ASXL1 Mutations in AML: Molecular Biomarker for Secondary AML?

• Published in: Blood 2014-12, Vol.124 (21), p.2343-2343
• Main Authors: Hsu, Jingmei, Kumar, Anita J., Carroll, Martin P., Frey, Noelle V., Shah, Nirav N., Jianhua, Zhao, Hexner, Elizabeth O., Loren, Alison W., Mangan, James K., Perl, Alexander E., Porter, David, Morrissette, Jennifer, Luger, Selina M.
• Format: Article
• Language: English
• ISSN: 0006-4971; 1528-0020
• DOI: 10.1182/blood.V124.21.2343.2343

Background: Additional sex combs like transcription factor 1 (ASXL1) is a member of the polycomb group protein. ASXL1 mutation has been implicated in myeloid malignancy transformation. It is hypothesized that mutated ASXL1 leads to the loss of polycomb repressive complex 2 (PRC2) mediated gene repression and subsequent transforming events. Recent studies identify ASXL1 mutation as a poor prognostic marker in patients (pts) with de novo acute myeloid leukemia (AML) who present with intermediate–risk cytogenetic lesions (Patel, NEJM 2012; Schnittger, Leukemia2013). To study the impact of ASXL1 mutations in an unselected AML population, we analyzed clinical and molecular characteristics of patients with untreated AML who express ASXL1 mutation at presentation. Methods: Using next generation sequencing, 254 adult patients with AML seen at the Hospital of the University of Pennsylvania were analyzed for mutations, including ASXL1, using a 33-gene hematologic malignancy panel. Clinical characteristics were obtained from retrospective chart review. Kaplan-Meier estimates were used to calculate overall survival (OS) from time of diagnosis. Living patients were censored at date last seen. Results: ASXL1 mutations were detected in 36/254 (14%) AML pts. There were 29 known pathologic mutations, 1 benign, 1 probable pathologic, and 9 variants of unknown clinical significance (VUS). In 6/36 (16.7%) pts, ASXL1 was the sole mutation identified. Of the 30 pts with additional mutations (Figure 1), 6/30 (20%) pts harbored 2 independent ASXL1 mutations. When the 27 patients with pathologic ASCL mutations were analyzed for co-mutations, TET2 (13/27, 48%) was the most frequent ASXL1 co-mutation. FLT3 (0/27, 0%) and NPM1 (1/27, 3.7%) were notable for their absence. Median age of pts at diagnosis was 69 years (range 23-80). Prior myelodysplastic syndrome (MDS) or myeloproliferative neoplasm (MPN) was noted in 9/36 (25%) and 11/36 (30.6%) pts, respectively. Four pts (11.1%) had received chemotherapy and/or radiation therapy for a prior non-myeloid neoplasm. Karyotype was normal in 18/36 (50%) pts, and 7 additional pts had intermediate cytogenetic lesions. There were 7 pts (19.4%) with unfavorable cytogenetics (complex karyotype (3 pts), 7q- (3 pts), and 5q- (1 pt)). Four pts (11.1%) had a favorable karyotype, with t(8;21) in 3 pts and t(15;17) in 1 pt. At presentation, median white blood cell count (WBC) was 6.4x103/uL (1.0 x -103). In pts whose AML transformed from prior MPN, me