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Introduction: Tyrosine kinase inhibitors (TKIs) dramatically improved the prognosis of chronic myelogenous leukemia (CML), as nearly half of CML patients presenting with a deep molecular response (DMR) over several years could achieve treatment-free remission. DASISION study reported dasatinib (DAS), a second-generation TKI was superior to imatinib to achieve faster and deeper response in treating newly-diagnosed chronic CML. However, standard initial dosage of 100 mg DAS/day might be too potent for patients aged >70 years with CML, possibly owing to the presence of other health conditions that threaten the life spans (e.g., lung and cardiovascular disease), thereby preventing TKI continuation. In this open-label, multicenter, single-arm, phase 2 study (DAVLEC), we evaluated the efficacy and safety of a reduced initial dose of DAS (20 mg/day) in the elderly with chronic CML. Patients and Methods: We included CML patients aged >70 years with an ECOG performance status of 0-2 and adequate organ function. After diagnosis, they began orally taking 20 mg of DAS per day. BCR-ABL mRNA values were measured and aligned to an international scale at a central laboratory to evaluate the drug's efficacy at 3, 6, 9, and 12 mo of therapy, per recommendations by European LeukemiaNet. The dosage was maintained in case of the optimal, increased by 20 mg/day when the warning appeared and could be decreased when an adverse event (AE) > grade 3 appeared. Patients were excluded if the respond was the failure or disease progression was detected. Primary endpoint was the cumulative major molecular response (MMR) rate at 12 mo. Secondary endpoints included the rates of the cumulative DMR, treatment discontinuation due to AEs, and failure to DAS treatment or disease progression. The non-inferiority of primary endpoint MMR (non-inferiority limit of 38%) was evaluated by binomial test with normal approximation. Other differences were investigated by Mann-Whitney tests, with p < 0.05 indicating significance. Results: Among the 56 patients enrolled from 25 centers, 4 declined participation, and so 52 (median age, 77.5 years) began taking 20 mg/day of DAS. In total, 73.1% of the patients had comorbidities. Median BCR-ABL values at 3, 6, and 12 mo were 1.47%, 0.23%, and 0.03%, respectively; cumulative MMR rate at 3, 6, 9, and 12 mo were 11.5%, 36.5%, 40.4%, and 59.6%, respectively. Calculated MMR at 12 mo was higher than 38%, a value selected based upon findings from the DASISION trial, accounting for a non-inferiority margin of 10% (p=0.047). At 12 mo, among the 31 patients achieving MMR, 23 were only given 20 mg DAS/day, and 14 and 7 respectively achieved MR4.0 and 4.5. Patients discontinued the study due to treatment failure (n=3), content withdrawal (n=2), drug-related AEs (Long QT Syndrome; n=1), or others (n=2). No patient discontinued it due to disease progression. Treatment-related AEs of all grades were noted in 96.2%and that of grade 3 or 4 events in 23.1% of the patients. Median dose interruptions for a median of 7 days (range: 5-36) were respectively noted in 3 and 2 patients due to hematological and non-hematological AEs. Furthermore, 4 patients experienced pleural effusion < grade 2, and 1 had lymphocytosis. Patients who achieved MMR at 12 mo (n=31) had a significantly lower BCR-ABL value at 3 mo (0.41% vs. 4.26%, p=0.0020) and a lower halving time from diagnosis to 3 mo (11.35 vs. 18.34 days, p=0.0050) than those who did not (n=21). Patients who achieved MMR by 12 mo with only 20 mg/day of DAS (n=23) had lower BCR-ABL values at 1 and 3 mo (25.51 vs. 63.63 %, p=0.00028; 0.33 vs. 5.89%, p Patients who achieved MMR at 12 mo (n=31) had higher plasma DAS concentration (23.5 vs. 8.0 ng/mL, p Conclusion: This study discovered that prescribing a starting very-low dose DAS (20 mg/day) while monitoring IS and AEs was a successful initial therapeutic strategy for the elderly with chronic CML comparable to previous studies using standard-dose. Notably, rapid BCR-ABL downregulation, early molecular responses at 1 and 3 mo, a shortened halving time from diagnosis to 3 mo, and sufficient increase in plasma DAS concentrations 2 h post-intake after 12 mo of treatment were key indicators for successful low-dose therapy. Disclosures Kumagai: Bristol-Myers Squibb: Honoraria; Novartis: Honoraria, Speakers Bureau; Pfizer: Honoraria; Otsuka Pharmaceuticals: Honoraria, Speakers Bureau. Murai: Bristol Myers Squibb: Honoraria; Otsuka Pharmaceutical Co., Ltd.: Honoraria; Novartis Pharma: Honoraria; Pfizer: Honoraria; CHUGAI Pharmaceutical Co., Ltd.: Honoraria; TAKEDA Pharmaceutical Co., Ltd.: Honoraria; DAIICHI SANKYO COMPANY, LIMITED.: Honoraria; ONO PHARMACEUTICAL CO., LTD.: Honoraria; Asahi Kasei Pharma Corporation.: Honoraria. Tanaka: Bristol-Myers Squibb: Honoraria; Novartis: Honoraria; Pfizer: Honoraria; Otsuka Pharmaceuticals: Honoraria. Nishiwaki: Kyowa-Kirin: Research Funding; Alexion: Honoraria. Inokuchi: Bristol-Myers Squibb: Research Funding. Yoshida: Bristol-Myers Squibb: Honoraria, Research Funding; Novartis KK,: Honoraria; Pfizer Japan Inc.: Honoraria; Otsuka Pharmaceutical.: Honoraria; AbbVie GK: Honoraria; Janssen Pharmaceutical KK: Honoraria; Nippon Shinyaku: Honoraria; Chugai Pharmaceutical Co., Ltd.: Honoraria. Uoshima: Janssen: Honoraria; Eisai: Honoraria. Usuki: MSD K.K.: Research Funding, Speakers Bureau; Eisai Co., Ltd.: Speakers Bureau; Alexion Pharmaceuticals, Inc.: Research Funding, Speakers Bureau; Pfizer Japan Inc.: Research Funding, Speakers Bureau; Kyowa-Kirin Co., Ltd.: Research Funding, Speakers Bureau; Nippon-Shinyaku Co., Ltd.: Research Funding, Speakers Bureau; Amgen-Astellas Biopharma K.K.: Research Funding; Mundipharma K.K.: Research Funding; Nippon-Boehringer-Ingelheim Co., Ltd.: Research Funding; Takeda Pharmaceutical Co., Ltd.: Research Funding, Speakers Bureau; Celgene K.K.: Research Funding, Speakers Bureau; Janssen Pharmaceutical K.K.: Research Funding; Ono Pharmaceutical Co., Ltd.: Research Funding, Speakers Bureau; Novartis Pharma K.K.: Research Funding, Speakers Bureau; Otsuka Pharmaceutical Co., Ltd.: Research Funding, Speakers Bureau; Sumitomo-Dainippon Pharma Co., Ltd.: Research Funding; Daiichi Sankyo Co., Ltd.: Research Funding, Speakers Bureau; SymBio Pharmaceuticals Ltd.: Research Funding, Speakers Bureau; Gilead Sciences, Inc.: Research Funding; AbbVie GK: Research Funding, Speakers Bureau; Astellas Pharma Inc.: Research Funding, Speakers Bureau; PharmaEssentia Japan KK: Research Funding, Speakers Bureau; Yakult Honsha Co., Ltd.: Research Funding, Speakers Bureau; Bristol-Myers-Squibb K.K.: Research Funding, Speakers Bureau; Apellis Pharmaceuticals, Inc.: Research Funding; Incyte Biosciences Japan G.K.: Research Funding; Chugai Pharmaceutical Co., Ltd.: Research Funding, Speakers Bureau; Sanofi K.K.: Speakers Bureau; Amgen K.K.: Research Funding. Kuroda: Otsuka Pharmaceutical: Honoraria, Research Funding; Astellas Pharma: Honoraria, Research Funding; Takeda: Honoraria, Research Funding; Celgene: Consultancy, Honoraria, Research Funding; MSD: Research Funding; Abbvie: Consultancy, Honoraria; Ono Pharmaceutical: Honoraria, Research Funding; Eisai: Honoraria, Research Funding; Sysmex: Research Funding; Pfizer: Honoraria, Research Funding; Fujimoto Pharmaceutical: Current Employment, Honoraria, Research Funding; Taiho Pharmaceutical: Research Funding; Asahi Kasei: Research Funding; Shionogi: Research Funding; Nippon Shinyaku: Honoraria, Research Funding; Janssen Pharmaceutical K.K: Consultancy; Bristol-MyersSquibb: Consultancy, Honoraria, Research Funding; Chugai Pharmaceutical: Honoraria, Research Funding; Dainippon Sumitomo Pharma: Honoraria, Research Funding; Daiichi Sankyo: Honoraria, Research Funding; Sanofi: Consultancy, Honoraria, Research Funding; Kyowa Kirin: Honoraria, Research Funding. Ono: Chugai Pharmaceutical Co., Ltd.: Honoraria, Research Funding; Kyowa Kirin Co., Ltd.: Honoraria, Research Funding; Novartis Pharma KK: Honoraria; Otsuka Pharmaceutical Co., Ltd.: Honoraria; DAIICHI SANKYO COMPANY, LIMITED.: Honoraria; Mundipharma K.K.: Honoraria; TAIHO PHARMACEUTICAL CO., LTD.: Research Funding; Merck Sharp & Dohme: Honoraria, Research Funding; Astellas Pharma Inc.: Honoraria; Eisai Co., Ltd.: Honoraria; Janssen Pharmaceutical K.K: Honoraria; Takeda Pharmaceutical Company Limited.: Honoraria; ONO PHARMACEUTICAL CO., LTD.: Honoraria, Research Funding; Pfizer Japan Inc.: Honoraria; Bristol-Myers Squibb Company: Honoraria; Celgene: Honoraria, Research Funding. Fujimaki: CSL Behring K.K.: Honoraria; Mundipharma K.K.: Honoraria; Takeda Pharmaceutical Company Limited: Honoraria; Meiji Seika Pharma Co., Ltd.: Honoraria; Janssen Pharmaceutical KK: Honoraria; AbbVie GK: Honoraria; Bristol-Myers Squibb: Honoraria; Novartis KK: Honoraria; Nippon Shinyaku: Honoraria; Chugai Pharmaceutical Co., Ltd.: Honoraria; Pfizer Japan Inc.: Honoraria; Otsuka Pharmaceutical.: Honoraria. Shibayama: Chugai: Research Funding; Eizai: Speakers Bureau; Nippon Shinyaku: Speakers Bureau; Kyowa Kirin: Speakers Bureau; AbbVie: Research Funding; Celgene: Research Funding; Novartis: Research Funding, Speakers Bureau; Ono: Research Funding, Speakers Bureau; Janssen: Research Funding, Speakers Bureau; Bristol-Myers Squibb: Speakers Bureau; Mundi Pharma: Speakers Bureau; Otsuka: Speakers Bureau; Sanofi: Research Funding, Speakers Bureau; AstraZeneca: Research Funding, Speakers Bureau; Takeda: Speakers Bureau. Kondo: Abbvie: Honoraria; Astellas Pharma Inc.: Consultancy, Honoraria; Otsuka Pharmaceutical: Consultancy, Honoraria, Research Funding; Novartis Pharma KK: Honoraria; Bristol-Myers Squibb Company: Honoraria; Sumitomo Dainippon Pharma: Honoraria; Sanwa Kagaku Kenkyusho CO.,LTD: Consultancy; Pfizer: Honoraria. Minami: Bristol-Myers Squibb Company: Honoraria; Novartis Pharma KK: Honoraria; Pfizer Japan Inc.: Honoraria; Takeda: Honoraria; Astellas: Honoraria; Ono: Research Funding; CMIC: Research Funding. Kimura: Eisai: Speakers Bureau; Kyowa-Kirin: Research Funding, Speakers Bureau; PharmaEssentia: Speakers Bureau; Astellas: Speakers Bureau; Sanifi: Speakers Bureau; Gilead: Research Funding; Nippon-Boehringer-Ingelheim: Research Funding; Celgene: Research Funding, Speakers Bureau; Sumitomo-Dainippon: Research Funding; Chugai: Research Funding, Speakers Bureau; Mundi: Research Funding; Yakult: Research Funding, Speakers Bureau; MSD: Research Funding, Speakers Bureau; Ono: Research Funding, Speakers Bureau; SymBio: Research Funding, Speakers Bureau; Daiichi-Sankyo: Research Funding, Speakers Bureau; Janssen: Research Funding; Astellas-Amgen-Biopharma: Research Funding; Takeda: Research Funding, Speakers Bureau; Nippon-Shinyaku: Research Funding, Speakers Bureau; Amgen: Research Funding; Alexion: Research Funding, Speakers Bureau; Incyte: Research Funding; Novartis: Honoraria, Research Funding, Speakers Bureau; Bristol-Myers Squibb: Honoraria, Research Funding, Speakers Bureau; Pfizer: Honoraria, Research Funding, Speakers Bureau; Otsuka Pharmaceutical: Honoraria, Research Funding, Speakers Bureau; Ohara Pharmaceutical: Research Funding; Astellas Pharma: Research Funding; AbbVie: Research Funding, Speakers Bureau; Apellis: Research Funding.

BACKGROUND: The overall survival of patients with newly diagnosed chronic myeloid leukemia (CML) has improved significantly since the introduction of tyrosine kinase inhibitors (TKIs), and recently, some patients with CML who achieve stable deep molecular response (DMR) to TKI therapy could safely suspend treatment. In addition to European LeukemiaNet criteria (ELN), the European Society for Medical Oncology (ESMO) proposed that less than 0.01% of BCR-ABL1 transcript (MR4.0) on the International Scale (IS) after 18 months is optimal for patients to achieve treatment-free remission. Branford et al. indicated that major molecular response (MMR; less than or equal to 0.1% of BCR-ABL1 IS ; MR3.0) at three months predicts stable undetectable BCR-ABL1 transcript levels during imatinib treatment. However, second-generation TKIs induce more rapid and deeper responses at early time points compared to imatinib; however, whether early molecular response predicts MR4.0 by 18 months to second-generation TKI therapy, remains unclear. AIMS: We retrospectively analyzed BCR-ABL1 transcript levels in patients with CML in chronic phase (CML-CP) at 3, 6, 12, and 18 months after initiating dasatinib treatment to identify molecular milestones that would predict MR4.0 by 18 months. METHODS: Fifty-nine newly diagnosed patients with CML-CP were included in this study. The median age was 61 years (18-81 years), 72% of whom were males, and patients older than 65 years comprised 31% of the overall enrollment. Eighty-six percent of them had low and intermediate Sokal scores. Patients received 100 mg of dasatinib once daily. Dose interruption or reduction was allowed if drug-related grade 3 non-hematological toxicity or grade 3 or worse hematological toxicity occurred.BCR-ABL1/ ABL ratio IS (BCR-ABL1 IS) was performed at approximately 3-month intervals. To assess the kinetics of response, we calculated halving time (HT) of BCR-ABL1 IS. HT-BCR-ABL1 was calculated as described by Branford et al. We used a receiver-operating characteristic (ROC) curve to identify the cut-offs in transcript levels at three and six months. Mann-Whitney test was used to determine statistical significance. Categorical variables were compared using Fisher's exact test. Factors were subjected to multivariate analysis using Cox regression; differences with p RESULTS: The median BCR-ABL1 IS level before therapy was 82.1% (range 13.5-157.9 %). The estimated MMR by 12 months and MR4.0 by 18 months were 86.4% and 50.8%, respectively. We analyzed each into a cohort that achieved MR4.0 by 18 months (MR4.0 cohort) and a cohort that did not achieve MR4.0 (non-MR4.0 cohort). The BCR-ABL1 IS level in each cohort is indicated in the Table. Median HT-BCR-ABL1 IS 0-3 months was 10.8 days (6.5-71.3 days) in MR4.0 cohort, and 13.0 days (8.5- 169.6 days, p CONCLUSION: Even though dasatinib is highly-priced, dasatinib treatment results in higher rates of molecular responses in newly diagnosed patients with CML-CP. Assessment of molecular reduction within six months has become an important landmark to predict MR4.0 by 18 months during dasatinib treatment for patients with the aim to achieve treatment-free remission. Disclosures Oyake: Astellas: Speakers Bureau; Celgene: Honoraria; Chugai: Honoraria; Kyowa-Hakko Kirin: Honoraria. Ito:Bristol-Myers Squibb: Honoraria; Celgene: Honoraria; Ono: Honoraria.

Menin functions as a critical oncogenic cofactor of mixed lineage leukemia (MLL) fusion proteins in the development of acute leukemias, and inhibition of the menin interaction with MLL fusion proteins represents a very promising strategy to reverse their oncogenic activity. MLL interacts with menin in a bivalent mode involving 2 N-terminal fragments of MLL. In the present study, we reveal the first high-resolution crystal structure of human menin in complex with a small-molecule inhibitor of the menin-MLL interaction, MI-2. The structure shows that the compound binds to the MLL pocket in menin and mimics the key interactions of MLL with menin. Based on the menin–MI-2 structure, we developed MI-2-2, a compound that binds to menin with low nanomolar affinity (Kd = 22nM) and very effectively disrupts the bivalent protein-protein interaction between menin and MLL. MI-2-2 demonstrated specific and very pronounced activity in MLL leukemia cells, including inhibition of cell proliferation, down-regulation of Hoxa9 expression, and differentiation. Our results provide the rational and essential structural basis to design next generation of inhibitors for effective targeting of the menin-MLL interaction in leukemia and demonstrate a proof of concept that inhibition of complex multivalent protein-protein interactions can be achieved by a small-molecule inhibitor.

Both clonal hematopoiesis as defined by genomic alteration and morphological cell dysplasia is a hallmark of pathology of myelodysplastic syndrome (MDS). Studies showed that, red cell distribution width (RDW), a quantitative non-subjective index of red cell anisocytosis, has diagnostic significance in anemia associated with MDS. Our recent study showed that increase of RDW has close association with dyserythropoiesis and also shorter overall survival (OS) in refractory anemia (Leuk Res 2018;67:56-59). To explore the clinical significance of RDW in MDS without increased blasts, we examined the details of correlation between RDW and morphological dysplasia which characterize MDS. We retrospectively analyzed 101 MDS patients, including 66 patients without increased blasts (blasts in the bone marrow of less than 5% and the peripheral blood of 1% or less). RDW was calculated using automated blood cell analyzer. Dysplasia was assessed according to the WHO 2008 classification by different two investigators. 100 cells (at least 25 cells) of myeloid and erythroid series were counted. At least 25 cells of megakaryocyte were also counted. Karyotype of bone marrow cells was analyzed by using routine G-band technique and categorized according to MDS cytogenetic scoring system. Correlations of RDW and clinical variables were analyzed. Based on previous study, MDS patients was divided into two groups, RDW-H (RDW was 15% or more, 48 cases) and RDW-L (RDW was lower than 15%, 18 cases). Comparisons of dysplasia or OS between these two groups were analyzed. In MDS without increase of blasts, weak inverse correlation was found between RDW and hemoglobin (rs = −0.31, P = 0.01). RDW was correlated with the presence of ring sideroblasts (RS) in the bone marrow (rs = 0.40, P = 0.001), and also weakly correlated with budding of nucleus of erythroblasts (rs = 0.33, P = 0.007). Dysgranulopoiesis was less observed than either dyserythropoiesis or dysmegakaryopoiesis (P Table showed the subtype of MDS, details of morphological dysplasia. Between two groups, RDW-H showed significantly higher percentages of dyserythropoiesis, dysgranulopoiesis, and dysmegakaryopoiesis. The increased RDW (≥15.0%) was associated with shorter OS (P = 0.02) (hazard ratio, 1.15e + 9 (95% confidence interval = 2.49-2.49)) (Figure). In contrast, there was no association between RDW and OS in MDS patients with increased blasts. Earlier studies showed increase of RDW was evident in refractory anemia with ring sideroblasts (RARS) which showed erythrocyte anisocytosis called dimorphism. Revised WHO classification (2017) defined MDS-RS with single lineage dysplasia (MDS-RS-SLD) which is characterized with specific mutation of splicing factors, such as SF3B1 and with favorable prognosis. This classification also defined MDS-RS with multi lineage dysplasia (MDS-RS-MLD) which has additional dysplasia in myeloid and/or megakaryocyte lineage in addition to RS. Pathology of MDS-RS-MLD is still to be remained. Our findings partly agree the earlier observations, showing close association between red cell anisocytosis evaluated with increase of RDW and the presence of RS. Furthermore, RDW-H group contained MDS with dysplasia of myeloid and/or megakaryocyte lineage not limited to the erythroid dysplasia(s) with RS. RDW could discriminate MDS-MLD with poor prognosis from MDS-SLD with favorable prognosis. To explore the significance of RDW in MDS, it is necessary to study large number of patient combined with genetic analysis. Nevertheless, RDW is potentially simple and useful laboratory parameters in clinical practice in MDS, representing hematopoietic defect (ineffective hematopoiesis), associated with iron metabolism and hemoglobin synthesis in MDS. Disclosures No relevant conflicts of interest to declare.

(INTRODUCTION) Several clinical studies have revealed that dasatinib demonstrated deep and fast responses. We report a phase II study to evaluate the efficacy and safety of dasatinib in patients with newly diagnosed chronic-phase chronic myeloid leukemia (CML-CP) in Japan (IMIDAS PART2 study). (PATIRNTS AND METHODS) Between July 2011 and June 2013, a total of 79 consecutive patients with CML-CP received 100 mg dasatinib daily as a first-line therapy. Treatment was continued until disease progression or until toxicity became unacceptable. The primary end-point was the rate of major molecular response by 12 months. Secondary end-points included the rate of complete cytogenetic response, rate of molecular responses with a 4.5 log reduction (MR4.5) by 12 months, and adverse events. The median age was 62 years, ranging from 27 to 80 years. Patients older than 65 years comprised 41.7% of all patients. Two-thirds of patients (68.4%) were male. Nearly all patients were ECOG performance status 0. Most patients (83.6%) had low and intermediate Sokal scores. The BCR-ABL1 International Scale (BCR-ABL1 IS) in the peripheral blood was measured by the central laboratory center (BML, Tokyo, Japan). (RESULTS) The median BCR-ABL1 IS before therapy was 54.0% (7.8-230.2). Seventy patients (88.6%) received dasatinib therapy for 12 months. The median BCR-ABL1 ISs were 0.25 % at 3 months (range 0.0002-52.2 %, n =77), 0.03 % at 6 months (range not detected-29.2 %, n = 75) and 0.008 % at 12 months (not detected -0.86 %, n = 70). MMR rate was 77.2% (95% CI, 67.9-86.5 %) by 12 months. The rates of CCyR and MR4.5 by 12 months were 88.6% (95% CI; 81.5-95.7 %) and 35.4% (95% CI; 24.8-46.1 %), respectively (Figure 1). Multivariate analysis of MMR or MR4.5 by 12 months showed that female sex (odds ratio 1.1, P = 0.92, odds ratio 1.7, P = 0.35, respectively), low and intermediate Sokal score (odds ratio 0.9, P = 0.90, odds ratio 3.2, P =0.23, respectively), and BCR-ABL1 IS less than 54% at diagnosis (RR =odds ratio 0.8, P = 0.74, odds ratio 0.7, P = 0.55, respectively) were not significantly correlated with MMR by 12 months nor MR4.5 by 12 months (Table 1). However, patients who were more than 62 years old were significantly correlated with MR4.0 and MR4.5 by 12 months (odds ratio 2.8, P =0.04, odds ratio 3.5, P =0.01). Treatment-related all AEs were reported in 98.7% patients (78 of 79). Grade 3/4 non-hematologic AEs were observed in only a few cases. Lymphocytosis (more than 4x 109/L) was observed in 34.1% of patients, which was within grade 2. Only 9 patients withdrew the study because of adverse events (4 patients), ineffectiveness (3 patients), and others (2 patients). (DISCUSSION AND CONCLUSION) The incidence of lymphocyte predominance may depend on a history of previous cytomegalovirus (CMV) infection in CML-CP patients (Leukemia. 2011 25(10): 1587-97). Although the frequency of CMV-positive patients was unknown in this study, that of blood donors in Japan was almost positive in the ages with 60s or older. The median age of CML-CP patients in this study was 62 years. Therefore, we assumed that some immunological effects induced by dasatinib might have improved the clinical efficacy in Japanese CML-CP patients compared to those worldwide. Our phase II study to evaluate the efficacy and safety of dasatinib in patients with newly diagnosed CML-CP in Japan revealed that the first-line dasatinib treatment of CML-CP leads to earlier achievement of MMR and MR4.5 with high safety. Elder age patients (>62 years) were significantly associated with achievement of MR4.5. Disclosures Shindo: Sysmex Corporation: Research Funding. Sakamoto:Yakult: Other: Remuneration; Takeda Pharmaceutical: Consultancy.

Background: Invasive fungal infections (IFIs) incur significant morbidity and mortality in neutropenic patients with hematological malignancies (HEM) after chemotherapy. The risk for these infections is related to the intensity and duration of neutropenia, and varies from 2% to 40%. Mortality rates associated with documented IFIs are considerable, reportedly ranging from 30% to 60%. Empirical antifungal therapy is the standard care for neutropenic patients with HEM, who remain febrile despite broad-spectrum antibacterial treatment. Several antifungal agents including voriconazole (VRCZ) or liposomal amphotericin B (L-AMB) have been studied as empirical therapy for febrile neutropenia (FN). However, limited data are available concerning the efficacy of micafungin (MCFG) in FN patients with acute myeloid leukemia (AML). Methods: We conducted a randomized, cooperative group, open-label trial comparing MCFG (150 mg once daily) with L-AMB (2.5 mg/kg once daily) as a first-line empirical antifungal treatment for 102 hospitalized FN patients with AML (MCFG, 53; L-AMB, 49). The efficacy end point was a favorable overall response, as determined by a five-component end point according to the criteria of Walsh et al (N Engl J Med 2004; 351: 1391). Results: At the time of enrolment, there were no significant differences in the demographics or baseline characteristics between the two groups. The mean treatment duration for MCFG and L-AMB was 14.8 and 17.1 days, respectively. The efficacy rates of MCFG and L-AMB were not significantly different (58.5% vs. 44.9%, p = 0.1698*), evaluated based on: (1) successful treatment of baseline fungal infection (3/5cases (5.7%) vs. 0/1case (0%), p = 0.170*), (2) absence of breakthrough fungal infection (90.6% vs. 98.0%, p = 0.112*), (3) survival for ≥7 days after study completion (88.7% vs. 89.8%, p = 0.855*), (4) absence of premature study drug discontinuation due to poor efficacy or drug-related adverse events (67.9% vs. 75.5%, p = 0.396*), and (5) resolution of fever during neutropenia (66.0% vs. 55.1%, p = 0.258*). However, discontinuation due to drug-related adverse events occurred less frequently in the MCFG group (1.9% vs. 12.2%, p = 0.038*). In safety evaluation, adverse events of creatinine increase and hypokalemia were less often in the MCFG group than in the L-AMB group (9.4% vs. 26.5%, P=0.023*, 22.6% vs. 57.1%, P=0.0004*). *: Chi square test. Conclusions: MCFG was as effective as L-AMB, and better tolerated than L-AMB as an empirical antifungal therapy in FN patients with AML. Disclosures Ishida: Kyowa Hakko Kirin Co: Research Funding; Nippon Shinyaku Co: Research Funding; CHUGAI PHARMACEUTICAL CO: Research Funding; Astellas Pharma Inc.: Other: Astellas Pharma Inc. (Tokyo, Japan) supported this clinical study with a grant; the sponsor was not involved in the design of study, the enrollment of patients, the collection, analysis, interpretation of the data., Research Funding.

Rituximab, anti-CD20 monoclonal antibody, shows anti-lymphoma effects by either activating host immune mechanism against lymphoma cells such as ADCC and CDC or suppressing signal(s) important for growth of B-cell lymphoma. Accumulated evidence shows de-regulated PI3K-AKT pathway is important therapeutic target in B-cell lymphoma. Although studies suggested suppression of PI3K-AKT pathway is possibly critical in rituximab-induced anti-lymphoma signals, details of molecular mechanisms covering CD20-mediated signals and PI3K-AKT pathway are still unknown. We analyzed signals in B-cell lymphoma cell line, SD07, which had bi-allelic deletions of both CD20(MS4A1) and PTEN gene. Briefly, SD07 was established from a patient with diffuse large B-cell lymphoma(DLBCL)who showed refractory CD20-negative relapse(Eur.J. Haematol. 2012). We transiently restored protein expression of either or both of CD20 and PTEN by electroporation of expression plasmid having cDNA of those genes in SD07. In this experiment, expression of both proteins were clearly detected by western blot until 72 hours after transfection. CD20 protein was also detectable on cell surface of SD07 cells by flow cytometric(FCM) analysis at comparable levels of those of Daudi cells after transfection on CD20 cDNA. Our previous study showed expression of both c-myc RNA and protein, as judged by FCM, was induced by transient transfection of CD20 cDNA in SD07 cells. Western blot analysis also showed significant increase of myc protein 24hrs after transfection (vector=13.7±0.2, CD20=14.5±0.4, P 24 hours after transfection, de-phosphorylation and down-regulation of retinoblastoma(RB) protein expression was evident only in SD07 cells transfected with both CD20 and PTEN, but not with either alone. Rituximab also augmented down-regulation of RB protein in SD07 cells transfected with both CD20 and PTEN. After transfection, in vitro cell growth of SD07, as evaluated by MTT, was as follows;vector=4.6±0.3, CD20=4.8±0.3(P=NS), PTEN=4.1±0.2(P 72 hours after transfection, by FCM, SD07 transfected with both CD20 and PTEN showed significant increase of subG1 DNA content potion compared with cells transfected with either alone(vector=2.5±0.2%,CD20=5.3±0.2%,PTEN=8.8 ±0.5%,CD20+PTEN= 16.1±0.6, P significantly increase of cells in subG1 in SD07 with transfected with both CD20 and PTEN(18.6±0.5%,P Accordance with proliferative effect of CD20 in SD07, transfection of CD20 alone produced significant increase of phosphorylation of AktSer473(vector=11.2±2.3, CD20=13.3±2.3,pAkt/total Akt,P In summary, although data is limited in a cell line, it clearly shows rituximab-induced CD20-mediated signals and suppression of PI3K-AKT pathway by tumor suppressor PTEN cooperatively inhibits growth and induce apoptosis of DLBCL cell line, SD07. Myc protein is critical molecules in this particular cooperative pathways. The present result partly agree studies which showed that inhibition of PI3K-AKT signaling and down-regulation of myc is important in PTEN-induced cytotoxicity in GCB(germinal center B cell)type DLBCL. In addition, we show here myc is not only for PTEN, but also involved in rituximab-induced anti-lymphoma effect. The present result provide a rationale for combination of rituximab and PI3K inhibitor in the treatment of DLBCL. In this context, myc is a candidate of the therapeutic target in rituximab-based immunochemotherapy for B cell lymphoma. Disclosures No relevant conflicts of interest to declare.

Background: The aberrant expression of the interleukin-3 receptor (IL3RA or CD123) alpha chain is frequently observed in a subset of leukemic disorders, including acute myeloid leukemia (AML), particularly in leukemia stem cells. Using flow cytometric (FCM) analysis, studies have shown that increased CD123 expression is associated with a poor prognosis of AML. Although FCM is a sensitive technique, the analysis may be limited in a clinical setting because live leukemia cells are required. Immunohistochemistry (IHC) is a more useful alternative compared with FCM because it can be tested long after specimens are collected; however, it is less sensitive. Here we evaluated the impact of blast CD123 expression via IHC analysis for the prognosis of AML. Patients and methods: This study was performed as a retrospective analysis of 70 patients who were diagnosed with de novo AML (M0-M5, n = 48) and AML with myelodysplasia-related changes (MRC) (n = 22) at our hospital from February 2008 to September 2015. The median age at diagnosis was 64.5 years (range: 21-93 years). The median follow-up period was 498 days (range: 2-3052 days). Morphological findings were obtained using HE stains of 3-µm sections. Formalin-fixed, paraffin-embedded specimens were used for immunohistochemical analysis. We analyzed the relationships between the patients' clinical outcome and CD123, p53, CD34, CD71, CD56, and c-kit expressions. [(CD123, CD34, CD71, CD56, and c-kit immunostained slides were defined as positive if >10% of the blast cells had a moderate to strong membranous staining. p53 was evaluated as positive when more than 5% of the cells were positively stained. For each case, the following data were obtained: patient age (>60 years or Results: Of the 70 cases, percentages of the positive immunohistochemical study dates were as follows: CD123: 25.7%; p53: 30%; CD34: 52.8%; CD71: 46.3%; CD56: 25.7%; and c-kit: 77.1%. There were 48 cases with de novo AML: CD123: 29.1%; p53: 75%; CD34: 52%; CD71: 37.5%; CD56: 27%; and c-kit: 79.1%. Moreover, there were 22 cases with MRC: CD123: 18.1%; p53: 31.8%; CD34: 54.5%; CD71: 66.6%; CD56: 22.7%; and c-kit: 72.7%. CD71 is highly expressed in MRC than de novo AML (P = 0.036). Among all patients, the CR rate following first induction therapy was 62.3%. Age (≥60 years), high p53 expression, disease (MRC), and poor karyotype were associated with induction failure (P = 0.011, P = 0.002, P Conclusion: This is the first study to demonstrate that CD123 expression using IHC is associated with poor a CR rate and OS in de novo AML patients; however, this association was not observed in MRC patients. Our results suggest that CD123 expression may predict the refractory to induction therapy and poor OS in de novo AML. Moreover, these results support previous reports using FCM. Therefore, CD123 expression may become one of the important factors used to characterize leukemia blasts and predict the prognosis of AML. In addition, novel therapy with antibodies targeting CD123 is currently under development. Therefore, we suggest that an analysis of CD123 expression using IHC is a clinically important assessment for de novo AML patients at the time of diagnosis. Disclosures No relevant conflicts of interest to declare.

Background: Bendamustine has demonstrated a favorable efficacy and toxicity profile in relapsed or refractory indolent lymphoma. Limited information is available regarding the prognostic factors (particularly laboratory parameters) of bendamustine treatment, although studies have shown a relationship between the hampered effect of bendamustine and an increase in lactate dehydrogenase (LDH) levels. Therefore, we retrospectively evaluated clinical and laboratory factors immediately prior to initiating bendamustine treatment and analyzed its correlation with the clinical outcome among patients with relapsed or refractory indolent lymphoma. Patients and methods: We analyzed 55 relapsed or refractory indolent lymphoma patients who had been treated with bendamustine alone (n = 19) or rituximab plus bendamustine (n = 36) at our hospital from 2000 to 2015. The median age at diagnosis was 65 years and the median follow-up period was 552.5 days. Histological analysis revealed follicular lymphoma (n = 21), mantle cell lymphoma (n = 10), MALT lymphoma (n = 7), lymphoplasmacytoid lymphoma (n = 5), and other low-grade B cell lymphomas (n = 4). We further analyzed the relationships between the clinical outcome [overall response rate (ORR), complete response (CR), progression-free survival (PFS), and overall survival (OS)] and clinical data, including sex, patient age (≥65 years), performance status (≥2), IPI (≥HI), FLIPI (≥HI), no. of previous therapies (≥2), prior purine analogue treatment, response to last treatment, and laboratory parameters [white blood cell count (≥5000/µl), lymphocyte count (≥1000/µl), platelet count (≥10000/µl), LDH (elevated or normal), sIL-2R (elevated or normal), and CRP (elevated or normal)], before starting bendamustine treatment. Results: The median number of cycles of bendamustine was 4 (range: 1-8). The ORR was 80.3% with a CR of 39.2%. Moreover, the CR rate was significantly worse in patients who had elevated sIL-2R and CRP, high or high-intermediate IPI scores, and a high WBC count (P = 0.002, P < 0.001, P = 0.072, and P < 0.046, respectively). Among follicular lymphoma patients, elevated CRP was only associated with a low CR rate (P = 0.028). In multivariate analysis, sIL-2R, CRP, and a high WBC count were all significantly associated with a worse CR rate (P = 0.044, P = 0.002, and P = 0.032, respectively). The 1- and 2- year OS rates were 80.3% and 76.1%, respectively. The OS was significantly higher in a group of the patients who obtained CR after bendamustine, were treated with rituximab plus bendamustine, and did not receive prior purine analogue treatment (P = 0.007, P = 0.008, and P < 0.001, respectively). An elevated CRP was associated with worse OS (P = 0.055). In multivariate analysis, only CR after bendamustine was significantly associated with improved OS (P = 0.023). The 1- and 2-year PFS rates were 69.2% and 60.5%, respectively. PFS was significantly better in patients who obtained CR after bendamustine treatment, had a normal CRP, had not received more than 2 previous therapies, and had a good performance status (P < 0.001, P = 0.007, P = 0.031, and P = 0.033, respectively). In multivariate analysis, any prognosis factors were significantly associated with PFS. Conclusion: This is the first study to demonstrate a correlation between laboratory parameters (i.e., CRP and sIL-2R) and the clinical outcome in patients with relapsed or refractory indolent lymphoma who were treated with bendamustine. In this study, CRP and sIL-2R levels as well as the WBC count were associated with the CR rate. In addition, the CRP levels were associated with OS and PFS, but LDH levels were not associated with any clinical outcomes. Previous studies have reported that the elevation of serum CRP and sIL-2R levels were associated with poor OS or PFS in patients who were treated with rituximab combined with CHOP in diffuse large B-cell lymphoma or follicular lymphoma. Our study indicates that serum CRP and sIL-2R levels are also important laboratory parameters for patients with indolent lymphoma who underwent bendamustine treatment. Disclosures No relevant conflicts of interest to declare.

T-cell large granular lymphocyte (T-LGL) leukemia is clinically indolent, but is associated with severe neutropenia in approximately 50% of cases. The pathogenesis of the neutropenia is unclear. We report reversal of severe neutropenia associated with T-LGL leukemia in five patients treated with cyclosporine (CSA). All five had persistent neutrophil counts below 0.5 × 109/L, two had agranulocytosis, and four had recurrent infections. Increased populations of LGL were present in blood and marrow, with a T-LGL immunophenotype (CD3+CD8+CD16±CD56±CD57+) shown by multiparameter flow cytometry, and clonal T-cell receptor (TCR) gene rearrangements in two of two pretreatment blood samples studied. CSA was initiated at doses of 1 to 1.5 mg/kg orally every 12 hours, with subsequent dose adjustments based on trough serum levels. Four patients attained normal neutrophil counts with CSA alone; one required addition of low-dose granulocyte-macrophage colony-stimulating factor. Time to attainment of 1.5 × 109/L neutrophils ranged from 21 to 75 days. Attempts to taper and withdraw CSA resulted in recurrent neutropenia. Three patients have maintained normal neutrophil counts on continued CSA therapy for 2, 8, and 8.5 years. Two patients died 1.7 and 4.6 years after initiation of CSA despite normal neutrophil counts—one of metastatic melanoma and one of complications after aortofemoral bypass surgery. Despite resolution of neutropenia, increased populations of T-LGL cells have persisted in all patients during CSA therapy, as shown by morphology and flow cytometry and by the presence of clonal TCR gene rearrangements in four patients' posttreatment blood samples. We conclude that CSA is an effective therapy for neutropenia associated with T-LGL leukemia, and that resolution of neutropenia despite persistence of abnormal cells implies that CSA may inhibit T-LGL secretion of yet unidentified mediators of neutropenia.

Background: In vitro observations have indicated that preplatelets, which are anucleate discoid particles that can reversibly into proplatelet fragments, are one of platelet progenitos from cultured megakaryocytes (MKs) (Thon JN, et al. JBC 2010). Recently, we identified that bone marrow (BM) MKs form and release two types of platelet progenitors, using intra-vital imaging and ultra-structural analysis of mice BM (Kowata S, et al. Thrombosis and Haemostasis 2014). However, in vivo, how the platelet progenitors translate into individual platelets after leaving BM remains poorly understood. To elucidate whether platelet progenitors have an ability of conversion into individual platelets, we performed following experiments. Methods: We isolated platelet progenitors rich fraction from whole blood of enhanced green fluorescence protein (EGFP) transgenic mice by the centrifugation (100 g, 15 min) and bovine serum albumin gradient. Mature platelets were isolated from whole blood of EGFP mice by the centrrifugation (100 g, 15 min). In vivo: The freshly enriched progenitor rich fraction or mature platelets, both of which were positive for EGFP, was transfused into wild type mice. The peripheral blood was obtained and analyzed by flow cytometry continually. The EGFP positive mature platelets in platelet gate were counted. In vitro: The freshly enriched progenitor isolates were cultured in IMDM medium at 37°C. The continual change of their characteristics in the shape and size were assessed using fluorescent microscopy with high resolution. Time-lapse images of the processes were also captured. All animal procedures were approved by the Institutional Animal Care and Use Committee of Iwate Medical University. Results: The length and size of platelet progenitors were extremely varied (Fig. 1). The red, yellow, green, and dark blue segments in the bar chart indicate the platelet progenitors (5um). The frequency of platelet progenitor was 4% at normal condition (Fig. 1 graph on the left), but increased remarkably to 3-fold at recovery from acute thrombocytopenia (Fig.1 graphs in the middle). The maximum length of platelet progenitor was more than 200 µm (Fig. 1 picture in the top right). These data were consisted with the concept from our previous study of intra-vital imaging of BM MKs (Thrombosis and Haemostasis 2014). In vivo: Flow cytometric analysis showed that there was a time-dependent increase in EGFP platelet number in the gate of mature platelet, after the injection of EGFP positive platelet progenitor rich fraction. The control was carried out using EGFP positive mature platelets instead of platelet progenitors rich fraction. (mean ± SD, 0 h: 100%, 3h: 111 ± 6.8%, 6h: 105 ± 7.1% n=3, control 0 h: 100%, 3h: 101± 6.0%, 6h: 94 ± 5.2% n=3, Data were shown as % of the number of EGFP positive mature platelets at 0 h. P Figure 1. Figure 1. Disclosures Ishida: Bristol-Myers Squibb: Honoraria.

Background: We conducted a phase II study to evaluate the efficacy and safety of dasatinib in patients with newly diagnosed chronic-phase chronic myeloid leukemia (CML-CP) in Japan (IMIDAS PART2 study; UMIN000006358). Several groups reported that some of CML patients who achieved stable deep molecular response (DMR) level or deeper could stop Tyrosine Kinase Inhibitor (TKI) and approximately 40% of these patients could keep therapy free survival by cessation of TKI. Discontinuation of TKI has emerged as a new goal of treatment in CML. Achievement of DMR is necessary for discontinuation of TKI. The aim of the present study was to analyze the prognostic significance of (i) BCR-ABL transcript International Scale (BCR-ABL IS) levels, (ii) the halving time and (iii) velocity of BCR-ABL transcript elimination using an optimized cutoff according to receiver operating characteristic (ROC) analysis. Methods: Eighty newly diagnosed CML-CP patients were included in this study. Patients received dasatinib 100mg once daily. Treatment has continued until disease progression or unacceptable toxicity. Clinical efficacy and safety was partially reported in 55th ASH Meeting. We sought to investigate the impacts of above 3 parameters within the initial 1 or 3 months of therapy. Halving time was calculated by the method, described by Branford et al. Velocity of BCR-ABL transcript elimination at 1 or 3 months (V-BCR-ABL1m or 3m respectively) was calculated as BCR-ABL IS at 1 or 3 months (BCR-ABL IS1m or 3m respectively) divided by that at diagnosis. Results: One patient was withdrawal before administration of dasatinib. Seventy-nine patients administered dasatinib 100 mg once daily. The estimated MMR and DMR rates were 92.1 % (95%CI, 76.8-97.3 %) and 60.9% (95%CI; 42.3-73.4 %) by 12 months respectively. The patients who had already achieved DMR at 3 months were excluded from landmark analysis. The cut off values for prediction of DMR at 12 months were obtained by ROC analysis. Those of BCR-ABL IS1m and BCR-ABL IS3m were 11.7% and 0.284% respectively. Those of halving times on 0-1 month and 0-3months (halving time1m and 3m) were 17.8 and 13.6 days respectively. Those of V-BCR-ABL1m and V-BCR-ABL3m were 0.321 and 0.018 respectively. The estimated DMR at 12 months, 95% CI and probability (P), obtained by Kaplan-Myer analysis, were shown in Figure 1. Odd' ratio, obtained by Chi-square test, was shown in Table 1. The patients with less than 0.321 at V-BCR-ABL1m showed the highest DMR at 12 months (80%), the least probability (P=0.009) and the least odd' ratio (0.175). At 3 months, there were similar data in these parameters among BCR-ABL IS3m, halving time3m and V-BCR-ABL3m. Figure 1 showed the cumulative DMR rate according to the cutoff values in V-BCR-ABL1m and V-BCR-ABL3m. V-BCR-ABL1m 0.321 and V-BCR-ABL3m 0.018 separated best. Conclusion: These data strongly suggested that V-BCR-ABL1m,3m would be a significant landmark to predict DMR at 12 months as well as BCR-ABL IS1m,3m, halving time1m,3m. Among them, less than 0.321 in V-BCR-ABL1m was identified as an optimized predictive cutoff value of DMR at 12 months. Disclosures Ishida: Bristol-Myers Squibb: Honoraria.

Background: Immune thrombocytopenia (ITP) is an autoimmune disease in which anti-platelet antibody (APA) is produced. APA-coated platelets are captured and phagocytized by macrophages in the spleen. Recent study revealed that spleen tyrosine kinase (Syk) inhibitor is effective in the treatment of ITP, because Syk phosphorylation is the key step of the phagocytosis by macrophages. Activated Fc receptor signal transduction is initiated by phosphorylation of immunoreceptor tyrosine-based activation motifs (ITAMs) tyrosine residues by SRC family kinases. Recruitment of Syk to dually phosphorylated ITAMs triggers the activation of Syk. To prove the hypothesis that the inhibition of SRC family kinase induces the decreased phosphorylation of Syk, resulting in decreased phagocytosis by macrophages, a SRC family kinase inhibitor, dasatinib, was used in the experiments. Methods, Results and Discussion: In vitro study; Murine macrophage cell line, RAW, was incubated with APA coated murine platelets for 30 minutes. Phagocytosis by RAW was significantly decreased with dasatinib (100nM, p In vivo study; (1) Three hours before APA intra-peritoneal injection, dasatinib (2.5mg/kg) was oral-administrated. Six hours after APA injection, platelet counts were measured. The platelet counts were 366 ± 164 x109/L with dasatinib (n=4, mean ± SD) and 114 ± 51 x109/L without dasatinib (n=4)(P=0.026)(Figure 2). (2) Osmotic pump, filled with APA, were inserted in murine intra-peritoneal cavity and dasatinib (2.5mg/kg) was oral-administered once daily for 7 days. The platelet counts were 499 ± 98 x109/L with dasatinib (n=4, mean ± SD) and 82 ± 131 x109/L without dasatinib (n=4) at day 7 (p Conclusion: Dasatinib inhibits phosphorylation of Syk, inducing decreased phagocytosis of APA-coated platelets via decreased SRC family kinase activity. These findings reveal that SRC family kinase controls the efficiency of phagocytosis in part through the regulation of Syk function. Dasatinib might be effective in the treatment of ITP. Disclosures No relevant conflicts of interest to declare.

BACKGROUND: Dasatinib is a second-generation BCR-ABL inhibitor that has a 325-fold higher potency than imatinib and a 16-fold higher potency than nilotinib in vitro. Recent reports suggested that absolute lymphocytosis in response to dasatinib for chronic phase (CP) –chronic myeloid leukemia (CML) might be associated with favorable response. However, as the fluctuation of lymphocytosis was often observed, it is sometimes difficult to define lymphocytosis. To evaluate how much increase and how long continuation of lymphocytosis affects the better clinical efficacy, we developed an index (DL index; Dasatinib induced Lymphocytosis index) that combines duration and increase of lymphocytosis. The aim of this study was to test the DL index as a predictor of Major Molecular Response (MMR) at 12 month. PATIENTS and METHODS: The DL area was based on a graph plotting the absolute lymphocyte counts and was the area under the lymphocyte curve using trapezoidal method. DL index was DL area divided by weeks. For example, DL index12W was defined as (DL area from 4 to 12 weeks) divided by (12-4) weeks. We tested the DL index12W in 30 patients who developed MMR at 12 months (MMR group) and 9 patients without MMR (non-MMR group). RESULTS and DISCUSSION: DL score12w in MMR group and non-MMR group were 2714.0 (95% CI; 2286.0-3142.2, n=30) and 1559.9 (95% CI; 1006.9- 2113.0, n=9) respectively. There was a significant difference between MMR group and non-MMR group in DL index12W by t-test(Figure 1, p=0.0016). A significant linear relationship was obtained between DL index12w and the peaked lymphocyte counts within 12 weeks by Spearman's correlation coefficient rank test (Figure 2, p=1.97E-07, correlation coefficient=0.91). The DL index12w, 2,113, which was the upper limit of non-MMR group 95% CI, is equivalent to 2,909/µl in lymphocyte count, and the DL index12w, 2,286, which is the lower limit of MMR group 95% CI, equivalent to 3,123/µl in lymphocyte count. Therefore, we divided all patients (n=39) into two groups, equal or more than 3,123/µl and less than 3,123/µl in the peaked lymphocyte counts. The patients with the peaked lymphocyte counts ≥ 3,123/µl reached MMR at 12 months (19/20=95.0%) to compare those less than 3,123/µl (11/19=57.9%) (p=0.0075). CONCLUSION: The peaked lymphocyte number, induced by the DL index12w, which calculation was extremely easy, was associated with molecular response. These data suggests that this tool can be useful in interpreting the results of molecular response at 12 months. Figure 1 Figure 1. Figure 2 Figure 2. Disclosures No relevant conflicts of interest to declare.

Specification and differentiation of the megakaryocyte and erythroid lineages from a common bipotential progenitor provides a well-studied model to dissect binary cell fate decisions. To understand how the distinct megakaryocyte- and erythroid-specific gene programs arise, we have examined the transcriptional regulation of the transcription factor GATA1, that is required for normal maturation of these two lineages. Megakaryocyte- and erythroid-specific mouse (m)GATA1 expression requires the mGata1 enhancer mHS-3.5. Within mHS-3.5, we previously showed that the 3′ 179 base pairs (bp) of mHS-3.5 are required for megakaryocyte but not red cell expression. Here, we show that mHS-3.5 binds key hemopoietic transcription factors in vivo (GATA1, SCL/TAL-1) and is required to maintain histone acetylation in the mGata1 locus in primary megakaryocytes. When deletional constructs containing mHS-3.5 were used to direct GATA1-LacZ reporter gene expression in transgenic mice, a 25 bp element within the 3′ 179bp in mHS-3.5, was critical for megakaryocyte expression. In vitro three uncharacterized DNA-binding activities A, B and C bind to the core of the 25 bp element, and these binding sites are conserved through evolution. Of these, only activity B is present in primary megakaryocytes but not red cells. Furthermore, mutation analysis in transgenic mice reveals that activity B is required for megakaryocyte-specific enhancer function. Bioinformatic analysis shows that sequence corresponding to the binding site for activity B is a previously unrecognised motif present in the cis-elements of other megakaryocyte-specific genes. In summary, we have identified a motif and a DNA-binding activity that are likely to be important in directing a megakaryocyte gene expression program distinct from that in red cells.

T-cell large granular lymphocyte (T-LGL) leukemia is clinically indolent, but is associated with severe neutropenia in approximately 50% of cases. The pathogenesis of the neutropenia is unclear. We report reversal of severe neutropenia associated with T-LGL leukemia in five patients treated with cyclosporine (CSA). All five had persistent neutrophil counts below 0.5 x 10(9)/L, two had agranulocytosis, and four had recurrent infections. Increased populations of LGL were present in blood and marrow, with a T-LGL immunophenotype (CD3(+)CD8(+)CD16(+/-)CD56(+/-)CD57(+)) shown by multiparameter flow cytometry, and clonal T-cell receptor (TCR) gene rearrangements in two of two pretreatment blood samples studied. CSA was initiated at doses of 1 to 1.5 mg/kg orally every 12 hours, with subsequent dose adjustments based on trough serum levels. Four patients attained normal neutrophil counts with CSA alone; one required addition of low-dose granulocyte-macrophage colony-stimulating factor. Time to attainment of 1.5 x 10(9)/L neutrophils ranged from 21 to 75 days. Attempts to taper and withdraw CSA resulted in recurrent neutropenia. Three patients have maintained normal neutrophil counts on continued CSA therapy for 2, 8, and 8.5 years. Two patients died 1.7 and 4.6 years after initiation of CSA despite normal neutrophil counts-one of metastatic melanoma and one of complications after aortofemoral bypass surgery. Despite resolution of neutropenia, increased populations of T-LGL cells have persisted in all patients during CSA therapy, as shown by morphology and flow cytometry and by the presence of clonal TCR gene rearrangements in four patients' posttreatment blood samples. We conclude that CSA is an effective therapy for neutropenia associated with T-LGL leukemia, and that resolution of neutropenia despite persistence of abnormal cells implies that CSA may inhibit T-LGL secretion of yet unidentified mediators of neutropenia.

Background Dasatinib is a second-generation BCR-ABL inhibitor that has a 325-fold higher potency than imatinib and a 16-fold higher potency than nilotinib in vitro. The previous report from the global DASISION trial showed dasatinib resulted in significantly higher and faster rates of complete cytogenetic response (CCyR) and major molecular response (MMR) compared with imatinib. We conducted a phase II study to evaluate the efficacy and safety of dasatinib in patients with newly diagnosed chronic-phase chronic myeloid leukemia (CML-CP) in Japan. Methods Eighty newly diagnosed CML-CP patients were include in this study. Patients received dasatinib 100mg once daily. Treatment was continued until disease progression or unacceptable toxicity. Primary end point was the rate of major molecular response (MMR) by 12 months. MMR defined as a BCR-ABL transcript level of 0.1% or lower on the International scale by means of a real-time quantitative reverse transcriptase-polymerase chain reaction (RT-PCR) in peripheral blood. Secondary end points were the rate of complete cytogenetic response (CCyR) by 12 months, the rate of MR4.5 (either (i) detectable disease with 32,000 ABL1 transcripts in the same volume of cDNA used to test for BCR-ABL1) by 12 months and adverse events of dasatinib (UMIN #000006358). Results Eighty newly diagnosed CML-CP patients were included in this study. All except one patient administered dasatinib 100 mg once daily. One patient was withdrawal before administration of dasatinib. So far, there were 71 patients with 6 months follow-up and 51 patients with 12 months follow-up. The estimated MMR rates were 69.5 % (95%CI, 58.7-80.3 %) by 6 months and 82.7% (95%CI, 73.0-92.4 %) by 12 months. The estimated MR4.5 rates were 27.1 % (95%CI, 16.7-37.5 %) by 6 months and 48.9% (95%CI, 36.0-61.7 %) by 12 months. Only 6 patients were withdrawal because of adverse event (5 patients) and ineffectiveness (1 patient). Conclusion Dasatinib treatment results in higher rates of molecular responses in newly diagnosed CML-CP patients in Japan. Dasatinib as the first-line agent might be acceptable for CML-CP patients because of better clinical efficacy and less toxicity. Disclosures: No relevant conflicts of interest to declare.

Purpose It has been proposed that imatinib can be discontinued without molecular relapse at least in some CML patients. But little is known about whether the assumption could be exploitable for the second-generation ABL-tyrosine kinase inhibitors. Here we conducted a prospective, multicenter clinical trial to assess whether dasatinib can be discontinued without occurrence of molecular relapse in CML patients in complete molecular response (CMR). Methods In our Dasatinib Discontinuation (DADI) trial (Japan Primary Registries Network #UMIN000005130, http://rctportal.niph.go.jp/), main eligibility criteria for pre-registration were; CML patients in chronic phase, 15 years and older, undergoing dasatinib treatment used as a second-line therapy after confirmation of resistance or intolerance to imatinib treatment. Previous treatments with interferon-α (IFN-α) or nilotinib were allowed. In this trial, CMR was defined as “No detectable BCR-ABL transcript determined by international scale (IS)-based RQ-PCR at a single central laboratory (BML Inc., Tokyo, Japan, which obtains conversion factor (CF) 0.87).” Patients in CMR status confirmed by RQ-PCR at the central laboratory were pre-registered before the full enrollment for the discontinuation. The pre-registration period was between April 1, 2011, and March 31, 2012. The levels of BCR-ABL transcripts were monitored every 3 months throughout the pre-registration period during the dasatinib treatment. Patients with sustained CMR for one-year duration were then enrolled for the dasatinib-discontinuation stage. In order to detect molecular relapse after the dasatinib-discontinuation, RQ-PCR was performed monthly for the first 12 months, and then every 3 months for the subsequent follow-up. Molecular relapse was defined as positivity of BCR-ABL transcript by RQ-PCR even at one analysis point. Dasatinib was immediately reintroduced in patients who showed molecular relapse during the discontinuation period. After the relapse, RQ-PCR monitoring was performed 1 month, 3 months, 6 months, and 12 months after the reintroduction of dasatinib. Primary endpoint of this study was “Molecular relapse-free survival (MoRFS) rate at 6 months after discontinuation of dasatinib.” Total follow-up duration was set to be 36 months after the discontinuation. In addition to the molecular assessment of the BCR-ABL transcript level, increase of large granular lymphocytes (LGL) in the peripheral blood, in combination with flow cytometry analysis, was also investigated. Results In total, 88 patients were pre-registered at 41 participating institutions in Japan. Among them, a total of 63 patients who maintained stable CMR for one year after pre-registration were enrolled for the dasatinib-discontinuation stage. All of these 63 patients (42 male, 21 female) had been treated with imatinib before the start of the dasatinib treatments. Among these 63, 14 were imatinib-resistant, and 35 were imatinib-intolerant. Other previous treatments were; IFN-α (n=12), nilotinib (n=4), IFN-α and nilotinib (n=1). Median age was 59.5 years (range 24-84). Sokal scores were; low 70%, intermediate 15%, and high 15%. In this interim analysis with a data cut-off date of 31 July 2013, 27 patients out of 88 pre-registered patients were over the observation period of 6 months after the dasatinib-discontinuation. Among 27, 12 patients achieved 6 months-sustained CMR after dasatinib-discontinuation. The estimated MoRFS at 6 months determined by Kaplan-Meier method was 44 % (95%CI 26-62). Reintroduction of dasatinib to the relapsed patients showed rapid molecular responses in all of them. Among the 15 patients who lost CMR after dasatinib-discontinuation, 13 patients were available for the evaluation of reintroduction to CMR. 12 out of 13 patients (92%) returned to CMR again within 3 months (7 patients at 1 month, and 5 patients at 3 months) after the reintroduction, and all these patients have sustained CMR up to now. The remaining one patient out of 13 also showed a marked reduction of the BCR-ABL transcript level at 3 months. Conclusion Dasatinib could be safely discontinued in a proportion of CML patients with stable CMR for at least one year, provided that frequent molecular monitoring is performed. Patients who lost CMR after dasatinib-discontinuation still maintained good sensitivity to the reintroduction of dasatinib. Disclosures: Nakamae: Novartis: Honoraria, Speakers Bureau, Travel/accommodations/meeting expenses, Travel/accommodations/meeting expenses Other; BMS.: Consultancy, Honoraria, Research Funding, Speakers Bureau, Travel/accommodations/meeting expenses Other. Hino:Chugai Pharma: Honoraria, Research Funding, Travel/accommodations/meeting expenses Other. Kimura:Bristol-Myers: Honoraria, Research Funding.

Background Dasatinib is a highly potent BCR-ABL inhibitor, with a 325-fold higher potency than imatinib and a 16-fold higher potency than nilotinib in vitro. Across a series of phase II and III trials with more than 2 years of follow-up, dasatinib has demonstrated durable efficacy in patients with CML following resistance or intolerance to imatinib. We conducted a phase II study to evaluate the efficacy and safety of dasatinib in Japanese patients with imatinib resistance or intolerance CML. Methods Fifty- five CML-CP patients from 2009 to 2011 with resistance (n=40) or intolerance (n=26) to imatinib were registered to dasatinib administration (100mg once daily). Eleven among 26 patients with intolerance also showed resistance to imatinib at the registration. Imatinib resistance was defined as a lack of partial cytogenetical response at 3 months, a lack of complete cytogenetic response at 6 months or a lack of a major molecular response at 12 months of imatinib treatment. This criteria was identical to the criteria in ELN 2013 recommendation for first line. In another words, the resistance in this study means non-optimal criteria (warning and failure) of definition of the response to TKIs, first line, in ELN 2013 recommendation. Efficacy and safety were assessed using rates of major molecular response (MMR)/ MR4.5 (either (i) detectable disease with32,000 ABL1 transcripts in the same volume of cDNA used to test for BCR-ABL1) at 12 months and drug-related adverse events (AEs) respectively. All analyses were based on the modified to intension-to treat. Results One patient was withdrawal before dasatinib administration. The median duration of imatinib therapy was 545 days. The overall incidence of MMR (primary endopoint) and MR4.5 at 12 months was 67.2% (95% confidence interval, 53.3-81.1%), and 20.2 % (95% CI, 8.4–32.0 %), respectively. Forty patients with resistance to imatinib, who were warning and failure patients judged by ELN 2013 criteria, were reassessed. Cumulative MMR and MR4.5 rate were 63.4% (95% CI: 46.3-80.6) and 18.0% (95% CI: 4.9-31.1) respectively at 12 months. Eleven patients, who showed more than 1% IS at 3 months of dasatinib treatment, did not reach to MMR at 12 months or discontinued dasatinib due to insufficient efficacy in this resistance cohort. However, progression to the accelerated or blastic phase had not been observed. When imatinib were changed to dasatinib, 5 patients showed the mutations, which were effective in dasatinib therapy. New mutations have not been observed during the treatment of dasatinib. Among 54 patients, most non-hematological AEs were in grade 1/2. including diarrhea (12.7%), rash (7.3%), myalgia (5.5%) and vomiting (3.6%). Grade 3/4 non-hematological AEs were infrequent, including decreased potassium (3.6%), and increased creatinine (3.6%). Grade 1/2 fluid retention AEs were shown in 9.1% of patients, including edema (3.6%). Pleural effusion, which was only in Grade 1/2, was shown in 32.7% of patients. Grade 3/4 hematological toxicities included anemia (7.3%) and thrombocytopenia (3.6 %). Only 3 patients have permanently discontinued dasatinib treatment due to AEs. Conclusions The patients with non-optimal responses (warning and failure) judged by ELN 2013 criteria should have early intervention to dasatinib, which is less toxicity in CML-CP patients. This intervention might induce good prognosis. The BCR-ABL1 IS less than 1% at 3 months of dasatinib administration will be the valuable landmark for outcome. Disclosures: No relevant conflicts of interest to declare.

Background Dasatinib is a highly potent BCR-ABL inhibitor with established efficacy and safety in imatinib-resistant/intolerant patients with chronic myeloid leukemia (CML). The DASISION reported a significantly higher rate of CCyR after 1 year (83%), MMR after 1 year (46%) and CMR4.5 after 3 years (22%). Grade 3/4 thrombocytopenia was more frequent adverse events. Although Mazharian et al (Blood 2011) reported the inhibition of PPF by dasatinib, molecular signals in dasatinib-induced PPF inhibition has remained unclear. In this study, we elucidated the biological effects of dasatinib on proliferation and maturation of megakaryocytic progenitor cells and maturation of megakaryocytes. In addition, the molecular signals of G-proteins were revealed in the process of PPF inhibition by dasatinib. Methods and Materials To evaluate the biological effects of dasatinib, the following experiments were performed in the presence of dasatinib; (1) CFU-Meg assay in vitro culture of murine bone marrow (BM) cells with murine TPO, IL-3 and IL-6, (2) megakaryocyte ploidy analysis in vitro culture of murine BM MNCs with murine TPO and SCF, (3) proplatelet formation (PPF) assay in vitro culture of murine megakaryocytes. To evaluate the molecular signals in inhibited PPF by dasatinib, Western blots were performed. Activated Rho, Rac, phosphorylated myosin light chain (p-MLC), phosphorylated Lyn (p-Lyn) and p-Src in murine platelets were evaluated. Results (1) CFU-Megs (colonies per 1x 105 BM-MNCs) did not decrease significantly at 0.01, 0.1, 1, 10, 100 nM (dasatinib 0 nM; 32.6 ± 13.1, 0.1 nM: 27.6 ± 8.4, 1 nM: 24.8 ± 7.8, 10 nM: 28.8 ± 12.1, 100 nM: 23.0 ± 7.6). (2) There was no difference in DNA ploidy of cultured megakaryocytes in the presence of dasatinib (0, 0.01 to 100 nM). (3) PPF decreased significantly at 1, 10, 100 nM of dasatinib (0 nM: 40.6 ± 2.5%, 1 nM: 29.4 ± 2.4% p Conclusion Dasatinib induced thrombocytopenia might not be due to the inhibition of megakaryocyte colony formations but the inhibition of PPF of megakaryocytes via pathways including Rho/Rock and Rac. Disclosures: No relevant conflicts of interest to declare.

Background Febrile neutropenia (FN) is often observed in the treatment of hematological malignancies including acute leukemia (AL). The pathogens of systemic infection are frequently unknown in FN patients. Carbapenem antibiotics are good candidates with a potent and broad antimicrobial activity against gram-positive and gram-negative bacteria including Pseudomonas aeruginosa. These antimicrobial agents are recommended to use early and sufficiently as empiric therapy for high-risk FN patients accompanied with profound neutropenia anticipated to > 7days. In the IDSA guideline published in 2010 on the use of antimicrobial agents in neutropenic patients, monotheapy with an anti-pseudomonal beta-lactam agent, such as cefepime (CFPM), meropenem (MEPM), imipenem-cilastatin (IPM) or piperacillin-tazobactam (TAZ/PIPC), is recommended as empiric therapy for high-risk FN patients. Several antimicrobial agents including MEPM, IPM or CFPM have been studied as empirical therapy for FN. However, limited data are available concerning the efficacy and safety of doripenem (DRPM), one of the carbapenem antibiotics, in FN with hematological malignancy. Methods We conducted a randomized, cooperative group, open-label trial comparing DRPM (1g, q8h IV) with MEPM (1g, q8h IV) as the first line empirical antimicrobial treatment for 165 hospitalized high-risk FN patients with AL (AML: n=90, APL: n=25, MDS-AML: n=13, ALL: n=35, ATL: n=2) during or after induction or consolidation chemotherapy (DRPM: n=83, MEPM: n=82). These study drugs were administered at least for 3 days without toxicity. The primary endpoint was response to treatment defined as complete defervescence by day 7 with improvement of infection-related symptoms and laboratory findings. We also evaluated the efficacy (resolution of fever by monotherapy at day 3 to 5, survival at day 30) and the safety of each drug, as a secondary endpoint. Results At the time of enrolment, there were no significant differences in the demographics or baseline characteristics, including as age, sex, body weight, underlying hematological malignancies, duration of initial antimicrobial therapy, median duration of severe neutropenia (neutrophil count < 100×106/L) and MASCC score, between the two groups. The response rate at day 7 was not significantly different between the two arms (DRPM: 75.8%, MEPM: 64.5% (p=0.14)). The resolution of fever by monotherapy at day 3 to 5 (DRPM: 58.6%, MEPM: 45.2% (p=0.10)), or survival at day 30 (DRPM: 97.6%, MEPM: 98.7% (p=0.33)) was not significantly different in the two groups. Adverse events were minimal in the two groups, and most of patients could continue the treatment by study drugs for 7days. Conclusions We could prove the non-inferiority of DRPM in comparison with MEPM for the initial treatment in FN patients with hematological malignancies. Both drugs were well tolerated as the first line empiric therapy for high-risk FN patients. Disclosures: No relevant conflicts of interest to declare.

Purpose Dasatinib is a novel kinase inhibitor of BCR-ABL and SRC family kinases. Dasatinib has shown promising anti-leukemic activity in chronic myeloid leukemi (CML). Tounderstand how to administer dasatinib with best efficacy and less adverse events, the pharmacokinetic (PK) properties of dasatinib and the relationship of PK and pharmacodynamic (PD) characteristics were investigated in newly diagnosed CML-chronic phase (CP) patients. Methods and Materials The PK analysis of dasatinib: The plasma concentrations of dasatinib (1, 2, 4 hr after taking dasatinib post 28 days) were determined by Francia's method using high performance liquid chromatography with mass spectrometry. PK analysis was performed using Phoenixâ NLMEâ1.2. The maximum plasma concentration (Cmax) was determined by visually inspecting the profiles of plasma drug levels. PD analysis of dasatinib: Phospho-CrkL in CD 34 positive cells was analyzed by flow cytometry using anti-phospho-CrkL (Tyr207) antibody after incubation of bone marrow mononuclear cells in the presence of dasatinib for 2 hours. PK/PD analysis: Area under the curve (AUC) and time above IC50 were calculated using Phonix WinNonlin 6.3. Results Twenty-eight newly diagnosed CML-CP patients were included. The correlation between the efficacy and PK/PD parameters were analyzed using Peason's correlation coefficient test (Table1). The efficacy(expression of bcr/abl at 1 month) was not correlated with AUC, Cmax, AUC/IC50 and Cmax/IC50 but significantly correlated with TAIC50 (r=0.4763, p=0.0104). The reduction rate at 1 month was correlated significantly with only TAIC50(r=0.5136, p=0.0052)(Figure 2). Eight cases reached MMR at 3 month among 15, whose TAIC50s were more than 12 hrs(53.3%), while only 2 cases reached MMR among 13, whose those were less than 12 hrs(15.4%). Conclusion Dasatinib has anti-leukemic activity in a time dependent manner. Exposure more than 12 hrs at TAIC50 will get benefits of better prognosis. Disclosures: No relevant conflicts of interest to declare.