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Background and Methods: FLT3-internal tandem duplication (FLT3-ITD) is a type of mutation present in approximately 20-30% of patients with acute myeloid leukemia (AML) and is associated with poor prognosis. We performed a comprehensive genome profiling assay in patients with relapsed and refractory (R/R) AML, using the Foundation One Heme (F1H) panel, as a part of hematologic malignancies (HM)-SCREEN-Japan 01 (UMIN000035233), an actionable mutation profiling multicenter study. In this study, we analyzed the high frequency of FLT3 mutations in patients with R/R AML and found several patients who were positive for FLT3-N676K, a subclonal gene without concurrent ITD. Moreover, clonal evolution was observed in most patients who received kinase inhibitors, suggesting that mutations in signaling pathways downstream of FLT3 and activation of alternative pathways contribute to resistance mechanisms after FLT3 inhibitor treatment. Upon treatment failure during gilteritinib or quizartinib monotherapy, we can switch to another FLT3 inhibitor treatment in Japan. However, few reports have investigated clonal evolution after multiple FLT3 inhibitor treatment failure, and the mutational resistance profile remains unknown. Thus, we extended our investigation to examine clonal evolution during the progression of leukemia harboring FLT3-ITD and tyrosine kinase domain mutation (TKD) mutations. In this study, we performed serial comprehensive genome profiling analyses to evaluate time-dependent changes in genomic profiles of patients receiving the FLT3 inhibitors gilteritinib, and quizartinib in AML. Results: This study was initiated in January 2019, and 91 patients were recruited by March 2020. The median turnaround time between sending specimens and receiving results was 15 days (9 to 56 days). In this study, a higher incidence of FLT3 mutations was observed in patients with AML (28.6%, 26/91), and those with relapse/refractory (R/R) AML (64.8%, 59/91), FLT3-ITD (20.3%, 12/59), and FLT3-TKD (15.3%, 9/59), than previously reported in newly diagnosed patients. Particularly, FLT3 mutations were much more frequently observed in patients with R/R AML (35.6 %, 21/59), whereas those with newly diagnosed AML unfit for standard treatment (15.6 %, 5/32). Furthermore, FLT3-TKD mutations were found in 10 patients, who were potential candidates for treatment with FLT3 inhibitors, such as gilteritinib. The N676K mutation within the FLT3 tyrosine kinase domain 1, which is not detectable through conventional mutational analyses, was observed using a multiplex polymerase chain reaction in 19.2% (5 of 26) of patients who were FLT3mutation-positive, including those with subclonal mutations. Moreover, patients with RUNX1 mutation were present in this cohort, and this finding supports previous reports showing the association between the core binding factor protein complex and FLT3 N676K mutation in leukemia. Interestingly, FLT3-ITD mutations usually occur in the juxtamembrane domain, but we found three patients with other abnormalities, including ITDs in the tyrosine kinase domain, which are associated with poor prognosis. Meanwhile, during FLT3 inhibitor treatment, the resistant clonal expansion was observed due to activation of alternative pathways such as NRAS pathway or acquired FLT3 mutation. Not only activating these alternative pathways, but the cases in which TKD point mutation was added to FLT3-ITD, or new mutations were acquired without the additional mutation site among the cases showing FLT3 inhibitor resistance as the treatment progressed. Conclusions: We conclude that F1H mutational analyses for R/R AML harboring FLT3-ITD/TKD mutations may reveal novel therapeutic targets that are sensitive to FLT3 inhibitors. Moreover, improved biomarker analysis methods for detecting additional FLT3 alternations, like FLT3 N676K, could guide patient selection for the most suitable anti-FLT3 therapies. Furthermore, serial comprehensive genome profiling analysis at the time of AML progression, especially after tyrosine kinase inhibitor treatment, will provide valuable information for clinical decision-making. Table Disclosures Shibayama: Fujimoto: Honoraria; Pfizer: Honoraria; Bristol-Myers Squibb: Honoraria; Otsuka: Honoraria; Kyowa Kirin: Honoraria; Chugai: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Janssen: Honoraria, Research Funding; Novartis: Honoraria, Research Funding; Daiichi Sankyo: Honoraria; Nippon Shinyaku: Honoraria, Research Funding; Sumitomo Dainippon: Honoraria, Research Funding; Merck Sharp & Dohme: Research Funding; Takeda: Honoraria, Research Funding; Ono: Honoraria, Research Funding; Celgene: Membership on an entity's Board of Directors or advisory committees, Research Funding; Eisai: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Taiho: Research Funding; Shionogi: Research Funding; Teijin: Research Funding; Astellas: Research Funding; Sanofi: Honoraria; AstraZeneca: Honoraria, Membership on an entity's Board of Directors or advisory committees; AbbVie: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Mundi Pharma: Honoraria. Yamauchi:Otsuka: Research Funding; Ono Pharmaceutical: Honoraria; Chugai: Honoraria; Abbie: Research Funding; Solasia Pharma: Research Funding; Astellas: Research Funding; Daiichi Sankyo: Research Funding; Pfizer: Honoraria, Research Funding. Gotoh:Eisai: Honoraria; Alexion pharmaceuticals: Research Funding; Ono Pharmaceutical: Honoraria; Nippon Shinyaku: Honoraria; Takeda pharmaceutical: Honoraria; Taiho pharmaceutical: Honoraria; Chugai: Honoraria; Novartis: Research Funding. Yamamoto:Chugai: Consultancy, Honoraria, Research Funding; Eisai: Consultancy, Honoraria, Research Funding; Sanofi: Honoraria; Sumitomo Dainippon: Honoraria; Stemline Therapeutics: Consultancy; Otsuka: Consultancy, Honoraria, Research Funding; Pfizer: Honoraria; IQIVA/HUYA: Honoraria; HUYA: Consultancy; IQIVA/Incyte: Research Funding; Solasia Pharma: Research Funding; SymBio: Research Funding; Takeda: Consultancy, Honoraria, Research Funding; Yakult: Research Funding; Zenyaku: Research Funding; Astra-Zeneca: Consultancy, Research Funding; Bayer: Research Funding; Bristol-Myers Squibb: Honoraria; Aichi Cancer Center: Current Employment; Kyowa Kirin: Honoraria; Meiji Seika Pharma: Consultancy, Honoraria; Mochida: Honoraria; Gilead Sciences: Research Funding; Daiichi Sankyo: Consultancy; MSD: Consultancy, Honoraria, Research Funding; Mundipharma: Consultancy, Honoraria, Research Funding; Nippon Shinyaku: Honoraria, Research Funding; Novartis: Honoraria, Research Funding; Ono: Consultancy, Honoraria, Research Funding; Janssen: Honoraria; AbbVie: Consultancy, Honoraria, Research Funding; Celgene: Consultancy, Honoraria, Research Funding. Fujishima:Pfizer: Speakers Bureau. Takahashi:Novartis Pharma KK: Honoraria, Research Funding; Pfizer Japan Inc.: Honoraria, Research Funding; Bristol-Myers Squibb Company: Honoraria. Usuki:Apellis: Research Funding; Alexion: Research Funding, Speakers Bureau; Novartis: Research Funding, Speakers Bureau; Chugai: Research Funding. ONO:Astellas Pharma Inc.: Honoraria; TAIHO PHARMACEUTICAL CO., LTD.: Research Funding; Mundipharma K.K.: Honoraria; Otsuka Pharmaceutical Co., Ltd.: Honoraria; Novartis Pharma KK: Honoraria; Celgene: Honoraria, Research Funding; Bristol-Myers Squibb Company: Honoraria; Pfizer Japan Inc.: Honoraria; Chugai Pharmaceutical Co., Ltd.: Honoraria, Research Funding; ONO PHARMACEUTICAL CO., LTD.: Honoraria, Research Funding; Takeda Pharmaceutical Company Limited.: Honoraria; Kyowa Kirin Co., Ltd.: Honoraria, Research Funding; DAIICHI SANKYO COMPANY, LIMITED.: Honoraria; Janssen Pharmaceutical K.K: Honoraria; Eisai Co., Ltd.: Honoraria. Kuroda:Sysmex: Research Funding; Otsuka Pharmaceutical: Honoraria, Research Funding; Astellas Pharma: Honoraria, Research Funding; Takeda: Honoraria, Research Funding; Celgene: Consultancy, Honoraria, Research Funding; Abbvie: Consultancy, Honoraria; Ono Pharmaceutical: Honoraria, Research Funding; Nippon Shinyaku: Honoraria, Research Funding; Pfizer: Honoraria, Research Funding; Asahi Kasei: Research Funding; Shionogi: Research Funding; Dainippon Sumitomo Pharma: Honoraria, Research Funding; Daiichi Sankyo: Honoraria, Research Funding; Sanofi: Consultancy, Honoraria, Research Funding; Kyowa Kirin: Honoraria, Research Funding; Janssen Pharmaceutical K.K: Consultancy; Eisai: Honoraria, Research Funding; Fujimoto Pharmaceutical: Honoraria, Research Funding; Taiho Pharmaceutical: Research Funding; Bristol-MyersSquibb: Consultancy, Honoraria, Research Funding; Chugai Pharmaceutical: Honoraria, Research Funding; MSD: Research Funding. Izutsu:Incyte: Research Funding; Eisai: Research Funding; AstraZeneca: Research Funding; Abbvie pharmaceuticals: Research Funding; Chugai: Research Funding; Novartis: Research Funding; Celgene: Research Funding; Symbio: Research Funding; Solasia: Research Funding; Janssen: Research Funding; Yakult: Research Funding; HUYA Japan: Research Funding; Sanofi: Research Funding; Daiichi Sankyo: Research Funding; Bayer pharmaceuticals: Research Funding; Ono Pharmaceutical: Research Funding. Minami:Novartis Pharma KK: Honoraria; Pfizer Japan Inc.: Honoraria; Takeda: Honoraria; Bristol-Myers Squibb Company: Honoraria.

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.

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.

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.

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.

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.

Background: Acute myeloid leukemias with KMT2A (formerly known as MLL-1) fusion genes (MLL-AML) and those with NPM1 mutations (NPM1-AML) are distinct subtypes as defined by the WHO classification. Although they have different clinical features and prognostic impact , recent studies suggest that the MLL1 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.). New targeted strategies for these AML subtypes are expected as preliminary data suggest that menin-MLL1 inhibition may inhibit malignancy. In addition to classical chromosomal analysis and prefixed fusion gene screening, next-generation sequencing (NGS) should help in identifying the precise prevalence of these alterations and understanding the relationship with other pathological mutations. We launched the HM-SCREEN-JAPAN01 study (UMIN000035233) in which gene alterations are analyzed by FoundationOne Heme® in patients with AML who are relapsed/refractory to, or ineligible for standard therapies. Aiming for 200 registrations, recruitment has reached approximately 100. The interim results are described here. Methods: HM-SCREEN-JAPAN01 is an observational study and conducted by 17 participating institutions. The eligibility criteria are as follows: 1) histological diagnosis of AML must be made by bone marrow testing; 2) one of the following conditions must be fulfilled: i) a patient with newly diagnosed AML and is ineligible for standard treatment, or ii) a patient with AML who has relapsed or is refractory to prior therapy; 3) sufficient amount of bone marrow sample must be available; 4) age at registration must be 20 or more; and 5) written informed consent must be taken. All samples were analyzed by FoundationOne Heme®. Results:Nine patients (9.9%) with MLL-AML and seventeen patients (18.7%) with NPM1-AML were found among 91 available cases (either one found in 28.6%). No patients demonstrated MLL-rearrangement and NPM1-mutation simultaneously. Median age of patients with MLL-AML (42-68 y) was a decade less than that of patients with NPM1-AML (55-74 y), and the majority of cases had a clinical relapse or were refractory to prior therapies. Translocations involving chromosome 11q23.3 (e.g. t(9;11)(p21.3;q23.3)) were found in 5 of 8 patients (62.5%) with MLL-AML (data not available due to insufficient cell count in one case) and no chromosomal abnormalities were detected in 10 of 16 patients (62.5%) with NPM1-AML (chromosomal analysis was not performed in one case). In patients with MLL-AML (see Figure), FLT3 mutations were found in 3 of 9 cases (33.3%), all of which were point mutations within the tyrosine kinase domain (FLT3-TKD). PTPN11 mutations were also found simultaneously in these three cases. Co-existing NRAS and TP53 mutations with high allele-frequency (32-50%) were also seen in two different cases. A targetable mutation of IDH2 was seen in one patient (11.1%) who had an FLT3 mutation with low allele-frequency (2%). In patients with NPM1-AML (see Figure), allele-frequency of mutated NPM1 ranged from 10 to 44%. Relatively common co-existing mutations were TET2 (7 of 17; 41.2%), DNMT3A (9 of 17; 52.9%), and FLT3 (9 of 17; 52.9%). Unlike in MLL-AML patients, all FLT3 alterations were internal tandem duplication (FLT-ITD) with one case of dual FLT3-ITD and -TKD mutation. IDH1 and IDH2 mutations were found in two (11.8%) and four (23.5%) separate cases, respectively. A rare fusion gene ETV6-NTRK3 (one of primary targets of NTRK inhibitors) was detected in one patient (5.9%) who had IDH1 mutation with moderate allele-frequency (17%). Conclusion: MLL-rearrangements and NPM1-mutations were found in approximately a quarter of the 91 AML patient (mostly relapsed or refractory) bone marrow samples analyzed. These alterations appeared to be mutually exclusive. FLT3 alterations were seen in a third of the MLL-AML cases and half of the NPM1-AML cases, seemingly more frequent than that previously reported. Interestingly, FLT3-TKDs were dominant in MLL-AML cases, whereas NPM1-AML cases carried FLT3-ITD. IDH1 and IDH2 mutations commonly co-existed in both groups. This HM-SCREEN-Japan01 study is now recruiting patients, and a further understanding of genomic distribution and correlation is expected. Figure Disclosures Yamauchi: Otsuka:Research Funding;Astellas:Research Funding;Daiichi Sankyo:Research Funding;Chugai:Honoraria;Pfizer:Honoraria, Research Funding;Abbie:Research Funding;Solasia Pharma:Research Funding;Ono Pharmaceutical:Honoraria.Shibayama:AstraZeneca:Honoraria, Membership on an entity's Board of Directors or advisory committees;Sanofi:Honoraria;Pfizer:Honoraria;Fujimoto:Honoraria;Janssen:Honoraria, Research Funding;Teijin:Research Funding;Novartis:Honoraria, Research Funding;Takeda:Honoraria, Research Funding;Nippon Shinyaku:Honoraria, Research Funding;Daiichi Sankyo:Honoraria;Chugai:Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding;Sumitomo Dainippon:Honoraria, Research Funding;Merck Sharp & Dohme:Research Funding;Shionogi:Research Funding;Astellas:Research Funding;Taiho:Research Funding;Otsuka:Honoraria;Bristol-Myers Squibb:Honoraria;Celgene:Membership on an entity's Board of Directors or advisory committees, Research Funding;Eisai:Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding;AbbVie:Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding;Kyowa Kirin:Honoraria;Ono:Honoraria, Research Funding;Mundi Pharma:Honoraria.Yamamoto:Stemline Therapeutics:Consultancy;Meiji Seika Pharma:Consultancy, Honoraria;MSD:Consultancy, Honoraria, Research Funding;Chugai:Consultancy, Honoraria, Research Funding;Eisai:Consultancy, Honoraria, Research Funding;Daiichi Sankyo:Consultancy;IQIVA/HUYA:Honoraria;HUYA:Consultancy;IQIVA/Incyte:Research Funding;Mundipharma:Consultancy, Honoraria, Research Funding;Kyowa Kirin:Honoraria;Mochida:Honoraria;Gilead Sciences:Research Funding;Solasia Pharma:Research Funding;Nippon Shinyaku:Honoraria, Research Funding;Novartis:Honoraria, Research Funding;Ono:Consultancy, Honoraria, Research Funding;Aichi Cancer Center:Current Employment;AbbVie:Consultancy, Honoraria, Research Funding;Astra-Zeneca:Consultancy, Research Funding;Bayer:Research Funding;Bristol-Myers Squibb:Honoraria;Celgene:Consultancy, Honoraria, Research Funding;Zenyaku:Research Funding;Takeda:Consultancy, Honoraria, Research Funding;Yakult:Research Funding;SymBio:Research Funding;Pfizer:Honoraria;Otsuka:Consultancy, Honoraria, Research Funding;Sanofi:Honoraria;Sumitomo Dainippon:Honoraria;Janssen:Honoraria.Fujishima:Pfizer:Speakers Bureau.Takahashi:Pfizer Japan Inc.:Honoraria, Research Funding;Novartis Pharma KK:Honoraria, Research Funding;Bristol-Myers Squibb Company:Honoraria.Usuki:Alexion:Speakers Bureau;Pfizer:Research Funding;Nippon Boehringer Ingelheim:Research Funding;Mundipharma:Research Funding;Astellas-Amgen-Biopharma:Research Funding;Nippon shinyaku:Research Funding, Speakers Bureau;Eisai:Speakers Bureau;MSD:Speakers Bureau;Takeda:Speakers Bureau;PharmaEssentia:Speakers Bureau;Yakult:Speakers Bureau;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;Kyowa Kirin:Research Funding, Speakers Bureau;Ono:Research Funding, Speakers Bureau;Janssen:Research Funding;Celgene:Research Funding, Speakers Bureau;Takeda:Research Funding;Astellas:Research Funding, Speakers Bureau;Abbvie:Research Funding;Gilead:Research Funding.Ono:Celgene:Honoraria, Research Funding;Kyowa Kirin Co., Ltd.:Honoraria, Research Funding;Chugai Pharmaceutical Co., Ltd.:Honoraria, Research Funding;Novartis Pharma KK:Honoraria;Mundipharma K.K.:Honoraria;TAIHO PHARMACEUTICAL CO., LTD.:Research Funding;Eisai Co., Ltd.:Honoraria;Otsuka Pharmaceutical Co., Ltd.:Honoraria;Astellas Pharma Inc.:Honoraria;Bristol-Myers Squibb Company:Honoraria;Pfizer Japan Inc.:Honoraria;Takeda Pharmaceutical Company Limited.:Honoraria;ONO PHARMACEUTICAL CO., LTD.:Honoraria, Research Funding;DAIICHI SANKYO COMPANY, LIMITED.:Honoraria;Janssen Pharmaceutical K.K:Honoraria.Kuroda:Daiichi Sankyo:Honoraria, Research Funding;Pfizer:Honoraria, Research Funding;Sysmex:Research Funding;Janssen Pharmaceutical K.K:Consultancy;Eisai:Honoraria, Research Funding;Sanofi:Consultancy, Honoraria, Research Funding;Kyowa Kirin:Honoraria, Research Funding;Otsuka Pharmaceutical:Honoraria, Research Funding;Ono Pharmaceutical:Honoraria, Research Funding;Abbvie:Consultancy, Honoraria;MSD:Research Funding;Celgene:Consultancy, Honoraria, Research Funding;Dainippon Sumitomo Pharma:Honoraria, Research Funding;Chugai Pharmaceutical:Honoraria, Research Funding;Takeda:Honoraria, Research Funding;Bristol-MyersSquibb:Consultancy, Honoraria, Research Funding;Astellas Pharma:Honoraria, Research Funding;Fujimoto Pharmaceutical:Honoraria, Research Funding;Taiho Pharmaceutical:Research Funding;Asahi Kasei:Research Funding;Shionogi:Research Funding;Nippon Shinyaku:Honoraria, Research Funding.Ishitsuka:Celgene:Other: Personal Fees;Kyowa Hakko Kirin:Other: Personal fees, Research Funding;BMS:Other: Personal fees;Chugai Pharmaceutical:Other: Personal fees, Research Funding;Takeda:Other: Personal fees, Research Funding;mundiharma: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, Research Funding;Genzyme:Other;Sumitomo Dainippon Pharma:Other, Research Funding;Eisai:Other, Research Funding;Mochida:Other, Research Funding;Shire:Other;Otsuka Pharmaceutical:Other;Ono Pharmaceutical:Other, Research Funding;Teijin Pharma:Research Funding;MSD:Research Funding;Asahi kasei:Research Funding;Eli Lilly:Research Funding;Daiichi Sankyo:Other;Huya Japan:Other.Minami:Bristol-Myers Squibb Company:Honoraria;Novartis Pharma KK:Honoraria;Pfizer Japan Inc.:Honoraria;Takeda:Honoraria.

Background:Recently, whole exome sequencing has been performed for acute myeloid leukemia (AML) by next generation sequencing. The results revealed that certain gene mutations are identified in patients with AML. Among them,FLT3(28%),NPM1(27%),DNMT3A(26%), andIDH1/2(20%) mutations are observed in 20 to 30% of cases, while the frequencies of more than 10 other types of mutations are less than 10%. Some of these low frequency mutations are actionable mutations, which are defined as genetic DNA aberrations that are expected to elicit a response to an approved targeted therapy that is available for off-label treatment or available in clinical trials. Thus, the treatment strategies for leukemia are drastically changing with the rapid development of new drugs. Moving forward, the proper use of new agents is one of the major AML treatment issues. Especially, genome profiling analysis for newly diagnosed patients will be needed to select an optimal first line treatment. The HM-SCREEN-Japan 01 is an actionable mutation profiling multicenter study of patients with newly diagnosed AML who are unsuitable for the first standard treatment or have relapsed/refractory AML. The objective of this study is to evaluate the frequency and characteristics of cancer-related genome alterations in AML using a comprehensive genome profiling assay (FoundationOne®Heme) and determine the quality of specimens that contribute to the gene analysis. Approval was obtained from the Institutional Review Board prior to starting patient accrual at each institution. This trial has been registered at the UMIN Clinical Trials Registry as UMIN000035233. Methods:This study was conducted by 17 participating institutions, with a sample size of 200. The eligibility criteria were as follows: 1) histological diagnosis of AML through bone marrow aspiration; 2) either of the following conditions fulfilled, i) patients with newly diagnosed AML unfit for standard treatment or ii) patients with relapsed/refractory AML; 3) sufficient sample is collected by bone marrow aspiration; 4) age at registration is 20 years or older; 5) written informed consent is taken. The primary outcome was the frequency of each genomic alteration in leukemia using FoundationOne®Heme (F1H), which is a comprehensive genomic profile that applies next-generation sequencing. The secondary outcomes evaluated the association between each cancer genome alteration and clinicopathological characteristics, prognosis, and quality of the specimens that contributed to the genetic analysis. In this study, we also performed serial genome profiling analyses to evaluate the time-dependent changes in genomic profiles in patients administered FLT3 inhibitors, gilteritinib, and quizartinib for AML. Results:This study commenced in January 2019, and 91 patients were recruited by March 2020. The median turnaround time between sending specimens and receiving results was 15 days (9 to 56 days). Of the 91 patients, 35.2% (32/91) were newly diagnosed with AML and unfit for standard treatment and 64.8% (59/91) had relapsed/refractory AML. Mutations were observed in the following genes in all 91 patients:FLT3(28.6%),RUNX1(25.0%),TP53(20.1%),DNMT3A(19.8%),NPM1(18.7%),IDH1/2(17.6%),CEBPA(16.5%),KMT2A(14.3%),NRAS(13.2%),TET2(12.1%),ASXL1(12.1%), and EZH2(2.2%). In 32 patients with newly diagnosed AML, mutations were observed in the following genes:FLT3(28.6%),RUNX1(20.3%),TP53(18.8%),DNMT3A(15.6%),NPM1(12.5%),IDH1/2(15.6%),CEBPA(15.6%),KMT2A(6.0%),NRAS(12.5%),TET2(9.0%),ASXL1(21.9%), and EZH2(6.3%). In 59 patients with relapsed/refractory AML, mutations were observed in the following genes:FLT3(28.6%),RUNX1(22.0%),TP53(22.0%),DNMT3A(22.0%),NPM1(22.0%),IDH1/2(18.6%),CEBPA(15.3%),KMT2A(18.6%),NRAS(13.6%),TET2(13.6%),ASXL1(6.8%), andEZH2(0%). In the FLT3 positive AML cohort, six patients were registered and one achieved remission by quizartinib after progression on gilteritinib. Conclusions:The evaluation of F1H for its use in HM-SCREEN-Japan 01 facilitates the analysis of leukemia-associated genes that can be used as therapeutic targets, which have rarely been identified in AML thus far. Figure Disclosures Shibayama: Shionogi:Research Funding;Taiho:Research Funding;Eisai:Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding;Celgene:Membership on an entity's Board of Directors or advisory committees, Research Funding;Ono:Honoraria, Research Funding;Takeda:Honoraria, Research Funding;Merck Sharp & Dohme:Research Funding;Sumitomo Dainippon:Honoraria, Research Funding;Nippon Shinyaku:Honoraria, Research Funding;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;Kyowa Kirin:Honoraria;Otsuka:Honoraria;Bristol-Myers Squibb:Honoraria;Pfizer:Honoraria;Fujimoto:Honoraria;AbbVie:Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding;AstraZeneca:Honoraria, Membership on an entity's Board of Directors or advisory committees;Sanofi:Honoraria;Mundi Pharma:Honoraria;Teijin:Research Funding;Astellas:Research Funding.Yamauchi:Chugai:Honoraria;Pfizer:Honoraria, Research Funding;Ono Pharmaceutical:Honoraria;Otsuka:Research Funding;Astellas:Research Funding;Abbie:Research Funding;Solasia Pharma:Research Funding;Daiichi Sankyo:Research Funding.Gotoh:Alexion pharmaceuticals:Research Funding;Eisai:Honoraria;Ono Pharmaceutical:Honoraria;Taiho pharmaceutical:Honoraria;Takeda pharmaceutical:Honoraria;Nippon Shinyaku:Honoraria;Chugai:Honoraria;Novartis:Research Funding.Yamamoto:Zenyaku:Research Funding;Yakult:Research Funding;Takeda:Consultancy, Honoraria, Research Funding;SymBio:Research Funding;Solasia Pharma:Research Funding;Stemline Therapeutics:Consultancy;Sumitomo Dainippon:Honoraria;Sanofi:Honoraria;Pfizer:Honoraria;Otsuka:Consultancy, Honoraria, Research Funding;Ono:Consultancy, Honoraria, Research Funding;Novartis:Honoraria, Research Funding;Nippon Shinyaku:Honoraria, Research Funding;Mundipharma:Consultancy, Honoraria, Research Funding;MSD:Consultancy, Honoraria, Research Funding;Mochida:Honoraria;Meiji Seika Pharma:Consultancy, Honoraria;Kyowa Kirin:Honoraria;Janssen:Honoraria;Gilead Sciences:Research Funding;IQIVA/Incyte:Research Funding;HUYA:Consultancy;IQIVA/HUYA:Honoraria;Daiichi Sankyo:Consultancy;Eisai:Consultancy, Honoraria, Research Funding;Chugai:Consultancy, Honoraria, Research Funding;Celgene:Consultancy, Honoraria, Research Funding;Bristol-Myers Squibb:Honoraria;Bayer:Research Funding;Astra-Zeneca:Consultancy, Research Funding;AbbVie:Consultancy, Honoraria, Research Funding;Aichi Cancer Center:Current Employment.Fujishima:Pfizer:Speakers Bureau.Takahashi:Bristol-Myers Squibb Company:Honoraria;Novartis Pharma KK:Honoraria, Research Funding;Pfizer Japan Inc.:Honoraria, Research Funding.Usuki:Novartis:Research Funding, Speakers Bureau;Chugai:Research Funding;Apellis:Research Funding;Alexion:Research Funding, Speakers Bureau.ONO:TAIHO PHARMACEUTICAL CO., LTD.:Research Funding;Mundipharma K.K.:Honoraria;DAIICHI SANKYO COMPANY, LIMITED.: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;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;Kyowa Kirin Co., Ltd.:Honoraria, Research Funding;Celgene:Honoraria, Research Funding.Kuroda:Astellas Pharma:Honoraria, Research Funding;Sanofi:Consultancy, Honoraria, Research Funding;Daiichi Sankyo:Honoraria, Research Funding;Shionogi:Research Funding;Nippon Shinyaku:Honoraria, Research Funding;Fujimoto Pharmaceutical: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;Dainippon Sumitomo Pharma:Honoraria, Research Funding;Chugai Pharmaceutical:Honoraria, Research Funding;Bristol-MyersSquibb:Consultancy, Honoraria, Research Funding;Janssen Pharmaceutical K.K:Consultancy;Asahi Kasei:Research Funding;Taiho Pharmaceutical:Research Funding;Kyowa Kirin:Honoraria, Research Funding;Otsuka Pharmaceutical:Honoraria, Research Funding;Pfizer:Honoraria, Research Funding.Izutsu:Sanofi:Research Funding;Symbio:Research Funding;Solasia:Research Funding;Janssen:Research Funding;Yakult:Research Funding;HUYA Japan:Research Funding;Abbvie pharmaceuticals:Research Funding;Incyte:Research Funding;Eisai:Research Funding;AstraZeneca:Research Funding;Daiichi Sankyo:Research Funding;Bayer pharmaceuticals:Research Funding;Ono Pharmaceutical:Research Funding;Novartis:Research Funding;Chugai:Research Funding;Celgene:Research Funding.Minami:Bristol-Myers Squibb Company:Honoraria;Pfizer Japan Inc.:Honoraria;Novartis Pharma KK:Honoraria;Takeda:Honoraria.

Recombinant human soluble thrombomodulin (rTM) comprises the active, extracellular domain of thrombomodulin (TM), and inactivates coagulation by binding to thrombin. In addition, the thrombin-rTM complex activates protein C to produce activated protein C (APC), which inactivates factors VIIIa and Va in the presence of protein S, further inhibiting thrombin formation. The use of rTM for the treatment of DIC was approved in Japan in in 2008, and since then it has proved effective in individuals with DIC complicated by a variety of underling diseases including sepsis and acute leukemia. Of note, rTM possesses anti-inflammatory and cytoprotective effects and the use of rTM successfully rescued individuals with sinusoidal obstruction syndrome, engraftment syndrome and transplantation-associated microangiopathy complicated by hematopoietic stem cell transplantation (HSCT). The present study retrospectively investigated whether the use of rTM improved the clinical outcome of individuals who received HSCT in our institution. From 2001 to 2012, 71 individuals with hematological diseases received HSCT in our institution. Of these, 41 developed coagulopathy in association with various underlying conditions. The patients who developed coagulopathy after 2008 (n=23) were treated by rTM, and the others (n=11) were treated by either heparin and/or antithrombin III concentrate. Seven patients did not receive any anticoagulant therapy. Of note, treatment of coagulopathy by rTM significantly improved clinical outcomes of patients at day 100 and dramatically prolonged their overall survival (p=0.044). Taken together, rTM is useful to improve clinical outcomes of transplant recipients with coagulopathy. Disclosures: No relevant conflicts of interest to declare.

Background Acute promyelocytic leukemia (APL) is an uncommon subtype of acute myelogenous leukemia (AML) with a high mortality rate, mostly attributable to intracranial hemorrhage caused by disseminated intravascular coagulation (DIC). Almost all patients with APL develop DIC. The introduction of all-trans retinoic acid (ATRA) into the induction chemotherapy regimen has revolutionized the treatment of individuals with APL, with nearly 90% of newly diagnosed APL patients achieving complete remission and over 70% of patients surviving longer than 5 years. However, population-based studies have shown that the early death-rate during induction chemotherapy remains extremely high with nearly 30% incidence and the most common cause of death is associated with hemorrhage. Thus, development of a novel treatment strategy to alleviate abnormal coagulation in APL patients is urgently required. In Japan, the conventional therapies for coagulopathy, such as low molecular heparin (LMWH), danaparoid sodium, and synthetic protease inhibitors were aggressively administered in addition to blood transfusions in DIC patients with APL. In 2008, a new anticoagulant, recombinant human soluble thrombomodulin (rTM) was approved for the treatment of DIC in Japan. Therefore, we accessed the difference of clinical safety and beneficial effects among these anticoagulant treatments in DIC patients with APL, by evaluating data on the multicenter, retrospective epidemiologic study of the DIC patients. Patients and Methods Patients with DIC associated with newly diagnosed APL were recruited from January 2000 through December 2012 in 3 Japanese hematology centers. APL was defined according to FAB classification and was confirmed by the presence of t(15;17) and/or the PML-RARα fusion gene. DIC was evaluated by the diagnostic criteria of the Japanese Ministry of Health and Welfare. The treatment algorithm for newly diagnosed APL patients was generally based on the protocol proposed by the Japan Adult Leukemia Study Group (JALSG). The concomitant use of fresh frozen plasma, platelets, and/or other anticoagulant drugs were generally based on the recommendation of the JALSG protocol as follows: Platelet concentrate and fresh frozen plasma were transfused to maintain platelet counts ³30 × 109/L and plasma fibrinogen levels ³150 mg/dL, respectively. Early death (death within 30 day from APL diagnosis), severe hemorrhagic events, and improvement of coagulopathy were analyzed between rTM and other anticoagulants treatment. The time to disappearance of hemorrhagic symptoms between the two groups were analyzed by the Kaplan-Meier method and the log-rank test. Results DIC developed at diagnosis in 64 APL patients. 35 patients with DIC were treated with rTM (rTM group) and 29 patients with DIC were treated with LMWH, danaparoid sodium, and/or synthetic protease inhibitors (control group). There were no significant differences in age nor gender between rTM group and control group. Number of patients treated with ATRA alone and ATRA plus chemotherapy were 7 and 28 in the rTM group, and 10 and 19 in the control group. Early death rate for the rTM group was significantly lower than that for the control group (14% vs. 38%, P=0.043). Two patients developed intracranial hemorrhagic early death in the control group. On the other hand, no severe hemorrhagic event and mortality was noted in the rTM group. The time to disappearance of hemorrhagic symptoms was shorter for the rTM group than the control group (P=0.021). Conclusions These findings suggest that supportive care with rTM in combination with ATRA and chemotherapy ameliorates coagulopathy and reduces the risk of hemorrhagic early deaths in patients with APL than other anticoagulants. Disclosures: No relevant conflicts of interest to declare.