[1603] FLT3 Mutations Occur More Frequently but Do Not Impact the Outcome in Childhood AML with Favorable Recurrent Genetic Abnormalities: A Single Institution Experience

Liqun Yin, Qi Wei, Micah Will, Dia Barakat, Xiayuan Liang. University of Colorado Denver School of Medicine, Aurora

Background: FLT3 mutations are known adverse prognostic factors in adult patients with acute myeloid leukemia (AML). It is also known that three recurrent genetic abnormalities (RGA) [t(8;21), inv(16)/t(16;16), and t(15;17)] are associated with favorable prognosis. In childhood AML, it is not uncommon to have coexistence of both FLT3 mutations and favorable RGA. However, the prognostic impact of FLT3 mutations in pediatric AML with favorable RGA has not been fully established. We studied a series of 73 cases of childhood AML to determine the frequency of FLT3 mutations and their potential impact on patients with favorable RGA.
Design: 73 cases of newly diagnosed AML at Children's Hospital CO from 1999 to 2011 are analyzed. FLT3 mutations, t(8;21), inv(16)/t(16;16) or t(15;17) were performed by RT-PCR and/ or FISH. The medical records were reviewed to determine patients' age and sex, and information of remission, relapse and death. Statistical differences in categorical variables (sex and prognostic outcome) and ages at diagnosis were analyzed by Fisher's exact test and t-test respectively.
Results: 1) Both FLT3 mutations and favorable RGA were frequently seen in older patients (mean age: 11.7 and 12.4; p = 0.0477 and 0.003 respectively). 2) FLT3 mutations occurred more often in AML with favorable RGA than other AML (33.3% vs 20%). 3) Patients with favorable RGA were associated with better outcome compared with other AML (remission rate: 85% vs 45.8%, p = 0.0027). 4) FLT3 mutations had no significant impact on outcome in the favorable RGA group.

Table 1
  #of casesAge (yr) SexOutcome 
   Mean (range)p valueM:FRemission vs Relapse/Deathp value
FLT3+ 1811.7 (3-18)0.004711:711/18 (61.1%) vs 7/18 (38.9%)0.5873
FLT3- 558.1 (0-18) 33:2226/50 (52%) vs 24/50 (48%) 
        
Favorable RGA 2112.4 (1-18)0.000314:617/20 (85%) vs 3/20 (15%)0.0027
Other AML 527.7 (0-18) 30:2321/48 (45.8%) vs 27/48 (54.2%) 
        
Favorable RGAFL3+7/21 (33.3%)11.9 (3-16)0.97126:15/7 (71.4%) vs 2/7 (28.6%)†/♠0.5743♠
 FL3-14/21 (66.7%)11.9 (1-18) 9:512/14 (85.7%) vs 2/14 (14.3%)*/♠1.0000†
Other AMLFL3+11/55 (20%)11.6 (3-18).0.3075:67/11 (63.6%) vs 4/11 (36.4%)†/◊0.1807◊
 FL3-44/55 (80%)6.8 (0-18) 24:1714/36 (38.9%) vs 22/36 (61.1%)*/◊0.0041*



Conclusions: In childhood AML, FLT3 mutations are more commonly detected in patients with favorable RGA and older patients. The status of FLT3 mutations has no significant impact on outcome in the favorable RGA group. A large series of study is necessary to confirm our observations.
Category: Hematopathology

Monday, March 19, 2012 9:30 AM

Poster Session I Stowell-Orbison/Surgical Pathology/Autopsy Awards Poster Session # 239, Monday Morning

 

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