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The optimal dosage of methotrexate (MTX) for graft-versus-host disease (GVHD) prophylaxis after cord blood transplantation (CBT) has not been well elucidated. Therefore, we conducted a retrospective study comparing a mini-MTX group (5 mg/m2 on day 1, 3 and 6) to a short-MTX group (10 mg/m2 on day 1 and 7 mg/m2 on day 3 and 6) after CBT. Sixty-three patients were classified as the mini-MTX group and 20 as the short-MTX group. The median time and cumulative incidence of neutrophil engraftment did not vary between the two groups. The cumulative incidence of grade 2–4 and grade 3–4 acute GVHD was similar in both groups. Overall survival in the mini-MTX group was significantly lower than in the short-MTX group (46.9% vs. 88.7% at 1 year, p

Multiple myeloma (MM) is still extremely difficult to cure, and new therapeutic drugs are needed. We recently found that integrin β7 is constitutively activated in MM cells, and chimeric antigen receptor (CAR) T cells targeting activated integrin β7 have a significant anti-MM effect. In this study, we performed flow cytometry analysis of the expression of activated integrin β7 in bone marrow cells from 137 symptomatic MM patients. In 60/137 (44%) MM patients, activated integrin β7 was detected in most MM cells (> 80% of MM cells were in the positive gate). Activated integrin β7 was highly expressed in MM cells even in heavily treated patients. It also showed high expression in many CD38lo/−CD138−CD19+B cells, which reportedly include clonotypic B cells, in the bone marrow of MM patients. Taken together, these results suggest that CAR T-cell therapy targeting activated integrin β7 has the potential to benefit many patients with relapsed or refractory MM.

Oral mucositis is a common and distressing complication in patients receiving high-dose chemotherapy followed by hematopoietic stem cell transplantation (HSCT). We reported previously in a single-center retrospective analysis that zinc-L-carnosine (polaprezinc [PZ]) reduced the incidence of oral mucositis associated with HSCT. To verify the accuracy of the prophylactic effect of PZ against oral mucositis, we carried out a multi-institutional prospective randomized controlled study. Patients were randomly allocated to either the prevention group, in which PZ lozenge treatment was started before chemotherapy, or the control group, in which administration of PZ lozenges was initiated immediately after the onset of Grade 2 oral mucositis. Oral mucositis was evaluated daily from the start of chemotherapy to 35 days after transplantation. A total of 91 patients were enrolled, and 88 patients (47 in the control group and 41 in the prevention group) were eligible for data analysis. The incidence of Grade ≥2 but not Grade ≥3 oral mucositis was significantly reduced in the prevention group compared to the control group (44.7% in control group vs 22.0% in the prevention group, P = .025). There were no significant differences in the incidence rates of other adverse events or the rate of engraftment (95.6% vs 97.2%, P = .693) between the two groups. These findings suggest that PZ lozenge is effective for prophylaxis against Grade ≥2 oral mucositis associated with chemotherapy in patients undergoing HSCT without any influence on the HSCT outcome.

Summary We conducted a randomised phase II study to determine the optimal dose and schedule of melphalan, prednisone, and bortezomib (MPB) (jRCTs031180097). Transplant‐ineligible untreated multiple myeloma patients were randomised to Arm A (twice weekly bortezomib in one six‐week cycle followed by eight five‐week cycles of four times once weekly bortezomib with melphalan and prednisolone on days 1–4) or Arm B (nine four‐week cycles of three times once weekly bortezomib with melphalan and prednisolone on days 1–4). The primary end‐point was complete response (CR) rate. Of 91 patients randomised to two arms, 88 were eligible. The median cumulative bortezomib doses were 45·8 and 35·1 mg/m2, CR rate was 18·6% [95% confidence interval (CI) 8·4–33·4] and 6·7% (95% CI 1·4–18·3), and the median progression‐free survival (PFS) was 2·5 and 1·4 years in Arms A and B [hazard ratio (HR) 1·93 (95% CI 1·09–3·42)], respectively. Frequent grade ≥3 haematologic toxicities in Arms A and B were neutropenia (64·4% vs. 28·3%) and thrombocytopenia (35·6% vs. 10·9%). Grade 2/3 peripheral neuropathy was observed in 24·4/2·2% in Arm A and 8·7/0% in Arm B. In conclusion, Arm A was the more promising regimen, suggesting that the twice weekly schedule of bortezomib in the first cycle and higher cumulative dose of both bortezomib and melphalan influences the efficacy of modified MPB.

The combination of bortezomib, lenalidomide, and dexamethasone (VRD) is used as induction treatment in multiple myeloma; however, the optimum schedule for this regimen remains controversial. In this retrospective study, we compared the efficacy and tolerability of twice-weekly VRD (twVRD) and modified VRD-lite in transplant-eligible myeloma patients. Fifty-five patients (median age 61 years) were included; 22 received twVRD (bortezomib [1.3 mg/m2 on days 1, 4, 8, and 11] and lenalidomide [25 mg/body on days 1–14] over 21-day cycles) and 33 received modified VRD-lite (bortezomib [1.3 mg/m2 on days 1, 8, 15, and 22) and lenalidomide [15 mg/body on days 2–7, 9–14, 16–21] over 28-day cycles). Overall response, very good partial response, and complete response rates after VRD were 96.4%, 45.5%, and 20.0%, respectively (median follow-up period, 17.7 months). The 1-year progression-free survival (PFS) and overall survival rates were 95.8% and 98.2%, respectively. The response rate and PFS were similar between the groups, regardless of cytogenetic risk and age. The incidence of peripheral neuropathy ≥ grade 2 and thrombocytopenia ≥ grade 3 was higher in the twVRD group (27.2% vs. 0.0%, P = 0.003 and 27.2% vs. 0.0%, P = 0.003). In conclusion, modified VRD-lite had similar efficacy with, but better tolerability than, twVRD in transplant-eligible patients.

Although multiple myeloma (MM) had been an incurable hematological malignancy with a poor prognosis, recent advances in novel anti-neoplastic agents, including carfilzomib (a proteasome inhibitor), have improved the prognosis. We herein report two cases of congestive heart failure in patients treated with carfilzomib. Although there are some reports on the cardiotoxicity of carfilzomib, to our knowledge, this is the first report on the cardiac involvement of carfilzomib in Japanese MM patients. We review the critical points from our two cases, with the aim of avoiding carfilzomib-associated heart failure in MM patients.

Negative immunofixation electrophoresis (IFE) of serum and/or urine is a diagnostic marker for determining a complete response (CR) after immunotherapy for multiple myeloma (MM). However, residual therapeutic antibodies such as elotuzumab (IgG-κ), can compromise IFE evaluation when the affected immunoglobulins belong to the same IgG-κ subclass. We thus sought to develop a simple and rapid method to treat patient serum before IFE to distinguish the residual elotuzumab. Serum samples from patients receiving elotuzumab were treated with a predetermined amount of soluble signaling lymphocyte activation molecule F7 (SLAMF7) protein and then subjected to conventional IFE testing. We tested our method in samples from 12 patients. The IgG-κ band in IFE disappeared or shifted after elotuzumab treatment in four patients with no bone marrow minimal residual disease and normalized free light chain, whereas seven patients with any sign of residual MM showed a remaining IgG-κ band after treatment. One-hour incubation of samples with 6-9 molar excess soluble SLAMF7 before IFE was sufficient to distinguish residual elotuzumab in 11 of 12 samples. This simple method does not require special reagents, can be performed in most clinical laboratories, and enables differentiation between patients with a CR and those requiring further treatment.

Background Congenital thrombotic thrombocytopenic purpura (cTTP), otherwise known as Upshaw-Schulman syndrome, is an extremely rare hereditary disease. Pregnancy is identified as a trigger for TTP episodes in patients with cTTP. Objectives To investigate the ideal management of pregnant patients with cTTP. Patients/methods We identified 21 patients with a reproductive history (38 pregnancies) in a Japanese cTTP registry. Fetal outcomes were compared between two groups: group 1 (n = 12), pregnancy after diagnosis of confirmed cTTP by ADAMTS13 gene analysis; and group 2 (n = 26), pregnancy before diagnosis of confirmed cTTP. Results In group 1, ADAMTS13 activity was closely monitored until delivery in most cases. Among 10 pregnancies in group 1, prophylactic fresh frozen plasma (FFP) infusions during pregnancy were performed to replenish ADAMTS13. In group 2, prophylactic FFP infusions were not administrated in 23 pregnancies and FFP test infusions were performed in only three pregnancies. The live birth rate of group 1 was significantly higher than that of group 2 (91.7% vs 50.0%, respectively, P = .027). The fetal survival rates of women without FFP infusions were dramatically decreased after 20 weeks of gestation. The FFP infusion dosage in group 1 was generally higher than 5 mL/kg/wk by 20 weeks of gestation. Conclusions Our results indicate that FFP infusions of more than 5 mL/kg/wk should be initiated as soon as patients become pregnant. However, even with these infusions, patients with repeated TTP episodes before pregnancy might have difficulty giving birth successfully. Recombinant ADAMTS13 products might be new treatment options for pregnant patients with cTTP.

Background. Eltrombopag, a nonpeptide thrombopoietin receptor agonist (TPO-RA), has been reported to be an effective therapy for chronic immune thrombocytopenia (ITP). However, a higher incidence of arterial and venous thromboembolic events was reported after using eltrombopag.Case Presentation. A 67-year-old man, treated with eltrombopag due to chronic ITP, was admitted due to acute coronary syndrome (ACS). Although coronary angiography revealed no occlusion, cardiac magnetic resonance imaging suggested a myocardial infarction in the territory of the left circumflex coronary artery. Three months after the ACS event, the obtuse marginal branches exhibited significant stenosis; hence, a percutaneous coronary intervention (PCI) was performed to implant a zotarolimus-eluting stent under the treatment of a dual antiplatelet therapy. However, stent thrombosis occurred 3 hours after PCI and required three other PCIs during the eltrombopag treatment.Conclusion. We present a case of an ITP patient, who experienced repeated coronary and stent thrombosis during the treatment with eltrombopag. We propose that the risk of ACS and consequent coronary stent thrombosis should be considered before the introduction of eltrombopag.

Lipid metabolic changes under diseased conditions, particularly in solid tumors, are attracting increased attention. However, in non-solid tumors, including most hematopoietic tumors, lipid analyses are scarce. Multiple myeloma (MM) is a plasma cell disorder arising from bone marrow, and the lipid status of MM cells has not been reported yet. In this study, we analyzed flow cytometry-sorted single MM cells and normal plasma cells (NPCs) using matrix-assisted laser desorption/ionization-imaging mass spectrometry (MALDI-IMS), a two-dimensional label-free mass spectrometry technique for biomolecular analysis, to obtain specific lipid information. We isolated 1.31-5.77% of MM cells and 0.03-0.24% of NPCs using fluorescence-activated cell sorting (FACS). Analysis of purified cells using MALDI-IMS at the single-cell level revealed that the peak intensity and ion signals of phosphatidylcholine [PC (16:0/20:4) + H](+) at m/z 782.5 were significantly decreased in MM cells compared to NPCs. By examining particular cell populations rather than cell mixtures, our method can become a suitable tool for the analysis of rare cell populations at the single-cell level and advance the understanding of MM progression.

Breast cancer is the most common cancer among women worldwide. The molecular characterization of breast tumor cells by using single-cell lipidomics remains relatively unexplored. Here, we introduce a time-of-flight secondary-ion mass spectrometry (TOF-SIMS) approach to visualize the lipids in individual breast cancer cells. The SKBR-3 breast cancer cell line was cultured and dispersed into individual cells. After attachment to a substrate, the cells were rinsed with ammonium acetate and were analyzed using TOF-SIMS. The instrument was operated with Bi32+ as the primary ion. The distributions of ions, including positively charged phosphocholine, and negatively charged phosphates and fatty acids, were simultaneously visualized. These ions were distributed predominantly at the cell attachment sites. The signal intensities of fatty acid ions were determined from the mass spectra at the regions-of-interest. The results of fatty acid analyses on breast cancer cells were consistent with those of our previous study in which prominent expression of stearoyl-CoA desaturase 1 in breast cancer cells was demonstrated. Static TOF-SIMS was shown to be an effective method for determining the lipid molecular signature of the plasma membrane of individual breast cancer cells. Copyright © 2014 John Wiley & Sons, Ltd.

Background: Among HLA-well-matched unrelated donor (UD) and umbilical cord blood (CB), HLA-8/8 allele-matched UD transplantation (UDT) showed superior overall survival (OS) to 7/8 allele-matched UDT and CBT, while a similar OS has been demonstrated between the HLA-7/8 allele-matched UDT and the CBT. However, a fair comparison between UDT and CBT is difficult, because graft availability and time required for donor-search is completely different. Once patients relapsed during UD-search period, most of those patients would choose immediate CBT. This means that patients who maintained CR in UD group may have more favorable characteristics, because those patients have been longer in remission and selected as a group of patients who maintained CR. Thus we thought that the factor of "donor-search duration" is important upon conducting a comparative study between UDT and CBT. We planned a clinical study that also taken "donor-search duration" into consideration to compare CBT outcomes with HLA well-matched UDT in a prospective trial setting. Purpose: The purpose of the current study is to compare the transplant outcomes of HLA-well-matched UDT with those of CBT in a prospective trial. Patients and Methods: From 2007 to 2015, 231 patients were provisionally registered for a single-arm phase 2 study of CBT (manuscript submitted). All provisionally registered patients were subjects of current study (Figure 1). After provisional registration, we attempted to find appropriate UD within a decent time period. After approximately 180 days of donor-search, patients received CBT if an appropriate UD was not available. In total, 91 patients received UDT, and 119 patients received CBT. Six patients withdrew and three died before transplantation. Twelve patients did not receive either UDT or CBT, but five received HLA-mismatched SCT from family donor (seven chose not to receive allogeneic SCT). Of 119 CBT recipients, 62 patients were eligible and registered to a phase 2 clinical trial reported elsewhere. Herein we analyzed transplant outcomes of 91 UDT and 119 CBT (UDT group; 49 AML, 37 ALL, 5 MDS: CBT group; 68 AML, 38 ALL, 13 MDS). Risk factors were analyzed by cox proportional hazard model, and survival estimates were depicted by Kaplan-Meier estimation and tested by log-rank test. Results: Patient age was median 39 yrs in both UDT and CBT (p=0.80). Patient body weight was median 59kg (37-90kg) in UDT, and median 55kg (35-90kg) in CBT (p=0.10). Sixty-six of 91 (72.5%) in UDT and 114 of 119 (95.8%) in CBT received myeloablative conditioning. More than 90% of patients received Tacrolimus and short-term methotrexate as GVHD prophylaxis in both UDT and CBT. Days from provisional registration to transplant were median 126 days (range, 77-261 days) in UDT, and median 99 days (8-286 days) in CBT (p Conclusion: Taken donor-search period into consideration, OS after UDT and CBT were similar in a prospective clinical study. CB may be the comparable alternative donor source to UDT. Disclosures Terakura: Novartis: Honoraria; Astellas Pharma Inc.: Honoraria; Amgen Astellas BioPharma K.K.: Honoraria; Sumitomo Dainippon Pharma: Honoraria; Chugai Pharmaceutical Co., Ltd.: Honoraria; Yakult Honsha, Co., Ltd.: Honoraria; Otsuka Pharmaceutical Co., Ltd.: Honoraria. Nishida:Sumitomo Dainippon Pharma Co., Ltd.: Honoraria; Takeda Pharmaceutical Co., Ltd.: Honoraria; MSD K.K.: Consultancy, Honoraria; Amgen Astellas BioPharma K.K.: Honoraria. Sawa:Mundi Pharma: Honoraria; Bristol-Myers Squibb: Honoraria; Sumitomo Dainippon Pharma: Honoraria; Sanofi: Honoraria; Astellas Pharma Inc.: Honoraria; Ono Pharmaceutical Co., Ltd: Honoraria; Otsuka Pharmaceutical: Honoraria; Kyowa-Hakko Kirin: Honoraria; Novartis: Honoraria; Shire: Honoraria; Eisai: Honoraria; Mochida: Honoraria; Pfizer Japan Inc.: Honoraria; Chugai Pharmaceutical Co., Ltd.: Honoraria; Nippon Shinyaku: Honoraria; MSD: Honoraria; Asahi-Kasei: Honoraria; Takeda: Honoraria; Celgene: Honoraria. Miyao:Bristol-Myers Squibb: Honoraria; Celgene Corporation: Honoraria; Novartis: Honoraria. Ozawa:Pfizer Japan Inc.: Honoraria; Kyowa-Hakko Kirin: Honoraria; Astellas Pharma Inc.: Honoraria; Novartis: Honoraria. Goto:Celgene Co., Ltd.: Honoraria; JCR Pharmaceuticals Co., Ltd.: Honoraria; Novartis Pharma Co., Ltd.: Honoraria; Takeda Pharmaceutical Co., Ltd.: Honoraria. Onishi:Sumitomo Dainippon Pharma: Honoraria; Janssen Pharmaceutical K.K.: Honoraria; Chugai Pharmaceutical Co., Ltd.: Honoraria; Bristol-Myers Squibb: Honoraria, Research Funding; ONO PHARMACEUTICAL CO., LTD.: Honoraria; Nippon Shinyaku: Honoraria; Kyowa-Hakko Kirin: Honoraria; Pfizer Japan Inc.: Honoraria; Astellas Pharma Inc.: Honoraria; Celgene: Honoraria; Otsuka Pharmaceutical Co., Ltd.: Honoraria; Novartis Pharma: Honoraria; Takeda Pharmaceutical Co., Ltd.: Research Funding; MSD: Honoraria, Research Funding. Fukuhara:Janssen Pharma: Honoraria; Eisai: Honoraria, Research Funding; Chugai Pharmaceutical Co., Ltd.: Honoraria; AbbVie: Research Funding; Celgene Corporation: Honoraria, Research Funding; Zenyaku: Honoraria; Bayer: Research Funding; Nippon Shinkyaku: Honoraria; Kyowa-Hakko Kirin: Honoraria; Mochida: Honoraria; Mundi: Honoraria; Ono Pharmaceutical Co., Ltd.: Honoraria; Takeda Pharmaceutical Co., Ltd.: Honoraria, Research Funding; Gilead: Research Funding; Solasia Pharma: Research Funding. Fujii:Novartis Pharma Co., Ltd.: Honoraria; Kyowa-Hakko Kirin Co., Ltd.: Honoraria. Iida:Chugai Pharmaceutical Co., Ltd.: Research Funding. Endo:Ono: Research Funding. Onizuka:Sumitomo Dainippon Pharma: Research Funding; Astellas: Research Funding; Novartis: Research Funding; pfizer: Research Funding; Chugai Pharma: Research Funding; Bristol-Myers Squibb: Research Funding. Iyama:Otsuka Pharmaceutical Co., Ltd.: Honoraria; Otsuka Pharmaceutical Factory: Honoraria; Astellas Pharma: Honoraria; Daiichi Sankyo: Honoraria; Allexion Pharma: Honoraria; CSL Behring: Honoraria. Nakamae:Japan Blood Products Organization: Honoraria; Chugai Pharmaceutical Co., Ltd.: Honoraria, Membership on an entity's Board of Directors or advisory committees; Otsuka Pharmaceutical: Honoraria, Membership on an entity's Board of Directors or advisory committees; Kyowa-Hakko Kirin Co.,Ltd: Honoraria; Nippon Shinyaku: Honoraria; Bristol-Myers Squibb: Honoraria; Shire Japan KK.: Honoraria; Pfizer Japan Inc.: Honoraria, Membership on an entity's Board of Directors or advisory committees; Astellas Pharma Inc.: Research Funding; Alexion: Honoraria; Celgene: Honoraria; Janssen: Honoraria; Novartis: Honoraria, Research Funding; Takeda Pharmaceutical Co., Ltd.: Honoraria. Nagata:Janssen Pharmaceutical K.K.: Honoraria; Bristol-Myers Squibb K.K.: Honoraria; Ono Pharmaceutical Co., Ltd: Honoraria; Novartis Pharma K.K.: Honoraria; Celgene K.K.: Honoraria; Takeda Pharmaceutical Co., Ltd: Honoraria, Membership on an entity's Board of Directors or advisory committees. Kurahashi:Novartis Pharma Co., Ltd.: Honoraria; Bristol-Myers Squibb, Ltd.: Honoraria; Sumitomo Dainippon Pharma Co., Ltd.: Honoraria; Takeda Pharmaceutical Co., Ltd: Honoraria. Suzuki:Celgene: Honoraria; Eisai: Honoraria; Novartis: Honoraria; Bristol-Myers Squibb: Honoraria; Kyowa Hakko Kirin: Honoraria; Chugai Pharmaceutical Co.,Ltd.: Honoraria; Meiji Seika: Honoraria; Merck Sharp & Dohme: Honoraria; Takeda Pharmaceutical Co., Ltd.: Honoraria; ONO Pharmaceutical Co., Ltd.: Honoraria; Janssen: Honoraria; AbbVie: Honoraria. Atsuta:Mochida Pharmaceutical Co. Ltd: Honoraria; Kyowa Kirin Co., Ltd: Honoraria; Chugai Pharmaceutical Co., Ltd.: Honoraria; Janssen Paharmaceutical K.K.: Honoraria. Miyamura:Bristol-Myers Squibb: Honoraria; Novartis: Honoraria; Pfizer Japan Inc.: Honoraria; Otsuka Pharmaceutical: Honoraria; Takeda Pharmaceutical: Honoraria; Kyowa-Hakko Kirin Co., Ltd: Honoraria; CHUGAI PHARMACEUTICAL CO., LTD.: Honoraria; Astellas Pharma Inc.: Honoraria; Celgene: Honoraria. Murata:Bristol-Myers Squibb, Ltd.: Honoraria; Kyowa-Hakko Kirin Co., Ltd.: Honoraria; Celgene Co., Ltd.: Honoraria; Sumitomo Dainippon Pharma Co., Ltd.: Consultancy, Honoraria; GSK Co., Ltd.: Consultancy; Astellas Pharma Inc.: Honoraria; Chugai Pharmaceutical Co., Ltd.: Honoraria; Otsuka Pharmaceutical Co., Ltd.: Honoraria; JCR Pharmaceuticals Co., Ltd.: Honoraria; Novartis Pharma Co., Ltd.: Honoraria; MSD Co., Ltd.: Honoraria.

Influenza virus infection can cause fatal complications (e.g., pneumonia) in immunodeficient long-term survivors of allogeneic hematopoietic stem cell transplantation (allo-HSCT). The immune response to the vaccine improves if it is administered at >1 year after allo-HSCT, although the response may vary according to the patient’s immune status. We sought to identify predictors of immune response to trivalent inactivated influenza vaccine (TIV) among patients vaccinated at >1 year after allo-HSCT. We included 27 allo-HSCT recipients, with a median interval of 4.3 years (range 1.0–10.1 years) from transplantation to vaccination. Nineteen patients achieved a response to TIV, although a low immune response to TIV was significantly associated with calcineurin inhibitor treatment, and moderate chronic graft-versus-host disease and IgM levels of

A 60-year-old man with Waldenström's macroglobulinemia (WM) was admitted to our hospital for evaluation of rapid progressive renal deterioration despite 3 cycles of oral melphalan and prednisolone (MP) therapy. Renal biopsy just before introducing hemodialysis revealed cast nephropathy and severe tubulo-interstitial infiltration of B lymphocytes. After 6 cycles of rituximab, cyclophosphamide, vincristine and prednisolone (R-COP) therapy, his renal function improved enough to discontinue hemodialysis. This is a rare case of WM-related renal involvement caused by both monoclonal protein and tumor infiltration and, to our knowledge, the second report on improved renal function by rituximab-based therapy.

Chronic myelogenous leukemia (CML) is characterized by a reciprocal chromosomal translocation (9;22) that generates the Bcr-Abl fusion gene. BCR-ABL transforming activity is mediated by critical downstream signaling pathways that are aberrantly activated by tyrosine kinases. However, the mechanisms of BCR-ABL anti-apoptotic effects and the signaling pathways by which BCR-ABL influences apoptosis in BCR-ABL-expressing cells are poorly defined. In this study, we found that treatment with ABL kinase inhibitors or depletion of BCR-ABL induced the expression of RAB45 messenger RNA and protein and induced apoptosis via reduction of mitochondrial membrane potential and p38 activation in CML cell lines and BCR-ABL + progenitor cells from CML patients. Overexpressed RAB45 induced the activation of caspases-3 and -9 and reduced the expression of Survivin, XIAP, c-IAP1 and c-IAP2 in CML cells. Moreover, in colony-forming cells derived from CML-aldehyde dehydrogenase hi / CD34 + cells, treatment with ABL kinase inhibitors induced RAB45 expression and reduced mitochondrial membrane potential, resulting in inhibited colony formation of Bcr-Abl + progenitor cells. The overexpression of RAB45 significantly decreased colony numbers and induced apoptosis through the activation of caspases-3 and -9. Furthermore, the overexpression of RAB45 increased the phosphorylation levels of p38, resulting in the induction of apoptosis and inhibition of proliferation of CML progenitor cells. Our results identify a new signaling molecule involved in BCR-ABL modulation of apoptosis and suggest that RAB45 induction strategies may have therapeutic utility in patients with CML.

Bcr-Abl activates various signaling pathways in chronic myelogenous leukemia (CML) cells. The proliferation of Bcr-Abl transformed cells is promoted by c-Myc through the activation of Akt, JAK2 and NF-κB. However, the mechanism by which c-Myc regulates CML cell proliferation is unclear. In our study, we investigated the role of Thanatos-associated protein 11 (THAP11), which inhibits c-Myc transcription, in CML cell lines and in hematopoietic progenitor cells derived from CML patients. The induction of THAP11 expression by Abl kinase inhibitors in CML cell lines and in CML-derived hematopoietic progenitor cells resulted in the suppression of c-Myc. In addition, over-expression of THAP11 inhibited CML cell proliferation. In colony forming cells derived from CML-aldehyde dehydrogenase (ALDH)(hi) /CD34(+) cells, treatment with Abl kinase inhibitors and siRNA depletion of Bcr-Abl induced THAP11 expression and reduced c-Myc expression, resulting in inhibited colony formation. Moreover, overexpression of THAP11 significantly decreased the colony numbers, and also inhibited the expression of c-myc target genes such as Cyclin D1, ODC and induced the expression of p21(Cip1) . The depletion of THAP11 inhibited JAK2 or STAT5 inactivation-mediated c-Myc reduction in ALDH(hi) /CD34(+) CML cells. Thus, the induced THAP11 might be one of transcriptional regulators of c-Myc expression in CML cell. Therefore, the induction of THAP11 has a potential possibility as a target for the inhibition of CML cell proliferation.