Intrapatient Complex Transcriptional Responses to Conventional Chemotherapy in Relapsed Acute Myeloid Leukemia Revealed By Single Cell RNA-Seq Analysis

Resistance to anthracycline and cytarabine based conventional chemotherapy often occurs and results in extremely poor prognosis in patients with acute myeloid leukemia (AML). Although chemotherapy resistance is the most critical clinical problem, the mechanisms by which AML confers resistance to conventional chemotherapy are not yet fully understood. In this study, we investigated the key mechanisms of chemotherapy resistance through single cell RNA-sequencing analysis using paired bone marrow AML cells longitudinally collected from two AML-MRC patients at diagnosis and relapse after anthracycline-based chemotherapy. AML blasts were sorted by CD45/SSC gating and subjected to single cell RNA-seq analysis. Single cell RNA-seq was performed using 10x Genomics' Chromium System. Mean estimated number of cells per sample was 3.403 (2,731-4,200) and median detected genes per cell ranged 3,030 to 3,918 among four samples. Data collected from paired samples were combined in following analysis. Transcriptome based clustering following UMAP dimensionality reduction distinguished 5 and 9 cluster groups in each paired sample. Chemotherapy sensitive cluster groups dominant at diagnosis and chemotherapy resistant cluster groups dominant at relapse were clearly divided. In each paired sample, a few AML cells at diagnosis were allocated to chemotherapy resistant cluster groups. This suggested that transcriptionally identifiable less frequent cells resistant to chemotherapy existed at diagnosis and may expand during and/or after chemotherapy maintaining its transcriptional features. Next, to determine whether these transcriptional features are correlated with DNA mutation profiles, we labeled DNA mutation status to each cell and compared frequencies of mutation. As far as we detected, AML recurrent mutations such as DNMT3A R882C and TP53 missense mutation were not related to chemotherapy resistant cluster groups, although this method was relatively limited by the nature of RNA-seq-based mutation detection. Then we sought to determine transcriptional features of resistant clones. Gene set enrichment analysis identified some gene groups such as E2F signaling pathway, MYC signaling pathway, hedgehog signaling pathway and TNFA signaling pathway as transcriptional signatures related to emergence after chemotherapy. Analysis of known hematopoietic differentiation gene signatures showed distinct differentiation profiles in each cluster groups, whereas resistant cluster groups were not necessarily related to hematopoietic stem cell signatures. Intrapatient variations of transcriptional signatures among the resistant cluster groups were detected, which indicated that accurate detection of transcriptional features related to chemotherapy resistance may be difficult by using bulk RNA-seq method. As for other cluster groups which were not dominant both at diagnosis and relapse, these cluster groups hardly changed its frequencies between at diagnosis and relapse, which suggested less proliferative leukemia cells persisted during chemotherapy and have various transcriptional features although whether these persisting cells contribute to relapse was unclear. Since enriched transcriptional signatures in resistant cluster groups were not consistent between the two patients, further analysis using samples collected from more patients would be needed to determine common critical chemotherapy resistant transcriptional signature. In conclusion, our analysis suggested that a transcriptionally identifiable small fraction of cells showing gene signatures related to chemotherapy resistance at diagnosis may expand during chemotherapy and revealed intrapatient transcriptional complexity of response to chemotherapy, which cannot be uncovered by bulk RNA-sequencing. Disclosures Honda: Takeda Pharmaceutical: Other: Lecture fee; Otsuka Pharmaceutical: Other: Lecture fee; Chugai Pharmaceutical: Other: Lecture fee; Ono Pharmaceutical: Other: Lecture fee; Jansen Pharmaceutical: Other: Lecture fee; Nippon Shinyaku: Other: Lecture fee. Kurokawa: MSD K.K.: Research Funding, Speakers Bureau; Kyowa Hakko Kirin Co., Ltd.: Research Funding, Speakers Bureau; Daiichi Sankyo Company.: Research Funding, Speakers Bureau; Astellas Pharma Inc.: Research Funding, Speakers Bureau; Pfizer Japan Inc.: Research Funding, Speakers Bureau; Nippon Shinyaku Co., Ltd.: Research Funding, Speakers Bureau; Sumitomo Dainippon Pharma Co., Ltd.: Research Funding, Speakers Bureau; Otsuka Pharmaceutical Co., Ltd.: Research Funding, Speakers Bureau; Eisai Co., Ltd.: Research Funding, Speakers Bureau; ONO PHARMACEUTICAL CO., LTD.: Research Funding, Speakers Bureau; Teijin Limited: Research Funding, Speakers Bureau; Takeda Pharmaceutical Company Limited.: Research Funding, Speakers Bureau; Chugai Pharmaceutical Company: Research Funding, Speakers Bureau; AbbVie GK: Research Funding, Speakers Bureau.

Increase in Antibody Titers Following Sars-Cov-2 Vaccination Remains Limited for More Than 3 Years after Final Dose of Anti-CD20 Antibody

COVID-19, caused by severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2), has become a global pandemic. Patients with hematological disorders are known to be at high risk of morbidity and mortality from COVID-19, and vaccines against SARS-CoV-2 have been rapidly developed. Although mRNA vaccines against SARS-CoV-2 are reported to be effective, efficacy in patients with hematological malignancies who have received anti-CD20 antibody treatment remains unclear. Here, we prospectively evaluated the efficacy of BNT162b2 mRNA COVID-19 vaccine in patients with B-cell malignancies treated with anti-CD20 antibody. We first evaluated antibody titers in 12 healthy volunteers (median age 75.5 years, range 57-82) and three lymphoma patients undergoing R-CHOP therapy (73, 81, and 81 years old) who had received 2 vaccine doses of BNT162b2 at pre-vaccination, 21 days after the first dose and 14 days after the second dose of vaccination. IgG antibody titers for S1 protein were measured in serum samples by ELISA. In healthy control subjects, titers were clearly increased. In contrast, no patient treated with R-CHOP developed antibodies even after the second vaccination (Figure A). To determine the SARS-CoV-2-specific T-cell reactivity in these three patients, we evaluated interferon (IFN)-γ response to the SARS-CoV-2 spike peptide before and after the second vaccination dose, and detected IFN-γ responses after vaccination in all three patients (Figure B). Next, to investigate the duration of the effect of anti-CD20 antibody on antibody production to BNT162b2, we enrolled 36 patients (median age 74 years, range 50-87) who had received the final dose of anti-CD20 antibody 48-1320 (median 571) days before vaccination. S1 antibody titers were measured 14 days after the second dose of vaccination. Diagnoses included diffuse large B-cell lymphoma (n = 21), follicular lymphoma (n = 9), lymphoplasmacytic lymphoma/Waldenström's macroglobulinemia (n = 3), and mantle cell lymphoma (n = 3). Thirty-four patients had received rituximab-based and 2 had received obinutuzumab-based therapy, with a median of 6 (range 3-20) courses. No patient had received any chemotherapy after the last anti-CD20 antibody dose. No patient vaccinated within close to one year or sooner after the last anti-CD20 antibody administration showed an increase in titers. Furthermore, titers in most patients were lower than in healthy volunteers even among those vaccinated more than three years after the last administration (Figure C). Finally, we investigated surrogate markers of antibody production ability. We found no relationship between the percent of B-cells (CD19-positive cells) and S1 antibody titers (Figure D), whereas all patients (n = 9) with total IgG level below lower normal limit (< 870 mg/dl) had low S1 antibody titers (< 0.16), below the lowest optical density (O.D.) value in healthy donors (Figure E). These findings indicate that the antibody-mediated response to vaccination in patients following treatment with anti-CD20 antibody was considerably impaired for an extended time. Alternative protection strategies for these patients are therefore warranted. Although T-cell responses were detected, we recommend that these patients continue to wear a face mask and wash their hands to prevent COVID-19 even after vaccination. Figure 1 Figure 1. Disclosures Yakushijin: Chugai pharmaceutical Co. Ltd.: Research Funding; Jazz pharmaceuticals: Research Funding; Nippon Shinyaku: Honoraria. Kiyota: Bristol-Myers Squibb: Honoraria, Research Funding; Ono Pharmaceutical: Honoraria, Research Funding; Astra-Zeneca: Honoraria, Research Funding; Roche Phamaceuticals: Research Funding; Merck Biopharma: Honoraria; Merck Sharp & Dohme: Honoraria; Eisai: Honoraria; Bayer: Honoraria. Matsuoka: Takeda Pharmaceutical Company: Research Funding; Sysmex: Research Funding. Minami: Behring: Research Funding; CSL: Research Funding; Yakult Honsha: Research Funding; Nippon Shinyaku: Research Funding; Astellas Pharma: Research Funding; Asahi-Kasei Pharma: Research Funding; Eli Lilly: Honoraria, Research Funding; Taiho Pharmaceutical: Honoraria, Research Funding; Takeda Pharmaceutical: Honoraria, Research Funding; Sanofi: Honoraria, Research Funding; Pfizer: Honoraria, Research Funding; Ono Pharmaceutical: Honoraria, Research Funding; Novartis: Honoraria, Research Funding; MSD: Honoraria, Research Funding; Merck Serono: Honoraria, Research Funding; Kyowa-Kirin: Honoraria, Research Funding; Eisai: Honoraria, Research Funding; DaiichiSankyo: Honoraria, Research Funding; Chugai Pharmaceutical: Honoraria, Research Funding; Bristol-Myers Squibb: Honoraria, Research Funding; Boehringer Ingelheim: Honoraria, Research Funding; Bayer Yakuhin: Honoraria, Research Funding; Nippon Kayaku: Research Funding; Celgene: Honoraria; Ohtsuka Pharmaceutical: Honoraria; Shire Japan: Honoraria; Genomic Health: Honoraria; Abbvie: Honoraria.

Clinical Significance of Small PNH-Type Cell Populations in Bone Marrow Failure Syndromes - an Interim Analysis of Japanese Multicentrer Prospective Study -

Background: Small populations of paroxysmal nocturnal hemoglobinuria (PNH)-type cells (<1.0%) are frequently found in bone marrow failure syndromes (BMF) including aplastic anemia (AA) and low-risk myelodysplastic syndromes (MDS) without evident hemolytic symptoms. The presence of small PNH-type cells has been reported to predict better response to immunosuppressive therapy (IST) both retrospectively (Blood 2006 107:1308-1314) and prospectively (Br J Haematol 2014 164:546-54), but its clinical significance is still to be elucidated. In addition, the kinetics of those small PNH-type cells have not been well studied. To better understand the clinical significance and the kinetics of PNH-type cells in BMF, we conducted a nationwide, multicenter, prospective, observational clinical study named SUPREMACY. Methods: Patients diagnosed with PNH, AA, MDS or indistinguishable BMF without malignant diseases were prospectively recruited to the study between April 1 st, 2016 and December 31 st, 2019 in Japan. Participants were excluded from the study if treated with eculizumab or ravulizumab. Peripheral blood samples were obtained with informed consent and sent to the single laboratory every 12months (mos) for 36 mos. A high-resolution flow cytometry assay known as OPTIMA method (Ann Hematol 97(12):2289-2297) was used to precisely detect a small population of GPI(-) cells, which defines ≥0.003% PNH-type granulocytes (Gran) and ≥0.005% erythrocytes as an abnormal increase. The quality of life (QOL) of the pts was assessed using the Functional Assessment of Chronic Illness Therapy-Fatigue (FACIT-Fatigue) and European Organization for Research and Treatment of Cancer Quality of Life Questionnaire (EORTC QLQ-C30) instruments. All other lab data and clinical information were obtained at each participating institute or hospital on sample collection, and were accumulated by the Japan PNH Study Group for analysis. Results: Total 1,985 pts were registered and 1,813 pts were eligible for analysis. Median age was 67 with 50.5% male patients. PNH-type cells were positive in 50.4% (235/466) of AA, 19.7% (70/355) of MDS, 22.3% (61/273) of suspected PNH, and 33.9% (232/685) of undiagnosed BMF. PNH-type cells were increased in nearly 30% of the pts with RCUD, RCMD, MDS-U, and 5q-, but not in RARS, RAEB-1, or RAEB-2. Time-course data of the size of PNH-type cells were available in 651 pts at 12mos and in 210 pts at 36mos. Small (<1.0%) PNH-type granulocytes (sPNHg) stayed below 1.0% at 36mos in 81/86 (94.2%) pts, but increased in 5/86 (5.8%) by median 2.75% or by average 17.86% at 36mos. Clinical data for IST were available in 277 pts (12mos) and 99 pts (36mos). Pts with PNH-type cells showed a better response rate [Complete response (CR) + Partial response (PR), 159/201 (79.1%) at 12mo, 68/73 (93.2%) at 36mo] to IST compared to the pts without PNH-type cells [48/76 (63.2%) at 12mos, 17/26 (65.4%) at 36mos] (P<0.01, Chi-square test)(Figure 1). Changes of QOL data were compared between the pts with sPNHg [PNH(+)] and the pts without PNH-type cells [PNH(-)] at 36mos, and PNH(+) showed significant improvement in FACIT-Fatigue score (n=36, p=0.0348, Chi-square test) and in 6 items of EORTC QLQ-C30 (global health status, emotional functioning, social functioning, fatigue, and financial difficulties)(n=40) but no significant change of QOL was observed except in one item (constipation) in PNH(-) (n=36)(Table 1). Conclusion: PNH-type cells were detected exclusively in AA and low-risk MDS, supporting the hypothesis that the increase of PNH-type cells in BMF underpin the benign immune-mediated feature of the disease. The presence of PNH-type cells predicts a better response to IST in BMF, which is consistent with previous reports. Detection of subclinical PNH-type cells was associated with an improvement of QOL scores in multiple items at 36mos. Those small populations of PNH-type cells stayed subclinical in most of the cases, but caution should be exercised in monitoring the sizes as some may evolve into clinical PNH. Figure 1 Figure 1. Disclosures Ueda: Chugai Pharmaceutical: Consultancy, Honoraria, Research Funding; Alexion Pharma: Consultancy, Honoraria; Sanofi: Consultancy, Honoraria; Novartis: Consultancy, Honoraria. Yonemura: Alexion Pharma: Honoraria, Research Funding; Chugai Pharmaceutical: Research Funding; Novartis Pharma: Honoraria. Obara: Novartis Pharma: Honoraria; Chugai Pharmaceutical: Honoraria, Research Funding; Alexion Pharma: Honoraria, Research Funding. Ando: Novartis: Honoraria; Kyowa Kirin: Research Funding; Chugai Pharmaceutical: Research Funding; Celgene: Honoraria; Astellas Pharma: Honoraria; Takeda Pharmaceutical: Research Funding. Kawaguchi: Alexion Pharma: Honoraria. Nishimura: Alexion Pharma: Consultancy; Chugai Pharmaceutical: Consultancy; Novartis Pharma: Consultancy; Roche: Consultancy; apellis pharmaceuticals: Consultancy; Biocryst: Consultancy; Sanofi: Consultancy. Nakao: Kyowa Kirin: Honoraria; Novartis Pharma: Honoraria; Symbio: Consultancy; Alexion Pharma: Research Funding.

The Outcomes of Systemic Chronic Active EBV Infection Treatment By Allogeneic Hematopoietic Stem Cell Transplantation: An Analysis of Japanese Registry Data

Background and aims Systemic chronic active Epstein-Barr virus infection (sCAEBV) is classified as T- or NK-cell neoplasms in the WHO classification revised in 2017. Although allogeneic stem cell transplantation (allo-HSCT) is efficacious for sCAEBV, the effects are yet to be analyzed in a large number of cases due to the disease rarity. To investigate the outcomes and the prognostic factors of allo-HSCT in sCAEBV under the definition of the WHO 2017 classification, we analyzed retrospectively using the database of Japanese Society for Transplantation and Cellular Therapy (JSTCT). Methods Data collection We used the clinical data of hematopoietic stem cell transplantation (HSCT) recipients of the Transplant Registry Unified Management Program (TRUMP) sponsored by JSTCT and Japanese Data Center for Hematopoietic Cell Transplantation (JDCHCT). Patients who underwent HSCT to cure EBV-associated diseases, secondary hemophagocytic lymphohistiocytosis (HLH), and virus-associated hemophagocytic syndrome between January 1993 and December 2016 were selected in TRUMP database, and on our behalf, JDCHCT sent out survey questions to the institutions of these patients to collect additional data to check if the diagnosis of sCAEBV matches our criteria, to analyze disease status at the time of HSCT, and to evaluate the efficacy of different treatment methods. The diagnosis of sCAEBV sCAEBV was diagnosed according to criteria suggested in 2016 by the Research group of Measures against Intractable Diseases by Ministry of Health, Labour and Welfare of Japan: (1) elevated EBV DNA load in peripheral blood (PB) (> 10 2.5 copies/μg DNA), (2) detection of EBV infection in T or NK cells from the affected tissues or PB, (3) systemic inflammatory symptoms such as fever, lymphadenopathy, liver dysfunction, progressive skin lesions, vasculitis, and uveitis persisting for > 3 months, and (4) exclusion of other possible diseases, such as primary EBV infection, autoimmune disease, immunodeficiencies, and lymphomas. Patients who fulfilled all (1) to (4) were diagnosed as sCAEBV. These criteria are compatible with the definition of sCAEBV described in the WHO definition of 2017. The definitions of disease activities and responses The disease activities are defined in previous reports (Blood. 2012;119, p673 and BMT. 2016;51, p879) as follows: positive of fever, ALT level elevation, vasculitis, progressive skin lesions, or uveitis. We defined the complete resolution of disease activity as complete response (CR) and CR with a significant decrease in PB EBV-DNA load (< 10 2.5 copies/μg DNA) as virological CR (vCR). Results 81 patients who met the diagnostic criteria of sCAEBV were analyzed. The median age at HSCT was 24 years old, and the three-year overall survival rate (3-year OS) was 74.0%. Of 74 patients whose viral load after HSCT evaluated, 49 (66.2%) achieved vCR. The multivariate cox proportional hazard model revealed that advanced age, adolescent and young adult (AYA) (age, 15-39; n = 48) and adult (age, > 40; n = 13), was a risk factor of poor OS. The hazard ratios (HR) of AYA and adult groups were 10.14 and 4.63 respectively. It also showed that the presence of HLH at HSCT (HR 4.55), high sIL-2R (≥ median, 691 U/mL) at HSCT (HR 5.27), and conditioning without total body irradiation (HR 3.23) were independently associated with poor survival. Moreover, the median survival time of patients with active disease and extremely high sIL-2R level (≥ 3 × median, 2073 U/mL) was 0.9 months, whereas the other groups did not reach the median. Conclusion Although HSCT is the only curative treatment for sCAEBV, the strategies need improvements in high-risk cases, especially of high sIL-2R. Disclosures Arai: ONO PHARMACEUTICAL CO., LTD.: Honoraria, Research Funding; CHUGAI PHARMACEUTICAL CO., LTD.: Honoraria, Research Funding; Kyowa Kirin CO., LTD.: Honoraria, Research Funding; Abbvie: Honoraria; BMS: Honoraria; Elsai Co Ltd: Research Funding; Abbott Japan LLC: Honoraria; Nippon Shinyaku Co. Ltd: Honoraria, Research Funding; Otsuka Pharmaceuticals Co. Ltd: Research Funding; Novartis Pharma KK: Honoraria; Takeda Pharmaceuticals Co Ltd: Honoraria, Research Funding; Shionogi & Co Ltd: Research Funding; Asahi Kasri Pharma Corporation: Research Funding; Sanofi: Honoraria; Pfizer japan: Honoraria; Astellas Pharma Inc.: Honoraria. Yamamoto: Bristol-Myers Squibb Company: Honoraria; Chugai Pharmaceutical Co., Ltd.: Honoraria; Eisai Co., Ltd.: Honoraria; Kyowa Kirin Co., Ltd.: Honoraria; NIPPON SINYAKU CO., LTD: Honoraria; Novartis Pharma: Honoraria; ONO PHARMACEUTICAL CO.: Honoraria; Otsuka Pharmaceutical: Honoraria; Pfizer Japan Inc.: Honoraria; Takeda: Honoraria. Nakamae: Astellas Pharma Inc.: Honoraria; Otsuka Pharmaceutical Co., Ltd: Honoraria; ONO PHARMACEUTICAL CO., LTD.: Honoraria; Simon-Kucher & Partners: Honoraria; Sumitomo Dainippon Pharma Co., Ltd.: Honoraria; Takeda Pharmaceutical Company Limited.: Honoraria; Novartis: Honoraria, Research Funding; Pfizer Japan Inc.: Honoraria; Bristol-Myers Squibb Company: Honoraria, Research Funding; Alexion: Research Funding; PPD-SNBL K.K: Research Funding; CMIC HOLDINGS Co., Ltd: Research Funding. Ichinohe: Repertoire Genesis Inc.: Honoraria, Research Funding; Novartis Pharma K.K.: Honoraria; Celgene: Honoraria; Zenyaku Kogyo Co.: Research Funding; Takara Bio Inc.: Research Funding; Taiho Pharmaceutical Co.: Research Funding; Sumitomo Dainippon Pharma Co.: Honoraria, Research Funding; Otsuka Pharmaceutical Co.: Research Funding; Nippon Shinyaku Co: Research Funding; Ono Pharmaceutical Co.: Honoraria, Research Funding; Kyowa Kirin Co.: Honoraria, Research Funding; FUJIFILM Wako Chemicals.: Honoraria, Research Funding; Daiichi Sankyo: Research Funding; Eisai Co.: Honoraria, Research Funding; CSL Behring: Honoraria, Research Funding; Chugai Pharmaceutical: Research Funding; Bristol-Myers Squibb: Honoraria; Takeda Pharmaceutical Co.: Honoraria; AbbVie Pharma: Research Funding; Astellas Pharma: Honoraria, Research Funding. Atsuta: Astellas Pharma Inc.: Speakers Bureau; Mochida Pharmaceutical Co., Ltd.: Speakers Bureau; AbbVie GK: Speakers Bureau; Kyowa Kirin Co., Ltd: Honoraria; Meiji Seika Pharma Co, Ltd.: Honoraria.

Hikoboshi Study: Remaining Burden and Current Medical Care Status of Patients with Congenital Hemophilia a: A Study Using Two Japanese Medical Information Databases

Introduction: FVIII prophylaxis for hemophilia A (HA) has reduced the bleeding frequency in patients and enabled the prevention of hemophilic arthropathy and severe bleeding. However, the treatment/disease burden remains a concern, as evidenced by requiring intravenous injections two/three times a week; regular hospital visits to receive a prescription for medication, as drug delivery is not a provision in Japan; and frequent hospital visits because of complications, like bleeding. Moreover, there is no national patient registry for hemophilia in Japan, and few studies have examined the state of medical care and patient burden due to symptoms and medical practices. Herein, data from medical information databases (DBs) were assessed to investigate the state of medical care and patient burden for HA patients in Japan. Methods: The DBs of health insurance subscribers provided by JMDC Inc. (JMDC-DB) and of electronic medical care records provided by Real World Data Co., Ltd. (RWD-DB) were reviewed. Two DBs were used because the differences between them, such as data source for HA patients, may lead to intergroup differences in the characteristics and traceability of each patient. The targets of analysis were HA patients (ICD-10 code: D66) prescribed FVIII concentrates, emicizumab, or bypassing agents. The definition of targets in this analysis was deemed appropriate in a separate validation study. The occurrence rates of intracranial hemorrhage, ischemic heart disease, hospitalizations, emergency visits, and outpatient visits were calculated to evaluate patient burden. Further, data on the number of hospitals visited and prescribed amounts of FVIII concentrates per month were tabulated and descriptive statistics, applied. Table 1 shows the outcome measures. Results: The number of patients included, based on the target period and inclusion criteria, was 459 from JMDC-DB (January 2005 to March 2020) and 229 from RWD-DB (January 1985 to March 2020). Both DBs had a large proportion of patients aged 0-9 years (23.09% in JMDC-DB and 47.16% in RWD-DB) and a small proportion of patients aged ≥60 years (2.61% in JMDC-DB and 5.68% in RWD-DB). The mean (standard deviation [SD]) and median values for the monthly prescribed amount of FVIII concentrate were 10526.36 IU (11260.42) and 8594.91 IU in JMDC-DB and 12569.11 IU (54846.02) and 1514.35 IU in RWD-DB, respectively. The yearly trends of monthly prescribed amounts of FVIII concentrate for patients in JMDC-DB were analyzed. The median values for every 3 years since 2007 were as follows: 1916.67 IU (2007), 3375.00 IU (2010), 7229.17 IU (2013), 8614.58 IU (2016), and 10000.00 IU (2019), indicating an increasing trend in recent years. The occurrence rates (95% confidence intervals [CIs]) of intracranial hemorrhage, ischemic heart disease, and hospitalizations were 2.61% (1.36-4.52), 0.00%, and 32.68% (28.40-37.18) in JMDC-DB and 4.42% (2.14-7.99), 0.44% (0.01-2.44), and 57.08% (50.35-63.62) in RWD-DB, respectively. The age-stratified occurrence rates (95% CIs) of intracranial hemorrhage in JMDC-DB and RWD-DB were 9.43% (4.62-16.67) for 0-9 years, 1.67% (0.04-8.94) for 40-49 years, and 4.00% (0.10-20.35) for 50-59 years and 3.70% (1.02-9.21) for 0-9 years, 13.04% (2.78-33.59) for 10-19 years, 9.09% (1.12-29.16) for 30-39 years, and 6.67% (0.17-31.95) for 40-49 years, respectively. The overall occurrence rates of intracranial hemorrhage were similar in the two DBs: 2.61% (JMDC-DB) vs. 4.42% (RWD-DB). Additional results of our analysis will be presented at the conference. Conclusions: The prescription of FVIII concentrates for Japanese patients with HA is increasing, probably because FVIII prophylaxis in the clinical setting has become more common. The widespread use of FVIII has many benefits for HA patients. However, there are still treatment burdens that should be considered, such as the need for several drug prescriptions and severe bleeding, such as intracranial hemorrhage. Figure 1 Figure 1. Disclosures Nagao: CHUGAI PHARMACEUTICAL CO., LTD.: Consultancy, Honoraria, Speakers Bureau; Takeda Pharmaceutical Company Limited.: Honoraria, Research Funding; Bayer Yakuhin, Ltd.: Honoraria, Research Funding; Sanofi K.K.: Honoraria; Fujimoto Pharmaceutical Corporation: Honoraria; KM Biologics Co., Ltd.: Honoraria; Pfizer Japan Inc.: Honoraria; Japan Blood Products Organization: Honoraria; Novo Nordisk Pharma Ltd.: Honoraria; CSL Behring K.K.: Honoraria. Ioka: Chugai Pharmaceutical, Co., Ltd.: Current Employment. Nakamura: Chugai Pharmaceutical Co., Ltd.: Current Employment. Murakami: Chugai Pharmaceutical Co., Ltd.: Current Employment. Makishima: Chugai Pharmaceutical, Co., Ltd.: Current Employment. Okada: Chugai Pharmaceutical Co., Ltd.: Current Employment. Sakai: Bayer Yakuhin, Ltd.: Consultancy, Speakers Bureau; Novo Nordisk Pharma Ltd.: Consultancy, Speakers Bureau; CSL Behring K.K.: Speakers Bureau; Takeda Pharmaceutical Company Limited.: Speakers Bureau; CHUGAI PHARMACEUTICAL CO., LTD.: Speakers Bureau; Sanofi K.K.: Speakers Bureau.

Orihime Study: Real World Treatment Patterns and Clinical Outcomes of 338 Patients with Acquired Hemophilia a from a Japanese Health Claims Database

Introduction: Acquired hemophilia A (AHA) is a rare disorder characterized by severe, spontaneous bleeding caused by autoantibodies against factor (F)VIII (inhibitors). It is known that onset of AHA is triggered by malignancy, autoimmune disease, dermatological disease, and pregnancy/delivery. As the standard therapy, immunosuppressive therapy (IST) should be started immediately to eliminate inhibitors and hemostatic therapy is also necessary in case of bleeding. Many patients require prolonged bed rest because of the bleeding risk; therefore, it is difficult to determine the best time to start rehabilitation. Additionally, the early deaths and high thrombotic rates are frequently reported in AHA. Since it is a rare disorder, the actual situation has not been fully clarified. This study was to describe the epidemiology and clinical practice of AHA in the real world using a large health claims database in Japan. Methods: This was a retrospective observational study using a health claims database provided by Medical Data Vision Co., Ltd. The data period was Apr. 2008-Mar. 2020. Patients who met all of the following criteria were included; patients with disease diagnosis of AHA; patients were hospitalized on the day of AHA diagnosis; and patients had immunosuppressants on/after the date of the first hospitalization. The first date of hospitalization was set as an Index date. Patients with disease diagnosis code of antiphospholipid syndrome, lupus anticoagulant, acquired factor XIII deficiency, acquired von Willebrand disease, or acquired factor V deficiency were excluded. Treatment/procedure patterns (IST, hemostatic therapy, and rehabilitation) and clinical outcome (Activities of Daily Living [ADL], death, and thromboembolism in the hospitalization) in AHA patients were investigated. Results: The study population of 338 patients (214 males: 124 females) was with the mean age of 75.7 (21-96) years. A total of 105 patients (pts) (31.1%) had concurrent diseases, including malignancy (61 pts, 18.0%), autoimmune diseases (40 pts, 11.8%), and dermatological diseases (18 pts, 5.3%). In bypassing agent use (153 pts, 45.3%), recombinant activated factor VII (rFVIIa) was the most frequently used (129 pts, 38.2%) followed by activated prothrombin complex concentrate (aPCC) (36 pts, 10.7%), and plasma-derived factor VIIa and factor X (FVIIa/FX) (14 pts, 4.1%). FVIII agent uses (8 pts) were very few. Median duration of treatment for bypassing agents ranged from 2.5 (FVIIa/FX) to 6.0 (aPCC) days. Steroids alone were used predominantly in the first line for immunosuppression (292 pts, 86.4 %) and oral prednisolone was the most frequently used. The category of rehabilitation most commonly implemented in AHA patients was disuse syndrome (104 pts, 30.8%) followed by locomotor (73 pts, 21.6%) and cerebrovascular (49 pts, 14.5%). Median time (days) from Index date to initiating rehabilitation was 16.5 for disuse syndrome, 23.0 for locomotor, 19.0 for cerebrovascular. In the total ADL scores (Barthel Index) in 196 patients with all 10 items, the proportions of patients with less than 70 points were high at both initial admission and final discharge (47.4% and 38.8%, respectively). The median number of times and length of hospitalization were 1.0 time and 62.0 days, respectively. Of evaluable population (328 pts), thromboembolism during hospitalization was recorded in 15 patients, by type of which disseminated intravascular coagulation (10 pts, 3.0%) was the most frequently recorded. Acute coronary syndrome (3 pts, 0.9%), pulmonary embolism and other (1 pt, 0.3%, each) were fewly recorded. The proportion of deaths during hospitalization was 18.6% (63 pts). Table 1 shows study result summary. Conclusions: This was the first study in a large AHA population using a health claims database in Japan. From an epidemiological point of view, the number of male patients was slightly larger and the mean age was slightly higher compared to the demographics in previous reports. The possible reason is regional variance or data source, whereas, the treatment patterns and the proportion of deaths during hospitalization are mostly aligned with the previous studies. Also this was the first report publishing the data on ADL and rehabilitation in AHA patients. The results showed that it took median 2-3 weeks to start rehabilitation. Further development of treatment strategies to enable early start of rehabilitation is awaited. Figure 1 Figure 1. Disclosures Ogawa: Chugai Pharmaceutical Co., Ltd.: Consultancy. Amano: Chugai Pharmaceutical Co., Ltd.: Consultancy, Speakers Bureau; KM Biologics Co., Ltd.: Research Funding, Speakers Bureau; Bioverativ Inc.: Speakers Bureau; Bayer AG: Speakers Bureau; Shire Plc: Speakers Bureau; Takeda Pharmaceutical Co., Ltd.: Speakers Bureau; Sanofi S.A.: Speakers Bureau; Novo Nordisk A/S: Speakers Bureau; CSL Behring: Speakers Bureau; Pfizer Inc.: Speakers Bureau; Japan Blood Products Organization: Speakers Bureau. Matsuo-Tezuka: Chugai Pharmaceutical Co., Ltd.: Current Employment. Okada: Chugai Pharmaceutical Co., Ltd.: Current Employment. Murakami: Chugai Pharmaceutical Co., Ltd.: Current Employment. Nakamura: Chugai Pharmaceutical Co., Ltd.: Current Employment. Yamaguchi-Suita: Chugai Pharmaceutical Co., Ltd: Current Employment. Nogami: Chugai Pharmaceutical Co., Ltd.: Consultancy, Honoraria, Research Funding, Speakers Bureau; Takeda Pharmaceutical Co., Ltd.: Honoraria, Research Funding, Speakers Bureau; CSL Behring: Honoraria, Research Funding, Speakers Bureau; Novo Nordisk A/S: Honoraria, Research Funding, Speakers Bureau; Bayer AG: Honoraria, Research Funding, Speakers Bureau; Sanofi S.A.: Honoraria, Research Funding, Speakers Bureau; KM Biologics Co., Ltd.: Honoraria, Research Funding, Speakers Bureau. OffLabel Disclosure: Data on the uses of cyclophosphamide, cyclosporin A, and rituximab for acquired hemophilia may be included in the poster presentation. However, with regard to these drugs, treatments for other diseases may also be included because this study was conducted with a secondary use of a health claims database. Off-label drug use is explained in the poster.

Prognostic Factors of Idiopathic Hypereosinophilic Syndrome: A Nationwide Survey in Japan

Background Idiopathic hypereosinophilic syndrome (iHES) is a rare disease characterized by prolonged hypereosinophilia and organ damage without any known cause of eosinophilia. Since iHES was first proposed, the concept of the disease has continued to change, and its clinical features, optimal treatment, and prognosis have not yet been elucidated. Therefore, to clarify the clinical features and prognostic factors of iHES, we conducted a nationwide survey and collected detailed clinical information of iHES in Japan. Methods We conducted a nationwide postal questionnaire survey of iHES. A first simple questionnaire was sent to departments of hematology across the country to determine presence or absence of iHES in their department. Subsequently, a detailed questionnaire was sent to the department that responded that they had experience with iHES. After collecting the questionnaires, the validity of the diagnosis was determined. Only those that corresponded to iHES were used for subsequent analysis. In this research, iHES was defined as follows: absolute eosinophil counts more than 1,500/µL, presence of organ damage due to eosinophilia, with no known cause of eosinophilia. Allergy, collagen diseases, infection, asthma, drugs, vasculitis, and other diseases that can cause eosinophilia were ruled out. The absence of hematopoietic malignancies was confirmed by bone marrow examination, fluorescence in situ hybridization for FIP1L1-PDGFRA fusion gene, and chromosomal analysis by G-banding. Results The 1st questionnaire was sent to 492 departments of hematology, and we identified 152 patients with iHES in Japan. Among those patients, a detailed clinical information was collected from 68 patients. Of the 68 patients, 23 did not meet the criteria for iHES, and the remaining were subjected to subsequent analysis. Of the 45 patients with iHES, 27 (60%) were male, and 18 (40%) were female. The median age of diagnosis was 54 (range: 16-95) years, and the median number of involved organs per patient was 2 (range: 1-7). Symptoms caused by hypereosinophilia were consisted of systemic symptom (22, 49%), hematopoietic disorder (17, 38%), skin (16, 36%), digestive (15, 33%), respiratory (14, 31%), cardiovascular (14, 31%), and kidney (4, 9%). The median white blood cell and absolute eosinophil count were 18,800/µL (5,300-73,000/µL) and 9587/µL (2,067-63,370/µL), respectively. The median hemoglobin level was 13.3 g/dL (6.6-16 g/dL), and the median platelet count was 255 × 10 9/L (4.7-54 × 10 9/L). The median levels of lactate dehydrogenase and C-reactive protein were 299 U/L (123-972 U/L) and 0.96 mg/dL (0.02-13.9 mg/dL), respectively. Of the 45 cases, 37 (82%) required treatment, and 35 (78%) received corticosteroid as 1st line treatment. Although 28 (80%) patients responded to corticosteroid, 12 (34%) patients required subsequent 2nd line treatment, and 2 (6%) patients died. In addition, 6 patients required 3rd line treatment. Six of 45 patients died from any cause during the follow-up, and the median follow-up period for censored cases was 3.1 years (0.2-23 years). The median survival from diagnosis for all cases was 2.5 years (0.1- 23 years). In univariate analysis, hemoglobin less than 10 g/dL (P=0.02), the presence of renal symptoms (P<0.001), and the presence of respiratory symptoms (P<0.01) were statistically significant factors for overall survival. In multivariate analysis, hemoglobin less than 10 g/dL was a statistically significant factor for overall survival (HR, 17.2; 95% CI, 1.51-197; P=0.02). Conclusion In this nationwide survey, we clarified the clinical characteristics of iHES in Japan. In addition to clinical features at the time of diagnosis, the response rate to corticosteroid and long-term prognosis were also clarified. Furthermore, the presence of anemia was found to be a poor prognostic factor for iHES. Further accumulation of cases is necessary to establish the optimal treatment strategy for iHES. Disclosures Honda: Takeda Pharmaceutical: Other: Lecture fee; Nippon Shinyaku: Other: Lecture fee; Ono Pharmaceutical: Other: Lecture fee; Otsuka Pharmaceutical: Other: Lecture fee; Chugai Pharmaceutical: Other: Lecture fee; Jansen Pharmaceutical: Other: Lecture fee. Toyama: Celgene Corporation: Other: Lecture fee; Otsuka Pharmaceutical Co., Ltd.: Other: Lecture fee; NIHON PHARMACEUTICAL CO., LTD.: Other: Lecture fee; ONO PHARMACEUTICAL CO., LTD.: Other: Lecture fee; DAIICHI SANKYO COMPANY, LIMITED: Other: Lecture fee; CHUGAI PHARMACEUTICAL CO., LTD.: Other: Lecture fee; Takeda Pharmaceutical Company Limited: Other: Lecture fee. Matsuda: Ono Pharmaceutical: Other: Lecture fee; Kyowa Kirin: Other: Lecture fee. Komatsu: Fujifilm Wako Pure Chemical Corporation: Research Funding; Fuso Pharmaceutical Industries, Ltd.: Research Funding; Japan Tobacco Inc.: Consultancy; Otsuka Pharmaceutical Co. Ltd: Membership on an entity's Board of Directors or advisory committees, Research Funding; Novartis Pharma KK: Consultancy, Research Funding, Speakers Bureau; Shire Japan KK: Consultancy, Research Funding, Speakers Bureau; PharmaEssentia Japan KK: Consultancy, Current Employment, Research Funding; Chugai Pharmaceutical Co., Ltd.: Research Funding; Kyowa Hakko Kirin Co., Ltd.: Research Funding. Kurokawa: Nippon Shinyaku Co., Ltd.: Research Funding, Speakers Bureau; Sumitomo Dainippon Pharma Co., Ltd.: Research Funding, Speakers Bureau; Chugai Pharmaceutical Company: Research Funding, Speakers Bureau; MSD K.K.: Research Funding, Speakers Bureau; Eisai Co., Ltd.: Research Funding, Speakers Bureau; Otsuka Pharmaceutical Co., Ltd.: Research Funding, Speakers Bureau; ONO PHARMACEUTICAL CO., LTD.: Research Funding, Speakers Bureau; Takeda Pharmaceutical Company Limited.: Research Funding, Speakers Bureau; Kyowa Hakko Kirin Co., Ltd.: Research Funding, Speakers Bureau; Astellas Pharma Inc.: Research Funding, Speakers Bureau; Daiichi Sankyo Company.: Research Funding, Speakers Bureau; Teijin Limited: Research Funding, Speakers Bureau; Pfizer Japan Inc.: Research Funding, Speakers Bureau; AbbVie GK: Research Funding, Speakers Bureau.

Novel Recurrent Mutations in Eldheim-Chester Disease Patients Identified By Whole Exome Sequencing and Whole Genome Sequencing

Background: Erdheim-Chester disease (ECD) is a type of systemic, non-Langerhans histiocytic disorder characterized by diffuse organ damage with infiltration of CD68-positive, CD163-positive, and CD1a-negative histiocytes. Although most patients have mutations associated with the hyperactivation of the MAPK pathway, including BRAF, MAP2K1, and NRAS, the remaining have no known driver mutations. So far, there is no specific target of treatment for them. To elucidate novel driver mutations and establish new treatment strategies in these patients, we performed whole-exome sequencing (WES) and whole-genome sequencing (WGS) using patient samples with ECD. In addition, we performed WES with multi-organ lesions in a patient with ECD to reveal the mutational profiles of each organ lesion. Methods: We performed a nationwide survey and collected clinical samples of ECD in Japan. We collected 22 samples of ECD lesions from 15 adult patients. All cases were pathologically proved. Twenty of 22 samples were formalin-fixed and paraffin-embedded tissue (FFPE) and were examined by WES. For WGS, DNA was extracted from 2 raw samples of ECD lesions. In addition, we collected multi-organ lesions in 3 patients. One patient developed myelodysplastic syndrome (MDS) and subsequent acute myeloid leukemia (AML). Therefore, we also performed WES with each bone marrow (BM) sample to reveal the relationship between ECD and these myeloid malignancies. We used 6 samples of peripheral blood, 1 BM sample, 1 skin sample, and 1 oral mucosa sample as normal controls. Result: We detected known driver mutations in seven of 15 cases (47%). Among them, BRAF V600E was detected in 5 cases (8 samples), MAP2K1 C121S in 1 case (1 sample), and NRAS Q61R in 1 case (2 samples) by WES and WGS. A mean of 69 nonsynonymous mutations per patient was identified in normal-tumor analysis (range, 2-491) and 188 in tumor-only analysis (range, 17-3598) of WES, and 3134 in normal-tumor analysis (range, 2588-3680) of WGS. The median variant allele frequency (VAF) for the 11 samples with known activating kinase mutations identified by WES and WGS was 14.4% (range, 6.3-34.7). We could not detect known driver mutations in the other 8 cases (53%). Therefore, to reveal novel driver mutations, we focused on these 8 cases. Notably, EPHA2 P786L, MYBPC3 D798N, TDRD5 P115L, and TCEAL4 F17L mutations are recurrently found in 2 out of the 8 cases, suggesting new driver mutations are contained in these. The VAFs of EPHA2 P786L were 9.1% and 9.3%, MYBPC3 D798N 5.5% and 11.9%, TDRD5 P115L 10.2% and 18.7%, and TCEAL4 F17L 7.5% and 9.0% in each case. We also analyzed multiple organ samples of a case with BRAF V600E mutation (5 samples of ECD lesions, BM with MDS, BM with AML, and skin as normal control). Interestingly, BRAF V600E mutation was identified in 3 samples (bone lesion, heart, and intestine) but was not in other samples (kidney lesion, dura matter, BM tumor, BM with MDS, and BM with AML), suggesting mutational profiles are different depending on the organ of the lesion. Conclusion: Our nation-wide analysis revealed that no well-known driver mutations were found in more than half of the ECD cases. We identified EPHA2 P786L, MYBPC3 D798N, TDRD5 P115L, and TCEAL4 F17L mutations as candidates of novel driver mutations in ECD. To elucidate the role of these mutations in pathogenesis of ECD, further functional analyses are warranted. In addition, we revealed heterogeneity of mutational profile of multi lesions in an ECD patient with BRAF V600E mutation. It is noteworthy that mutational profiles might be different depending on the organ of the lesion. Disclosures Honda: Chugai Pharmaceutical: Other: Lecture fee; Ono Pharmaceutical: Other: Lecture fee; Nippon Shinyaku: Other: Lecture fee; Takeda Pharmaceutical: Other: Lecture fee; Otsuka Pharmaceutical: Other: Lecture fee; Jansen Pharmaceutical: Other: Lecture fee. Matsuda: Kyowa Kirin: Other: Lecture fee; Ono Pharmaceutical: Other: Lecture fee. Taoka: ONO PHARMACEUTICAL CO., LTD.: Other; Chugai Pharmaceutical Company: Other. Kurokawa: Teijin Limited: Research Funding, Speakers Bureau; Chugai Pharmaceutical Company: Research Funding, Speakers Bureau; Takeda Pharmaceutical Company Limited.: Research Funding, Speakers Bureau; ONO PHARMACEUTICAL CO., LTD.: Research Funding, Speakers Bureau; Otsuka Pharmaceutical Co., Ltd.: Research Funding, Speakers Bureau; Eisai Co., Ltd.: Research Funding, Speakers Bureau; Astellas Pharma Inc.: Research Funding, Speakers Bureau; MSD K.K.: Research Funding, Speakers Bureau; Nippon Shinyaku Co., Ltd.: Research Funding, Speakers Bureau; Daiichi Sankyo Company.: Research Funding, Speakers Bureau; Sumitomo Dainippon Pharma Co., Ltd.: Research Funding, Speakers Bureau; Kyowa Hakko Kirin Co., Ltd.: Research Funding, Speakers Bureau; AbbVie GK: Research Funding, Speakers Bureau; Pfizer Japan Inc.: Research Funding, Speakers Bureau.

Functional Roles of DDX41 Mutations in the Development of Myeloid Malignancies

DDX41 is a newly identified leukemia predisposition gene encoding an RNA helicase, whose germline mutations are tightly associated with late-onset myeloid malignancies. Importantly, germline DDX41 mutations were also found in as many as ~7 % of sporadic cases of high-risk MDS, conferring the largest germline risk for myeloid malignancies. In typical cases, a germline loss-of-function allele (most commonly p.A500fs or p.D140fs, depending on the ethnicity) is compounded by a somatic missense mutation affecting the helicase domain in the remaining allele (p.R525H). However, little is known about the molecular mechanism by which DDX41 mutations lead to myeloid neoplasms. To clarify the role of these distinct DDX41 alleles, we generated mice models carrying either or both of conditional/constitutive Ddx41 knock-out (KO) and conditional R525H knock-in (KI) alleles. BM-specific biallelic Ddx41 deletion using Vav1-Cre resulted in embryonic lethality, suggesting that Ddx41 is indispensable for normal hematopoietic development. Next, by crossing these mice and further breeding with Rosa26-CreERT2 transgenic mice, we engineered mice that were wild-type for Ddx41 (Ddx41+/+), heterozygous Ddx41 KO (Ddx41+/-), homozygous Ddx41 KO (Ddx41-/-), heterozygous for the Ddx41 R525H mutation (Ddx41R525H/+), or hemizygous for the Ddx41 R525H mutation (Ddx41R525H/-), in which expression of the mutant allele was induced by tamoxifen administration. First, we assessed cell intrinsic effects of these Ddx41 alleles, using noncompetitive transplantation experiments. Shortly after tamoxifen administration, most of the recipient mice that were reconstituted with BM from Ddx41-/- or Ddx41R525H/- mice died within a month after CreERT2 induction due to severe BM failure (BMF). None of the mice transplanted with BM from Ddx41+/+, Ddx41+/- or Ddx41R525H/+ mice developed myeloid neoplasms. We also assessed the reconstitution capacity of whole BM cells from different Ddx41 mutant mice in competitive transplantation experiments. The donor chimerism of Ddx41-/- or Ddx41R525H/- mice-derived cells in PB was markedly reduced compared to that of cells derived from Ddx41+/+ mice. In contrast, Ddx41+/- or Ddx41R525H/+ mice-derived cells showed no significant changes in competitive bone marrow reconstitution compared to Ddx41+/+ mice-derived cells. Notably, about half of the recipient mice died due to BMF when Ddx41R525H/--derived BM cells were co-transplanted with Ddx41+/--derived BM cells but not with wild-type BM cells, suggesting some non-cell autonomous effect of Ddx41R525H/- cells on Ddx41+/- cells. Transcriptome analysis of stem cells (Kit +Sca-1 -Lin low cells) from different Ddx41 mutant mice revealed significant changes in gene expression and splicing patterns in many genes in stem cells from all the mutant mice, with larger changes for Ddx41R525H/- than Ddx41+/- or Ddx41 R525H/+ cells. Notably, Ddx41R525H/- -derived stem cells exhibited a significant upregulation of genes involved in innate immunity, including an upregulation of cGAS-STING innate immunity pathways, as well as an enhanced Trp53 pathway, whereas there was a downregulation of genes related to RNA metabolism and ribosome biogenesis. Proteomics analysis confirmed the significant downregulation of ribosomal proteins in hematopoietic cells derived from Ddx41R525H/- mice. In summary, our results revealed an essential role of Ddx41 in normal hematopoiesis. While both heterozygous Ddx41 KO and heterozygous R525H knock-in did not develop myeloid neoplasm, compound biallelic loss-of function and R525 alleles led to a compromised function of hematopoietic stem cells, which was evident from reduced competitive repopulation capacity and impaired hematopoietic differentiation, where activated innate immunity and impaired ribosome functions may play important roles. Their roles in myeloid neoplasms need further evaluation. Disclosures Nakagawa: Sumitomo Dainippon Pharma Oncology, Inc.: Research Funding. Kataoka: Celgene: Honoraria; Eisai: Honoraria; Astellas Pharma: Honoraria; Novartis: Honoraria; Chugai Pharmaceutical: Honoraria; AstraZeneca: Honoraria; Sumitomo Dainippon Pharma: Honoraria; Kyowa Kirin: Honoraria; Janssen Pharmaceutical: Honoraria; MSD: Honoraria; Takeda Pharmaceutical: Honoraria; Otsuka Pharmaceutical: Honoraria; Asahi Genomics: Current equity holder in publicly-traded company; Otsuka Pharmaceutical: Research Funding; Chordia Therapeutics: Research Funding; Chugai Pharmaceutical: Research Funding; Takeda Pharmaceutical: Research Funding; Bristol-Myers Squibb: Research Funding; Eisai: Other: Scholarship; Otsuka Pharmaceutical: Other: Scholarship; Ono Pharmaceutical: Other: Scholarship; Kyowa Kirin: Other: Scholarship; Shionogi: Other: Scholarship; Takeda Pharmaceutical: Other: Scholarship; Summitomo Dainippon Pharma: Other: Scholarship; Chugai Pharmaceutical: Other: Scholarship; Teijn Pharma: Other: Scholarship; Japan Blood Products Organization: Other: Scholarship; Mochida Pharmaceutical: Other: Scholarship; JCR Pharmaceuticals: Other: Scholarship; Genetic Alterations: Patents & Royalties: PD-L1 abnormalties . Ogawa: Ashahi Genomics: Current holder of individual stocks in a privately-held company; Otsuka Pharmaceutical Co., Ltd.: Research Funding; Eisai Co., Ltd.: Research Funding; Kan Research Laboratory, Inc.: Consultancy, Research Funding; Dainippon-Sumitomo Pharmaceutical, Inc.: Research Funding; ChordiaTherapeutics, Inc.: Consultancy, Research Funding.

Cytomegalovirus Gastroenteritis in Patients with Acute Graft-Versus-Host Disease

[Background] A pre-emptive strategy has successfully decreased the incidence of cytomegalovirus (CMV) disease after allogeneic hematopoietic cell transplantation (HCT). However, it is difficult to completely prevent breakthrough CMV gastroenteritis, especially after acute graft-versus-host disease (GVHD) because a routine monitoring test with antigenemia or PCR assay often shows negative results before the development of CMV gastroenteritis that is considered as a localized infection initially. Actually, gastroenteritis is the predominant CMV disease in a pre-emptive strategy era. In addition, letermovir has recently been available for prophylactic strategies against CMV in clinical practice. However, little is known about the incidence, prognostic factors, and impact of subsequent CMV gastroenteritis after acute GVHD under recent advances in HCT including the introduction of letermovir. [Methods] This nationwide retrospective study evaluated adult patients who received their first allogeneic transplantation between 2008 and 2019 and developed grade II-IV acute GVHD (G24GVHD). Patients with a CMV-seronegative donor and recipient were excluded. Weekly monitoring using pp65 antigenemia assay was performed from the time of engraftment. A diagnosis of CMV gastroenteritis was made by gastrointestinal symptoms with histological proof of CMV on biopsy samples. The day when patients developed G24GVHD was considered as day 0 in all analyses. Nonrelapse mortality (NRM) by day 365 was set as the primary end-point. Cox proportional hazards regression models were used in all multivariate analyses. The impact of CMV reactivation and gastroenteritis as a time-dependent covariate were graphically plotted using a Simon-Makuch method. This study was approved by the data management committee of the Japan Society for Transplantation and Cellular Therapy (JSTCT) and by the Institutional Review Board of Jichi Medical University Saitama Medical Center. [Results] In total, 3759 patients with G24GVHD fulfilled eligibility and were included in this analysis. The median age at HCT was 50 years (range, 16 to 74). Of the 3759 patients with G24GVHD, 1120 (29.8%) developed grade III-IV acute GVHD. Letermovir prophylaxis was administered in 275 patients (7.3%), and the median start timing was 1 day after HCT (range, -8 to 36). The median duration of letermovir administration was 91 days (range, 2 to 332). The median observation period of survivors with letermovir prophylaxis was 320 days from the development of G24GVHD. By day 365, 207 patients developed CMV gastroenteritis and the cumulative incidence was 5.7% (95% CI, 5.0-6.5%). The median duration between the development of G24GVHD and CMV gastroenteritis was 22 days (range, 1 to 235). Before the onset of CMV gastroenteritis, 37 (17.9%) did not develop CMV reactivation. In multivariate analyses, advanced age (hazard ratio [HR], 1.60; 95% confidence interval [CI], 1.16-2.22; P = 0.004), GVHD prophylaxis using mycophenolate mofetil with calcineurin inhibitor (HR, 1.73; 95% CI, 1.08-2.77; P = 0.024), lower-gut acute GVHD at the development of G24GVHD (HR, 2.17; 95% CI, 1.58-2.98; P < 0.001), and use of systemic steroids (HR, 1.78; 95% CI, 1.16-2.74; P = 0.008) were independent risk factors for cytomegalovirus gastroenteritis. Moreover, CMV prophylaxis with letermovir was significantly associated with a decreased risk of CMV reactivation (HR, 0.25; 95% CI, 0.20-0.32; P < 0.001) and cytomegalovirus gastroenteritis (HR, 0.50; 95% CI, 0.25-0.99; P = 0.047). Then, we evaluated the impact of cytomegalovirus gastroenteritis on NRM by day 365. We found that patients who developed cytomegalovirus gastroenteritis (time-dependent covariate) had a higher risk of NRM (HR, 1.89; 95% CI, 1.50-2.39; P < 0.001) (Figure A). Meanwhile, letermovir prophylaxis reduced the risk of NRM (HR, 0.72; 95% CI, 0.52-0.99; P = 0.043). We illustrated the adjusted cumulative incidence of NRM in patients with and without letermovir prophylaxis in Figure B. [Conclusion] To our knowledge, this is the largest study summarizing the characteristics and outcomes of cytomegalovirus gastroenteritis after acute GVHD. Our findings underscore the importance of more stringent surveillance with endoscopy and prevention with letermovir based on a comprehensive risk assessment. Figure 1 Figure 1. Disclosures Kimura: SymBio Pharmaceutical: Honoraria; Takeda Pharmaceutical: Honoraria; Nippon Kayaku: Honoraria; Eisai: Honoraria; Ono Pharmaceutical: Honoraria; Bristol-Myers Squibb: Honoraria; Chugai Pharmaceutical: Honoraria; Kyowa Kirin: Honoraria; Pfizer: Honoraria; Astellas: Honoraria; Sumitomo Dainippon Pharma: Honoraria; MSD: Honoraria. Uchida: Chugai Pharmaceutical Co., Ltd.: Honoraria; Astellas Pharma Inc.: Honoraria; Otsuka Pharmaceutical Co., Ltd.: Honoraria; Sumitomo Dainippon Pharma Co., Ltd.: Honoraria; Novartis Pharma Inc.: Honoraria. Nakamae: Astellas Pharma Inc.: Honoraria; Otsuka Pharmaceutical Co., Ltd: Honoraria; ONO PHARMACEUTICAL CO., LTD.: Honoraria; Simon-Kucher & Partners: Honoraria; Sumitomo Dainippon Pharma Co., Ltd.: Honoraria; Takeda Pharmaceutical Company Limited.: Honoraria; Novartis: Honoraria, Research Funding; Pfizer Japan Inc.: Honoraria; Bristol-Myers Squibb Company: Honoraria, Research Funding; Alexion: Research Funding; PPD-SNBL K.K: Research Funding; CMIC HOLDINGS Co., Ltd: Research Funding. Kanda: Sanofi: Research Funding; MSD: Honoraria; Otsuka Pharmaceutical: Honoraria, Research Funding. Atsuta: Mochida Pharmaceutical Co., Ltd.: Speakers Bureau; Astellas Pharma Inc.: Speakers Bureau; AbbVie GK: Speakers Bureau; Kyowa Kirin Co., Ltd: Honoraria; Meiji Seika Pharma Co, Ltd.: Honoraria. Murata: GlaxoSmithKline: Honoraria; Asahi Kasei: Honoraria; Miyarisan Pharmaceutical: Honoraria; Astellas: Honoraria; JCR Pharmaceutical: Honoraria; Novartis: Honoraria; Toyama Chemical: Honoraria; FUJIFILM: Honoraria; Sumitomo Dainippon Pharma: Honoraria; Kyowa Kirin: Honoraria; MSD: Honoraria; Celgene: Honoraria; Otsuka Pharmaceutical: Honoraria. Nakasone: Eisai: Honoraria; Janssen Pharmaceutical K.K.: Honoraria; Novartis: Honoraria; Pfizer: Honoraria; Celgene: Honoraria; Bristol-Myers Squibb: Honoraria; Otsuka Pharmaceutical: Honoraria; Takeda Pharmaceutical: Honoraria; Chugai Pharmaceutical: Honoraria; Nippon Shinyaku: Honoraria.