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Background: Sarcopenia, the loss of muscle mass, has been recognized as a prognostic factor for cancer patients. For example, low body mass index (BMI) was reported to be a risk of poor overall survival (OS) among allogeneic hematopoietic stem cell transplantation (allo-HSCT) recipients. However, low BMI was not associated with high non-relapse mortality (NRM) rate, and BMI may not directly reflect the physical condition. (Bone Marrow Transplant. 2014;49:1505-12). To evaluate the clinical impact of the muscle volume on the prognosis of allo-HSCT recipients, other biomarkers that directly reflect muscle mass may be warranted. Urinary creatinine excretion (UCE) has been reported to estimate muscle mass and have prognostic value for kidney transplant patients (Transplantation. 2008;86:391-8.). There is no report to evaluate clinical impact of UCE on the prognosis of allo-HSCT recipients. Therefore, we retrospectively analyzed the association between pre-transplant UCE and the transplant outcomes. Methods: We included 173 adult patients with acute myeloid leukemia (AML) in complete remission (CR) who underwent first allo-HSCT from 2006 to 2017 at our institute and measured UCE before allo-HSCT. Concerned the possibility of urine storage failure, two patients with low total daily urine volume ( We used receiver operating characteristics curve in order to determine the cutoff value of the WA-UCE and classified the patients into the high and low WA-UCE group. We evaluated transplant outcomes such as OS, progression-free survival (PFS), NRM, and cumulative incidence of relapse (CIR) between two groups. Results: The median age at allo-HSCT was 52 (range, 18-73) and there were more male patients (n=111) than female patients (n=60). Regarding cytogenetic risk, 15 (9.1%), 112 (65.8%), and 38 (23.0%) were categorized as favorable, intermediate, and poor risk, respectively (There were five patients without cytogenetic data). The median follow-up period of survivors was 704 (range, 9 to 3,857) days. We defined the cutoff value of the weight adjusted UCE as 148 μmol/kg/day in male and 128 μmol/kg/day in female. Among 171 patients, 90 patients (male = 59, female = 31) were in the high WA-UCE group and 81 patients (male = 52, female = 29) were in the low WA-UCE group. We found no significant differences between two groups in terms of the number of relapse before allo-HSCT, cytogenetic risks, conditioning regimens, hematopoietic cell transplantation comorbidity index, donor-recipient HLA matching, donor source, or estimated glomerular filtration rate. On the other hand, patient's age at allo-HSCT was significantly younger (low vs. high WA-UCE group: median, 53 [range, 18 - 73] vs. 48 [range, 19 - 68] years, P = 0.02) and BMI was lower (low vs. high WA-UCE group: median, 22.3 [range, 15.4 - 38.8] vs. 21.9 [range, 15.4 - 29.3] kg/m2, P = 0.003) in high WA-UCE group. In univariate analysis, we observed a significant difference in OS, PFS, and NRM between two groups (low vs. high WA-UCE group: 1-year OS, 60.1% vs. 80.9%, P < 0.01; 1-year PFS, 54.1% vs. 70.9%, P = 0.02; 1-year NRM, 24.8% vs. 12.3%, P = 0.02) (Figure1). On the other hand, there was no significant difference in 1-year CIR between two groups (low vs. high WA-UCE group: 21.1% vs. 16.8%, P = 0.63). In our cohort, the low BMI (< 18.5 kg/m2) was not significantly associated with OS, PFS, CIR, and NRM (low vs. high BMI group: 1-year OS, 77.6% vs. 69.9%, P = 0.51; 1-year PFS, 74.1% vs. 60.9%, P = 0.45; 1-year CIR, 14.8% vs. 19.5%, P = 0.02, 1-year NRM, 11.1% vs. 19.5%, P = 0.70) In multivariate analysis, the low WA-UCE was an independent risk factor for OS (Hazard ratio (HR) [95% confidence interval (CI)]; 2.29 [1.38 - 3.80], P < 0.01), PFS (HR [95% CI]; 1.76 [1.11 - 2.79], P = 0.02), and NRM (HR [95% CI]; 2.22 [1.13 - 4.36], P = 0.02) (table1). Conclusion: In allo-HSCT adult recipients with AML in CR, low WA-UCE before transplantation was associated with poor prognosis, which related to high NRM within 1 year. WA-UCE can be an independent, objective, simple, and reliable biomarker for evaluating muscle mass and predicting transplant outcome. Disclosures No relevant conflicts of interest to declare.

Background Myelodysplastic syndromes (MDS), commonly seen in elderly patients, represent a heterogeneous group of clonal hematopoietic stem cell disorders caused by the accumulation of gene mutations. By contrast, congenital bone marrow failure syndromes and genetic predispositions associated with MDS are known in pediatric patients. However, little is known about the pathogenesis of MDS in adolescent and young adult (AYA) patients. Previous reports showed the patients with MDS aged under 40 or 41.5 years at allo-HSCT were associated with good survival compared to those among the older population (N Engl J Med. 2017;376:536-547, Blood. 2017;129:2347-2358). However, AYA-MDS is rare, and its clinical features and genetic abnormalities have not been analyzed enough. It is suspected that the clinical and genetic features of AYA-MDS patients might be different from those of elderly patients or pediatric patients. Therefore, we investigated the gene abnormalities of AYA-MDS patients and aimed to elucidate the genetic characteristics associated with the good outcome of allogeneic hematopoietic stem cell transplantation (allo-HSCT). We analyzed the patients younger than 50 years of age in order to reduce the variation of patient-related factors. Methods We analyzed the outcomes of all consecutive patients aged under 50 years who were diagnosed with MDS or acute myeloid leukemia evolving from MDS in our hospital between January 2005 and July 2018. The study was approved by the institutional review board, and patients gave written informed consent for the study, according to the Declaration of Helsinki. Cytogenetic analysis and genomic DNA extraction were carried out using diagnostic bone marrow samples. We performed targeted next-generation sequencing to identify mutations in 68 driver genes using AmpliSeq for Illumina Myeloid Panel and On-Demand Panel on the MiniSeq system (Illumina). Gene variants were detected by in-house analysis pipeline. Overall survival (OS) was analyzed for all patients, and the Kaplan-Meier survival curve was used to assess OS using the log-rank test. Additionally, the cumulative incidence of relapse (CIR) was analyzed for patients who underwent allo-HSCT. Gray's test was used to evaluate the CIR. Results A total of 85 patients with MDS aged under 50 years (U40 between 15 and 39 years old: N=37, 40s between 40 and 49 years old: N=48) were analyzed. The median follow-up time of survivors was 2,041 days (range 176-5,085). There were no significant differences in patient characteristics between U40 and 40s. The 3-year OS of U40 were superior to 40s (79.9% vs. 58.1%, P=0.018), especially lower risk IPSS categories (3-year OS, 95.5% vs. 50.8%, P=0.002). In total, 69 of 85 patients (U40: N=31, 40s: N=38) had undergone allo-HSCT. U40 patients had lower percentage of bone marrow blasts at just before HSCT than 40s patients (over 10%, 12.9% vs. 36.8%, P=0.048), and better 3-year OS from HSCT in lower-IPSS (88.8% vs. 53.8%, P=0.024); but not in higher-IPSS (45.0% vs. 43.2%, P=0.834). In this cohort, at least one driver mutation was detected in 61% of allo-HSCT recipients. Frequently mutated genes (more than 10%) were ASXL1 and RUNX1; however, both of the genes did not have significant impact on the outcomes. While, only one patient in 40s had TP53 mutation. We detected 0.8 (range 0-3) and 1.8 (range 0-6) mutations at average in U40 and 40s, respectively (P=0.06). The proportions of the patients without any gene mutations were 52% in U40 and 30% in 40s. Transplanted patients with 0 or 1 mutation showed lower relapse rate than those with 2 or more mutations (3-year CIR, 23.3% vs. 45.2%, P=0.049). Conclusions The clinical outcomes of U40 patients with MDS were favorable than those in the 40s, especially in lower disease risk. The number of driver mutations in U40 tended to be lower than that in 40s. MDS in adult is regarded as a stem-cell aging disease with gene mutations; however, MDS-associated mutations were not detected in the half of U40. Moreover, TP53 mutation that is associated with extremely poor posttransplant survival was not detected in U40 patients. MDS patients with less than 2 mutations showed lower relapse rate, which maybe indicate genetic mutations have a great impact on transplant outcomes between 15 and 49 years old. Disclosures No relevant conflicts of interest to declare.

Background Constitutional partial trisomy 8 mosaicism (CT8M) is a congenital chromosomal abnormality with an estimated occurrence rate as one out of 25,000-50,000 pregnancies. CT8M has a wide variability in physical manifestation ranging from apparently normal to severe disablement. However, diagnosis of CT8M in adult without physical abnormality is difficult . Acquired trisomy 8, which is restricted to the malignant cells, is one of the most common chromosomal abnormalities in acute myeloid leukemia (AML) and myelodysplastic syndromes (MDS), and clinical implication of carrying isolated trisomy 8 is considered as intermediate cytogenetic risk in MDS. However, isolated trisomy 8 without morphological dysplastic features is not definitive evidence for MDS. 15 to 20% of trisomy 8 in MDS are supposed to be derived from CT8M. We therefore diagnosed CT8M patients among patients with cytopenia and analyzed clinical and genetic features to uncover the association with MDS. Methods . Clinical features including cytogenetic analysis were analyzed regularly. Genomic DNA was extracted from whole PB cells or BM mononuclear cells. We performed targeted next-generation sequencing to identify mutations in 68 driver genes of myeloid neoplasms using AmpliSeq for Illumina Myeloid Panel and On-Demand Panel on the MiniSeq system (Illumina). Gene variants were detected by in-house analysis pipeline. The study was approved by the institutional review board and patients gave written informed consent for the study. Results We identified nine CT8M patients with cytopenia.They comprised 3 males and 6 females at a median age of 56 years (range 24-84 years) (Table). All the patients carried no physical abnormality nor conspicuous phenotypic features. Four patients (Patient #3, #4, #6 and #7) did not show apparent morphological dysplasia at the initial BM examination, and they were not diagnosed as MDS. Their cytopenia has not been exacerbated until now without any treatment, and the duration of stable cytopenia was from 2 to 12 years in these patients. By contrast, five patients with CT8M were diagnosed as MDS . Two patients (#5 and #8) were diagnosed as MDS-single lineage dysplasia (SLD), and their cytopenia has not become worse without any treatment for about 4 years. Other three patients diagnosed as MDS-multilineage dysplasia (MLD) showed various clinical courses. Patient #1 was treated with azacitidine and maintains complete hematological improvement after 34 courses of the treatment. Patient #2 was treated with erythropoietin stimulating agent and azacytidine but developed to AML 3 years after initial diagnosis but leukemic blasts has del(20), not +8. Patient #9 developed advanced pancytopenia in 3 months from initial diagnosis and received red blood cell transfusion regularly. Gene mutations were detected in five out of nine patients with CT8M. In three patients, gene mutations were detected at high (20 to 50%) variant allele frequency (VAF). Patient #2 who was analyzed at the AML phase had gene mutations of SRSF2, SF3B1, STAG2 and NOTCH1. BM sample from patient #9 showed ASXL1 mutation and two TET2 mutations. Patient #4 who did not show apparent myelodysplasia had a high VAF ASXL1 mutation, indicating clonal idiopathic cytopenias of undetermined significance. Two patients had low (2 to 5%) VAF mutations; patient #1 was analyzed after 34 courses of azacitidine had a TET2 mutation; patient #5 with MDS-SLD had a WT1 mutation and two PHF6 mutations. Four patients (#3, #6, #7 and #8) did not have any mutations. The clinical and genetic features showed that CT8M with cytopenia without MDS-related mutations were under 56 years old and did not develop to MDS or stayed at MDS-SLD. Patients with low VAF mutations were also stable. By contrast, patients with advanced diseases gained multiple MDS-related gene mutations with high VAF. One patient without dysplasia had a high VAF ASXL1 mutation. All the patients with gene mutations were age of 56 to 84 years. Conclusion Our results indicated that isolated trisomy 8 may cause cytopenia, but the cytopenia is not exacerbated without MDS-related driver gene mutations. CT8M patients with cytopenia might get gene mutations gradually with age, which leads to MDS or AML. Disclosures No relevant conflicts of interest to declare.

[Background] Philadelphia chromosome positive (Ph+) leukemia is characterized by highly proliferative nature and clone instability that evokes the emergence of mutated clones, including BCR-ABL1 T315I mutated clone. Established evidence on the use of tyrosine kinase inhibitors (TKIs) after allogeneic hematopoietic stem cell transplantation (HSCT) is still lacking. The use of second-generation TKIs as a maintenance treatment after HSCT has been studied, and it is expected that their use would improve the prognosis by suppressing recurrence. The advent of ponatinib (PON), a potent inhibitor of tyrosine kinase including T315I mutated BCR-ABL1, is expected to improve clinical outcome of Ph+leukemia. However, there are few reports of a maintenance treatment using PON after HSCT. [Methods] We retrospectively reviewed data of 13 patients (pts) who received PON for Ph+leukemia after HSCT while in hematological complete remission (CR) between April 1, 2016 and July 15, 2019. Prophylactic treatment (Pro) was defined as post-transplant administration of PON while in minimal residual disease (MRD) negative CR. Pre-emptive treatment (Pre) was defined as starting PON when the bcr-abl transcript was detected by either quantitative or nested qualitative PCR after HSCT. ABL1 mutation was analyzed through the direct sequencing method. Adverse events were evaluated according to the Common Terminology Criteria for Adverse Events version 5.0. Overall survival (OS) was estimated using Kaplan-Meier method. Non-relapse mortality (NRM) and cumulative incidence of hematological relapse (CIR) were calculated using Gray's test. This study protocol was approved by the ethics committee of Tokyo Metropolitan Komagome Hospital. [Results] Underlying diseases were Ph+ALL in 8 pts (5 in CR, 3 in non-CR at HSCT), CML in 5 (all in second chronic phase). ABL1 mutations were analyzed in 12 pts and T315I mutation was detected in 4 pts with Ph+ALL and 2 with CML. Furthermore, compound mutations (CMs) in BCR-ABL1 were detected in 4 pts before HSCT. PON was used in 6 only after HSCT, and in 7 both before and after HSCT. During the median observation after HSCT of 584 days (range, 116-1,110) for survivors, no vascular occlusion event occurred. With regard to adverse events (AEs), grade 3 AEs occurred in 2 pts (15.4%) and no grade 4 AE was observed. Two had liver dysfunction and one of them discontinued PON due to grade 3 abnormalities in liver function tests. One suffered from grade 3 thrombocytopenia. Four had skin rashes lower than grade 3 that were indistinguishable from skin graft-versus-host disease, and all of them resolved through topical steroid therapy. Of all, 6 were in Pro group and 7 were in Pre group. The initial dose of PON was median 15mg (range 45mg/twice a week - 15mg/day) in Pro and median 30mg (range, 15-45mg) in Pre. The median days from HSCT to the start of PON was 107 days (range, 32-174) in Pro and 208 days (range, 50-364) in Pre. The median duration of PON treatment was 297 days (range, 20-699) in Pro and 188 days (range, 5-608) in Pre. At final observation in Pro group, 2 pts relapsed and died during the salvage therapy, 1 pt discontinued PON due to hepatic adverse event, and 3 pts were still on PON. Meanwhile, in Pre group, 5 pts achieved MRD negative CR after PON administration (1 pt also received donor lymphocyte infusion and stop PON due to liver dysfunction, 1 discontinued PON by the patient's request, and 3 of them were still on PON). One pt with CM relapsed but achieved CR through salvage therapy and 1 pt with low performance status (KPS 60) died at home of unknown cause six days after taking PON 30mg daily. For all the 13 pts receiving PON maintenance therapy, OS was 74.6% (95%CI; 39.8-91.1), CIR was 23.1% (95%CI; 5.1-48.5), and NRM was 7.7% (95%CI; 0.4-30.6) at 1 year after transplant (Figure 1). Two out of 4 pts with CMs (V299L/F317L and E255K/T315I/F317L) remains in MRD negative CR. The other 2 with CMs (E255K/T315I and D276G/T315I) had progressed to hematological relapse, suggesting the resistance to PON. In contrast, only one out of 9 without CMs relapsed on PON treatment. [Conclusion] Our results suggested that post-transplant maintenance treatment using PON was tolerable in the majority of patients with Ph+leukemia, although the optimal dose or the initiation strategy (Pre or Pro) are still undetermined. Furthermore, some patients with T315I-inclusive CMs seemed to be resistant to PON. The longer observation in a larger cohort is warranted. Disclosures No relevant conflicts of interest to declare.

[Background] Cytomegalovirus (CMV) disease is a major complication after allogeneic stem cell transplantation (SCT). However, mechanisms of adoptive immunity against CMV are not fully elucidated. Recently, high-throughput next-generation sequencing (NGS) technology made it possible to shed light on the detailed and comprehensive landscape of T-cell receptor (TCR) repertoire. In this study, we analyzed TCR repertoire of CMV-specific cytotoxic T-cells (CMV-CTLs) in patients who suffered from CMV reactivation after SCT to clarify the diversity and dynamics of CMV-specific T-cell immunity. [Methods] We sequentially collected peripheral blood mononuclear cells from patients with HLA-A*24:02 who received SCT in our institution. Samples were collected weekly or every two weeks from their neutrophil engraftment until approximately 100 days after SCT. CMV reactivation was evaluated weekly with CMV antigenemia test. CD8 and CMV pp65 tetramer positive cells were sorted and unbiased next-generation sequencing-based analyses of TRBV/TRBJ gene segments were performed at the timing of CMV reactivation in 16 patients, and TRA gene segments were also analyzed in 10 patients. In addition, TCR beta repertoires after 2-4 weeks were analyzed in 12 patients. In the 12 patients, the dynamics of TCR repertoire diversity and proportional changes of each clone were assessed. We evaluated the diversity by Shannon-Weber index, and we defined TCR beta clonotypes found in two or more patients using the same TRBV/TRBJ gene segments and CDR3 amino acid sequences as public. This study was approved by the ethics committee of Tokyo Metropolitan Komagome Hospital. [Results] Among 16 patients, 11 received bone marrow, 3 received peripheral blood stem cells, and 2 received cord blood transplant. Underlying diseases were acute myeloid leukemia in 7, acute lymphoblastic leukemia in 7, and myelodysplastic syndromes in 2 patients. Median age at SCT was 50 years old (range: 20-71). Median duration from SCT to first CMV reactivation was 39 days (range: 16-55) and 7 patients (43.8%) were administered systemic corticosteroid at the time of reactivation (prednisolone 10-30mg/day). Median peripheral blood CMV-CTLs count at that time was 29.47/uL (range: 4.65-229.6). In most patients TCR beta repertoire of CMV-specific CTLs when CMV reactivated was highly skewed (median Shannon-Weber index was 1.44 [range: 0.542-3.164]). TCR alpha and beta were analyzed together in 10 patients and their diversity correlated well (p [Conclusion] TCR repertoire of CMV-CTLs at the time of CMV reactivation after SCT is highly oligoclonal and frequently shared among different patients, but can dynamically change in a short period in some patients. Functional analyses of the dominant TCRs to understand their reactivity against CMV epitope and elucidation of the clinical significance and developmental mechanisms of clone shift are strongly warranted. Figure Disclosures Kitaura: Repertoire Genesis Inc.: Employment. Suzuki:Repertoire Genesis Inc.: Equity Ownership.