Amplification of AML1 in acute lymphoblastic leukemia is ... - Nature

Correspondence

2249

Amplification of AML1 in acute lymphoblastic leukemia is associated with a poor outcome

Leukemia (2003) 17, 2249–2250. doi:10.1038/sj.leu.2403140 Published online 18 September 2003

Recently, we confirmed that partial duplication of the long arm of chromosome 21, dup(21), including the 21q22 chromosomal region and amplification of AML1, is a recurring chromosomal abnormality in acute lymphoblastic leukemia (ALL). Multiple copies of the AML1 gene were identified in 20 patients during routine screening by interphase fluorescence in situ hybridization (FISH) for the presence of the TEL/AML1 fusion.1 Together with the sporadic cases reported in the literature, our study raised the total number of published cases to 30. We now report a further eight patients with the same abnormality and comment on the survival of the 28 patients from our original series. The eight new cases were from the same ALL childhood treatment trials as previously reported,1 and were included in this study with parental consent. They were identified using similar procedures.1 Additional copies of signals for the AML1 gene were observed in six of the new cases by routine interphase FISH screening. The other two cases were identified during a retrospective cytogenetic review of G-banded slides from cases that showed monosomy 21 in association with unidentified marker chromosomes. The markers in all eight cases had the characteristic morphology of a dup(21) chromosome (Table 1), as previously described.1 Although observed by others (Najfeld V. Blood 1998; 92: 396a),2,3 we are still unable to confirm AML1 amplification in cases with a normal karyotype. In all the eight cases, metaphase FISH with the TEL/AML1 probe confirmed that the multiple copies of AML1 were confined to duplicated chromosomes 21. The number of AML1 signals per cell for each case is shown in Table 1. The involvement of the AML1 gene within the amplified regions was confirmed using two AML1 exon-specific probes in cases with available material (patients 3767, 4780, 5655, 5674 and 5898), as previously described.1 The karyotypes defined by conventional cytogenetics, or in two cases by multiplex-FISH (M-FISH) (4780, 5898), were similar to those seen in the previously reported cases. They were near-diploid with 45–47 chromosomes, the dup(21) replacing one normal copy of chromosome 21, this being the sole abnormality in two patients. The patients had a median age of 8 years (range 5–11 years). The seven cases with known immunophenotypes were all common/pre-B ALL. All the original 20 patients had a WBC o20  109/l. However, in three of the new patients, the WBC was 450  109/l at presentation. The most recent follow-up on all 28 patients showed that 12 of them had relapsed, either as an isolated bone marrow (n ¼ 9) or an isolated central nervous system (n ¼ 3) relapse (Figure 1). Correspondence: Dr CJ Harrison, Leukaemia Research Fund Cytogenetics Group, Cancer Sciences Division, University of Southampton, MP 822 Duthie Building, Southampton General Hospital, Southampton SO16 6YD, UK; Fax: þ 44 (0)23 8079 6432 Received 21 July 2003 ; accepted 13 August 2003; Published online 18 September 2003

Proportion surviving event free

TO THE EDITOR

1.00

0.75

0.50

0.25

0.00 0

1

2

3

4

5

Years from diagnosis

Figure 1 Event-free survival of 28 patients with AML and amplification of the AML1 gene.

Relapse occurred between 4 and 57 months. Eight patients relapsed while still on treatment and nine of the 12 patients have subsequently died, six of them having only a short second remission. One patient (4414) died in remission 8 months following diagnosis. Among the 16 patients who have not so far suffered an adverse event, nine have o2 years follow-up, and only two are alive and well more than 3 years after diagnosis (Figure 1). Overall, these data suggest that the amplification of AML1 is associated with a poor outcome. There was no association between the form of the dup(21) and relapse, since all the five morphological types were observed in the relapse patients. Fixed cell suspensions were available from two relapse bone marrow samples (patients 2423 and 4134). Although there was evidence of minor karyotypic evolution between the diagnostic and relapse samples in both patients, interphase FISH and cytogenetic analysis revealed that the level of amplification, as established by AML1 signal copy number, and the G-banded appearance of the dup(21) remained unchanged. This indicates that, although the dup(21) chromosomes are clearly heterogeneous in form, they appear to be stable throughout cell division. Identification of further eight patients with amplification of AML1 on a duplicated chromosome 21 reinforces this as a cytogenetic subgroup in ALL, occurring at an estimated incidence of 1.5% in childhood ALL. The inclusion of two other recently described cases4,5 increases the total number reported to 40. A longer follow-up of our 28 cases suggests that the presence of a duplicated chromosome 21, together with multiple copies of the AML1 gene, is indicative of a poor prognosis in ALL.

Acknowledgements We thank the Leukaemia Research Fund for financial support; Dr Anne Hagermeijer (EU Concerted Action) and Dr Roland Berger (Paris) for cosmids ICRF c103C0664 and H11086, respectively; Leukemia

Correspondence

2250 Table 1 Patient no.

Karyotypes and clinical details of the eight patients with dup(21) Sex/age (years)

WBC x109/l

EFS (months)

OS (months)

AML1 signals/cell

Form of dup(21)

2848 3382 3767 4414

M/5 M/11 F/10 M/7

2 6 1 9

57 16 32 8

62+ 39 35+ 8

5 5 4–6 5+

LA SM M M

4780 5655 5674 5898

M/10 F/8 M/6 M/5

80 55 55 31

13 + 8+ 5+ NK

13+ 8+ 5+ NK

5 4–6 6+ 4–6

SA M SA M

Karyotype 46,XY,dup(21)(q?) 46,XY,i(9)(q10),del(11)(q2?1),der(21)dup(21)(q?) 46,XX,dup(21)(q?) 45,XY,t(6;19)(p21;p13),der(7)t(7;15)(p1;q1),del(11)(p13), -15,del(16)(q2),ider(21)(q10)dup(21)(q?) 45,XY,11,del(12)(p1?2),der(20)t(11;20)(q?;q?),dup(21)(q?) 46,XX,del(1)(q4?),del(6)(q1?5),del(7)(q2?2q3?1),dup(21)(q ?) 47,XY,+X,dup(21)(q?) 47,XY,+X,del(16)(q13),i(17)(q10),ider(21)(q10)dup(21)(q?)/ 47,idem,add(7)(p1)

EFS, event-free survival; OS, overall survival; LA, large acrocentric; SA, small acrocentric; M, metacentric; SM, small acrocentric.

Dr John Crolla and his team, Wessex Regional Genetics Laboratory, Salisbury, for growing and preparation of the AML1specific cosmids; the Clinical Trial Service Unit (CTSU), Oxford, for clinical and survival data. We are grateful to the following UKCCG cytogenetic laboratories for providing cytogenetic and FISH data as well as fixed cell suspensions: West Midlands Regional Genetics Services, Birmingham Women’s Hospital; Haematology Cytogenetics Laboratory, University Hospital of Wales, Cardiff; SE Scotland Cytogenetics Services, Western General Hospital, Edinburgh; LRF Centre for Childhood Leukemia, Great Ormond Street Hospital, London; Cytogenetics Department, St James Hospital, Leeds; Merseyside & Cheshire Genetics Laboratory, Liverpool Women’s Hospital, Liverpool; Oncology Cytogenetics Service, Christie Hospital, Manchester; North Trent Cytogenetics Service, Sheffield Children’s Hospital NHS Trust, Sheffield.

HM Robinson1 ZJ Broadfield1 KL Cheung1 L Harewood1 RL Harris1 GR Jalali1 M Martineau1 AV Moorman1 KE Taylor1 S Richards2 C Mitchell3 CJ Harrison1

1

Leukaemia Research Fund Cytogenetics Group, Cancer Sciences Division, University of Southampton, Southampton, UK; 2 Clinical Trial Service Unit, Radcliffe Infirmary, Oxford, UK; 3 Paediatric Oncology, John Radcliffe Hospital, Oxford, UK

References 1 Harewood L, Robinson H, Harris R, Jabbar Al-Obaidi MS, Jalali GR, Martineau M et al. Amplification of AML1 on a duplicated chromosome 21 in acute lymphoblastic leukemia: a study of 20 cases. Leukemia 2003; 17: 547–553. 2 Jabbar Al-Obaidi MS, Martineau M, Bennett CF, Franklin IM, Goldstone AH, Harewood L et al. ETV6/AML1 fusion by FISH in adult acute lymphoblastic leukemia. Leukemia 2002; 16: 669–674. 3 Mikhail FM, Serry KA, Hatem N, Mourad ZI, Farawela HM, El Kaffash DM et al. AML1 gene over-expression in childhood acute lymphoblastic leukemia. Leukemia 2002; 16: 658–668. 4 Morel F, Herry A, Le Bris M-J, Douet-Guilbert N, Le Calvez G, Marion V et al. AML1 amplification in a case of childhood acute lymphoblastic leukemia. Cancer Genet Cytogenet 2002; 137: 142–145. 5 Alvarez Y, Coll MD, Bastida P, Ortega JJ, Caballin MR. AML1 amplification in a child with acute lymphoblastic leukemia. Cancer Genet Cytogenet 2003; 140: 58–61.

Comprehensive analysis of gene alterations in acute megakaryoblastic leukemia of Down’s syndrome

Leukemia (2003) 17, 2250–2252. doi:10.1038/sj.leu.2403121 Published online 21 August 2003

TO THE EDITOR Down’s syndrome (DS) children have the 10- to 20-fold increased risk of developing acute leukemia compared with non-DS children. Acute myeloid leukemia (AML) in DS children shows unique characteristics as to be a predominance of the megakaryoblastic leukemia (AMkL) and a preceding history of the transient myeloproliferative disorder (TMD), whose blasts are morphologically and phenotypically indistinguishable from those Leukemia

of AMkL. TMD is developed in about 10% of DS infants and resolves spontaneously in most cases. However, 20% of TMD cases develop AMkL within 3 years, suggesting that additional genetic alterations might occur during the progression from TMD to AMkL. Recently, somatic mutations of the GATA1 gene were reportedly associated with AMkL of DS children.1 In addition, it was reported that GATA1 mutations were present in the TMD blasts, and that the identical GATA1 mutation was found in sequential samples collected from a patient during TMD and subsequent AMkL.2–5 These results suggested that GATA1 mutations are an early event in DS leukemogenesis and contribute