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  • American Society of Hematology  (14)
  • 1
    In: Blood, American Society of Hematology, Vol. 140, No. Supplement 1 ( 2022-11-15), p. 10722-10724
    Type of Medium: Online Resource
    ISSN: 0006-4971 , 1528-0020
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    Language: English
    Publisher: American Society of Hematology
    Publication Date: 2022
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  • 2
    In: Blood, American Society of Hematology, Vol. 91, No. 7 ( 1998-04-01), p. 2452-2458
    Abstract: Complete remission is achieved in a high proportion of patients with acute promyelocytic leukemia (APL) after all-trans retinoic acid (RA) treatment, but most patients relapse and develop RA-resistant APL. We have previously reported that both RA-resistant HL-60 (HL-60R) and APL cells express P-glycoprotein and MDR1 transcripts; and these cells differentiate to mature granulocytes after culture with RA and P-glycoprotein antagonist. Ribozymes have been shown to be able to intercept a target RNA by catalytic activity. To address the role of MDR1 in overcoming RA-resistance in APL cells, we investigated the biologic effects of ribozymes against the MDR1 transcript in HL-60R cells. These ribozymes efficiently cleaved MDR1 mRNA at a specific site in vitro. The 196 MDR1 ribozyme was cloned into an expression vector, and stably transfected (HL-60R/196Rz) cells were obtained. Expression of MDR1 transcripts was decreased in HL-60R/196Rz cells compared with parental HL-60R and empty vector-transfected (HL-60R/neo) cells. Interestingly, RA inhibited cellular proliferation and induced differentiation of HL-60R/196Rz cells in a dose-dependent manner, suggesting reversal of drug resistance in HL-60R cells by the MDR1 ribozyme. These data are direct evidence that P-glycoprotein/MDR1 is responsible in part for acquired resistance to RA in myeloid leukemic cells. The MDR1 ribozyme may be a useful tool for investigating the biology of retinoid resistance and may have therapeutic potential for patients with RA-resistant APL.
    Type of Medium: Online Resource
    ISSN: 1528-0020 , 0006-4971
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    Language: English
    Publisher: American Society of Hematology
    Publication Date: 1998
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  • 3
    In: Blood, American Society of Hematology, Vol. 118, No. 21 ( 2011-11-18), p. 721-721
    Abstract: Abstract 721 Hematopoietic stem/progenitor cells (HSPCs) are released from the bone marrow (BM) to the circulation by granulocyte-colony stimulating factor (G-CSF) via sympathetic nervous system (SNS)-mediated osteoblast suppression (Katayama et al. Cell 2006). We further elucidated that vitamin D receptor is essential for this neuronal control of endosteal niche (Kawamori et al. Blood 2010). Osteoblasts are known to adopt three fates: die by apoptosis, become bone-lining cells, or become embedded in osteoid and then in mineralized bone matrix to terminally differentiate into osteocytes, which constitute more than 95% of bone cells. Osteocytes have been shown to control the functional balance between osteoblast and osteoclast via mechanotransduction. In order to address the role of bone-embedded osteocytes in HSPCs niche function, we first quantified mRNA expression of bone-related genes in the femur of wild-type (WT) mice to examine if osteocytic function changes during G-CSF treatment (125μg/kg/dose, 8 divided doses, every 12 hours). Whereas markers relating to osteoblast function, osteocalcin and osteopontin, started to decrease late at 6 doses of G-CSF administration when mild mobilization of HSPCs had occurred, osteocyte-specific genes, including neuropeptide y, SOST, MEPE, E11/gp38 and Phex, were rapidly suppressed at 1 dose when no mobilization was observed. These data suggest that osteocytes respond to G-CSF with altered gene expression much earlier than osteoblasts. Further, the number and thickness of osteocyte projections extending toward the endosteal surface were markedly reduced, as assessed by fluorescently labeled phalloidin, at 8 doses of G-CSF treatment when full mobilization was achieved; these morphological changes were observed specifically in newly-embedded osteoid osteocytes, but not in mature osteocytes embedded deep inside mineralized bone. These findings suggest that osteoid osteocytes may sense the signal triggered by G-CSF. We confirmed the presence of β2-adrenergic receptor in osteoid osteocytes and tyrosine hydroxylase-positive nerve fibers in the vicinity by immunofluorecence staining, suggesting that osteoid osteocytes may be regulated by SNS. To directly address osteocyte involvement in G-CSF-induced mobilization, we utilized a transgenic (TG) mice in which inducible and specific ablation of osteocytes is achieved through targeted expression of diphtheria toxin (DT) receptor under DMP-1 promoter. A single injection of DT in TG mice generates “osteocyte-less (OL)” mice. We found that mobilization by G-CSF was drastically impaired in OL mice for progenitors (CFU-Cs, mean±SEM, WT vs Tg: 1673±271 vs 242±94/ml blood, n=6-13, p 〈 0.01; lineage-Sca-1+c-kit+ (LSK) cells, WT vs Tg: 6878±1209/ml vs 1763±502/ml, n=6-13, p 〈 0.01) and stem cells (repopulating units at 4 months, WT vs Tg: 2.5±0.7 vs 0.5±0.2, n=6-7, p 〈 0.05), while the OL BM showed normal HSPC number. The levels of CXCL12 mRNA and protein in BM and bone were markedly decreased during G-CSF treatment even in OL mice despite the mobilization defect, and a CXCR4 antagonist AMD3100 induced mobilization normally in the absence of osteocytes. Thus, osteocytes embedded within the bone are indispensable for G-CSF-induced mobilization through a CXCL12-independent mechanism. Although most of bone-related genes exhibited drastic decreases following G-CSF treatment, we found that fibroblast growth factor 23 (fgf23) mRNA displayed a 4-fold increase at 6 doses of G-CSF. FGF23 is mainly produced by osteocytes and Klotho is an obligate coreceptor for FGF23 to bind and activate FGF receptors. Since we confirmed that klotho hypomorphic (kl/kl) mice showed remarkably disrupted osteocyte network, we injected G-CSF into these mice. As we expected, G-CSF induced virtually no mobilization in kl/kl mice while the number of HSPCs in the BM remained comparable to control mice. Collectively, our results demonstrate a novel function of bone-embedded osteocytes as a critical regulator of HSPC trafficking perhaps by controlling the endosteal niche and establish the important physiologic function of skeletal tissue for hematopoietic microenvironment. Disclosures: No relevant conflicts of interest to declare.
    Type of Medium: Online Resource
    ISSN: 0006-4971 , 1528-0020
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    Language: English
    Publisher: American Society of Hematology
    Publication Date: 2011
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  • 4
    In: Blood Advances, American Society of Hematology, Vol. 6, No. 11 ( 2022-06-14), p. 3207-3219
    Abstract: We investigated genome-wide DNA methylation patterns in 64 pediatric patients with acute myeloid leukemia (AML). Based on unsupervised clustering with the 567 most variably methylated cytosine guanine dinucleotide (CpG) sites, patients were categorized into 4 clusters associated with genetic alterations. Clusters 1 and 3 were characterized by the presence of known favorable prognostic factors, such as RUNX1-RUNX1T1 fusion and KMT2A rearrangement with low MECOM expression, and biallelic CEBPA mutations (all 8 patients), respectively. Clusters 2 and 4 comprised patients exhibiting molecular features associated with adverse outcomes, namely internal tandem duplication of FLT3 (FLT3-ITD), partial tandem duplication of KMT2A, and high PRDM16 expression. Depending on the methylation values of the 1243 CpG sites that were significantly different between FLT3-ITD+ and FLT3-ITD− AML, patients were categorized into 3 clusters: A, B, and C. The STAT5-binding motif was most frequently found close to the 1243 CpG sites. All 8 patients with FLT3-ITD in cluster A harbored high PRDM16 expression and experienced adverse events, whereas only 1 of 7 patients with FLT3-ITD in the other clusters experienced adverse events. PRDM16 expression levels were also related to DNA methylation patterns, which were drastically changed at the cutoff value of PRDM16/ABL1 = 0.10. The assay for transposase-accessible chromatin sequencing of AMLs supported enhanced chromatin accessibility around genomic regions, such as HOXB cluster genes, SCHIP1, and PRDM16, which were associated with DNA methylation changes in AMLs with FLT3-ITD and high PRDM16 expression. Our results suggest that DNA methylation levels at specific CpG sites are useful to support genetic alterations and gene expression patterns of patients with pediatric AML.
    Type of Medium: Online Resource
    ISSN: 2473-9529 , 2473-9537
    Language: English
    Publisher: American Society of Hematology
    Publication Date: 2022
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  • 5
    In: Blood, American Society of Hematology, Vol. 138, No. Supplement 1 ( 2021-11-05), p. 3797-3797
    Abstract: Introduction Multiple myeloma (MM) is caused by the proliferation of monoclonal malignant plasma cells in the bone marrow (BM). Imaging has played a major role in visualizing myeloma lesions, assessing tumor volume, and predicting the prognosis. Recently, we reported that the total diffusion volume (tDV), assessed using a pretreatment whole-body diffusion-weighted imaging (WB-DWI), was associated with a high BM plasma cells (BMPCs) and a poor prognosis in patients with MM (Terao. et al., Eur Radiol 2021). During that study, we unexpectedly found the frequent absence of a spleen signal in patients with MM and its reappearance after treatment. Therefore, this study aimed to investigate the association between spleen visualization changes on WB-DWI and myeloma tumor load and prognosis in patients with MM. Methods The data of 96 consecutive patients with symptomatic newly-diagnosed MM (NDMM) at Kameda Medical Center from January 2016 to December 2020, 15 consecutive patients with smoldering MM (sMM), and two autopsied spleens of patients with PC dysplasia were retrospectively reviewed. All patients underwent at least one WB-DWI prior to treatment. The detail of WB-DWI was previously reported (Terao. et al., Eur Radiol 2021). "Loss of spleen visualization" (LSV) was defined as a visual loss of the spleen in maximum intensity projection on the WB-DWI (Fig1). The spleen-to-spinal cord (SC) ratio (SSR) was used in each regions-of-interest (ROI) to compare the signal intensity. The spleen ROIs were defined as non-overlapping ROIs of 30-50 pixels. The SC ROI was the largest ROI without overhanging in the image depicting the maximum size of the spleen. This study was approved by the institutional review board and conducted in accordance with the Declaration of Helsinki. All participants provided informed consent. Results The median patient age was 75.5 years and 81 patients (84.4%) were 65 years or older. Almost all patients (n=91) received proteasome inhibitors (PIs) as remission induction therapy and 33 patients received autologous stem-cell transplantation (ASCT). LSV was observed on the WB-DWI of 56/96 (58.3%) patients with NDMM and in one patient with sMM (1/15, 6.7%). Patients with NDMM and LSV had a higher median BMPC infiltration as assessed by CD138-immunohistochemistry (80.0% vs. 50.0%, p & lt;0.001), a higher median tDV (540.2 mL vs. 137.0 mL, p=0.003), higher rate of ISS stage III (p & lt;0.01), a lower SSR (0.36 vs. 0.96; p & lt;0.001), and lower tDV (540.2 mL vs. 137.0 mL; p=0.003) than those without LSV. The three-year PFS (p=0.27) and three-year OS (p=0.021) were lower in patients with NDMM with LSV (PFS: 51.2% and OS: 72.5%) than in patients without LSV (PFS: 63.4% and OS: 100%). Next, we investigated the spleen signal change of patients who underwent WB-DWI twice or more during treatment (n=74). Of 42 out of the 74 patients with LSV at diagnosis, the spleen during treatment became visible on 31/42 (73.8%) patients. Representative patients with various spleen signal changes during treatment are shown in Figure 3 as group A (n=32; patients without LSV at diagnosis and during treatment), group B (n=31; patients who had LSV at diagnosis but the spleen reappeared after treatment), and group C (n=11; patients who had LSV at diagnosis, and despite treatment response, did not regain the spleen signal). Patients in group C showed significantly worse three-year PFS and OS (not available due to early events) than those in group A and B, even after excluding patients who did not achieve partial response or worse (n=11) (Fig1). In the multivariate analysis, the group C retained its prognostic significance for both PFS (hazard ratio [HR], 1.98, 95% confidence interval [CI] 1.00-3.90, p = 0.049) and OS (HR, 5.16, 95% CI 1.27-21.0, p = 0.022) even after adjustment for age over 70 years and the revised-ISS stage III. At last, to investigate the pathological cause of LSV, we reviewed two patients who underwent autopsies, who had both received WB-DWI within 3 months before their deaths (Fig1). One patient showed diffuse myeloma cell infiltration in the spleen and the other showed the amyloid deposition without myeloma cell infiltration. Conclusion This study showed that LSV and a low SSR on pretreatment WB-DWI are correlated with a high tumor volume and poor prognosis. As patients with LSV during treatment had very poor prognosis, the relationships between LSV and other variables should be investigated. Figure 1 Figure 1. Disclosures No relevant conflicts of interest to declare.
    Type of Medium: Online Resource
    ISSN: 0006-4971 , 1528-0020
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    RVK:
    Language: English
    Publisher: American Society of Hematology
    Publication Date: 2021
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  • 6
    In: Blood, American Society of Hematology, Vol. 138, No. Supplement 1 ( 2021-11-05), p. 3510-3510
    Abstract: Introduction: This study investigated the prognostic relevance between tumor-infiltrating T-lymphocytes (TIL) in lymphoma tissue and total metabolic tumor volume (TMTV) measured by positron emission tomography/computed tomography (PET/CT) in patients with diffuse large B-cell lymphoma (DLBCL). We further examined the effect of combining these on the predictive efficacy in DLBCL patients receiving R-CHOP (rituximab, cyclophosphamide, doxorubicin, vincristine, and prednisone) or R-CHOP-like chemotherapy. Methods: Newly diagnosed DLBCL patients at the Kameda Medical Center between 2007 and 2019 were retrospectively analyzed. The patients were selected based on data, including baseline PET/CT, flow-cytometry data of biopsied specimens, and the use of R-CHOP or R-CHOP-like regimens. TMTV was defined as the volume of lymphoma-associated lesions with a standardized uptake value of ≥ 2.5 as the absolute threshold. To calculate TMTV, a semi-automatic computer-aided analysis of PET/CT images for TMTV was conducted using the open-source software Metavol (Hokkaido University, Sapporo, Japan). To assess the degree of TIL, mononuclear cells from biopsied specimens stained with monoclonal antibodies, including CD19, CD3, CD4, CD8, and CD45, were measured using a Navios flow cytometer (Beckman Coulter, USA). Results: Among 536 DLBCL patients, 288 were excluded because of insufficient flow cytometry data, while another 140 were excluded due to lacking baseline TMTV measurements. Lastly, 18 patients, who did not receive R-CHOP or R-CHOP-like regimens, were excluded. Ninety patients were enrolled in this study. The median age of the patients was 68 years (range: 36-86). 44% of the patients had a poor risk of revised-international prognostic index (R-IPI) score. After a median follow-up period of 53 months, the five-year progression-free survival (PFS) and five-year overall survival (OS) rates were 69% and 74%, respectively. First, the prognostic value of TMTV was evaluated at baseline. The median TMTV was 302 cm 3 (range: 3-3923 cm 3). The optimal cut-off value, calculated by the receiver operating curve, was 564 cm 3 (area under the curve, 0.701). Using this cut-off value, high TMTV was associated with a significantly worse PFS (hazard ratio [HR] =2.669; 95% confidence interval [CI] 1.209-5.892; p=0.01) and OS (HR=3.845; CI 1.699-8.704; p=0.001, Figure 1). Next, the prognostic value of TIL was assessed. The median percentages of CD3 +, CD4 +, and CD8 + cells within the tumor were 43% (range: 1-91), 23% (range: 0.5-81), and 15% (range: 0.4-41), respectively. Using the median cut-off value for each percentage of T-cell subsets, low percentages of CD3 + and CD4 + cells were associated with worse PFS and OS, but the difference was not statistically significant for PFS (PFS: HR=1.71; CI 0.767-3.81; p=0.18 and HR=1.799; CI 0.808-4.007; p=0.15, respectively; OS: HR=3.045; CI 1.279-7.246; p=0.01, Figure 2, and HR=3.275; CI 1.375-7.803; p=0.007, respectively), while a low percentage of CD8 + cells was not associated with either PFS or OS. (HR=1.33; CI 0.603-2.93; p=0.47, and HR=1.672; CI 0.755-3.699; p=0.2, respectively). The positivity of CD4 + cells was strongly correlated with that of CD3 (Pearson's correlation analysis, r=0.881, p & lt;0.0001). On multivariate analysis, including TMTV, CD3 + TIL, and R-IPI poor risk as variables, TMTV and CD3 + TIL predicted worse OS (HR=2.943; CI 1.133-7.64; p=0.02, and HR=2.753; CI 1.153-6.575; p=0.02, respectively). Finally, a prognostic model, combining TMTV and CD3 + TIL, was constructed. The model demonstrated that patients with low TMTV and high CD3 + TIL had favorable outcomes (5-year OS: 100%), and patients with high TMTV or low CD3 + TIL had an intermediate prognosis (5-year OS: 70%). However, patients with high TMTV and low CD3 + TIL had a poor prognosis with a five-year OS of 41% (Figure 3). Conclusions: This study indicated that baseline high TMTV and low percentages of TIL in DLBCL patients were associated with a worse prognosis. The combination of TMTV and TIL improved the TMTV-based prognostic stratification of DLBCL patients. Figure 1 Figure 1. Disclosures No relevant conflicts of interest to declare.
    Type of Medium: Online Resource
    ISSN: 0006-4971 , 1528-0020
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    Language: English
    Publisher: American Society of Hematology
    Publication Date: 2021
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  • 7
    In: Blood, American Society of Hematology, Vol. 138, No. Supplement 1 ( 2021-11-05), p. 3798-3798
    Abstract: Introduction Carfilzomib (K or Cfz) is a widely used second-generation proteasome inhibitor for patients with multiple myeloma (MM). However, despite the numerous positive clinical results, there were only a few "real-world" studies, particularly among elderly patients. Avoiding Cfz for the elderly may be based on a potential selection bias to avoid rare but serious cardiovascular adverse events (CVAEs) associated with Cfz. Moreover, although Cfz-associated thrombotic microangiopathy (TMA) has been recently recognized, the incidence rate of TMA varied from less than 1% to 5.0%. To determine the efficacy of Cfz and occurrence of CVAEs in the elderly patients and the incidence of TMA, we reviewed 96 patients, including 28 elderly patients (aged ≥76 years) at our center. All participants or their family members provided written informed consent for inclusion in the study. The study was conducted according to the Declaration of Helsinki and approved by the ethical review board of our institute. Methods Cfz was administered in the same protocol as in each clinical trial. The choice of the Cfz regimen and the criteria for dose reduction, including dexamethasone use, were based on the patient's background and discretion of the treating physician. Severe CVAEs were defined as events of grade ≥3 including heart failure, acute coronary syndrome, relative reduction in the left ventricular ejection fraction ≥20% from baseline, QT prolongation (corrected QT: ≥501 ms), and hypertension (systolic blood pressure of ≥160 mm Hg and/or diastolic blood pressure of ≥100 mm Hg, requiring two or more additional intensive medications than before) that were observed within three months after the initiation of Cfz therapy. The diagnosis of TMA was made as follows: when clinical findings were consistent with microangiopathic hemolytic anemia, such as thrombocytopenia, progressive anemia with schistocytes, elevated lactate dehydrogenase, and other differential diseases, including bacteremia or tumor progression, could be excluded. Results The patients' median age at Cfz initiation was 71 (range, 30-91) years. In total, 96 (100%), 86 (89.6%), 22 (22.9%), and 23 (23.9%) patients received bortezomib, lenalidomide, daratumumab, and autologous stem cell transplantation before Cfz therapy. Until the end of the study, 13 CVAEs (13.5%) of grade ≥3 were observed, including 2 (11.1%), 1 (11.1%), and 10 (15.2%) in patients who received Kd (Cfz and dexamethasone), DKd (Daratumumab, Cfz, and dexamethasone), and KRd (Cfz, lenalidomide, and dexamethasone), respectively. Despite the use of appropriate supportive care, grade ≥3 AEs resulting in Cfz withdrawal were noted in 25 patients: CVAEs in 11, thrombocytopenia in 4, TMA in 3, and infection in two patients. Notably, one patient with end-stage myeloma who received KRd 20/27 mg/m 2 died of CVAE on day 10 of cycle 1. At Cfz initiation, 28 patients were aged 76-80 (n=14) and ≥81 years (n=14) (Fig. 1). Three elderly patients had severe CVAEs (10.7%). The median numbers of prior chemotherapy to Cfz, time to next treatment, and overall survival from Cfz initiation were 2.5, 28.0, and 41.1 months, respectively. Although 10 patients (35.7%) discontinued Cfz therapy due to disease progression, only four patients (14.3%) discontinued Cfz owing to grade ≥3 AEs, including TMA (n = 1) and CVAEs (n = 3). Overall, five patients (5.2%) showed TMA. All patients received Kd-based regimens upon TMA development (Kd, n = 2 and DKd, n = 3). The median age of the patients who developed TMA was 74 years, and the Cfz dose was 20/27 in 1, 20/36 in 1, and 20/56 mg/m 2 in three patients. Although three patients developed TMA during the first Cfz cycle (on days 11, 16, and 21, respectively), two patients received KRd therapy before the Kd therapy that caused TMA. Two patients required temporary dialysis and four patients discontinued Cfz therapy. Eculizumab was administered in a patient and a kidney biopsy showed that the lumen of most glomerular capillaries was occluded by fibrin thrombi (Fig. 1). Furthermore, the vessel in the vascular pole of the glomerulus had necrotic lesions, suggesting drug-induced and complement-mediated TMA. Conclusion Cfz could be used safely in the elderly patients. The incidence of CVAEs by Cfz in elderly patients was similar to that in the entire cohort. The incidence of TMA was 5.2%, and Cfz-induced TMA should be carefully considered, particularly in patients using high-dose Cfz. Figure 1 Figure 1. Disclosures No relevant conflicts of interest to declare.
    Type of Medium: Online Resource
    ISSN: 0006-4971 , 1528-0020
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    Language: English
    Publisher: American Society of Hematology
    Publication Date: 2021
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  • 8
    In: Blood Advances, American Society of Hematology, Vol. 5, No. 19 ( 2021-10-12), p. 3830-3838
    Abstract: We report a 19-year-old Vietnamese woman who experienced several life-threatening bleeding events, including ovarian hemorrhage. Blood analysis revealed a decreased fibrinogen level with markedly elevated fibrinogen/fibrin degradation products and D-dimer levels. Despite hemostatic surgery and administration of several medications, such as nafamostat mesylate, tranexamic acid, and unfractionated heparin, the coagulation abnormalities were not corrected, and the patient experienced repeated hemorrhagic events. We found that administration of recombinant human thrombomodulin (rhTM) remarkably improved the patient’s pathophysiology. Screening and sequencing of the TM gene (THBD) revealed a previously unreported homozygous variation: c.793T & gt;A (p.Cys265Ser). Notably, the Cys265 residue forms 1 of 3 disulfide bonds in the epidermal growth factor (EGF)–like domain 1 of TM. Transient expression experiments using COS-1 cells demonstrated markedly reduced expression of TM-Cys265Ser on the plasma membrane relative to wild-type TM. The TM-Cys265Ser mutant was intracellularly degraded, probably because of EGF-like domain 1 misfolding. The reduced expression of TM on the endothelial cell membrane may be responsible for the disseminated intravascular-coagulation–like symptoms observed in the patient. In summary, we identified a novel TM variant, c.793T & gt;A (p.Cys265Ser). Patients homozygous for this variant may present with severe bleeding events; rhTM should be considered a possible treatment option for these patients.
    Type of Medium: Online Resource
    ISSN: 2473-9529 , 2473-9537
    Language: English
    Publisher: American Society of Hematology
    Publication Date: 2021
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  • 9
    In: Blood, American Society of Hematology, Vol. 91, No. 7 ( 1998-04-01), p. 2452-2458
    Abstract: Complete remission is achieved in a high proportion of patients with acute promyelocytic leukemia (APL) after all-trans retinoic acid (RA) treatment, but most patients relapse and develop RA-resistant APL. We have previously reported that both RA-resistant HL-60 (HL-60R) and APL cells express P-glycoprotein and MDR1 transcripts; and these cells differentiate to mature granulocytes after culture with RA and P-glycoprotein antagonist. Ribozymes have been shown to be able to intercept a target RNA by catalytic activity. To address the role of MDR1 in overcoming RA-resistance in APL cells, we investigated the biologic effects of ribozymes against the MDR1 transcript in HL-60R cells. These ribozymes efficiently cleaved MDR1 mRNA at a specific site in vitro. The 196 MDR1 ribozyme was cloned into an expression vector, and stably transfected (HL-60R/196Rz) cells were obtained. Expression of MDR1 transcripts was decreased in HL-60R/196Rz cells compared with parental HL-60R and empty vector-transfected (HL-60R/neo) cells. Interestingly, RA inhibited cellular proliferation and induced differentiation of HL-60R/196Rz cells in a dose-dependent manner, suggesting reversal of drug resistance in HL-60R cells by the MDR1 ribozyme. These data are direct evidence that P-glycoprotein/MDR1 is responsible in part for acquired resistance to RA in myeloid leukemic cells. The MDR1 ribozyme may be a useful tool for investigating the biology of retinoid resistance and may have therapeutic potential for patients with RA-resistant APL.
    Type of Medium: Online Resource
    ISSN: 1528-0020 , 0006-4971
    RVK:
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    Language: English
    Publisher: American Society of Hematology
    Publication Date: 1998
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  • 10
    In: Blood, American Society of Hematology, Vol. 134, No. Supplement_1 ( 2019-11-13), p. 1419-1419
    Abstract: Introduction Recent medical advances and development of comprehensive genetic understanding dramatically improve the clinical outcome of whole pediatric cancers, particularly in pediatric acute lymphoblastic lymphoma. However, approximately 50% of patients have disease relapse, and overall survival (OS) of pediatric acute myeloid leukemia (AML) is less than 70% as of the major therapeutic challenges. AML is caused by various chromosomal aberrations, gene mutations/epigenetic modifications, and deregulated/overregulated gene expressions, leading to increased proliferation and decreased hematopoietic progenitor cell differentiation. AML with RUNX1-RUNX1T1 gene fusions are generally classified as a low-risk group and resulted in favorable prognosis. However approximately 30% of the patients relapsed within 3 years. Conversely, KIT mutations were found in approximately 30% of AML cases with RUNX1-RUNX1T1 and thought to be a risk factor for relapse, particularly when occurring in D816V within KIT exon 17. Recently, droplet digital PCR (ddPCR), a method for measuring target nucleic acid sequence quantity, has been used to determine low-prevalence somatic mutations that were not detectable using Sanger sequencing. It shows the possibility that there are some of Pediatric AML cases which were not detected minor clones with somatic KIT mutation by using ordinary PCR. In this study, we explored KIT D816V mutations including the cases which are not detected by Sanger sequencing and found the prognosis of them by using Japanese pediatric AML cases. Methods We reanalyzed somatic KIT mutations (p.D816V) in the DNA extracted from 335 pediatric AML patients with RUNX1-RUNX1T1 who participated in the Japanese Pediatric Leukemia/Lymphoma Study Group (JPLSG) AML-05 trial using ddPCR . In this trial, we conducted the tests as follows,: PCR mixture containing 10 μL 2x ddPCR Supermix for probes, 900 nM target-specific PCR primers, and 250 nM mutant-specific (FAM) and wild-type-specific (HEX) probes.20 µL of PCR mixture and 70 μL Droplet generation oil were mixed, and droplet generation was performed using a Bio-Rad QX100 Droplet Generator. The droplet emulsion was thermally cycled in the following conditions: denaturing at 95 °C for 10 min, 40 cycles of PCR at 94 °C for 30 s and at 57 °C for 2 min, and a final extension at 98 °C for 10 min. PCR amplification in the droplets was confirmed using Bio-Rad QX200 Droplet Reader. ThresholdThe threshold was determined by comparing the non-template ddPCR results. All the data were evaluated above the threshold. We also performed targeted gene mutation analysis of KIT in all patients using Sanger sequencing. Results We identified 24 KIT D816V mutations (7.2%) in the 335 pediatric AML. Variant allele frequency (VAF) was 0.1%-46.9%.It is noteworthy that 12 out of 24 KIT D816V mutations were undetected in our previous study using Sanger sequencing. Fourteen out of these 24 patients were AML with RUNX1-RUNX1T1, 5 cases with inv(16), and 5 cases with other alterations. Ten of the 14 RUNX1-RUNX1T1 (71%) patients were newly identified using ddPCR. Six of these 14 RUNX1-RUNX1T1 patients had relapsed, and D816V mutations were only detected using ddPCR in 4 of these 6 relapsed cases. The mean VAF of KIT D816V was 3.8% (0.1%-13.4%) in the 10 undetected patients with RUNX1-RUNX1T1. Two of the 5 patients with inv(16) were newly identified, and 1 had relapsed. All 5 cases with other alterations were already identified using Sanger sequencing. The mean VAF of KIT D816V in the 3 patients with inv(16) was 44.8% (42.7%-46.9%), detected using Sanger sequencing, whereas the mean VAF of KIT D816V was 8.6% (6.5% and 10.7%) in the undetected patients with inv(16). The mean VAF of KIT D816V with other alterations was 28.1% (16.2%-42.9%). Conclusion We identified 12 KIT D816V mutations using ddPCR that were undetected using Sanger sequencing. ddPCR may be useful for detecting accurate frequencies of mutations that were undetected using Sanger sequencing. Potential co-existing gene mutations may contribute different significance of leukemogenesis and relapse. Disclosures Ito: Asahi Kasei Pharma: Consultancy, Other: Grants; Astellas Pharma: Consultancy, Other: Grants; Teijin: Other: Grants; Novartis Pharma: Consultancy; Zenyaku Kogyo Co. Ltd: Consultancy; Chugai Pharma: Consultancy, Other: Grants; Japan Blood Products Organization: Other: Grants; Pfizer inc.: Other: Grants.
    Type of Medium: Online Resource
    ISSN: 0006-4971 , 1528-0020
    RVK:
    RVK:
    Language: English
    Publisher: American Society of Hematology
    Publication Date: 2019
    detail.hit.zdb_id: 1468538-3
    detail.hit.zdb_id: 80069-7
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