ALBERT

Description: Abstract 1015 Poster Board I-37 Background: Early mortality, mostly from hemorrhagic complications, occurs in less than 10% of patients currently treated in clinical trials for acute promyelocytic leukemia (APL). However, data about the proportion of patients developing such complications prior to clinical trial enrollment are scarce in the literature (Sanz M, et al Blood 2009). Approximately 5% of newly diagnosed patients with APL have been reported not to be eligible for participation in clinical trials due to very poor clinical condition, and their outcome has never been reported. However, enrollment on clinical trials may be difficult in specific clinical situations, such as after hours/weekend admissions and/or emergent requirement for therapy. This study reports the incidence, time of occurrence and clinical features of APL patients with a focus on early mortality. Methods: 150 consecutive APL patients treated at Stanford University between 8/1986 and 7/2009 were identified. Thirteen patients were excluded for lack of appropriate clinical information. Clinical features of patients with APL were analyzed for factors that might be relate to prognosis, including age, gender, white blood cell count, platelet count, fibrinogen, PTT, and INR. Continuous variables were compared with the t-test and categorical variables by Fisher's exact test or X-square statistic. The Kaplan–Meier method was applied to assess overall survival time. Results: Of the 137 patients included in this analysis, the median age at diagnosis was 45 (1-93) years and 78 (57%) were females. Using the PETHEMA criteria, there were 37, 46 and 20 patients with high-, intermediate- and low-risk disease (34 patients could not be classified based on partial/missing data). With a median follow-up time of 748 (0-6,235) days for the entire cohort, 52 (38%) have died. 19 (14%) and 11 (8%) of these patients died within 7 and 3 days of presentation, respectively. Patients with high-risk features had a 13% and 24% chance of dying with 3 and 7 days of presentation, respectively, with significantly inferior outcomes (p=0.045) when compared to those with intermediate-risk patients (6% and 13%) and low-risk disease (5% and 5%). Patients with unknown risk category faired similarly to low-risk patients. The most common cause of early mortality in these 19 patients was intracranial hemorrhage (n=11). Patients with early death (ED) (either

Description: Abstract 2951 Poster Board II-927 Background: Expression signatures of infiltrating immune cells [1] have been shown to predict survival in follicular lymphoma (FL), but have not been cross-validated in independent patient cohorts [2,3]. These signatures may relate biologically to the frequency of infiltrating including T-cells and macrophages, or to specific transcription programs within tumor cells and/or the tumor microenvironment. We sought to evaluate the validity of this model in an independent cohort of patients with FL, assessing its relationship to outcomes including histological transformation and death. Methods: The immune response (IR) predictor score proposed by Dave et al. [1] was applied to gene expression data from an independent cohort of 88 FL patients [4] with known survival outcomes and history of transformation to diffuse large B-cell lymphoma (DLBCL). Genes (n=66) corresponding to IR1 and IR2 signatures were mapped from Affymetrix microarrays [1] to a custom cDNA array [4] via Entrez Gene ID, and the composite IR score was calculated per the scheme proposed by Dave et al. Results: The IR score was predictive of patient outcome in the 88 patient test set as a continuous variable (p=0.001, HR=2.01, 95% CI 0.50-1.30). Partitioning of patients into high and low risk groups based on the median IR score across the cohort robustly separated survival curves (Figure A). The IR score was significantly higher in FL patients known to undergo transformation to DLBCL (Figure B: mean IR score of -0.6 in non-transforming FL vs. -0.2 in transforming FL; p∼10-11, t-test). Conclusions: The IR score of Dave et al. was highly significant as a predictor of survival in the independent patient cohort [4]. Moreover, the score was significantly associated with propensity of FL to transform to DLBCL. To our knowledge, immune cell infiltration has not previously been implicated in transformation. 1. Dave SS et al. (2004) Prediction of survival in follicular lymphoma based on molecular features of tumor-infiltrating immune cells. N Engl J Med 351(21): 2159-2169. 2. Tibshirani R (2005) Immune signatures in follicular lymphoma. N Engl J Med 352: 1496-1497. 3. Chu G Hong WJ, Warnke R, Chu G (2005). Immune Signatures in Follicular Lymphoma (Corres). N Engl J Med. 352: 1496-1497. 4. Glas AM et al. (2005) Gene expression profiling in follicular lymphoma to assess clinical aggressiveness and to guide the choice of treatment. Blood 105(1): 301-307. Disclosures: No relevant conflicts of interest to declare.

Description: Abstract 622 Background: Several gene-expression signatures are predictive of prognosis in diffuse large-B-cell lymphoma (DLBCL), but the lack of practical methods for a genome-scale analysis has restricted their routine clinical applicability. Methods: We studied genes whose expression had been reported to predict survival in DLBCL, attempting to validate genes and prognostic models with robust survival associations that are amenable to rapid diagnostic testing. Results: Among a previously described set of 6-genes shown to predict survival independent of measurement platform or therapy era (Lossos, et al. 2004 NEJM 350:1828), we identified LMO2 as the single gene with strongest independent prognostic value in 3 independent cohorts of patients with DLBCL. To assess the independent contribution of other genes in predicting survival, using existing microarray gene expression data (Lenz, et al. 2008 NEJM 359:2313), we evaluated all pairwise models that included LMO2 toward construction of a robust bivariate survival predictor. Among 54674 possible models, one combining expression of LMO2 with TNFRSF9 (encoding 4-1BB, also known as CD137) emerged as among the best in cross-validation when assessed in training (n=233) and test (n=181) cohorts. This bivariate predictor remained prognostic in both CHOP (p=1.7e-6) and R-CHOP (p=6.5e-8) therapy eras, was highly independent of the International Prognostic Index, Cell-of-Origin classification, 6-gene predictive model, ‘stromal' model, and added significantly to their prognostic power. While LMO2 expression was highly restricted to tumor cells and was linked to Cell-of-Origin (GCB, p=2.2e-16), TNFRSF9 expression was highest in non-tumor cells (P=0.02), particularly in an activated subset of infiltrating CD8 T-cells. To validate this bivariate model and devise a practical diagnostic assay, we used quantitative real-time polymerase-chain-reaction to measure the expression of LMO2 and TNFRSF9 as well as other components of the 6-gene model (BCL2, BCL6, FN1, CCL3, and CCND2) in diagnostic formalin fixed and paraffin-embedded samples of lymphoma from an independent set of 147 patients with de novo DLBCL treated with R-CHOP. The IPI distribution for these patients was: 0-1 factor (n=70), 2 factors (n=40), 3 factors (n=26), ≥4 factors (n=11). In univariate and multivariate analyses of this independent cohort, LMO2 and TNFRSF9 expression remained individually prognostic of both progression free and overall survival. The bivariate model combining LMO2/TNFRSF9 could be used to stratify distinct risk groups for overall survival (p=0.004), and remained independent of IPI. Conclusion: Measurement of the expression of two genes integrating contributions of tumor cells and the tumor microenvironment is sufficient to predict overall survival in patients with DLBCL treated with R-CHOP. Disclosures: Advani: Seattle Genetics, Inc.: Research Funding.

Description: Abstract 2716 Poster Board II-692 The anti-CD20 antibody, rituximab, is standard therapy for many CD20 positive B-cell lymphomas, significantly improving long-term survival in combination with chemotherapy. However, rituximab alone is not curative in many non-Hodgkin lymphoma (NHL) patients with observation of primary and acquired resistance, arguing for a need for additional targeted therapies. We identified the cell surface protein CD47 as a potential therapeutic antibody target in human NHL. A major function of CD47 is to inhibit phagocytosis through binding its receptor SIRPα, on phagocytes. We hypothesize that NHL cells over-express CD47 to evade immune phagocytosis and that blockade of CD47 signaling with a monoclonal antibody can eliminate NHL cells by enabling phagocytic engulfment. We have previously shown that an anti-CD47 antibody enables phagocytosis of acute myeloid leukemia (AML) stem cells and eliminates AML in vivo. Here we investigate the therapeutic potential of an anti-CD47 antibody alone and in combination with rituximab for the treatment of NHL. We predict that the combination of anti-CD47 antibody and rituximab will result in synergistic elimination of NHL cells by both blocking an inhibitory signal and delivering a positive signal for phagocytosis. We found that CD47 protein is highly expressed on primary human B-cell NHL cells compared to normal peripheral blood B-cells. Higher CD47 gene expression independently predicted a worse clinical outcome in several cohorts of NHL patients including diffuse large B-cell lymphoma (DLBCL), mantle cell lymphoma, and chronic lymphocytic leukemia. Blocking anti-CD47 antibodies preferentially enabled phagocytosis of NHL cells but not normal cell counterparts in vitro. Using isobologram analyses, the combination of anti-CD47 antibody and rituximab resulted in synergistic phagocytosis of NHL cells at higher levels compared to either anti-CD47 antibody or rituximab alone. In addition, anti-CD47 antibody and rituximab mediated their therapeutic effects through Fc-receptor-independent and Fc-receptor-dependent effector mechanisms, respectively. In vivo, anti-CD47 antibody treatment of NHL-engrafted mice reduced lymphoma burden and prolonged survival compared to IgG control. Furthermore, combination treatment with anti-CD47 antibody and rituximab led to elimination of lymphoma and cure of NHL-engrafted mice. These in vivo results were observed in both a disseminated and localized human NHL cell line mouse model as well as in primary human DLBCL mouse xenotransplants. Together, these data provide the rationale for utilizing an anti-CD47 antibody either alone or in combination with rituximab in treating human NHL. Disclosures: Weissman: U.S. Patent Application 11/528,890 entitled “Methods for Diagnosing and Evaluating Treatment of Blood Disorders.”: Patents & Royalties; Stem Cells Inc.: Cofounder and director; Cellerant Inc.: cofounder; Amgen: Equity Ownership.

Description: Despite the success of passive immunotherapy with monoclonal antibodies (mAbs), many lymphoma patients eventually relapse. Induction of an adaptive immune response may elicit active and long-lasting antitumor immunity, thereby preventing or delaying recurrence. Immunomodulating mAbs directed against immune cell targets can be used to enhance the immune response to achieve efficient antitumor immunity. Anti-CD137 agonistic mAb has demonstrated antitumor efficacy in various tumor models and has now entered clinical trials for the treatment of solid tumors. Here, we investigate the therapeutic potential of anti-CD137 mAb in lymphoma. We found that human primary lymphoma tumors are infiltrated with CD137+ T cells. We therefore hypothesized that lymphoma would be susceptible to treatment with anti-CD137 agonistic mAb. Using a mouse model, we demonstrate that anti-CD137 therapy has potent antilymphoma activity in vivo. The antitumor effect of anti-CD137 therapy was mediated by both natural killer (NK) and CD8 T cells and induced long-lasting immunity. Moreover, the antitumor activity of anti-CD137 mAb could be further enhanced by depletion of regulatory T cell (Tregs). These results support the evaluation of anti-CD137 therapy in clinical trials for patients with lymphoma.

Description: Diffuse large B-cell lymphomas (DLBCLs) can be subclassified into germinal center B-cell (GCB)-like and activated B-cell (ABC)-like tumors characterized by long and short survival, respectively. In contrast to ABC-like DLBCL, GCB-like tumors exhibit high expression of components of the interleukin 4 (IL-4) signaling pathway and of IL-4 target genes such as BCL6 and HGAL, whose high expression independently predicts better survival. These observations suggest distinct activity of the IL-4 signaling pathway in DLBCL subtypes. Herein, we demonstrate similar IL-4 expression but qualitatively different IL-4 effects on GCB-like and ABC-like DLBCL. In GCB-like DLBCL, IL-4 induces expression of its target genes, activates signal transducers and activators of transcription 6 (STAT6) signaling, and increases cell proliferation. In contrast, in the ABC-like DLBCL, IL-4 activates AKT, decreases cell proliferation by cell cycle arrest, and does not induce gene expression due to aberrant Janus kinase (JAK)-STAT6 signaling attributed to STAT6 dephosphorylation. We found distinct expression profiles of tyrosine phosphatases in DLBCL subtypes and identified putative STAT6 tyrosine phosphatases—protein tyrosine phosphatase nonreceptor type 1 (PTPN1) and PTPN2, whose expression is significantly higher in ABC-like DLBCL. These differences in tyrosine phosphatase expression might underlie distinct expression profiles of some of the IL-4 target genes and could contribute to a different clinical outcome of patients with GCB-like and ABC-like DLBCLs.

Description: Abstract 1359 Poster Board I-381 Background Hemophagocytic lymphohistiocytosis (HLH) is a rare condition in which dysregulation of innate immune effectors including natural killer (NK) cells and macrophages leads to destruction of hematopoietic elements. HLH is most frequently reported in association with malignancies or viral infections, with heritable deficiencies in cytotoxicity pathways predisposing children (and rarely adults) to HLH. Criteria for diagnosing HLH include: histological evidence of hemophagocytosis, two or more cytopenias, hyperferritinemia, hypofibrinogenemia or hypertriglyceridemia, elevated soluble IL-2R, decreased in vitro NK cell function, fever, and splenomegaly. Patients meeting 〉=5 of these criteria are diagnosed with HLH. Source: We identified 19 consecutive adult patients (53% male; median age 43y, range 16-83) admitted to Stanford Hospital with clinical suspicion for HLH and histological evidence of hemophagocytosis between 1997 and 2009; 2 patients were excluded from analysis due to incomplete data. Of the remaining 17 patients, 11 (65%) met criteria for a diagnosis of HLH. Results At presentation, all patients were anemic with a median Hgb concentration of 8.6 g/dL. Leukopenia was present in 8/11 (73%) with a median WBC count of 2 K/uL. Thrombocytopenia was present in 10/11 (91%) patients with a median Plt count of 30 K/uL. In 6 patients not meeting HLH criteria, median hematologic findings were Hgb 8.6 g/dL, WBC 2.6 K/uL, and Plts 126 K/uL. All patients demonstrated marked elevations of ferritin, median 3915 ng/dL (range 1039 – 29,700). Triglycerides were elevated in 7/10 (70%) for whom data were available, median 296 mg/dL (range 204 – 1,506). Fibrinogen was decreased in 3/13 (23%). Soluble IL-2 receptor level was above normal limits in all patients in whom it was measured (range 796 – 17,378 U/mL), but met the 〉2,400 U/mL criteria in only 3/6 (50%). In vitro NK function was diminished in 2/5 (40%) patients tested. Fever and splenomegaly were found in 94% and 59% of patients, respectively. Of 11 patients meeting HLH criteria, 5 had associated malignancies (DLBCL, NK cell leukemia, T cell lymphoma, AML, and Kaposi sarcoma) and 4 had concomitant viral infections (2 EBV, 1 EBV/B19, and 1 HIV-1/HHV-8). Three patients had isolated viral infections (all EBV), while 3 had idiopathic HLH. Amongst 6 patients not meeting HLH diagnostic criteria, 2 (33%) had an associated malignancy (SLL and NK cell lymphoma), 1 had an isolated EBV infection, and 3 had idiopathic disease. At a median follow-up of 16 months for surviving patients, the case fatality rate amongst those with established HLH diagnoses was 55%, with all deaths occurring within 2 months from diagnosis. Five patients were treated according the HLH-94/04 protocol combining dexamethasone, cyclosporine and etoposide. Two patients died within 2 months of initiating treatment, and 3 remain alive (survival to date ranges 4-31 months). The longest surviving patient underwent allogeneic HCT. A patient who presented with AML-associated HLH underwent induction chemotherapy then proceeded to allogeneic HCT and remains alive 9 months after diagnosis. Amongst 6 patients not meeting HLH criteria, the case fatality rate was 67% with a median survival of 2.3 months. None of these patients were treated with the HLH-94/04 protocol; however, 2 were treated with cyclosporine and remain alive 16 and 24 months after diagnosis. Conclusions Of the HLH diagnostic criteria, multiple cytopenias, hyperferritinemia, and hypertriglyceridemia were sensitive measures, whereas hypofibrinogenemia, markedly elevated sIL-2R, and decreased in vitro NK cell function were found in fewer than half of patients. At our institution, EBV-associated HLH predominates (7/17 cases, 41%). Most of the malignancy-associated HLH we have seen also occurred in the context of EBV infection. The case fatality rate amongst all patients with histologic evidence of hemophagocytosis, including those not meeting HLH criteria, is high. In most patients, treatment according to HLH-94/04 may be appropriate and likely improves survival. In our experience with the HLH-94/04 protocol, 60% of patients remain alive. Until sufficient evidence emerges that this treatment strategy leads to durable remissions in the majority of patients, allogeneic HCT should remain a consideration for most patients. Disclosures No relevant conflicts of interest to declare.

Description: A growing body of evidence has added to our fundamental knowledge by demonstrating that human acute myelogenous leukemia (AML) is organized as a cellular hierarchy initiated and maintained by rare self-renewing leukemia stem cells (LSC). One implication of this cancer stem cell model is that in order to eradicate the leukemia and cure the patient, therapies must target and eliminate the leukemia stem cells. For the development of such LSC-targeted therapies, it is necessary to identify molecules that are preferentially expressed in LSC compared to their normal counterparts and that are critical for their function. We report here the identification of increased expression of CD47 on human AML LSC compared to normal hematopoietic stem cells (HSC). Furthermore, we demonstrate that differential CD47 expression on Lin-CD34+CD38− cells can be utilized to prospectively separate normal (CD47lo) from leukemic (CD47hi) progenitors from the same patient sample. CD47 serves as the ligand for signal regulatory protein alpha (SIRP-alpha) on phagocytic cells, which in turn delivers an inhibitory signal for phagocytosis. We hypothesize that increased CD47 expression on human AML contributes to pathogenesis by inhibiting phagocytosis of leukemia cells through the interaction of CD47 with SIRP-alpha. One prediction from this hypothesis is that increased expression of CD47 will be associated with a worse clinical outcome. We analyzed microarray gene expression data and associated clinical outcomes for a cohort of 123 AML patients with normal cytogenetics. Patients were stratified into low CD47 and high CD47 expression groups, based on expression relative to the median. Increased CD47 expression was found to be associated with worse event-free and overall survival. Patients in the low CD47 expression group had a median event-free survival of 18.2 months compared to 9.9 months in the high CD47 expression group, corresponding to a hazard ratio of 1.61 (p=0.04). For overall survival, patients in the low CD47 expression group had a median of 24.3 months compared to 14.1 months in the high CD47 expression group, corresponding to a hazard ratio of 1.70 (p=0.02). In multivariable analysis considering age, FLT3-ITD status, and CD47 expression as a continuous variable, increased CD47 expression remained associated with worse event-free survival with a hazard ratio of 1.33 (p=0.03) and overall survival with a hazard ratio of 1.31 (p=0.05). A second prediction from our hypothesis is that disruption of the CD47-SIRP-alpha interaction with a monoclonal antibody directed against CD47 will enable the phagocytosis of AML LSC. We obtained mouse anti-human CD47 monoclonal antibodies that are able to disrupt the CD47-SIRP-alpha interaction and tested their ability to enable phagocytosis of AML LSC both in vitro and in vivo. Unlike isotype control or an anti-CD45 antibody, anti-CD47 antibodies enabled phagocytosis of AML LSC by both mouse and human macrophages in vitro. Furthermore, unlike isotype control or anti-CD45 antibody, coating of AML LSC with anti-CD47 antibody completely eliminated in vivo engraftment upon xenotransplantation into NOG mice. Finally, treatment of NOG mice already engrafted with human AML LSC with daily intraperitoneal injections of anti-CD47 antibody for two weeks, resulted in complete elimination of circulating leukemia and a statistically significant reduction in bone marrow leukemia compared to control IgG. In summary, increased CD47 expression is an independent poor prognostic factor that can be targeted on AML stem cells with a monoclonal antibody capable of stimulating phagocytosis and in vivo elimination of LSC.

Description: Abstract 759 Introduction: Tumor infiltrating T cells present within biopsy specimens of human B cell non-Hodgkin's lymphomas (NHL) provide a valuable opportunity to examine immune system function in the presence of cancer. We recently used flow cytometry to characterize signaling in subpopulations of tumor samples from patients with follicular lymphoma (FL). In FL, we identified a novel lymphoma cell subset with impaired B cell antigen receptor (BCR) signaling, the prevalence of which correlated with adverse clinical outcome. Here, we turned our attention to signaling differences in subsets of the tumor-infiltrating T cells from FL and two other NHLs, diffuse large B cell lymphoma (DLBCL) and mantle cell lymphoma (MCL). Signaling differences that distinguish the tumor infiltrating T cells from each malignancy might be expected to be a reflection of the specific disease microenvironment, whereas T cell signaling differences distinguishing cases of the same malignancy might be related to the biology of each patient's tumor. Methods: Single cell flow cytometry measurements of signaling were acquired for samples of DLBCL (N=13), MCL (N=20), and FL (N=14). Phosphorylation of 14 signaling proteins was measured under 12 stimulation conditions in every cell, including lymphoma B cells and tumor-infiltrating T cells within the same specimen. Stimulation conditions included those that were B cell specific (BCR crosslinking, CD40 ligand), T cell specific (IL-7), and those that stimulated both B and T cells (IL-4, IL-10, IL-21, PMA + ionomycin, and IFN-γ). Results: Striking differences were observed in the signaling responses of tumor infiltrating T cells. T cells infiltrating FL patient samples showed significantly lower responses to cytokines where signal transduction is mediated by the common γ chain receptor. Specifically, we observed significant lower induction of p-STAT6 after IL-4 stimulation, p-STAT5 after IL-7 stimulation, and p-STAT3 after IL-21 stimulation (p 〈 0.001 for FL vs. MCL in all cases). In contrast, receptor-independent signaling was not significantly different as FL tumor infiltrating T cells responded at a level comparable to MCL and DLBCL tumor infiltrating T cells when stimulated with PMA and ionomycin. The lower response to common γ chain family cytokines could be the result of a partial suppression of all tumor infiltrating T cells or a complete suppression of a distinct subset. To distinguish between these possibilities, we analyzed signaling in tumor infiltrating T cell subsets. This single cell approach showed that tumor infiltrating T cells were a heterogeneous mixture of non-responsive cells and highly responsive T cells in response to cytokines. Specifically, the mean percentage of T cells that did not induce p-STAT3 after IL-21 stimulation was 50.3% in FL samples in contrast to only 26.2% in MCL samples. Phenotypic analysis showed that the vast majority of T cells infiltrating FL patient samples were CD4+CD45RO memory cells, and the single cell signaling approach revealed that the FL nonresponsive T cell subset had this phenotype. Furthermore, FL T cells were composed of a significantly larger fraction of T regulatory cells than MCL T cells, on average 17% FoxP3+CD25+ cells compared to only 9% in MCL (p

Description: Abstract 1617 Poster Board I-643 Background A rapid decline of circulating blasts in response to induction therapy is one of the most important prognostic factors of clinical outcome in childhood acute lymphoblastic leukemia. However, the prognostic significance of time to blast clearance in adult AML has not been well-established. The Mayo Clinic recently reported improved OS with early clearance ('3 days) of peripheral blood (PB) blasts among 86 adult patients with AML. In a separate series, age is suggested to modify the effect of time with shorter interval from diagnosis to induction therapy (TDT) predicting improved OS in younger but not older AML patients. We retrospectively reviewed the Stanford Leukemia Database to validate the prognostic relevance of time and age as a putative effect modifier with respect to OS in AML. Methods From 1993 to 2008 outcomes of 1,909 adult patients with leukemia were reviewed to select eligible patients with previously untreated AML (non-acute promyelocytic leukemia) having received cytarabine-based induction regimens. We defined the day of PB blast clearance (the first day after initiating induction chemotherapy that PB blasts were absent), and three “blast risk groups” (good, intermediate and poor, according to PB blast clearance on or before day 3, on days 4 or 5, or on day 6 or beyond, respectively) identical to the Mayo Clinic model. A 100 cell manual slide differential count was evaluated from the first day of induction through nadir with PB blasts enumerated unless the WBC was less than 0.5 ×109/L. For purposes of TDT analysis, patients receiving therapy on day of diagnosis were excluded (24 patients) as performed in the Cleveland Clinic-MD Anderson (CC-MDA) model. We defined delayed versus immediate treatment (delayed meaning more than 5 days from day of diagnosis to first day of induction therapy) identical to the CC-MDA model. Results Among 333 patients (55% males; median age 53y, range 18-88, including 224 patients11). The distribution of good, intermediate and poor blast risk groups was 28.3%, 26.1%, and 45.6%, without significantly different median OS of 63.8, 56.2, and 51.6 weeks, respectively (Fig 1, p=0.61). In univariate analysis there was no relationship between TDT and OS among all patients as a continuous variable (p=0.791) or classified as delayed versus immediate treatment (Fig 2, p=0.92). When stratified by older and younger AML patients, age did not modify the effect. Conclusion In adults with non-APL AML, both TDT and PB blast clearance after induction chemotherapy with cytarabine-based regimens failed to predict OS. Current practice standards should not be modified until further studies validate the significance of time from diagnosis to treatment and to clearance of circulating blasts. Disclosures No relevant conflicts of interest to declare.