Adverse Prognostic Role of IDH2 Mutations at Diagnosis and during Follow-up in Patients with Acute Myeloid Leukemia and Normal Karyotype
Authors: Borlenghi Erika , Bertoli Diego , Cattaneo Chiara , Sciumé Margherita , Cerqui Elisa , Pagani Chiara , Bianchetti Nicola , Oberti Margherita , Leopaldo Rossella , Carbone Cecilia , Archetti Silvana , Rossi Giuseppe , Tucci Alessandra 
Published: November 2021

Abstract
Introduction: Acute Myeloid Leukemia (AML) is a heterogeneous disorder characterized by a wide range of cytogenetic and molecular aberrations, that affect prognosis and guide treatment decisions. However there is a still large group of patients (pts) considered at intermediate risk whose outcome needs to be better defined. Next-generation sequencing (NGS) can simultaneously detect various mutations, leading to better define its prognostic profile. The role of some mutations, including isocitrate dehydrogenase (IDH) mutations (IDHm), is still controversial.
Aim: We evaluated by NGS monitoring at different time points the prognostic role of IDH1/2m in AML pts with normal karyotype, both in the subgroup with mutations of NPM1 (NPM1m) or FLT3 (FLT3m) and in the subgroup without detectable mutations (wt-AML).
Methods: Using Sophia Myeloid Solution kit (SOPHiA Genetics), we performed targeted NGS, covering 30 gene regions, in 104 bone marrow samples collected at diagnosis (53), after first consolidation (30) and at relapse (21), in 53 pts (M/F: 24/29; median age: 56 y, range 22-74), treated according to NILG-AML00 protocol (NCT00400673). Standard PCR to detect NPM1m and FLT3m was performed and we identified 20 NPM1m, 3 NPM1+FLT3-ITDm, 4 FLT3-ITDm and 26 wt-AML.
Results: At diagnosis, among 219 pathogenic mutations detected, IDHm represented 10.5% of them (median VAF: 39.1%; range 6.2-49.6%). IDHm was observed in 23/53 pts (43.4%) (IDH1m in 11 and IDH2m in 12). In these pts , more frequently commutated genes were DNMT3A (28%), NPM1 (13%), FLT3-ITD/TKD (14%), ASXL1 (6%), SRSF2 and NRAS (9% each).
Complete remission (CR) was achieved in 49/53 (92.5%) pts without difference in response rate according to IDH status (86% in IDHm vs 94% in IDH wild-type, wt).
Relapse occurred in 28/49 (57%) pts after a median of 11 months (mo), range 2-61. The frequency of relapse was not significantly different across all types of mutations identified, except for IDH2m which was associated with a higher risk of relapse (10/11 in IDH2m vs 18/38 in IDH2wt; p: 0.014), without differences between R172K and R140Q. On the contrary, IDH1m, present in 18% of relapsed pts, did not impact on relapse (5/10 vs 23/39, p: 0.7). Particularly, in the wt-AML group, the IDH2m was prevalent in pts developing relapse (6/11, 54.5%) and all pts with IDH2m relapsed, with median of 13 mo, range 6-24 (6/6 in IDH2m vs 5/17 in IDH2wt, p:0.0046).
Among the co-occurrence mutations, the IDH2/DNMT3A was associated with higher relapse risk (9/9 vs 19/40; p: 0.0063). DNMT3A associated with other mutations did not impact on relapse risk.
At a median follow-up of 23 mo, median relapse free survival (RFS) and overall survival (OS) of whole population were 24 and 53 mo, respectively.
The IDH2m impacted on OS: 23.5 mo in IDH2m vs 72 in IDH2wt pts (p:0.0093) (Fig 1a), but not in RFS (13 vs 29 mo in IDH2m and IDH2wt, respectively (p:0.1). Considering the subgroups of wt-AML, the RFS (Fig. 1b) and OS were 13 and 23.5 mo in IDH2m vs undefined in IDH2-wt (p:0.0014 and p:0.1), respectively. In pts with NPM1 or FLT3m, RFS and OS were 9 and 53 mo in IDH2m vs 29 and 73 mo in IDH2-wt (p:0.2 and p:0.15), respectively. We did not find the other genomic pattern predicting relapse in this group.
After consolidation, NGS monitoring was performed in 30 pts in CR. Of the 13 IDH AML pts evaluated, no mutations was observed in 4 (28.5%); the persistence of IDHm was not associated with a significantly higher relapse (p:0.5). Among other mutations present at diagnosis, NGS clearance after consolidation occurred in pts with NRAS, KRAS, PTPN11 and FLT3-ITD/TKD. Conversely, it was limited for the following mutations: TET2 (8/11), DNMT3A (7/13), SRSF2 (6/6), IDH2 (4/5), ASXL1 (2/2), IDH1 (2/4) and NPM1 (1/12). Overall, the persistence of any type of gene mutations after consolidation was predictive of relapse (2/9 vs 6/7, p:0.04), only in wt-AML subgroup.
At relapse, of the 11 IDHm pts analyzed, 7/7 IDH2m and 3/4 IDH1m showed the reappearance of mutations.
Conclusion: In this retrospective monocentric study, the presence at diagnosis of IDH2m correlated with relapse risk and with survival, suggesting that additional treatment with targeted agents and or consolidation with allogeneic transplant should be considered. In addition, in AML without NPM1m or FLT3m, the persistence of genes mutation detected by NGS monitoring after consolidation had a significant prognostic value to predict subsequent relapse.
Figure 1 Figure 1.

Disclosures
Borlenghi: Amgen, Janssen: Consultancy. Rossi: Janssen: Membership on an entity's Board of Directors or advisory committees; Celgene: Membership on an entity's Board of Directors or advisory committees; Jazz: Membership on an entity's Board of Directors or advisory committees; Astellas: Membership on an entity's Board of Directors or advisory committees; Daiichi Sankyo: Consultancy, Honoraria; Amgen: Honoraria, Membership on an entity's Board of Directors or advisory committees; Novartis: Membership on an entity's Board of Directors or advisory committees; Alexion: Membership on an entity's Board of Directors or advisory committees; Pfizer: Membership on an entity's Board of Directors or advisory committees; Sanofi: Honoraria; Abbvie: Membership on an entity's Board of Directors or advisory committees; Takeda: Membership on an entity's Board of Directors or advisory committees. Tucci: Gentili: Membership on an entity's Board of Directors or advisory committees; janssen: Membership on an entity's Board of Directors or advisory committees; Takeda: Membership on an entity's Board of Directors or advisory committees.