Paired Samples Analyses Of GATA2 mutations During Clinical Follow-Ups In 138 Patients With Acute Myeloid Leukemia-The Mutation Is Unstable During Disease Evolution
Authors: Lin Yun-Chu , Hou Hsin-An , Chou Wen-Chien , Chen Chien-Yuan , Tang Jih-Luh , Yao Ming , Huang Shang-Yi , Ko Bor-Sheng , Hsu Szu-Chun , Wu Shang-Ju , Tsay Woei , Chen Yao-Chang , Tien Hwei-Fang 
Published: October 2019

Abstract

Background
Heritable mutation in GATA2, a zinc-finger (ZF) transcription factor crucial for hematopoietic stem cell proliferation and differentiation, was identified in the families with myelodysplastic syndrome related acute myeloid leukemia (MDS-AML). Recently, GATA2 mutations were found to be strongly associated with CEBPA double mutations (CEBPAdouble-mut) in AML, which define a distinct genetic entity of AML. However, the stability of the mutation during the clinical course remains unclear. In this study, we evaluated the clinical and biological features of AML with GATA2 mutation and analyze its sequential changes during the clinical follow-ups.

Materials and Methods
Mutation analysis of GATA2 exons 3-7 was performed by polymerase chain reaction and direct sequencing in 192 de novo AML patients. The association between GATA2 mutations and clinical features, chromosomal changes and genetic mutations were analyzed. Furthermore, sequential analyses of GATA2 mutation during the clinical course were performed in 375 samples from 138 patients.

Results
GATA2 mutations were seen in 27.4%, 6.7% and 1% of patients with CEBPAdouble-mut, CEBPA single mutation and CEBPA-wild type, respectively. Fourteen different missense GATA2 mutations, which were all clustered in the highly conserved N-terminal ZF-1 domain, were identified in 20 patients, most commonly A318V (n=4), followed by L321F (n=3) and A318T (n=2).
GATA2 mutations were detected much more frequently in younger patients, and were closely associated with FAB M1 subtype, intermediate-risk cytogenetics, and expression of HLA-DR, CD7, CD15 or CD34 on leukemic cells. In contrast, GATA2 mutations were negatively associated with FAB M4 subtype and favorable-risk cytogenetics.
A thorough mutation screening in 166 patients, including 15 GATA2-mutated ones, was performed to investigate the association between mutations of GATA2 and 17 other genes. The most common additional genetic aberrations in 15 GATA2-mutated patients at initial diagnosis were CEBPA mutation (n=14), followed by TET2 mutation (n=3) and NRAS mutation (n=2). Patients with GATA2 mutations had a significantly higher incidence of CEBPA mutation than those with GATA2-wild type (93.3% versus 34.4%, P<0.0001). Of note, CEBPA mutations concurrent with GATA2 mutations were mostly CEBPAdouble-mut.
Of the 154 AML patients undergoing conventional intensive induction chemotherapy, 124 (81%) patients achieved a complete remission (CR). Patients with GATA2 mutation had a higher CR rate and a trend of lower relapse rate compared with those with GATA2 wild-type (CR rate: 95% versus. 78.5%; relapse rate: 21% versus. 44.8%). With a median follow-up of 24.3 months (ranges, 0.1 to 150), patients with GATA2 mutation had significantly better overall survival (OS) and relapse-free survival (RFS) than those without GATA2 mutation (P=0.010 and P=0.033, respectively). Interestingly, among the subgroup of CEBPAdouble-mut patients, GATA2-mutated patients still had a trend of better OS and RFS than GATA2-wild type (median, not reached versus. 61 months, P=0.068 and not reached versus. 17 months, P=0.066, respectively). Multivariate analysis demonstrated that GATA2 mutation was an independent favorable prognostic factor for OS irrespective of age, white blood cell counts, cytogenetics and NPM1/FLT-ITD (HR: 0.0133, 95% CI: 0.018-0.978, P=0.047).
In the serial studies of GATA2 mutations in 375 samples from 138 patients, including 14 GATA2-mutated and 124 GATA2-wild patients, all 14 GATA2-mutated patients lost the original mutations when first CR was achieved. Among them, four patients relapsed; two regained the original mutations and the other two lost them. On the other hand, two of the 124 GATA2-wild patients acquired a novel GATA2 mutation at first relapse and lost it at second CR. Interestingly, one of them regained the same GATA2 mutation at the second relapse.

Conclusion
AML patients with GATA2 mutations presented distinct clinical and biological features and a favorable prognosis in the total cohort. In the subgroup of patients with CEBPAdouble-mut, those with GATA2 mutations also had a trend of better OS and RFS compared with GATA2-wild patients. Sequential studies showed GATA2 mutation was not stable during disease evolution; it might be lost or acquired at disease progression, implying it was a second hit in the leukemogenesis of AML with CEBPA mutation.

Disclosures:
No relevant conflicts of interest to declare.