ALBERT

Description: Myeloid sarcoma (MS) is defined as a tumor mass consisting of myeloid blasts with or without maturation occurring at an anatomical site other than bone marrow (BM). MS may occur before, concurrently or after a characterized acute myeloid leukemia (AML). Cytogenetic abnormalities are found in 50% of the cases but molecular alterations are less well described and involved FLT3 and/or NPM1 mutations. Mutations in IDH1 and IDH2 genes are found in 15% to 20% of patients with AML but have never been described in MS. Mutated IDH enzymes produce in vast excess D-2-hydroxyglutarate (2-HG) in leukemic cells, which can act as a biomarker predictive of the presence of IDH1 and IDH2 mutations. As availability of DNA sequencing techniques on paraffin samples are limited, molecular characterization of MS remained difficult. We asked whether in MS, serum 2-HG would predict the presence of IDH1/2 mutations at diagnosis, and could provide a biomarker for follow up. Tissue samples and serum samples from 8 patients with a MS diagnosis were analyzed. High quality genomic DNA was extracted from frozen MS samples using conventional phenol/chloroforme extraction procedures. Exon 4 of IDH1 and IDH2 genes (IDH1/R132 and IDH2/R140 and /R172 codons) was amplified by PCR using HotStar Taq polymeraze (Qiagen) and primers. Direct sequencing was performed using the Sanger method as previously described. In case of MS relapse or AML evolution, IDH1 and IDH2 genes were analyzed in the same way from frozen tissue sample or bone marrow sample. Serum samples at MS diagnosis were analyzed for total 2-HG, D-2-HG and L-2-HG by reverse-phase liquid chromatography coupled to mass spectrometry. In case of myeloid sarcoma with IDH1/2 mutation, 2-HG values were compared to 18F-FDG-PET results when available during remission phase and at relapse. Three patients (3/8; 37.5%) had an IDH2 R140Q mutation at diagnosis of MS localized to lymph node, soft tissue, skin or pharynx. At MS diagnosis, serum total 2-HG, D-2-HG and ratio D/L-2-HG were significantly higher in case of myeloid sarcoma with IDH2 R140Q mutation compared to patients with no IDH mutation (Table 1). Serum total 2-HG level ≥2µM or D-2-HG level ≥1.8µM or ratio D/L 2-HG 〉2.5 were significantly associated with the presence of IDH2 mutation (Fisher's exact test P≤0.02). Table 1. Myeloid sarcoma with IDH2 R140Q mutation (N=3) Myeloid sarcoma without IDH2 R140Q mutation (N=5) Median total 2-HG (µM) 4.1 (range: 3.1-30.1) 1.4 (range: 1-1.6) Median D-2-HG (µM) 3.7 (range: 2.3-28) 0.6 (range: 0.5-0.8) Median L-2-HG (µM) 0.8 (range: 0.4-2.1) 0.8 (range: 0.4-0.8) Median ratio D/L 2-HG 8.3 (range: 2.9-18.8) 1 (range: 0.7-1.7) All 3 patients with IDH2 R140Q mutated MS received intensive chemotherapy treatment and achieved complete remission (CR). Two patients relapsed: one experienced isolated extramedullary relapse (thigh muscle); one had a bone marrow relapse. IDH2 R140Q mutation was found at the site of relapse in both cases. When available, serum 2-HG values and 18F-fluorodeoxyglucose-positron-emission tomography (FDG-PET) were compared at different time points (at diagnosis, remission and relapse; Table 2). Table 2. Patient #1 Patient #2 Patient #3 FDG-PET at diagnosis (SUVmax) - 17 5.25 Serum 2-HG at diagnosis (µM) 4.1 3.1 30.1 FDG-PET in remission (SUVmax) 0 - 9.6 (N=4) 0 (N=4) - Serum 2-HG in remission (µM) 0.5 - 1.1 (N=4) 0.6 - 3.1 (N=4) 3.4 - 17.9 (N=3) FDG-PET at MS relapse/evolution to AML (SUVmax) 6.1 - 0 Serum 2-HG at MS relapse/evolution to AML (µM) 2.3 - 16.7 Time between diagnosis and MS relapse/evolution to AML (months) 30 - 9 Serum 2-HG values were in accordance with FDG-PET interpretations except in patient #1 who presented a transient hypermetabolic splenic nodule (SUVmax 9.6) without serum 2-HG increase. Patient #2 remained in CR but had recently increased 2-HG values without overt relapse. Patient #3 presented relapse as a refractory anemia with excess of blast without extra-medullary localization. FDG-PET didn't find any abnormality contrary to the persistent increased value of serum 2-HG (total 2-HG: 16.7µM). These data show that myeloid sarcoma can be associated with IDH2 R140Q mutation and suggest that 2-HG measurement in the serum predicts the presence of IDH1/2 mutations at diagnosis. During follow-up, serum 2-HG values could be representative of the disease status. Because of IDH inhibitors promising results in AML, 2-HG screening at MS diagnosis could be useful. Disclosures Ribrag: Celgene: Research Funding; Esai: Membership on an entity's Board of Directors or advisory committees, Research Funding; Pharmamar: Honoraria, Membership on an entity's Board of Directors or advisory committees; Gilead: Membership on an entity's Board of Directors or advisory committees; Servier: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding. De Botton:Agios pharmaceuticals: Research Funding.

Description: Introduction: Mutations in IDH1 and IDH2 genes are found in 15% to 20% of patients with acute myeloid leukemia (AML). Mutated IDH enzymes produce in excess the D stereoisomer 2-hydroxyglutarate (2-HG) in leukemic cells, which can act as a biomarker predictive of the presence of IDH1 and IDH2 mutations. Total serum 2-HG (D and L stereoisomers) 〉2µM and ratio D/L 2-HG 〉2.5 are strong predictors of the presence of IDH1/2 mutations at diagnosis (Janin et al; JCO 2014). We measured 2-HG levels in serial samples of 47 patients with IDH1/2 mutations during induction or first salvage therapy to determine whether 2HG can serve as a surrogate marker of treatment efficacy. Methods: Between 2007 and 2015, 47 AML patients with IDH1 or IDH2 mutation received intensive chemotherapy as induction therapy (n=42) or as first salvage regimen (n=5) in our center (Table 1). Genomic DNA was extracted from BM samples using conventional procedures. IDH1-(codon R132) and IDH2- targeted (codons R140 and R172) regions were amplified by PCR with primers containing Ion Torrent adapters and unique barcodes to generate libraries. Pooled amplicons libraries were clonally amplified on Ion Spheres using the Ion Xpress Template 200 Kit. All available serum samples (n=394) prior and during induction/salvage chemotherapy were analyzed for total 2-HG, D-2-HG and L-2-HG by reverse-phase liquid chromatography coupled to mass spectrometry. We studied the serum 2-HG values (D-2-HG and ratio D/L 2-HG) evolution during IC according to complete remission (CR) evaluated at the end of IC. When a patient had a missing value for 2-HG, the missing value was replaced by the last available observation (up to 7 days before the missing value). At each day we tested the difference between the dosage values of the responders and the non-responders with non-parametric Wilcoxon 2-sided tests. The analyses were done with SAS software (version 9.3; SAS Institute, Cary, NC). Table 1. Patients and treatment characteristics: AML at diagnosis / RR AML (N) 42 / 5 Median age (years) 58.2 (23.1 - 75.7) Sex ratio (M/F) 23/24 Conventional cytogenetic: - Normal karyotype - Trisomy 8 - Monosomy 7 39 (83%) 3 (6%) 2 (4%) Associated gene mutations: - NPM1- FLT3-ITD- FLT3-TKD 24 (51%) 10 (21%) 5 (11%) IDH mutation: - IDH1 R132 (N) - IDH2 R140 (N) - IDH2 R172 (N) 8 (17%) 32 (65%) 7 (15%) Intensive treatment: - "3+7" regimen - Intensified induction chemotherapy - High-dose cytarabine based chemotherapy 24 (51%) 19 (40%) 4 (8%) Results: Complete remission (CR) 1 was obtained in 35/42 patients (83%) and CR2 in 3/5 (60%) after IC. All (8/8) IDH1 -R132 mutated patients achieved CR1, 25/28 (89%) IDH2 -R140 mutated patients and 3/4 achieved CR1 and CR2 respectively; 2/6 (33%) IDH2 -R172 mutated patients and 0/1 achieved CR1 and CR2, respectively. Median serum 2-HG values before IC were as follow: total 2-HG 10.9 µM (range: 2.1-135.5); D-2-HG 10.7 µM (range: 1.7-132.6) and ratio D/L 36.9 (range: 3.9-131.2). Median number of serum 2-HG values per patient was 7 (range: 5-10). Serum D-2-HG and ratio D/L 2-HG evolution according to CR status after IC began to differ significantly at day 5 after IC (Wilcoxon test P=0.02, Figure 1). The difference between responders and non-responders increased overtime (Wilcoxon test P