 February 2011Available online 13 April 2011