Introduction: AML is a heterogeneous disease with various chromosomal aberrations. The karyotype at diagnosis provides important prognostic information that influences therapy and outcome. The TP53 gene is the most frequently mutated gene in human tumors. The reported TP53 mutation rate in AML is low (2.1%). In contrast, the incidence of TP53 mutations in AML with a complex aberrant karyotype (CK-AML) is higher (69-78%).

Aims: to investigate the frequency and the prognostic role of TP53 mutations in adult AML patients (pts) focusing the screening on subgroups of pts with chromosome abnormalities.

Patients and Methods: 106 adult AML pts with FAB-M0, M1, M2, M3, M4, M5, miscellaneous cytogenetic abnormalities and normal karyotype (nK-AML, 14/106 pts) were examined. Forty-four pts (41.1%) showed 3 or more chromosome abnormalities (CK-AML), 42 (39.6%) presented one or two cytogenetic abnormalities (other-AML) and in 6 cases the karyotype was not available. Genomic DNA and/or cDNA were isolated from mononuclear AML blast cells. TP53 mutation screening was performed on all 106 AML pts, in particular in 42 from exon (ex) 2 to 11, in 48 from ex 4 to 11 and in 16 pts from ex 2 to 8. Analysis was focused on coding sequences (RefSeq GRCh37/hg19 NG_017013.2).

Results: By PCR and subsequent Sanger sequencing, mutations of TP53 were detected in 23 pts (21.1%). Seven pts revealed 2 mutations. 83% of all mutated pts had CK (19/23) by contrast the frequency of mutations was very low in “no CK-AML” pts (6.5%). Overall, mutated patients included 19/44 with CK-AML (43.2%); 1/6 (16.7%) with nK and 3/42 (7.1%) with other-AML. 26 TP53 point mutations [19 missense, 1 silent, 5 intron and 1 3’ untranslated region (UTR)] and 4 TP53 deletions were found. Twenty-six out of 30 mutations/deletions (86.6%) were located in the DNA binding domain, 2 in the carboxyl-terminal tetramerization and regulatory domains and 2 in the transcriptional activation domain. All mutations in coding regions were classified by the IARC database (http://p53.iarc.fr/TP53GeneVariations.aspx) as deleterious. Of note, alterations of TP53 were significantly associated with poor outcomes in terms of overall survival and disease free-survival (P < 0.0001). Conclusions: Our data demonstrated that mutations of TP53 occur in 21.7% of AML with a higher frequency in the subgroup of CK-AML (p< 0.0001-Fischer's exact test). Since TP53 mutations have predicted to be deleterious and significantly correlated with prognosis, TP53 mutation screening should be recommended in CK-AML pts.

Supported by: EuropeanLeukemiaNet, AIL, AIRC, PRIN 2010-2011, Fondazione del Monte di Bologna e Ravenna, European Union

Seventh Framework Programme [FP7/2007-2013].

Citation Format: Anna Ferrari, Ilaria Iacobucci, Cristina Papayannidis, Carmen Baldazzi, Chiara Sartor, Emanuela Ottaviani, Nicoletta Testoni, Valentina Robustelli, Margherita Perricone, Claudia Venturi, Maria Chiara Abbenante, Viviana Guadagnuolo, Antonella Padella, Federica Cattina, Giorgia Simonetti, Domenico Russo, Giovanni Martinelli. Tp53 mutation screening in adult acute myeloid leukemia (AML) patients shows a strong association with complex karyotype and poor outcome. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 570. doi:10.1158/1538-7445.AM2014-570