Abstract: Background: Isocitrate dehydrogenase (IDH)-1 and -2 are TCA cycle-involved enzymes which convert isocitrate to alpha-ketoglutarate. Mutations that alter the enzymatic activity causes accumulation of a mal-metabolite D-2-hydroxyglutarate, which results in inhibition of DNA methylation and tumorigenesis. IDH-1 and IDH-2 mutation are present in approximately 7-10% and 10% of patients with acute myeloid leukemia (AML), respectively. Recently, whole exome sequencing has been used for the next-generation sequencing of AML, and certain gene mutations have been identified in patients with AML. The treatment strategies for leukemia have undergone drastic changes with the rapid development of new drugs. However, the proper use of newly developed agents poses a major challenge in AML treatment. Genome profiling analysis can be used to select the optimal treatment for patients with newly diagnosed AML. IDH mutant-specific inhibitors such as ivosidenib and enasidenib were already approved in the US, and combination treatment with venetoclax and Azacitidine was recently approved in Japan. Methods and Results: We lunched an actionable mutation profiling multicenter study named Hematologic Malignancies (HM)-SCREEN-Japan 01 (UMIN000035233), in which a comprehensive genomic assay was performed by Foundation One Heme (F1H) panel. The primary outcome was the frequency of each genomic alteration, as determined using F1H, which is a comprehensive genome profiling test based on next-generation sequencing, in the AML specimens. The secondary outcome was the association between each genomic alteration and the clinicopathological characteristics, prognosis, and quality of specimens used in the genetic analysis. The eligibility criteria were as follows: 1) histological diagnosis of AML through bone marrow aspiration; 2) fulfillment of either of the following conditions: i) newly diagnosed AML unfit for standard treatment (ND-unfit AML) or ii) R/R-AML; 3) sufficient sample collection via bone marrow aspiration; 4) Age of participants 20 years or above during registration; 5) provision of written informed consent by participants. Paraffin-embedded bone marrow samples were gathered from 17 Japanese faculties and the F1H reports were returned to the patients. The median turnaround time was 13 days (minimum 8 days). We found 13 patients (7.3%) with IDH1 mutation and 17 patients (9.6%) with IDH2 mutation out of 177 patients who joined this study and the F1H report was successfully returned. Only one patient had both mutations, and each mutation was mutually exclusive in all the other patients (Figure 1). The major amino acid alteration of IDH1 and IDH2 were R132C/G/H/L and R140Q/W, respectively. Frequently co-occurring mutations include FLT3 (44.8%), NPM1 (34.5%), DNMT3A (31.0%) and RUNX1 mutation (20.7%). Mutations of RAS pathway-related genes (e.g., KRAS, NRAS and PTPN11) were seen in 6 patients (20.7%). Any gene alterations didn't show statistically significant co-occurrence with IDH1 and IDH2 mutation. Serial genome profiling analyses were performed to evaluate the time-dependent changes in the genome profiles of patients administered FLT3 inhibitors, gilteritinib, and quizartinib for treating FLT3-mutated AML. Also in this cohort, we are examining the properties and distribution of IDH1/2 mutations during treatment with FLT3 inhibitors. In the several patients, expansion and persistence of IDH mutated clones seemed to be cause of resistance (Figure 2 as the representative result). The detailed clinical outcomes of AML patients with IDH1/2 mutations are under investigation. Conclusions: In our evaluation of the suitability of F1H for HM-SCREEN-Japan 01, we successfully identified IDH-1/2 mutation that can be used as therapeutic targets in AML, which have rarely been identified thus far. Figure 1 Figure 1. Disclosures Shibayama: Eisai: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Celgene: Research Funding; Ono: Honoraria, Research Funding; Takeda: Honoraria, Research Funding; Nippon Shinyaku: Honoraria; Daiichi Sankyo: Honoraria; Novartis: Honoraria, Research Funding; Janssen: Honoraria, Research Funding; Chugai: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Otsuka: Honoraria; Bristol-Myers Squibb: Honoraria; Pfizer: Honoraria; Fujimoto: Honoraria; AbbVie: Honoraria, Research Funding; AstraZeneca: Honoraria, Membership on an entity's Board of Directors or advisory committees; Sanofi: Honoraria; Mundi Pharma: Honoraria; Essentia Pharma Japan: Research Funding. Yamauchi: Otsuka: Research Funding; Ono Pharmaceutical: Honoraria; Pfizer: Honoraria, Research Funding; Chugai: Honoraria; Abbie: Research Funding; Astellas: Research Funding; Daiichi Sankyo: Research Funding; Solasia Pharma: Research Funding. Kondo: Otsuka Pharmaceutical: Consultancy, Honoraria, Research Funding; Novartis Pharma KK: Honoraria; Bristol-Myers Squibb Company: Honoraria; Sumitomo Dainippon Pharma: Honoraria; Sanwa Kagaku Kenkyusho CO.,LTD: Consultancy; Pfizer: Honoraria; Astellas Pharma Inc.: Consultancy, Honoraria; Abbvie: Honoraria. Yamamoto: AbbVie: Honoraria, Research Funding; AstraZeneca: Honoraria, Research Funding; Bristol-Myers Squibb/Celgene: Honoraria, Research Funding; Chugai: Honoraria, Research Funding; Daiichi Sankyo: Honoraria; Eisai: Honoraria, Research Funding; IQIVA/Incyte: Research Funding; IQIVA/HUYA: Honoraria; HUYA: Consultancy; Janssen: Honoraria; Kyowa Kirin: Honoraria; Meiji Seika Pharma: Consultancy, Honoraria, Research Funding; MSD: Honoraria; Mundipharma: Research Funding; Nippon Shinyaku: Honoraria, Research Funding; Novartis: Honoraria, Research Funding; Ono: Honoraria, Research Funding; Otsuka: Honoraria, Research Funding; Sanofi: Honoraria; Solasia Pharma: Research Funding; SymBio: Honoraria, Research Funding; Takeda: Honoraria, Research Funding; Yakult: Honoraria, Research Funding; Zenyaku: Honoraria, Research Funding; Micron: Honoraria; IQIVA/Genmab: Research Funding; ADC Therapeutics: Honoraria. Kuroda: Taiho Pharmaceutical: Research Funding; Fujimoto Pharmaceutical: Current Employment, Honoraria, Research Funding; Asahi Kasei: Research Funding; Shionogi: Research Funding; Nippon Shinyaku: Honoraria, Research Funding; Pfizer: Honoraria, Research Funding; Sysmex: Research Funding; Eisai: Honoraria, Research Funding; Ono Pharmaceutical: Honoraria, Research Funding; Abbvie: Consultancy, Honoraria; MSD: Research Funding; Celgene: Consultancy, Honoraria, Research Funding; Takeda: Honoraria, Research Funding; Astellas Pharma: Honoraria, Research Funding; Otsuka Pharmaceutical: Honoraria, Research Funding; Kyowa Kirin: Honoraria, Research Funding; Sanofi: Consultancy, Honoraria, Research Funding; Daiichi Sankyo: Honoraria, Research Funding; Dainippon Sumitomo Pharma: Honoraria, Research Funding; Chugai Pharmaceutical: Honoraria, Research Funding; Bristol-MyersSquibb: Consultancy, Honoraria, Research Funding; Janssen Pharmaceutical K.K: Consultancy. Usuki: Astellas: Research Funding, Speakers Bureau; Abbvie: Research Funding; Gilead: Research Funding; Symbio: Research Funding, Speakers Bureau; Daiichi Sankyo: Research Funding, Speakers Bureau; Sumitomo Dainippon: Research Funding; Otsuka: Research Funding, Speakers Bureau; Novartis: Research Funding, Speakers Bureau; Brisol-Myers Squibb: Research Funding, Speakers Bureau; Ono: Research Funding, Speakers Bureau; Janssen: Research Funding; Celgene: Research Funding, Speakers Bureau; Takeda: Research Funding, Speakers Bureau; Nippon Boehringer Ingelheim: Research Funding; Astellas-Amgen-Biopharma: Research Funding; Nippon shinyaku: Research Funding, Speakers Bureau; Kyowa Kirin: Research Funding, Speakers Bureau; Pfizer: Research Funding; Alexion: Speakers Bureau; Eisai: Speakers Bureau; MSD: Speakers Bureau; PharmaEssentia: Speakers Bureau; Yakult: Speakers Bureau; Mundipharma: Research Funding. Yoshimitsu: Novartis: Honoraria; Takeda: Honoraria; Sanofi: Honoraria. Ishitsuka: Asahi kasei: Research Funding; Eli Lilly: Research Funding; MSD: Research Funding; Daiichi Sankyo: Consultancy, Other: Personal fees; Kyowa Kirin: Other: Personal fees, Research Funding; Ono Pharmaceutical: Other: Personal fees, Research Funding; Celgene: Honoraria, Other: Personal fees; Chugai Pharmaceutical: Honoraria, Other: Personal fees, Research Funding; BMS: Other; Takeda: Other: Personal fees, Research Funding; Mundipharma: Other: Personal fees; Taiho Pharmaceuticals: Other: Personal fees, Research Funding; Janssen Pharmaceuticals: Other: Personal fees; Huya Japan: Other: Personal fees; Novartis: Other: Personal fees; Pfizer: Other: Personal fees; Astellas Pharma: Other: Personal fees, Research Funding; Genzyme: Other: Personal fees; Sumitomo Dainippon Pharma: Other: Personal fees, Research Funding; Eisai: Other: Personal fees, Research Funding; Mochida: Other: Personal fees, Research Funding; Shire: Other; Otsuka Pharmaceutical: Other: Personal fees; Teijin Pharma: Research Funding. Ono: Pfizer Japan Inc.: Honoraria; Bristol-Myers Squibb Company: Honoraria; Celgene: Honoraria, Research Funding; Otsuka Pharmaceutical Co., Ltd.: Honoraria; Janssen Pharmaceutical K.K: Honoraria; Eisai Co., Ltd.: Honoraria; Astellas Pharma Inc.: Honoraria; Takeda Pharmaceutical Company Limited.: Honoraria; ONO PHARMACEUTICAL CO., LTD.: Honoraria, Research Funding; DAIICHI SANKYO COMPANY, LIMITED.: Honoraria; Novartis Pharma KK: Honoraria; Chugai Pharmaceutical Co., Ltd.: Honoraria, Research Funding; Kyowa Kirin Co., Ltd.: Honoraria, Research Funding; Mundipharma K.K.: Honoraria; TAIHO PHARMACEUTICAL CO., LTD.: Research Funding; Merck Sharp & Dohme: Honoraria, Research Funding. Takahashi: Toyamakagaku: Research Funding; Novartis Pharmaceuticals: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau; Pfizer: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau; Otsuka Pharmaceutical: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau; Chugai: Research Funding; Kyowahakko-Kirin: Research Funding; Ono: Research Funding; Asahikasei: Research Funding; Eizai: Research Funding. Iyama: Alexion Pharmaceuticals: Honoraria, Research Funding; Astellas: Honoraria; CSL Behring: Honoraria; Daiichi Sankyo: Honoraria; Otsuka Pharmaceuticals Factory: Honoraria; Otsuka Pharmaceuticals Factory: Honoraria; MSD: Research Funding; Nippon Shinyaku: Honoraria; Novartis: Honoraria; Otsuka: Honoraria, Research Funding; Sanofi: Honoraria, Research Funding; SymBio Pharmaceuticals: Research Funding. Izutsu: Genmab: Honoraria, Research Funding; Daiichi Sankyo: Honoraria, Research Funding; Fuji Film Toyama Chemical: Honoraria; Eisai: Honoraria, Research Funding; Incyte: Research Funding; Huya Biosciences: Research Funding; Chugai: Honoraria, Research Funding; Symbio: Honoraria; Solasia: Research Funding; Pfizer: Research Funding; Ono Pharmaceutical: Honoraria, Research Funding; Novartis: Honoraria, Research Funding; MSD: Research Funding; Kyowa Kirin: Honoraria, Research Funding; Janssen: Honoraria, Research Funding; Celgene: Honoraria, Research Funding; Beigene: Research Funding; Bayer: Research Funding; AstraZeneca: Honoraria, Research Funding; Allergan Japan: Honoraria; AbbVie: Honoraria; Takeda: Honoraria, Research Funding; Yakult: Research Funding. Minami: Novartis Pharma KK: Honoraria; Ono: Research Funding; Pfizer Japan Inc.: Honoraria; Astellas: Honoraria; Takeda: Honoraria; Bristol-Myers Squibb Company: Honoraria; CMIC: Research Funding.

Abstract: Next‐generation sequencing of AML has identified specific genetic mutations in AML patients. Hematologic Malignancies (HM)‐SCREEN‐Japan 01 is a multicenter study to detect actionable mutations using paraffin‐embedded bone marrow (BM) clot specimens rather than BM fluid in AML patients for whom standard treatment has not been established. The purpose of this study is to evaluate the presence of potentially therapeutic target gene mutations in patients with newly diagnosed unfit AML and relapsed/refractory AML (R/R‐AML) using BM clot specimens. In this study, 188 patients were enrolled and targeted sequencing was undertaken on DNA from 437 genes and RNA from 265 genes. High‐quality DNA and RNA were obtained using BM clot specimens, with genetic alterations successfully detected in 177 patients (97.3%), and fusion transcripts in 41 patients (23.2%). The median turnaround time was 13 days. In the detection of fusion genes, not only common fusion products such as RUNX1 ‐ RUX1T1 and KMT2A rearrangements, but also NUP98 rearrangements and rare fusion genes were observed. Among 177 patients (72 with unfit AML, 105 with R/R‐AML), mutations in KIT and WT1 were independent factors for overall survival (hazard ratio = 12.6 and 8.88, respectively), and patients with high variant allele frequency (≥40%) of TP5 3 mutations had a poor prognosis. As for the detection of actionable mutations, 38% ( n  = 69) of patients had useful genetic mutation ( FLT3 ‐ ITD / TKD , IDH1 / 2 , and DNMT3A R822 ) for treatment selection. Comprehensive genomic profiling using paraffin‐embedded BM clot specimens successfully identified leukemic‐associated genes that can be used as therapeutic targets.

Abstract: Background and Methods: NPM1 mutation and KMT2A(MLL)-rearrangement/amplification are present in approximately 27% and 8.5% patients with acute myeloid leukemia (AML), respectively (data from cBioPortal). Although they have different clinical features and prognostic impact, recent studies suggest that the MLL co-factor, menin, plays a key role in maintaining self-renewal of immature leukemic cells by upregulating transcription of HOXA and MEIS (Gundry et al.). However, the real-world epidemiology of these mutations and co-existing gene alterations have not been thoroughly investigated in Japan. We launched an actionable mutation profiling multicenter study entitled Hematologic Malignancies (HM)-SCREEN-Japan 01 (UMIN000035233). In this study, a comprehensive genomic assay was performed by Foundation One Heme (F1H) panel for patients with relapsed/refractory (R/R) AML as well as patients with newly-diagnosed (ND) AML who are ineligible for standard chemotherapy. Paraffin-embedded bone marrow samples were gathered from 17 Japanese faculties and the F1H reports were returned to the patients. Results: One-hundred-eighty-two patients were recruited in this study and the F1H report was successfully returned in 177 patients (97.3%). Median age of 68 patients with ND-AML was 73 [63-79] years and those of 109 patients with R/R-AML was 50 [40-68.5] years. Median turn-around time was 13 days (minimum 8 days).We found 32 patients (18.1%) with NPM1 mutation and 23 patients (13.0%) of KMT2A(MLL)-rearrangement/amplification out of the 177 patients. These two alterations were mutually exclusive in this study. The median age of patients with NPM1 mutation (NPM1 mt.) and KMT2A-rearrangement (KMT2A-r) were 56.5 [43.5-73.8] and 62 [45-71] years, respectively. Three quarters or more patients were R/R-AML in both groups. WT1 expression levels were much higher in patients with NPM1 mt. than the other group (6,000 [77-110,000] vs. 93 [34-5,800] copies/mcgRNA). The major amino acid alteration of NPM1 was a frameshift mutation at the 288 th histidine (W288fs*12). Patterns of KMT2A(MLL)-rearrangement included MLL fusion (e.g., MLL-MLLT3) and partial tandem duplication (PTD) in ten patients each. MLL amplification was observed in three patients. Frequently co-occurring mutations with NPM1 mt. included FLT3 (56.3%), DNMT3A (46.9%), TET2 (34.4%), WT1 (18.8%), IDH1 (18.8%), and IDH2 (15.6%). Those with KMT2A-r included FLT3 (39.1%), TP53 (26.1%), PTPN11 (21.7%), DNMT3A (17.4%), and IDH2 (17.4%). Mutations of RAS pathway-related genes (e.g., KRAS, NRAS, PTPN11, and NF1) were observed in five patients with NPM1 mt. (15.6%) and 11 patients (47.8%) with KMT2A-r. None of the six patients with TP53 mutation had NPM1 mutation. The prognostic impact of each genes is currently being analyzed. Conclusions: Approximately three in ten patients with AML had NPM1 mutation and/or KMT2A(MLL)-rearrangement/amplification. No single patient had both the alterations. FLT3 and DNA methylation-associated genes (e.g., DNMT3A and TET2) were frequently seen in patients with NPM1 mt. In contrast, TP53 and RAS pathway-related gene alterations (e.g., NRAS, KRAS, PTPT11 and NF1) were relatively dominant in patients with KMT2A-r. TP53 mutation seemed unlikely to occur along with NPM1 mutation. Figure 1 Figure 1. Disclosures Shibayama: Celgene: Research Funding; Ono: Honoraria, Research Funding; Takeda: Honoraria, Research Funding; Avvie: Honoraria, Research Funding; Eisai: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Novartis: Honoraria, Research Funding; Janssen: Honoraria, Research Funding; Chugai: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Essentia Pharma Japan: Research Funding; AstraZeneca: Honoraria, Membership on an entity's Board of Directors or advisory committees; Daiichi Sankyo: Honoraria; Fujimoto: Honoraria; Nippon Shinyaku: Honoraria; Sanofi: Honoraria; Bristol-Myers Squibb: Honoraria; Pfizer: Honoraria; Otsuka: Honoraria; Mundi Pharma: Honoraria. Yamauchi: Otsuka: Research Funding; Ono Pharmaceutical: Honoraria; Pfizer: Honoraria, Research Funding; Chugai: Honoraria; Abbie: Research Funding; Astellas: Research Funding; Daiichi Sankyo: Research Funding; Solasia Pharma: Research Funding. Kondo: Otsuka Pharmaceutical: Consultancy, Honoraria, Research Funding; Pfizer: Honoraria; Novartis Pharma KK: Honoraria; Bristol-Myers Squibb Company: Honoraria; Sumitomo Dainippon Pharma: Honoraria; Sanwa Kagaku Kenkyusho CO.,LTD: Consultancy; Astellas Pharma Inc.: Consultancy, Honoraria; Abbvie: Honoraria. Yamamoto: Bristol-Myers Squibb/Celgene: Honoraria, Research Funding; AstraZeneca: Honoraria, Research Funding; Chugai: Honoraria, Research Funding; Daiichi Sankyo: Honoraria; Eisai: Honoraria, Research Funding; IQIVA/Incyte: Research Funding; IQIVA/HUYA: Honoraria; HUYA: Consultancy; Janssen: Honoraria; Kyowa Kirin: Honoraria; Meiji Seika Pharma: Consultancy, Honoraria, Research Funding; MSD: Honoraria; Mundipharma: Research Funding; Nippon Shinyaku: Honoraria, Research Funding; Novartis: Honoraria, Research Funding; Ono: Honoraria, Research Funding; Otsuka: Honoraria, Research Funding; Sanofi: Honoraria; Solasia Pharma: Research Funding; SymBio: Honoraria, Research Funding; Takeda: Honoraria, Research Funding; Yakult: Honoraria, Research Funding; Zenyaku: Honoraria, Research Funding; Micron: Honoraria; IQIVA/Genmab: Research Funding; ADC Therapeutics: Honoraria; AbbVie: Honoraria, Research Funding. Kuroda: Fujimoto Pharmaceutical: Current Employment, Honoraria, Research Funding; Taiho Pharmaceutical: Research Funding; Asahi Kasei: Research Funding; Shionogi: Research Funding; Nippon Shinyaku: Honoraria, Research Funding; Pfizer: Honoraria, Research Funding; Sysmex: Research Funding; Eisai: Honoraria, Research Funding; Ono Pharmaceutical: Honoraria, Research Funding; Abbvie: Consultancy, Honoraria; MSD: Research Funding; Celgene: Consultancy, Honoraria, Research Funding; Takeda: Honoraria, Research Funding; Astellas Pharma: Honoraria, Research Funding; Otsuka Pharmaceutical: Honoraria, Research Funding; Kyowa Kirin: Honoraria, Research Funding; Sanofi: Consultancy, Honoraria, Research Funding; Daiichi Sankyo: Honoraria, Research Funding; Dainippon Sumitomo Pharma: Honoraria, Research Funding; Chugai Pharmaceutical: Honoraria, Research Funding; Bristol-MyersSquibb: Consultancy, Honoraria, Research Funding; Janssen Pharmaceutical K.K: Consultancy. Usuki: Astellas: Research Funding, Speakers Bureau; Abbvie: Research Funding; Gilead: Research Funding; Symbio: Research Funding, Speakers Bureau; Daiichi Sankyo: Research Funding, Speakers Bureau; Sumitomo Dainippon: Research Funding; Otsuka: Research Funding, Speakers Bureau; Novartis: Research Funding, Speakers Bureau; Brisol-Myers Squibb: Research Funding, Speakers Bureau; Ono: Research Funding, Speakers Bureau; Janssen: Research Funding; Celgene: Research Funding, Speakers Bureau; Takeda: Research Funding; Nippon Boehringer Ingelheim: Research Funding; Mundipharma: Research Funding; Astellas-Amgen-Biopharma: Research Funding; Nippon shinyaku: Research Funding, Speakers Bureau; Kyowa Kirin: Research Funding, Speakers Bureau; Pfizer: Research Funding; Alexion: Speakers Bureau; Eisai: Speakers Bureau; MSD: Speakers Bureau; PharmaEssentia: Speakers Bureau; Yakult: Speakers Bureau. Yoshimitsu: Novartis: Honoraria; Takeda: Honoraria; Sanofi: Honoraria. Ishitsuka: Kyowa Kirin: Other: Personal fees, Research Funding; Daiichi Sankyo: Consultancy, Other: Personal fees; Ono Pharmaceutical: Other: Personal fees, Research Funding; Celgene: Honoraria, Other: Personal fees; Chugai Pharmaceutical: Honoraria, Other: Personal fees, Research Funding; BMS: Other; Takeda: Other: Personal fees, Research Funding; Mundipharma: Other: Personal fees; Taiho Pharmaceuticals: Other: Personal fees, Research Funding; Janssen Pharmaceuticals: Other: Personal fees; Novartis: Other: Personal fees; Pfizer: Other: Personal fees; Astellas Pharma: Other: Personal fees, Research Funding; Genzyme: Other: Personal fees; Sumitomo Dainippon Pharma: Other: Personal fees, Research Funding; Eisai: Other: Personal fees, Research Funding; Mochida: Other: Personal fees, Research Funding; Shire: Other; Otsuka Pharmaceutical: Other: Personal fees; Teijin Pharma: Research Funding; MSD: Research Funding; Asahi kasei: Research Funding; Eli Lilly: Research Funding; Huya Japan: Other: Personal fees. Ono: DAIICHI SANKYO COMPANY, LIMITED.: Honoraria; Mundipharma K.K.: Honoraria; Celgene: Honoraria, Research Funding; Kyowa Kirin Co., Ltd.: Honoraria, Research Funding; Janssen Pharmaceutical K.K: Honoraria; Eisai Co., Ltd.: Honoraria; Astellas Pharma Inc.: Honoraria; Takeda Pharmaceutical Company Limited.: Honoraria; ONO PHARMACEUTICAL CO., LTD.: Honoraria, Research Funding; Otsuka Pharmaceutical Co., Ltd.: Honoraria; Pfizer Japan Inc.: Honoraria; Bristol-Myers Squibb Company: Honoraria; Novartis Pharma KK: Honoraria; Chugai Pharmaceutical Co., Ltd.: Honoraria, Research Funding; TAIHO PHARMACEUTICAL CO., LTD.: Research Funding; Merck Sharp & Dohme: Honoraria, Research Funding. Fujishima: Pfizer: Speakers Bureau. Takahashi: Toyamakagaku: Research Funding; Novartis Pharmaceuticals: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau; Pfizer: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau; Otsuka Pharmaceutical: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau; Chugai: Research Funding; Eizai: Research Funding; Asahikasei: Research Funding; Kyowahakko-Kirin: Research Funding; Ono: Research Funding. Iyama: Alexion Pharmaceuticals: Honoraria, Research Funding; Astellas: Honoraria; CSL Behring: Honoraria; Daiichi Sankyo: Honoraria; Otsuka Pharmaceuticals Factory: Honoraria; Otsuka Pharmaceuticals Factory: Honoraria; MSD: Research Funding; Nippon Shinyaku: Honoraria; Novartis: Honoraria; Otsuka: Honoraria, Research Funding; Sanofi: Honoraria, Research Funding; SymBio Pharmaceuticals: Research Funding. Izutsu: Symbio: Honoraria; Takeda: Honoraria, Research Funding; Solasia: Research Funding; Pfizer: Research Funding; Ono Pharmaceutical: Honoraria, Research Funding; Novartis: Honoraria, Research Funding; MSD: Research Funding; Kyowa Kirin: Honoraria, Research Funding; Janssen: Honoraria, Research Funding; Incyte: Research Funding; Huya Biosciences: Research Funding; Genmab: Honoraria, Research Funding; Fuji Film Toyama Chemical: Honoraria; Eisai: Honoraria, Research Funding; Daiichi Sankyo: Honoraria, Research Funding; Chugai: Honoraria, Research Funding; Celgene: Honoraria, Research Funding; Beigene: Research Funding; Bayer: Research Funding; AstraZeneca: Honoraria, Research Funding; Yakult: Research Funding; Allergan Japan: Honoraria; AbbVie: Honoraria. Minami: Bristol-Myers Squibb Company: Honoraria; Novartis Pharma KK: Honoraria; Pfizer Japan Inc.: Honoraria; Takeda: Honoraria; Astellas: Honoraria; Ono: Research Funding; CMIC: Research Funding.

Abstract: Background and Methods: FMS-like tyrosine kinase 3 (FLT3) internal tandem duplication (FLT3-ITD) and tyrosine kinase domain mutation (FLT3-TKD) are types of mutations present in approximately 30% of patients with acute myeloid leukemia (AML). Currently, FLT3 inhibitors (FLT3i) are available in clinical practice, and the second-generation FLT3i, gilteritinib and quizartinib, are being used in Japan. However, the actual epidemiology of FLT3 mutations and co-existing gene alterations, particularly resistance mechanisms after FLT3i treatment, have not been thoroughly investigated in a Japanese population. Therefore, we conducted an actionable mutation profiling multicenter study, Hematologic Malignancies (HM)-SCREEN-Japan 01 (UMIN000035233), in which a comprehensive genomic assay was performed using the FoundationOne Heme (F1H) panel for patients with relapsed/refractory (R/R) AML and patients with newly diagnosed AML who were ineligible for standard chemotherapy (ND unfit). Paraffin-embedded bone marrow samples were used for next-generation sequencing (NGS) examination using the F1H panel. We analyzed the relationships between FLT3 gene mutations and other mutations and then chronologically evaluated the variant allele frequency (VAF) of gene mutations in the genomic profiles of patients with AML receiving FLT3i. Results: Of the 171 patients who participated in this study, 49 (28.7%) had FLT3 mutations. FLT3-ITD and FLT3-TKD accounted for 59% and 43% of all cases of FLT3 mutations, respectively. Two patients (4%) were found to have dual mutations: one with FLT3-ITD plus FLT3-TKD and another with FLT3-ITD plus FLT3-F691L. Eight patients (4.5%) were found to have the FLT3-N676K mutation, which is sensitive to gilteritinib but undetectable by currently available PCR-based companion diagnostic tools in Japan. Frequently co-occurring mutations included those of NPM1 (37%), DNMT3A (33%), IDH1/IDH2 (27%), WT1 (24%), and RUNX1 (22%). Mutations in RAS pathway-related genes (e.g., KRAS, NRAS, and PTPN11) were observed in 15 patients (31%). No gene alteration showed statistically significant co-occurrence with the FLT3mutation. However, the median number of mutations that co-exist with FLT3-TKD was slightly higher than that of FLT3-ITD (four genes [3-5] vs. three genes [2-5] ). Sequential changes in the VAF of each gene alteration were investigated in nine patients with FLT3 mutations who eventually gained resistance to FLT3i. It was suggested that there were various patterns in clone evolution. Some showed the acquisition of not only CBL or NRAS as RAS pathways, but also other driver mutations: one showed a persistent FLT3mutation, one showed FLT3-ITD plus FLT3-TKD, and one showed a newly acquired FLT3 mutation substituting an existing FLT3 mutation. We also found that founder mutations, such as the DNMT3Amutation, remain even after eradication of FLT3 mutation during treatment with FLT3i, which could be the cause of the outcome of complete remission with incomplete hematologic recovery. Conclusions: This is the first report to analyze R/R and ND unfit AML cases in a Japanese cohort using F1H NGS, revealing a higher incidence of FLT3-ITD/TKD mutations than previously reported. Therefore, F1H mutational analyses for R/R and ND unfit AML patients harboring FLT3-ITD/TKD mutations may reveal novel therapeutic targets that are sensitive to FLT3i. Samples from these patients showed non-canonical gain-of-function mutations, such as N676K, S451F, V592D, and F691L, which could guide the selection of optimal anti-FLT3 therapies. In addition, longitudinal NGS analysis revealed clonal evolution in cases in which resistance to the FLT3i, gilteritinib and quizartinib were observed. Time-dependent analysis of allele frequencies can help evaluate the details of leukemia clonal evolution and provide optimal treatment options. Figure Legends Fig.1 Overview of gene mutations using F1H NGS analyses. The color of each column indicates the type of genetic mutation. Blue column; point mutation/insertion/deletion, green column; fusion gene, purple column; dual mutations. Fig.2 The chronological changes of leukemic cells fractions bearing each gene mutations during treatment with FLT3 inhibitors, gilteritinib and quizartinib. Figure 1 Figure 1. Disclosures Shibayama: Otsuka: Honoraria; Pfizer: Honoraria; Bristol-Myers Squibb: Honoraria; Sanofi: Honoraria; Nippon Shinyaku: Honoraria; Fujimoto: Honoraria; Daiichi Sankyo: Speakers Bureau; AstraZeneca: Honoraria, Membership on an entity's Board of Directors or advisory committees; Chugai: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Janssen: Honoraria, Research Funding; Novartis: Research Funding, Speakers Bureau; Eisai: Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau; AbbVie: Research Funding, Speakers Bureau; Takeda: Research Funding, Speakers Bureau; Ono: Research Funding, Speakers Bureau; Celgene: Research Funding; Mundi Pharma: Honoraria; Essentia Pharma Japan: Research Funding. Yamauchi: Otsuka: Research Funding; Ono Pharmaceutical: Honoraria; Pfizer: Honoraria, Research Funding; Chugai: Honoraria; Abbie: Research Funding; Astellas: Research Funding; Daiichi Sankyo: Research Funding; Solasia Pharma: Research Funding. Kondo: Sumitomo Dainippon Pharma Co., Ltd.: Honoraria; Bristol-Myers Squibb Company: Honoraria; Novartis Pharma KK: Honoraria; Otsuka Pharmaceutical Co., Ltd.: Honoraria, Research Funding; Astellas Pharma Inc.: Consultancy, Honoraria; SANWA KAGAKU KENKYUSHO CO.,LTD.: Consultancy. Yamamoto: IQIVA/Genmab: Research Funding; Micron: Honoraria; Zenyaku: Honoraria, Research Funding; Yakult: Honoraria, Research Funding; Takeda: Honoraria, Research Funding; SymBio: Honoraria, Research Funding; Solasia Pharma: Research Funding; Sanofi: Honoraria; Otsuka: Honoraria, Research Funding; Ono: Honoraria, Research Funding; Novartis: Honoraria, Research Funding; Nippon Shinyaku: Honoraria, Research Funding; Mundipharma: Research Funding; MSD: Honoraria; Meiji Seika Pharma: Consultancy, Honoraria, Research Funding; Kyowa Kirin: Honoraria; Janssen: Honoraria; HUYA: Consultancy; IQIVA/HUYA: Honoraria; IQIVA/Incyte: Research Funding; Eisai: Honoraria, Research Funding; Daiichi Sankyo: Honoraria; Chugai: Honoraria, Research Funding; Bristol-Myers Squibb/Celgene: Honoraria, Research Funding; AstraZeneca: Honoraria, Research Funding; AbbVie: Honoraria, Research Funding; ADC Therapeutics: Honoraria. Kuroda: Kyowa Kirin: Honoraria, Research Funding; Otsuka Pharmaceutical: Honoraria, Research Funding; Astellas Pharma: Honoraria, Research Funding; Takeda: Honoraria, Research Funding; Celgene: Consultancy, Honoraria, Research Funding; MSD: Research Funding; Abbvie: Consultancy, Honoraria; Ono Pharmaceutical: Honoraria, Research Funding; Eisai: Honoraria, Research Funding; Sysmex: Research Funding; Pfizer: Honoraria, Research Funding; Nippon Shinyaku: Honoraria, Research Funding; Shionogi: Research Funding; Asahi Kasei: Research Funding; Taiho Pharmaceutical: Research Funding; Fujimoto Pharmaceutical: Current Employment, Honoraria, Research Funding; Dainippon Sumitomo Pharma: Honoraria, Research Funding; Daiichi Sankyo: Honoraria, Research Funding; Sanofi: Consultancy, Honoraria, Research Funding; Chugai Pharmaceutical: Honoraria, Research Funding; Bristol-MyersSquibb: Consultancy, Honoraria, Research Funding; Janssen Pharmaceutical K.K: Consultancy. Usuki: Otsuka Pharmaceutical Co., Ltd.: Research Funding, Speakers Bureau; Novartis Pharma K.K.: Research Funding, Speakers Bureau; Ono Pharmaceutical Co., Ltd.: Research Funding, Speakers Bureau; Janssen Pharmaceutical K.K.: Research Funding; Celgene K.K.: Research Funding, Speakers Bureau; Takeda Pharmaceutical Co., Ltd.: Research Funding, Speakers Bureau; Nippon-Boehringer-Ingelheim Co., Ltd.: Research Funding; Mundipharma K.K.: Research Funding; Amgen-Astellas Biopharma K.K.: Research Funding; Nippon-Shinyaku Co., Ltd.: Research Funding, Speakers Bureau; Kyowa-Kirin Co., Ltd.: Research Funding, Speakers Bureau; Pfizer Japan Inc.: Research Funding, Speakers Bureau; Alexion Pharmaceuticals, Inc.: Research Funding, Speakers Bureau; Eisai Co., Ltd.: Speakers Bureau; MSD K.K.: Research Funding, Speakers Bureau; PharmaEssentia Japan KK: Research Funding, Speakers Bureau; Yakult Honsha Co., Ltd.: Research Funding, Speakers Bureau; Daiichi Sankyo Co., Ltd.: Research Funding, Speakers Bureau; Sumitomo-Dainippon Pharma Co., Ltd.: Research Funding; SymBio Pharmaceuticals Ltd.: Research Funding, Speakers Bureau; Gilead Sciences, Inc.: Research Funding; Bristol-Myers-Squibb K.K.: Research Funding, Speakers Bureau; Apellis Pharmaceuticals, Inc.: Research Funding; AbbVie GK: Research Funding, Speakers Bureau; Astellas Pharma Inc.: Research Funding, Speakers Bureau; Incyte Biosciences Japan G.K.: Research Funding; Chugai Pharmaceutical Co., Ltd.: Research Funding, Speakers Bureau; Sanofi K.K.: Speakers Bureau; Amgen K.K.: Research Funding. Yoshimitsu: Novartis: Honoraria; Takeda: Honoraria; Sanofi: Honoraria. Ishitsuka: Eisai: Other: Personal fees, Research Funding; Sumitomo Dainippon Pharma: Other: Personal fees, Research Funding; Genzyme: Other: Personal fees; Astellas Pharma: Other: Personal fees, Research Funding; Pfizer: Other: Personal fees; Novartis: Other: Personal fees; Janssen Pharmaceuticals: Other: Personal fees; Taiho Pharmaceuticals: Other: Personal fees, Research Funding; Mundipharma: Other: Personal fees; Takeda: Other: Personal fees, Research Funding; BMS: Other; Chugai Pharmaceutical: Honoraria, Other: Personal fees, Research Funding; Celgene: Honoraria, Other: Personal fees; Ono Pharmaceutical: Other: Personal fees, Research Funding; Kyowa Kirin: Other: Personal fees, Research Funding; Daiichi Sankyo: Consultancy, Other: Personal fees; MSD: Research Funding; Teijin Pharma: Research Funding; Otsuka Pharmaceutical: Other: Personal fees; Shire: Other; Mochida: Other: Personal fees, Research Funding; Asahi kasei: Research Funding; Eli Lilly: Research Funding; Huya Japan: Other: Personal fees. Ono: Kyowa Kirin Co., Ltd.: Honoraria, Research Funding; Celgene: Honoraria, Research Funding; Janssen Pharmaceutical K.K: Honoraria; Eisai Co., Ltd.: Honoraria; Astellas Pharma Inc.: Honoraria; Takeda Pharmaceutical Company Limited.: Honoraria; ONO PHARMACEUTICAL CO., LTD.: Honoraria, Research Funding; Otsuka Pharmaceutical Co., Ltd.: Honoraria; Pfizer Japan Inc.: Honoraria; Bristol-Myers Squibb Company: Honoraria; Novartis Pharma KK: Honoraria; Chugai Pharmaceutical Co., Ltd.: Honoraria, Research Funding; DAIICHI SANKYO COMPANY, LIMITED.: Honoraria; Mundipharma K.K.: Honoraria; TAIHO PHARMACEUTICAL CO., LTD.: Research Funding; Merck Sharp & Dohme: Honoraria, Research Funding. Takahashi: Kyowahakko-Kirin: Research Funding; Toyamakagaku: Research Funding; Otsuka Pharmaceutical: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau; Pfizer: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau; Novartis Pharmaceuticals: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau; Chugai: Research Funding; Eizai: Research Funding; Asahikasei: Research Funding; Ono: Research Funding. Iyama: SymBio Pharmaceuticals: Research Funding; Astellas: Honoraria; CSL Behring: Honoraria; Daiichi Sankyo: Honoraria; Otsuka Pharmaceuticals Factory: Honoraria; Otsuka Pharmaceuticals Factory: Honoraria; MSD: Research Funding; Nippon Shinyaku: Honoraria; Novartis: Honoraria; Otsuka: Honoraria, Research Funding; Sanofi: Honoraria, Research Funding; Alexion Pharmaceuticals: Honoraria, Research Funding. Izutsu: Allergan Japan: Honoraria; Symbio: Honoraria, Research Funding; Pfizer: Research Funding; Ono: Honoraria, Research Funding; Novartis: Honoraria, Research Funding; MSD: Research Funding; Janssen: Honoraria, Research Funding; Incyte: Research Funding; Genmab: Honoraria, Research Funding; Chugai: Honoraria, Research Funding; Beigene: Research Funding; Bayer: Research Funding; AstraZeneca: Honoraria, Research Funding; AbbVie: Honoraria, Research Funding; Yakult: Research Funding; Takeda Pharmaceutical: Honoraria, Research Funding; Kyowa Kirin: Honoraria, Research Funding; HUYA Bioscience International: Research Funding; Eisai: Honoraria, Research Funding; Daiichi Sankyo: Honoraria, Research Funding; Celgene: Honoraria, Research Funding; FUJI FILM Toyama Chemical: Honoraria. Minami: Bristol-Myers Squibb Company: Honoraria; Pfizer Japan Inc.: Honoraria; Takeda: Honoraria; Novartis Pharma KK: Honoraria; Astellas: Honoraria; Ono: Research Funding; CMIC: Research Funding.

Abstract: Background: Recently, whole exome sequencing has been used for the next-generation sequencing of acute myeloid leukemia (AML), and certain gene mutations have been identified in patients with AML. The treatment strategies for leukemia have undergone drastic changes with the rapid development of new drugs. However, the proper use of newly developed agents poses a major challenge in AML treatment. Genome profiling analysis can be used to select the optimal treatment for patients with newly diagnosed AML. Methods and Results: Hematologic malignancies (HM)-SCREEN-Japan 01 is an actionable mutation profiling multicenter study of patients with newly diagnosed AML who cannot be treated with first standard treatment or patients who have relapsed/refractory AML (R/R-AML). The objective of this study was to evaluate the frequency and characteristics of cancer-related genomic alterations in patients with AML using a comprehensive genome profiling assay (FoundationOne®Heme (F1H)) and determine the quality of specimens used in gene analysis. Before participant recruitment, approval was obtained from the institutional review board at each participating institution. The trial was registered in the UMIN Clinical Trials Registry (UMIN000035233). This study was conducted at 17 participating institutions and had a sample size of 200. The eligibility criteria were as follows: 1) histological diagnosis of AML through bone marrow aspiration; 2) fulfillment of either of the following conditions: i) newly diagnosed AML unfit for standard treatment (ND-unfit AML) or ii) R/R-AML; 3) sufficient sample collection via bone marrow aspiration; 4) Age of participants 20 years or above during registration; 5) provision of written informed consent by participants. The primary outcome was the frequency of each genomic alteration, as determined using F1H, which is a comprehensive genome profiling test based on next-generation sequencing, in the AML specimens. The secondary outcome was the association between each genomic alteration and the clinicopathological characteristics, prognosis, and quality of specimens used in the genetic analysis. Serial genome profiling analyses were performed to evaluate the time-dependent changes in the genome profiles of patients administered FLT3 inhibitors, gilteritinib, and quizartinib for treating AML. One hundred and eighty-two patients were recruited, and the F1H report was successfully obtained for 177 patients (97.3%). The median age of the 66 patients with ND-unfit AML was 73 years (63-79 years), and that of the 105 patients with R/R-AML was 50 years (41-68 years). The median turnaround time was 13 days (minimum 8 days). Recurrent alterations were observed in FLT3 (28.7%), TP53 (21.6%), RUNX1 (20.5%), DNMT3A (18.7%), NPM1 (18.7%), ASXL1 (15.2%), TET2 (14.0%), KMT2A-rearrangement (13.5%), and NRAS (13.5%). IDH1 and/or IDH2 mutations were identified in specimens collected from 30 patients (17.5%). Compared with the prevalence in 2247 patients with AML in the US and Europe who underwent F1H analysis, the frequencies of mutations in FLT3 (28.7% vs. 20.5%) and TP53 (21.6% vs. 17.0%) were higher in this Japanese cohort. Mutations in IDH2, PTPN11, and SF3B1 were observed along with KMT2A rearrangement. Mutations in TP53 tended to be exclusive to the FLT3 mutation. In comparison between the ND-unfit AML and R/R-AML, mutations in TET2 and ASXL1 tended to be more frequnt in ND-unfit AML (17.9% vs. 7.0%, p=0.038, 18.9% vs. 8.5%, p=0.055, respectively). The median expression level of WT1 mRNA at the time of sample collection was 4,490 copies/μgRNA (n=158), and WT1 mutation was frequently found in the WT1-high expression group (13.9% vs. 3.8%, p=0.03), suggesting that the mutation of WT1 may cause overexpression of WT1 as an oncogene. Conclusions: In our evaluation of the suitability of F1H for HM-SCREEN-Japan 01, we successfully identified leukemia-associated genes that can be used as therapeutic targets in AML, which have rarely been identified thus far. Figure 1 Figure 1. Disclosures Yamauchi: Astellas: Research Funding; Abbie: Research Funding; Chugai: Honoraria; Pfizer: Honoraria, Research Funding; Ono Pharmaceutical: Honoraria; Otsuka: Research Funding; Daiichi Sankyo: Research Funding; Solasia Pharma: Research Funding. Shibayama: Celgene: Research Funding; Ono: Honoraria, Research Funding; Takeda: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Avvie: Honoraria, Research Funding; Eisai: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Novartis: Honoraria, Research Funding; Janssen: Honoraria, Research Funding; Chugai: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Essentia Pharma Japan: Research Funding; AstraZeneca: Honoraria, Membership on an entity's Board of Directors or advisory committees; Daiichi Sankyo: Honoraria; Fujimoto: Honoraria; Nippon Shinyaku: Honoraria; Sanofi: Honoraria; Bristol-Myers Squibb: Honoraria; Pfizer: Honoraria; Otsuka: Honoraria; Mundi Pharma: Honoraria. Kondo: Astellas Pharma Inc.: Consultancy, Honoraria; Otsuka Pharmaceutical: Honoraria, Research Funding; Novartis Pharma KK: Honoraria; Bristol-Myers Squibb: Honoraria; Sumitomo Dainippon Pharma: Honoraria; Sanwa Kagaku Kenkyusho: Consultancy. Yamamoto: Eisai: Honoraria, Research Funding; IQIVA/Incyte: Research Funding; IQIVA/HUYA: Honoraria; HUYA: Consultancy; Janssen: Honoraria; Kyowa Kirin: Honoraria; Meiji Seika Pharma: Consultancy, Honoraria, Research Funding; MSD: Honoraria; Mundipharma: Research Funding; Nippon Shinyaku: Honoraria, Research Funding; Novartis: Honoraria, Research Funding; Ono: Honoraria, Research Funding; Otsuka: Honoraria, Research Funding; Sanofi: Honoraria; Solasia Pharma: Research Funding; SymBio: Honoraria, Research Funding; Takeda: Honoraria, Research Funding; Yakult: Honoraria, Research Funding; Zenyaku: Honoraria, Research Funding; Micron: Honoraria; IQIVA/Genmab: Research Funding; ADC Therapeutics: Honoraria; Daiichi Sankyo: Honoraria; Chugai: Honoraria, Research Funding; Bristol-Myers Squibb/Celgene: Honoraria, Research Funding; AstraZeneca: Honoraria, Research Funding; AbbVie: Honoraria, Research Funding. Kuroda: Sanofi: Consultancy, Honoraria, Research Funding; Kyowa Kirin: Honoraria, Research Funding; Otsuka Pharmaceutical: Honoraria, Research Funding; Astellas Pharma: Honoraria, Research Funding; Takeda: Honoraria, Research Funding; Celgene: Consultancy, Honoraria, Research Funding; MSD: Research Funding; Abbvie: Consultancy, Honoraria; Ono Pharmaceutical: Honoraria, Research Funding; Eisai: Honoraria, Research Funding; Sysmex: Research Funding; Pfizer: Honoraria, Research Funding; Nippon Shinyaku: Honoraria, Research Funding; Shionogi: Research Funding; Asahi Kasei: Research Funding; Taiho Pharmaceutical: Research Funding; Fujimoto Pharmaceutical: Current Employment, Honoraria, Research Funding; Daiichi Sankyo: Honoraria, Research Funding; Dainippon Sumitomo Pharma: Honoraria, Research Funding; Chugai Pharmaceutical: Honoraria, Research Funding; Bristol-MyersSquibb: Consultancy, Honoraria, Research Funding; Janssen Pharmaceutical K.K: Consultancy. Usuki: Nippon Boehringer Ingelheim: Research Funding; Takeda: Research Funding, Speakers Bureau; Celgene: Research Funding, Speakers Bureau; Janssen: Research Funding; Ono: Research Funding, Speakers Bureau; Brisol-Myers Squibb: Research Funding, Speakers Bureau; Novartis: Research Funding, Speakers Bureau; Otsuka: Research Funding, Speakers Bureau; Sumitomo Dainippon: Research Funding; Daiichi Sankyo: Research Funding, Speakers Bureau; Symbio: Research Funding, Speakers Bureau; Gilead: Research Funding; Abbvie: Research Funding; Astellas: Research Funding, Speakers Bureau; Astellas-Amgen-Biopharma: Research Funding; Nippon shinyaku: Research Funding, Speakers Bureau; Kyowa Kirin: Research Funding, Speakers Bureau; Pfizer: Research Funding; Alexion: Speakers Bureau; Eisai: Speakers Bureau; MSD: Speakers Bureau; PharmaEssentia: Speakers Bureau; Yakult: Speakers Bureau; Mundipharma: Research Funding. Yoshimitsu: Sanofi: Honoraria; Takeda: Honoraria; Novartis: Honoraria. Ishitsuka: Eli Lilly: Research Funding; Mochida: Other: Personal fees, Research Funding; Eisai: Other: Personal fees, Research Funding; Sumitomo Dainippon Pharma: Other: Personal fees, Research Funding; Genzyme: Other: Personal fees; Astellas Pharma: Other: Personal fees, Research Funding; Pfizer: Other: Personal fees; Novartis: Other: Personal fees; Janssen Pharmaceuticals: Other: Personal fees; Taiho Pharmaceuticals: Other: Personal fees, Research Funding; Mundipharma: Other: Personal fees; Takeda: Other: Personal fees, Research Funding; BMS: Other; Chugai Pharmaceutical: Honoraria, Other: Personal fees, Research Funding; Celgene: Honoraria, Other: Personal fees; Ono Pharmaceutical: Other: Personal fees, Research Funding; Kyowa Kirin: Other: Personal fees, Research Funding; Daiichi Sankyo: Consultancy, Other: Personal fees; Shire: Other; Otsuka Pharmaceutical: Other: Personal fees; Teijin Pharma: Research Funding; MSD: Research Funding; Asahi kasei: Research Funding; Huya Japan: Other: Personal fees. Ono: DAIICHI SANKYO COMPANY, LIMITED.: Honoraria; Novartis Pharma KK: Honoraria; Bristol-Myers Squibb Company: Honoraria; Pfizer Japan Inc.: Honoraria; Otsuka Pharmaceutical Co., Ltd.: Honoraria; ONO PHARMACEUTICAL CO., LTD.: Honoraria, Research Funding; Takeda Pharmaceutical Company Limited.: Honoraria; Astellas Pharma Inc.: Honoraria; Eisai Co., Ltd.: Honoraria; Janssen Pharmaceutical K.K: Honoraria; Mundipharma K.K.: Honoraria; TAIHO PHARMACEUTICAL CO., LTD.: Research Funding; Kyowa Kirin Co., Ltd.: Honoraria, Research Funding; Chugai Pharmaceutical Co., Ltd.: Honoraria, Research Funding; Celgene: Honoraria, Research Funding; Merck Sharp & Dohme: Honoraria, Research Funding. Takahashi: Kyowahakko-Kirin: Research Funding; Ono: Research Funding; Asahikasei: Research Funding; Toyamakagaku: Research Funding; Eizai: Research Funding; Chugai: Research Funding; Otsuka Pharmaceutical: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau; Pfizer: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau; Novartis Pharmaceuticals: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau. Iyama: Otsuka: Honoraria, Research Funding; Novartis: Honoraria; Nippon Shinyaku: Honoraria; MSD: Research Funding; Otsuka Pharmaceuticals Factory: Honoraria; Otsuka Pharmaceuticals Factory: Honoraria; Daiichi Sankyo: Honoraria; CSL Behring: Honoraria; Astellas: Honoraria; Alexion Pharmaceuticals: Honoraria, Research Funding; Sanofi: Honoraria, Research Funding; SymBio Pharmaceuticals: Research Funding. Izutsu: Yakult: Research Funding; Takeda: Honoraria, Research Funding; Chugai: Honoraria, Research Funding; Daiichi Sankyo: Honoraria, Research Funding; Eisai: Honoraria, Research Funding; Fuji Film Toyama Chemical: Honoraria; Genmab: Honoraria, Research Funding; Huya Biosciences: Research Funding; Incyte: Research Funding; Janssen: Honoraria, Research Funding; Kyowa Kirin: Honoraria, Research Funding; MSD: Research Funding; Novartis: Honoraria, Research Funding; Ono Pharmaceutical: Honoraria, Research Funding; Pfizer: Research Funding; Solasia: Research Funding; Symbio: Honoraria; Celgene: Honoraria, Research Funding; Beigene: Research Funding; Bayer: Research Funding; AstraZeneca: Honoraria, Research Funding; Allergan Japan: Honoraria; AbbVie: Honoraria. Minami: Bristol-Myers Squibb Company: Honoraria; Novartis Pharma KK: Honoraria; Pfizer Japan Inc.: Honoraria; Takeda: Honoraria; Astellas: Honoraria; Ono: Research Funding; CMIC: Research Funding.

Abstract: Background and Methods: Acute myeloid leukemia (AML) bearing the RUNX1-RUNX1T1 fusion gene is known to be one of the core-binding factor AML (CBF-AML) which exerts relatively good prognosis. The RUNX1-RUNX1T1 fusion gene are present in approximately 3.5% of patients with AML (data from cBioPortal). However, the real-world epidemiology of this mutation and co-existing gene alterations have not been fully investigated in Japan. We launched an actionable mutation profiling multicenter study named Hematologic Malignancies (HM)-SCREEN-Japan 01 (UMIN000035233), in which a comprehensive genomic assay was performed by Foundation One Heme (F1H) panel for patients with relapsed/refractory (R/R) AML as well as patients with newly-diagnosed (ND) AML who were ineligible for standard chemotherapy. Paraffin-embedded bone marrow samples were gathered from 17 Japanese faculties and the F1H reports were returned to the patients. Results: We found 12 patients (6.8%) with the RUNX1-RUNX1T1 fusion gene out of 177 patients who joined this study and the F1H report was successfully retuned. Eight of these patients were enrolled as R/R AML and four were enrolled as ND AML who are ineligible for standard chemotherapy. Four (50%) of R/R patients were received allogeneic hematopoietic stem cell transplantation. Among the 12 patients with the RUNX1-RUNX1T1 fusion gene, eight (66.7%) had KIT mutation. The major amino acid alteration of KIT was D816V/Y and two patients had two different point-mutations of KIT (one with D816Y plus D816V and the other with D816V plus N822K). No particular mutations, other than KIT, were predominantly co-occurred with RUNX1-RUNX1T1 fusion gene. Especially in R/R patients, 75 % of them had the KIT mutation. Two R/R patients without the KITmutation had JAK2 V617F and FLT3 D835Y respectively. Conclusions: AML with RUNX1-RUNX1T1 fusion gene is currently not indicated for transplantation in the first remission. Previous studies have demonstrated that approximately 30% of patients with CBF-AML harbored the KIT mutations at diagnosis, which might be an indicator of poor prognosis. In our study, the KIT mutations were detected much more frequently than in previously studies of newly-diagnosed CBF-AML. This result may suggest that patients with the KIT mutations were concentrated because our study targeted AML patients who were R/R to prior therapy or ineligible for standard chemotherapy. In addition, no specific mutations highly related to the RUNX1-RUNX1T1 fusion gene were detected other than the KIT mutation, suggesting the KIT mutation might be a suitable molecular marker to predict poor prognosis in AML with the RUNX1-RUNX1T1 fusion gene. Our study revealed the importance of KIT mutations in patients with R/R AML with RUNX1-RUNX1T1 fusion gene, and that the KITmutations may be a promising therapeutic target for this population. Furthermore, it is interesting that driver mutations such as JAK2 and FLT3 mutation were detected in R/R patients without KIT mutation, although further investigation is needed. This suggests that comprehensive genomic assays are highly useful in establishing precision medicine, even in this type of AML, which is generally considered to have a good prognosis. Since most of R/R patients need allo-SCT, precision medicine targeting KIT may be considered for post-recurrence treatment in AML with RUNX1-RUNX1T1 fusion gene, such as bridge therapy to transplantation, in the future. Figure 1 Figure 1. Disclosures Shibayama: Janssen Pharmaceutical K.K.: Research Funding, Speakers Bureau; Nippon Shinyaku Co., Ltd.: Speakers Bureau; Fujimoto Pharmaceutical Corp.: Speakers Bureau; Daiichi Sankyo Co., Ltd.: Speakers Bureau; Chugai Pharmaceutical Co., Ltd.: Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau; AstraZeneca K.K.: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; PharmaEssentia Japan KK: Research Funding; Eisai Co., Ltd.: Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau; Novartis Pharma K.K.: Research Funding, Speakers Bureau; Takeda Pharmaceutical Co., Ltd.: Research Funding, Speakers Bureau; AbbVie GK: Research Funding, Speakers Bureau; Celgene K.K.: Research Funding; Ono Pharmaceutical Co., Ltd.: Research Funding, Speakers Bureau; Sanofi K.K.: Speakers Bureau; Bristol-Myers Squibb K.K.: Speakers Bureau. Yamauchi: Daiichi Sankyo: Research Funding; Astellas: Research Funding; Abbie: Research Funding; Chugai: Honoraria; Pfizer: Honoraria, Research Funding; Ono Pharmaceutical: Honoraria; Otsuka: Research Funding; Solasia Pharma: Research Funding. Kondo: Astellas Pharma Inc.: Consultancy, Honoraria; Otsuka Pharmaceutical: Honoraria, Research Funding; Novartis Pharma KK: Honoraria; Bristol-Myers Squibb Company: Honoraria; Sumitomo Dainippon Pharma: Honoraria; Sanwa Kagaku Kenkyusho CO.,LTD: Consultancy. Yamamoto: IQIVA/Incyte: Research Funding; AstraZeneca: Honoraria, Research Funding; IQIVA/HUYA: Honoraria; HUYA: Consultancy; Janssen: Honoraria; Kyowa Kirin: Honoraria; Meiji Seika Pharma: Consultancy, Honoraria, Research Funding; MSD: Honoraria; Mundipharma: Research Funding; Nippon Shinyaku: Honoraria, Research Funding; Novartis: Honoraria, Research Funding; Ono: Honoraria, Research Funding; Otsuka: Honoraria, Research Funding; Sanofi: Honoraria; Solasia Pharma: Research Funding; SymBio: Honoraria, Research Funding; Takeda: Honoraria, Research Funding; Yakult: Honoraria, Research Funding; Zenyaku: Honoraria, Research Funding; Micron: Honoraria; IQIVA/Genmab: Research Funding; ADC Therapeutics: Honoraria; Eisai: Honoraria, Research Funding; Daiichi Sankyo: Honoraria; Chugai: Honoraria, Research Funding; Bristol-Myers Squibb/Celgene: Honoraria, Research Funding; AbbVie: Honoraria, Research Funding. Kuroda: Fujimoto Pharmaceutical: Current Employment, Honoraria, Research Funding; Taiho Pharmaceutical: Research Funding; Asahi Kasei: Research Funding; Shionogi: Research Funding; Nippon Shinyaku: Honoraria, Research Funding; Pfizer: Honoraria, Research Funding; Sysmex: Research Funding; Eisai: Honoraria, Research Funding; Ono Pharmaceutical: Honoraria, Research Funding; Abbvie: Consultancy, Honoraria; MSD: Research Funding; Celgene: Consultancy, Honoraria, Research Funding; Takeda: Honoraria, Research Funding; Astellas Pharma: Honoraria, Research Funding; Otsuka Pharmaceutical: Honoraria, Research Funding; Kyowa Kirin: Honoraria, Research Funding; Sanofi: Consultancy, Honoraria, Research Funding; Daiichi Sankyo: Honoraria, Research Funding; Dainippon Sumitomo Pharma: Honoraria, Research Funding; Chugai Pharmaceutical: Honoraria, Research Funding; Bristol-MyersSquibb: Consultancy, Honoraria, Research Funding; Janssen Pharmaceutical K.K: Consultancy. Usuki: Otsuka Pharmaceutical Co., Ltd.: Research Funding, Speakers Bureau; Novartis Pharma K.K.: Research Funding, Speakers Bureau; Ono Pharmaceutical Co., Ltd.: Research Funding, Speakers Bureau; Janssen Pharmaceutical K.K.: Research Funding; Celgene K.K.: Research Funding, Speakers Bureau; Takeda Pharmaceutical Co., Ltd.: Research Funding, Speakers Bureau; Nippon-Boehringer-Ingelheim Co., Ltd.: Research Funding; Mundipharma K.K.: Research Funding; Amgen-Astellas Biopharma K.K.: Research Funding; Nippon-Shinyaku Co., Ltd.: Research Funding, Speakers Bureau; Kyowa-Kirin Co., Ltd.: Research Funding, Speakers Bureau; Pfizer Japan Inc.: Research Funding, Speakers Bureau; Alexion Pharmaceuticals, Inc.: Research Funding, Speakers Bureau; Eisai Co., Ltd.: Speakers Bureau; MSD K.K.: Research Funding, Speakers Bureau; PharmaEssentia Japan KK: Research Funding, Speakers Bureau; Yakult Honsha Co., Ltd.: Research Funding, Speakers Bureau; Bristol-Myers-Squibb K.K.: Research Funding, Speakers Bureau; Sumitomo-Dainippon Pharma Co., Ltd.: Research Funding; Daiichi Sankyo Co., Ltd.: Research Funding, Speakers Bureau; SymBio Pharmaceuticals Ltd.: Research Funding, Speakers Bureau; Apellis Pharmaceuticals, Inc.: Research Funding; Gilead Sciences, Inc.: Research Funding; AbbVie GK: Research Funding, Speakers Bureau; Astellas Pharma Inc.: Research Funding, Speakers Bureau; Incyte Biosciences Japan G.K.: Research Funding; Chugai Pharmaceutical Co., Ltd.: Research Funding, Speakers Bureau; Sanofi K.K.: Speakers Bureau; Amgen K.K.: Research Funding. Yoshimitsu: Sanofi: Honoraria; Takeda: Honoraria; Novartis: Honoraria. Ishitsuka: BMS: Other; Takeda: Other: Personal fees, Research Funding; Mundipharma: Other: Personal fees; Taiho Pharmaceuticals: Other: Personal fees, Research Funding; Janssen Pharmaceuticals: Other: Personal fees; Novartis: Other: Personal fees; Pfizer: Other: Personal fees; Astellas Pharma: Other: Personal fees, Research Funding; Genzyme: Other: Personal fees; Sumitomo Dainippon Pharma: Other: Personal fees, Research Funding; Eisai: Other: Personal fees, Research Funding; Chugai Pharmaceutical: Honoraria, Other: Personal fees, Research Funding; Celgene: Honoraria, Other: Personal fees; Ono Pharmaceutical: Other: Personal fees, Research Funding; Kyowa Kirin: Other: Personal fees, Research Funding; Daiichi Sankyo: Consultancy, Other: Personal fees; MSD: Research Funding; Teijin Pharma: Research Funding; Otsuka Pharmaceutical: Other: Personal fees; Shire: Other; Mochida: Other: Personal fees, Research Funding; Asahi kasei: Research Funding; Eli Lilly: Research Funding; Huya Japan: Other: Personal fees. Ono: Novartis Pharma KK: Honoraria; Merck Sharp & Dohme: Honoraria, Research Funding; Bristol-Myers Squibb Company: Honoraria; Pfizer Japan Inc.: Honoraria; Otsuka Pharmaceutical Co., Ltd.: Honoraria; ONO PHARMACEUTICAL CO., LTD.: Honoraria, Research Funding; Takeda Pharmaceutical Company Limited.: Honoraria; Astellas Pharma Inc.: Honoraria; Eisai Co., Ltd.: Honoraria; Janssen Pharmaceutical K.K: Honoraria; DAIICHI SANKYO COMPANY, LIMITED.: Honoraria; Mundipharma K.K.: Honoraria; TAIHO PHARMACEUTICAL CO., LTD.: Research Funding; Chugai Pharmaceutical Co., Ltd.: Honoraria, Research Funding; Kyowa Kirin Co., Ltd.: Honoraria, Research Funding; Celgene: Honoraria, Research Funding. Takahashi: Kyowahakko-Kirin: Research Funding; Ono: Research Funding; Asahikasei: Research Funding; Toyamakagaku: Research Funding; Eizai: Research Funding; Chugai: Research Funding; Otsuka Pharmaceutical: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau; Pfizer: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau; Novartis Pharmaceuticals: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau. Iyama: Novartis: Honoraria; Nippon Shinyaku: Honoraria; MSD: Research Funding; Otsuka Pharmaceuticals Factory: Honoraria; Otsuka Pharmaceuticals Factory: Honoraria; Daiichi Sankyo: Honoraria; CSL Behring: Honoraria; Astellas: Honoraria; Alexion Pharmaceuticals: Honoraria, Research Funding; Otsuka: Honoraria, Research Funding; Sanofi: Honoraria, Research Funding; SymBio Pharmaceuticals: Research Funding. Izutsu: Celgene: Honoraria, Research Funding; Daiichi Sankyo: Honoraria, Research Funding; Eisai: Honoraria, Research Funding; HUYA Bioscience International: Research Funding; Kyowa Kirin: Honoraria, Research Funding; Takeda Pharmaceutical: Honoraria, Research Funding; Yakult: Research Funding; AbbVie: Honoraria, Research Funding; AstraZeneca: Honoraria, Research Funding; Bayer: Research Funding; Beigene: Research Funding; Chugai: Honoraria, Research Funding; Genmab: Honoraria, Research Funding; Incyte: Research Funding; Janssen: Honoraria, Research Funding; MSD: Research Funding; Novartis: Honoraria, Research Funding; Ono: Honoraria, Research Funding; Pfizer: Research Funding; Symbio: Honoraria, Research Funding; Allergan Japan: Honoraria; FUJI FILM Toyama Chemical: Honoraria. Minami: Bristol-Myers Squibb Company: Honoraria; Pfizer Japan Inc.: Honoraria; Novartis Pharma KK: Honoraria; Takeda: Honoraria; Astellas: Honoraria; Ono: Research Funding; CMIC: Research Funding.