Journal List > Korean J Hematol > v.44(2) > 1032867

Lee, Joo, Oh, Shin, Kim, Lee, and Lee: Prognostic Significance of FLT3 Internal Tandem Duplication in Acute Myeloid Leukemia with Normal Karyotype

Abstract

Background

Activating mutations of the fms-like tyrosine kinase 3 gene (FLT3) by internal tandem duplication (ITD) in the juxtamembrane region are found in 20∼30% of the adults with acute myeloid leukemia (AML). The allelic ratio of FLT3/ITD (ITD-AR), as assessed by Genescan analysis, has been reported to carry prognostic significance in AML patients who have normal karyotype.

Methods

FLT3/ITD was studied by PCR in 113 adults with AML including 55 patients with normal karyotype. Genescan analysis was performed for the PCR products to determine the allelic distribution. The results were correlated with the prognostic factors.

Results

FLT3/ITD was found in 23% of the total AML patients and in 32.7% of those patients with normal karyotype. The mutation was related to a high WBC count, a high serum LD level and a low percentage of CD34 positive cells. The ITD-AR ranged from 0.05 to 8.27 (median, 0.61). The patients with a high ITD-AR (≥0.7) had significantly higher WBC count and LD level than those without FLT3/ITD. On multivariate analysis, a high ITD-AR as well as FLT3/ITD were confirmed to be independent adverse prognostic factors for AML patients with normal karyotype.

Conclusion

This study demonstrated that a high ITD-AR and FLT3/ITD had major adverse impacts on the prognostic relevance for AML patients with normal karyotype.

References

1. Boissel N, Cayuela JM, Preudhomme C, et al. Prognostic significance of FLT3 internal tandem repeat in patients with de novo acute myeloid leukemia treated with reinforced courses of chemotherapy. Leukemia. 2002; 16:1699–704.
crossref
2. McKenna HJ, Stocking KL, Miller RE, et al. Mice lacking FLT3 ligand have deficient hematopoiesis affecting hematopoietic progenitor cells, dendritic cells, and natural killer cells. Blood. 2000; 95:3489–97.
crossref
3. Whitman SP, Archer KJ, Feng L, et al. Absence of the wild-type allele predicts poor prognosis in adult de novo acute myeloid leukemia with normal cytogenetics and the internal tandem duplication of FLT3: a cancer and leukemia group B study. Cancer Res. 2001; 61:7233–9.
4. Rosnet O, Schiff C, Pebusque MJ, et al. Human FLT3/FLK2 gene: cDNA cloning and expression in hematopoietic cells. Blood. 1993; 82:1110–9.
crossref
5. Small D, Levenstein M, Kim E, et al. STK-1, the human homolog of Flk-2/Flt-3, is selectively expressed in CD34+ human bone marrow cells and is involved in the proliferation of early progenitor/stem cells. Proc Natl Acad Sci USA. 1994; 91:459–63.
crossref
6. Kottaridis PD, Gale RE, Linch DC. Prognostic implications of the presence of FLT3 mutations in patients with acute myeloid leukemia. Leuk Lymphoma.
7. Fenski R, Flesch K, Serve S, et al. Constitutive activation of FLT3 in acute myeloid leukaemia and its consequences for growth of 32D cells. Br J Haematol. 2000; 108:322–30.
crossref
8. Hayakawa F, Towatari M, Kiyoi H, et al. Tandem-duplicated FLT3 constitutively activates STAT5 and MAP kinase and introduces autonomous cell growth in IL-3-dependent cell lines. Oncogene. 2000; 19:624–31.
crossref
9. Thiede C, Steudel C, Mohr B, et al. Analysis of FLT3-activating mutations in 979 patients with acute myelogenous leukemia: association with FAB subtypes and identification of subgroups with poor prognosis. Blood. 2002; 99:4326–35.
crossref
10. Abu-Duhier FM, Goodeve AC, Wilson GA, Care RS, Peake IR, Reilly JT. Identification of novel FLT3 Asp835 mutations in adult acute myeloid leukaemia. Br J Haematol. 2001; 113:983–8.
crossref
11. Shih LY, Huang CF, Wu JH, et al. Heterogeneous patterns of FLT3 Asp (835) mutations in relapsed de novo acute myeloid leukemia: a comparative analysis of 120 paired diagnostic and relapse bone marrow samples. Clin Cancer Res. 2004; 10:1326–32.
12. Abu-Duhier FM, Goodeve AC, Wilson GA, et al. FLT3 internal tandem duplication mutations in adult acute myeloid leukaemia define a high-risk group. Br J Haematol. 2000; 111:190–5.
crossref
13. Kiyoi H, Naoe T, Nakano Y, et al. Prognostic implication of FLT3 and N-RAS gene mutations in acute myeloid leukemia. Blood. 1999; 93:3074–80.
14. Kottaridis PD, Gale RE, Frew ME, et al. The presence of a FLT3 internal tandem duplication in patients with acute myeloid leukemia (AML) adds important prognostic information to cytogenetic risk group and response to the first cycle of chemotherapy: analysis of 854 patients from the United Kingdom Medical Research Council AML 10 and 12 trials. Blood. 2001; 98:1752–9.
crossref
15. Lee JN, Kim HR, Shin JH, Joo YD. Prevalence of FLT3 internal tandem duplication in adult acute myelogenous leukemia. Korean J Lab Med. 2007; 27:237–43.
crossref
16. Rombouts WJ, Blokland I, Löwenberg B, Ploema-cher RE. Biological characteristics and prognosis of adult acute myeloid leukemia with internal tandem duplications in the FLT3 gene. Leukemia. 2000; 14:675–83.
crossref
17. Meshinchi S, Alonzo TA, Stirewalt DL, et al. Clinical implications of FLT3 mutations in pediatric AML. Blood. 2006; 108:3654–61.
crossref
18. Zwaan CM, Meshinchi S, Radich JP, et al. FLT3 internal tandem duplication in 234 children with acute myeloid leukemia: prognostic significance and relation to cellular drug resistance. Blood. 2003; 102:2387–94.
crossref
19. Mrózek K, Bloomfield CD. Chromosome aberrations, gene mutations and expression changes, and prognosis in adult acute myeloid leukemia. Hematology Am Soc Hematol Educ Program. 2006. 169–77.
20. Schnittger S, Schoch C, Dugas M, et al. Analysis of FLT3 length mutations in 1,003 patients with acute myeloid leukemia: correlation to cytogenetics, FAB subtype, and prognosis in the AMLCG study and usefulness as a marker for the detection of minimal residual disease. Blood. 2002; 100:59–66.
crossref
21. Haferlach T, Schoch C, Schnittger S, Kern W, Loffler H, Hiddemann W. Distinct genetic patterns can be identified in acute monoblastic and acute monocytic leukaemia (FAB AML M5a and M5b): a study of 124 patients. Br J Haematol. 2002; 118:426–31.
crossref
22. Colovic N, Tosic N, Aveic S, et al. Importance of early detection and follow-up of FLT3 mutations in patients with acute myeloid leukemia. Ann Hematol. 2007; 86:741–7.
crossref
23. Frohling S, Schlenk RF, Breitruck J, et al. Prognostic significance of activating FLT3 mutations in younger adults (16 to 60 years) with acute myeloid leukemia and normal cytogenetics: a study of the AML Study Group Ulm. Blood. 2002; 100:4372–80.
24. Kim S, Kim Y, Lee I, et al. FLT3 Internal tandem duplication in acute myeloid leukemia with normal karyotype. Korean J Hematol. 2007; 42:250–7.
crossref
25. Mori Y, Yoshimoto G, Kumano T, et al. Distinctive expression of myelomonocytic markers and downregulation of CD34 in acute myelogenous leukaemia with FLT3 tandem duplication and nucleophosmin mutation. Eur J Haematol. 2007; 79:17–24.
crossref

Fig. 1.
Genescan analysis of FLT3/ITD levels in AML patients. (A) wild type of FLT3 gene, (B∼D) wild type and various size of ITD in FLT3 gene. Abbreviations: FLT3, fms-like tyrosine kinase; ITD, internal tandem duplication; AML, acute myeloid leukemia.
kjh-44-74f1.tif
Table 1.
Clinical characteristics of total AML patients including patients with FLT3/ITD and distribution of patients with FLT3/ITD
Characteristics Total patients FLT3/ITD
No. of cases 113 26
Age (yr, median) 20∼85 (51) 20∼80 (54)
Male:Female 55:58 13:13
FAB subgroup (de novo, N)
M0 8 1
M1 32 8
M2 41 7
M3 21 6
M4e 5 2
M5 2 1
M6 0 0
M7 1 0
Unclassified∗ 2 1
Secondary AML 1 0

Bone marrow aspiration is inadequate for FAB classification of AML because of dry tap. Abbreviations: FLT3/ITD, fms-like tyrosine kinase internal tandem duplication; AML, acute myeloid leukemia.

Table 2.
Cytogenetic classification of total AML patients including patients with FLT3/ITD and distribution of patients with FLT3/ITD
Cytogenetic prognostic group Total FLT3/ITD
Cytogenetic prognostic group patients N %
Favorable 32 6 18.8
t(8;21) 12 2 16.7
t(15;17) 16 3 18.8
inv(16)/t(16;16) 4 1 25.0
Intermediate∗ 71 20 28.8
Normal karyotype 52 17 32.7
Numerical aberration 11 3 27.3
Balanced structural rearrangement 2 0 0.0
Unbalanced structural rearrangement 6 0 0.0
Unfavorable 10 0 0.0
?7 5 0 0.0
Complex chromosomal abnormalities 2 0 0.0
Others 3 0 0.0

Numerical aberration, +8, +11, +21, ?X, ?Y; Balanced structural rearrangement, t(1;19), t(7;11); Unbalanced structural rearrangement, add(1p), del(9q), del(12q), del(15q), del(17q), der(14q). Others are included in t(3;3), del(11) (q23).

Table 3.
Genescan analysis in patients with FLT3/ITD
No. Allele FLT3/ITD ratio (mutant/wild)
1 329–393 0.06
2 329–335 0.10
3 329–386 0.18
4 329–402 0.19
5 329–384 0.21
6 329–353 0.31
7 329–379 0.38
8 329–382 0.43
9 329–350 0.50
10 329–376 0.54
11 329–373 0.60
12 329–356 0.60
13 329–350 0.61
14 329–439 0.61
15 329–384 0.70
16 329–411 0.72
17 329–382 0.72
18 329–370 0.72
19 329–390 0.72
20 329–373 0.74
21 329–344–347 0.78
22 329–344 0.83
23 329–353 0.89
24 329–382 1.12
25 329–350 1.44
26 329–353–382 8.27
27∗ 329–350 1.71
28∗ 329–382 3.20

Results from the patients with FLT3/ITD in relapse of AML.

Table 4.
Characteristics according to FLT3/ITD status in AML patients with normal karyotype
Characteristics Total patients FLT3/ITD positive FLT3/ITD negative P
No. of cases 52 17 35  
Male:Female 24:28 9:8 15:20 0.44
Age (yr, median) 55 60 54 0.36
Range (20∼80) (20∼80) (22∼79)  
WBC count (×109/L, median) 16.2 67.3 12.9 0.003
Range (0.4∼349.9) (2.0∼349.9) (0.4∼204.3)  
LD level (U/L, median) 1,039 1,780 706 0.003
Range (305∼5,401) (388∼5,401) (305∼3,179)  
Bone marrow blasts (%, median) 78.2 86.0 74.7 0.56
Range (21.5∼96.3) (21.5∼94.3) (27.2∼96.3)  
CD34+ cells (%, median) 44.5 20.1 84.6 0.005
Range (0.03∼99.4) (0.03∼68.1) (0.06∼99.4)  

Abbreviation: LD, lactate dehydrogenase.

Table 5.
Comparison of ch haracteristics of AML patients with high, low ITD-AR, or ITD wild typ pe
Characteristics ITD wild type Low ITD-AR (<0.7) High ITD-AR (≥0.7)   P  
Wild vs low Wild vs high Low vs high
No. of cases 87 14 12      
Age (yr, median) 49 48 55 0.5 0.36 0.9
Range (22∼85) (26∼80) (20∼67)      
WBC count (×109/L, median) 10.3 38.6 93.9 0.01 <0.0001 0.07
Range (0.2∼204.3) (4.0∼195.2) (2.0∼349.9)      
LD level (U/L, median) 765 1,255 2,055 0.09 <0.0001 0.1
Range (286∼9,319) (338∼6,255) (709∼5,401)      
BM blasts (%, median) 71.1 84.7 81 0.46 0.74 0.86
Range (0.6∼96.6) (34.6∼94.3) (2.7∼91.9)      
BM CD34+ cells (%, median) 80.5 35.2 35 0.41 0.05 0.82
Range (0.06∼99.7) (0.03∼98.4) (0.58∼61.3)      

Abbreviation: ITD-AR, internal tandem duplication allelic ratio.

Table 6.
Results of Cox regression analysis of survival in AML patients with normal karyotype
Variable Overall survival   Disease free survival
Hazard ratio 95% CI P   Hazard ratio 95% CI P
FLT3/ITD 0.233 0.054∼1.000 0.051 0.321 0.060∼1.717 0.186
ITD-AR (≥0.7) 3.012 1.274∼7.119 0.012   3.505 1.049∼11.706 0.042

Abbreviation: CI, confidence interval.

TOOLS
Similar articles