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GENETIC LANDSCAPE OF FLT3-MUTATED ACUTE MYELOID LEUKEMIA (AML) PATIENTS TREATED WITHIN THE RATIFY TRIAL: CALGB 10603 (ALLIANCE)

PS968

Jahn, N.1; Panina, E.1; Bullinger, L.2; Dolnik, A.2; Herzig, J.1; Blätte, T. J.1; Benner, A.3; Gambietz, A.3; Krzykalla, J.3; Gathmann, I.4; Larson, R. A.5; Lo-Coco, F.6; Amadori, S.6; Prior, T. W.7; Brandwein, J. M.8; Appelbaum, F. R.9; Medeiros, B. C.10; Tallman, M. S.11; Tiecke, E.4; Pallaud, C.4; Ehninger, G.12; Heuser, M.13; Ganser, A.13; Stone, R. M.14; Thiede, C.12; Döhner, H.1; Bloomfield, C. D.7; Döhner, K.1

doi: 10.1097/01.HS9.0000562176.15402.a3
Poster Session II: Acute myeloid leukemia - Biology & translational research
Free

1Department of Internal Medicin III, University Hospital of Ulm, Ulm

2Department of Hematology, Oncology and Tumor Immunology, Charité University, Berlin

3Division of Biostatistics, German Cancer Research Center, Heidelberg, Germany

4Novartis Pharmaceuticals, Basel, Switzerland

5Department of Medicine and Comprehensive Cancer Center, University of Chicago, Chicago, United States

6Department of Biomedicine and Prevention, Università di Roma ”Tor Vergata“, Rome, Italy

7The Ohio State Comprehensive Cancer Center, Columbus, United States

8Department of Medicine, University of Alberta, Edmondo, Canada

9Clinical Research Division, Fred Hutchinson Cancer Research Center, Seattle

10Division of Hematology-Oncology, Stanford University, Stanford

11Department of Medicine, Memorial Sloan Kettering Cancer Center and Weill Cornell Medical College, New York, United States

12Medizinische Klinik und Poliklinik I, Universitätsklinikum Carl Gustav Carus der TU Dresden, Dresden

13Department of Hematology, Hemostasis, Oncology and Stem Cell Transplantation, Hannover Medical School, Hannover, Germany

14Department of Medical Oncology, Dana-Farber/Partners CancerCare, Boston, United States

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Background:

Recently, the oral multi-targeted FLT3 inhibitor midostaurin (M) was approved in combination with standard chemotherapy for treatment of FLT3 mutated (FLT3mut) AML. In the international RATIFY (NCT00651261) trial, M significantly improved overall (OS) and event-free survival (EFS) compared to placebo, thus defining a new standard of care in this AML subset (Stone RM et al. NEJM 2017).

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Aims:

To comprehensively delineate the mutational profile of FLT3mut AML patients (pts) treated within the RATIFY trial and to correlate genetic findings with clinical outcome.

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Methods:

Targeted sequencing was performed of 262 candidate genes including 20 kinases targeted by M (M kinome, MK) using SureSelectXT (Agilent). Diagnostic specimens were available from 475 (66%) of 717 FLT3mut pts. Sequencing was carried out on a HiSeq (Illumina). FLT3 mutation (mut) status was available for all 475 pts [tyrosine kinase domain (TKD: 24%); internal tandem duplication (ITD: 76%)]; cytogenetic data were present for 371 pts (78%).

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Results:

Overall, 1813 mut were identified (median coverage: 978x) with an average of 3.8 mut per pt (FLT3 strata; TKD: 3.9; ITD: 3.8). Mut ≥5% were found for NPM1 (61%), DNMT3A (39%), WT1 (21%), TET2 (12%), RUNX1 (11%), NRAS (11%), PTPN11 (9%), ASXL1 (8%), IDH1 (8%), IDH2 (7%; R140 only), and SMC1A (6%). In contrast, MK mut were rare events (7% in total) with KIT (2%), MAP3K11 (1%), and NTRK3 (1%) being most frequently mutated. First, we categorized all pts to the recently defined 11 genomic AML classes (Papaemmanuil E et al. NEJM 2016). The majority of cases fell into two classes, namely the NPM1 (N; 60%), and the chromatin-spliceosome (C-S; 15%) classes. Core-binding factor (CBF) AML [t(8;21) and inv(16)] accounted for 4% only; in 13% no class-defining lesion was identified (no class, NC). In terms of clinical outcome, CBF and N classes showed better response to induction therapy than C-S and NC (Complete remission (CR) rate: 83%, 70%, 60%, 38%; p = .0005), which translated into significantly superior OS (p < .0001) and EFS (p < .0001) for CBF and N compared to C-S and NC. When stratified according to treatment arm, addition of M resulted in improved OS in N, C-S, as well as NC, irrespective of the genetic background. Next, we categorized pts according to the 2017 European LeukemiaNet (ELN) genetic risk groups (Döhner H et al. Blood 2017). CR rate was inferior within the adverse (ADV) and intermediate (INT) as compared to the favorable (FAV) risk group (52%, 62%, 74%; p = .002) translating into significantly shorter EFS (p < .0001) and OS (p < .0001) in INT and ADV than FAV. Of note, M showed consistent beneficial effects across all ELN risk groups. When comparing pts with MK gene mut vs. pts with wildtype MK, no differences in outcome were observed. Within the group of MK mut pts there was no benefit for M; however, the results have to be interpreted cautiously due to the small sample size.

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Summary/Conclusion:

In this comprehensive targeted sequencing approach of 475 FLT3mut AML pts treated within the RATIFY trial, remarkable differences in the underlying AML genomic classes were found. Predominant classes were N, C-S, CBF, showing significant differences with regard to response to treatment and survival. Of note, treatment with M showed beneficial effects across all genomic AML classes. In addition, M was associated with a better outcome in all 2017 ELN risk categories, demonstrating a consistent benefit of M across various genetic AML subgroups.

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Support:

U10CA180821, - U10CA180882, U24CA196171; Novartis; https://acknowledgments.alliancefound.org

Copyright © 2019 The Authors. Published by Wolters Kluwer Health Inc., on behalf of the European Hematology Association.