CPX-351 versus 7+3 cytarabine and daunorubicin chemotherapy in older adults with newly diagnosed high-risk or secondary acute myeloid leukaemia: 5-year results of a randomised, open-label, multicentre, phase 3 trial

BACKGROUND

Daunorubicin and cytarabine are used as standard induction chemotherapy for patients with acute myeloid leukaemia. CPX-351 is a dual-drug liposomal encapsulation of daunorubicin and cytarabine in a synergistic 1:5 molar ratio. Primary analysis of the phase 3 trial in adults aged 60-75 years with newly diagnosed high-risk or secondary acute myeloid leukaemia provided support for approval of CPX-351 by the US Food and Drug Administration and European Medicines Agency. We describe the prospectively planned final 5-year follow-up results.

METHODS

This randomised, open-label, multicentre, phase 3 trial was done across 39 academic and regional cancer centres in the USA and Canada. Eligible patients were aged 60-75 years and had a pathological diagnosis of acute myeloid leukaemia according to WHO 2008 criteria, no previous induction therapy for acute myeloid leukaemia, and an Eastern Cooperative Oncology Group performance status of 0-2. Patients were randomly assigned 1:1 (stratified by age and acute myeloid leukaemia subtype) to receive up to two induction cycles of CPX-351 (100 units/m² administered as a 90-min intravenous infusion on days 1, 3, and 5; on days 1 and 3 for the second induction) or standard chemotherapy (cytarabine 100 mg/m² per day continuous intravenous infusion for 7 days plus intravenous daunorubicin 60 mg/m² on days 1, 2, and 3 [7+3]; cytarabine for 5 days and daunorubicin on days 1 and 2 for the second induction [5+2]). Patients with complete remission or complete remission with incomplete neutrophil or platelet recovery could receive up to tw cycles of consolidation therapy with CPX-351 (65 units/m² 90-min infusion on days 1 and 3) or chemotherapy (5+2, same dosage as in the second induction cycle). The primary outcome was overall survival analysed in all randomly assigned patients. No additional adverse events were collected with long-term follow-up, except data for deaths. This trial is registered with ClinicalTrials.gov, NCT01696084, and is complete.

FINDINGS

Between Dec 20, 2012, and Nov 11, 2014, 309 patients with newly diagnosed high-risk or secondary acute myeloid leukaemia were enrolled and randomly assigned to receive CPX-351 (153 patients) or 7+3 (156 patients). At a median follow-up of 60·91 months (IQR 60·06-62·98) in the CPX-351 group and 59·93 months (59·73-60·50) in the 7+3 group, median overall survival was 9·33 months (95% CI 6·37-11·86) with CPX-351 and 5·95 months (4·99-7·75) with 7+3 (HR 0·70, 95% CI 0·55-0·91). 5-year overall survival was 18% (95% CI 12-25%) in the CPX-351 group and 8% (4-13%) in the 7+3 group. The most common cause of death in both groups was progressive leukaemia (70 [56%] of 124 deaths in the CPX-351 group and 74 [53%] of 140 deaths in the 7+3 group). Six (5%) of 124 deaths in the CPX-351 group and seven (5%) of 140 deaths in the 7+3 group were considered related to study treatment.

INTERPRETATION

After 5 years of follow-up, the improved overall survival with CPX-351 versus 7+3 was maintained, which supports the previous evidence that CPX-351 can contribute to long-term remission and improved overall survival in patients aged 60-75 years with newly diagnosed high-risk or secondary acute myeloid leukaemia.

FUNDING

Jazz Pharmaceuticals.

A clinical transcriptome approach to patient stratification and therapy selection in acute myeloid leukemia

As more clinically-relevant genomic features of myeloid malignancies are revealed, it has become clear that targeted clinical genetic testing is inadequate for risk stratification. Here, we develop and validate a clinical transcriptome-based assay for stratification of acute myeloid leukemia (AML). Comparison of ribonucleic acid sequencing (RNA-Seq) to whole genome and exome sequencing reveals that a standalone RNA-Seq assay offers the greatest diagnostic return, enabling identification of expressed gene fusions, single nucleotide and short insertion/deletion variants, and whole-transcriptome expression information. Expression data from 154 AML patients are used to develop a novel AML prognostic score, which is strongly associated with patient outcomes across 620 patients from three independent cohorts, and 42 patients from a prospective cohort. When combined with molecular risk guidelines, the risk score allows for the re-stratification of 22.1 to 25.3% of AML patients from three independent cohorts into correct risk groups. Within the adverse-risk subgroup, we identify a subset of patients characterized by dysregulated integrin signaling and RUNX1 or TP53 mutation. We show that these patients may benefit from therapy with inhibitors of focal adhesion kinase, encoded by PTK2, demonstrating additional utility of transcriptome-based testing for therapy selection in myeloid malignancy.

Five-year final results of a phase III study of CPX-351 versus 7+3 in older adults with newly diagnosed high-risk/secondary AML

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Background: CPX-351 (Vyxeos; daunorubicin and cytarabine liposome for injection), a dual-drug liposomal encapsulation of cytarabine [C] and daunorubicin [D], is approved by the FDA and EMA for the treatment of adults with newly diagnosed therapy-related AML or AML with myelodysplasia-related changes. Primary analysis of the pivotal phase 3 study (NCT01696084) that formed the basis for these approvals evaluated patients (pts) aged 60-75 y with newly diagnosed high-risk/secondary AML and found that CPX-351 significantly improved median overall survival (OS) vs conventional 7+3, with a comparable safety profile. Here, we report the prospectively planned final 5-y follow-up results from this phase 3 study. Methods: Pts were randomized 1:1 to receive ≤2 induction cycles of CPX-351 (100 units/m2 [C 100 mg/m2 + D 44 mg/m2] as a 90-min infusion on Days 1, 3, 5 [2nd induction: Days 1, 3]) or 7+3 (C 100 mg/m2/d continuously for 7 d + D 60 mg/m2 on Days 1-3 [2nd induction: 5+2]). Pts achieving complete remission (CR) or CR with incomplete platelet or neutrophil recovery could receive up to 2 consolidation cycles. Pts could receive a hematopoietic cell transplant (HCT) at the physician’s discretion. Pts were followed until death or up to 5 y following randomization. Results: In total, 309 pts were randomized to CPX-351 (n = 153) or 7+3 (n = 156). The survival rate at 5 y was higher for CPX-351 vs 7+3 (18% vs 8%; Table). Among pts who died, the most common primary cause of death was progressive leukemia in both arms (CPX-351: 56%; 7+3: 53%). After a median follow-up of 60.65 mo, improved median OS with CPX-351 vs 7+3 was maintained: 9.33 vs 5.95 mo; Kaplan-Meier (KM) OS curves plateaued at ~30 mo. HCT was received by 53 (35%) vs 39 (25%) pts after CPX-351 vs 7+3; among these pts, the survival rate at 5 y was higher for CPX-351 vs 7+3 (52% vs 23%), and median OS landmarked from the HCT date was not reached for CPX-351 vs 10.25 mo for 7+3 (Table). Conclusions: After 5 y of follow-up, improved OS was maintained in this phase 3 study, supporting that CPX-351 has the ability to produce or contribute to long-term remission and survival in older pts with newly diagnosed high-risk/secondary AML. Clinical trial information: NCT01696084 . [Table: see text]

Day 14 Bone Marrow Evaluation During Acute Myeloid Leukemia Induction in a Real-world Canadian Cohort

INTRODUCTION

The 2017 National Comprehensive Cancer Network guidelines for acute myeloid leukemia have recommended performing bone marrow (BM) aspiration and BM trephine biopsy (BMTB) 14 to 21 days after starting induction therapy (commonly referred to as "day 14 [D14] marrow"). Those who do not achieve a hypoplastic marrow, with cellularity < 20% and blasts < 5%, are recommended to undergo 2-cycle induction (2CI). We performed a retrospective analysis to determine the impact of D14 BM characteristics in predicting for remission, association with overall survival (OS), and the effect of 2CI according to the D14 BM results.

PATIENTS AND METHODS

Patients aged 18 to 70 years undergoing induction therapy with standard "7 + 3" regimens were included. D14 cellularity was determined from BMTB samples and the blast percentage was assessed by morphology on BM aspiration and BMTB samples. The outcomes evaluated included the rates of complete remission (CR) and OS.

RESULTS

A total of 486 patients with results from D14 BM evaluation were included in the present study. On multivariate analysis, cytogenetic risk and D14 blasts < 5% were predictive of CR/CR with incomplete count recovery (P < .001). Cytogenetic risk (P < .001), age < 60 years (P = .001), and D14 blasts < 5% (P = .045) predicted for OS. 2CI was performed in 131 patients (27%). Patients with hypocellular D14 BM but residual blasts (n = 106) underwent 2CI in 46% of cases, with improved remission rates (43.9% vs. 72.0%; P = .004) but no difference in OS.

CONCLUSIONS

The results from D14 BM evaluations are predictive of subsequent remission and OS. Our findings did not show a survival benefit with D14 BM-driven 2CI.

Quizartinib versus salvage chemotherapy in relapsed or refractory FLT3-ITD acute myeloid leukaemia (QuANTUM-R): a multicentre, randomised, controlled, open-label, phase 3 trial

BACKGROUND

Patients with relapsed or refractory FLT3 internal tandem duplication (FLT3-ITD)-positive acute myeloid leukaemia have a poor prognosis, including high frequency of relapse, poorer response to salvage therapy, and shorter overall survival than those with FLT3 wild-type disease. We aimed to assess whether single-agent quizartinib, an oral, highly potent and selective type II FLT3 inhibitor, improves overall survival versus salvage chemotherapy.

METHODS

QuANTUM-R is a randomised, controlled, phase 3 trial done at 152 hospitals and cancer centres in 19 countries. Eligible patients aged 18 years or older with ECOG performance status 0-2 with relapsed or refractory (duration of first composite complete remission ≤6 months) FLT3-ITD acute myeloid leukaemia after standard therapy with or without allogeneic haemopoietic stem-cell transplantation were randomly assigned (2:1; permuted block size of 6; stratified by response to previous therapy and choice of chemotherapy via a phone-based and web-based interactive response system) to quizartinib (60 mg [30 mg lead-in] orally once daily) or investigator's choice of preselected chemotherapy: subcutaneous low-dose cytarabine (subcutaneous injection of cytarabine 20 mg twice daily on days 1-10 of 28-day cycles); intravenous infusions of mitoxantrone (8 mg/m² per day), etoposide (100 mg/m² per day), and cytarabine (1000 mg/m² per day on days 1-5 of up to two 28-day cycles); or intravenous granulocyte colony-stimulating factor (300 μg/m² per day or 5 μg/kg per day subcutaneously on days 1-5), fludarabine (intravenous infusion 30 mg/m² per day on days 2-6), cytarabine (intravenous infusion 2000 mg/m² per day on days 2-6), and idarubicin (intravenous infusion 10 mg/m² per day on days 2-4 in up to two 28-day cycles). Patients proceeding to haemopoietic stem-cell transplantation after quizartinib could resume quizartinib after haemopoietic stem-cell transplantation. The primary endpoint was overall survival in the intention-to-treat population. This trial is registered with ClinicalTrials.gov, number NCT02039726, and follow-up is ongoing.

FINDINGS

Between May 7, 2014, and Sept 13, 2017, 367 patients were enrolled, of whom 245 were randomly allocated to quizartinib and 122 to chemotherapy. Four patients in the quizartinib group and 28 in the chemotherapy group were not treated. Median follow-up was 23·5 months (IQR 15·4-32·3). Overall survival was longer for quizartinib than for chemotherapy (hazard ratio 0·76 [95% CI 0·58-0·98; p=0·02]). Median overall survival was 6·2 months (5·3-7·2) in the quizartinib group and 4·7 months (4·0-5·5) in the chemotherapy group. The most common non-haematological grade 3-5 treatment-emergent adverse events (within ≤30 days of last dose or >30 days if suspected to be a treatment-related event) for quizartinib (241 patients) and chemotherapy (94 patients) were sepsis or septic shock (46 patients [19%] for quizartinib vs 18 [19%] for chemotherapy), pneumonia (29 [12%] vs eight [9%]), and hypokalaemia (28 [12%] vs eight [9%]). The most frequent treatment-related serious adverse events were febrile neutropenia (18 patients [7%]), sepsis or septic shock (11 [5%]), QT prolongation (five [2%]), and nausea (five [2%]) in the quizartinib group, and febrile neutropenia (five [5%]), sepsis or septic shock (four [4%]), pneumonia (two [2%]), and pyrexia (two [2%]) in the chemotherapy group. Grade 3 QT prolongation in the quizartinib group was uncommon (eight [3%] by central reading, ten [4%] by investigator report); no grade 4 events occurred. There were 80 (33%) treatment-emergent deaths in the quizartinib group (31 [13%] of which were due to adverse events) and 16 (17%) in the chemotherapy group (nine [10%] of which were due to adverse events).

INTERPRETATION

Treatment with quizartinib had a survival benefit versus salvage chemotherapy and had a manageable safety profile in patients with rapidly proliferative disease and very poor prognosis. Quizartinib could be considered a new standard of care. Given that there are only a few available treatment options, this study highlights the value of targeting the FLT3-ITD driver mutation with a highly potent and selective FLT3 inhibitor.

FUNDING

Daiichi Sankyo.

Health state utilities associated with treatment options for acute myeloid leukemia (AML)

Aims: Acute myeloid leukemia (AML) treatment typically involves remission induction chemotherapy followed by consolidation chemotherapy. New treatments for AML have recently been introduced, including a chemotherapy formulation called CPX-351, which is administered via less time-intensive IV infusion than the standard "7 + 3" continuous infusion regimen of cytarabine plus an anthracycline. The purpose of this study was to estimate utilities that could be used in economic modeling of AML treatment. Materials and methods: In time trade-off interviews, participants from the UK general population valued 12 health states drafted based on literature and clinician interviews. To identify disutility associated with chemotherapy, two types of induction and four types of consolidation were added to an otherwise identical health state describing AML. The decrease in utility when adding these chemotherapy regimens represents the disutility of each regimen. Five additional health states were valued to estimate utilities associated with other AML treatments. Results: Two hundred participants completed interviews. Mean (SD) utilities were 0.55 (0.31) for pre-treatment AML and 0.66 (0.29) for AML in temporary remission. Adding any chemotherapy significantly decreased utility (p < 0.0001). Induction had a mean disutility of -0.11 with CPX-351 and -0.15 with 7 + 3. Mean disutility for consolidation ranged from -0.03 with outpatient CPX-351 to -0.11 with inpatient 5 + 2. Utilities are also reported for other AML treatments (e.g. transplant, low-intensity chemotherapy). Limitations: One limitation is that the differences in adverse event profiles between the treatment regimens were based on clinician opinion. Future use of CPX-351 in clinical trials or clinical settings will provide additional information on its adverse event profile. Conclusions: While all chemotherapy regimens were associated with disutility, regimens with shorter hospitalization and less time-intensive infusion were generally perceived as preferable. These utilities may be useful in cost-utility models comparing the value of AML treatments.

CPX-351 (cytarabine and daunorubicin) Liposome for Injection Versus Conventional Cytarabine Plus Daunorubicin in Older Patients With Newly Diagnosed Secondary Acute Myeloid Leukemia

Purpose

CPX-351 is a dual-drug liposomal encapsulation of cytarabine and daunorubicin that delivers a synergistic 5:1 drug ratio into leukemia cells to a greater extent than normal bone marrow cells. Prior clinical studies demonstrated a sustained drug ratio and exposure in vivo and prolonged survival versus standard-of-care cytarabine plus daunorubicin chemotherapy (7+3 regimen) in older patients with newly diagnosed secondary acute myeloid leukemia (sAML).

Patients and Methods

In this open-label, randomized, phase III trial, 309 patients age 60 to 75 years with newly diagnosed high-risk/sAML received one to two induction cycles of CPX-351 or 7+3 followed by consolidation therapy with a similar regimen. The primary end point was overall survival.

Results

CPX-351 significantly improved median overall survival versus 7+3 (9.56 v 5.95 months; hazard ratio, 0.69; 95% CI, 0.52 to 0.90; one-sided P = .003). Overall remission rate was also significantly higher with CPX-351 versus 7+3 (47.7% v 33.3%; two-sided P = .016). Improved outcomes were observed across age-groups and AML subtypes. The incidences of nonhematologic adverse events were comparable between arms, despite a longer treatment phase and prolonged time to neutrophil and platelet count recovery with CPX-351. Early mortality rates with CPX-351 and 7+3 were 5.9% and 10.6% (two-sided P = .149) through day 30 and 13.7% and 21.2% (two-sided P = .097) through day 60.

Conclusion

CPX-351 treatment is associated with significantly longer survival compared with conventional 7+3 in older adults with newly diagnosed sAML. The safety profile of CPX-351 was similar to that of conventional 7+3 therapy.

Overall survival (OS) and stem cell transplant (SCT) in patients with FLT3 mutations treated with CPX-351 versus 7+3: Subgroup analysis of a phase III study of older adults with newly diagnosed, high-risk acute myeloid leukemia (AML)

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Background: FLT3+ AML patients (pts; 20%-30% of AML pts) often have rapid post-induction relapse, highlighting the need for therapies that improve the bridge to SCT. CPX-351 is a liposomal formulation that delivers a synergistic 5:1 molar ratio of cytarabine (C) and daunorubicin (D). CPX-351 demonstrated efficacy versus 7+3 in a randomized, open-label, controlled phase III trial in pts aged 60-75 years with newly diagnosed, high-risk AML; our analysis investigated outcomes in the subset of FLT3+ pts. Methods: Pts were randomized 1:1 to induction with 1-2 cycles of CPX-351 (100 u/m2 [C 100 mg/m2 + D 44 mg/m2] on Days 1, 3, and 5 [2nd induction: Days 1 and 3]) or 7+3 (C 100 mg/m2/day x 7 days [2nd induction: x 5 days] + D 60 mg/m2on Days 1, 2, and 3 [2nd induction: Days 1 and 2]). Pts with complete remission (CR) or CR with incomplete platelet or neutrophil recovery (CRi) could receive up to 2 consolidation cycles. Results: Of the pts who had FLT3 mutations assessed and received study treatment, 22/138 (16%) pts in the CPX-351 arm and 20/136 (15%) pts in the 7+3 arm had baseline FLT3 mutations. AML subtypes in FLT3+ pts were: tAML (19%); AML after MDS with (38%) or without (10%) prior hypomethylating agents; AML after CMMoL (12%); and de novo AML with MDS karyotype (21%). In FLT3+ pts, median OS was longer with CPX-351 (10.25 mo) versus 7+3 (4.55 mo; HR = 0.57 [95% CI: 0.24, 1.33]; P= 0.093) and the rate of CR+CRi was higher (68% vs 25%). A greater number of FLT3+ pts treated with CPX-351 were able to undergo SCT (n = 10/22 [45%]; 4 pts were alive as of this analysis, after a median post-SCT follow up of 692 days [range: 96-769]) compared with 7+3 (n = 2/20 [10%]; neither pt still alive). The on-study safety profile of CPX-351 in FLT3+ pts was comparable to 7+3 and consistent with the overall study population. Serious adverse events were experienced by 7 (32%) FLT3+ pts in the CPX-351 arm and 10 (50%) in the 7+3 arm. Conclusions: CPX-351 demonstrated numerical improvement in median OS in older pts with newly diagnosed, FLT3+ high-risk AML and allowed more pts to undergo SCT. The analysis was limited by small number of pts. Clinical trial information: NCT01696084.

Efficacy by consolidation administration site: Subgroup analysis of a phase III study of CPX-351 versus 7+3 in older adults with newly diagnosed, high-risk acute myeloid leukemia (AML)

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Background: The CPX-351 liposomal formulation delivers a synergistic 5:1 molar ratio of cytarabine (C) and daunorubicin (D) preferentially to leukemia cells. CPX-351 has demonstrated significantly improved overall survival (OS) versus 7+3 in a randomized, open-label, phase III study in patients (pts) aged 60-75 years with newly diagnosed, high-risk AML. In contrast to 7+3, which includes C continuous infusion, CPX-351 is administered as a 90-minute infusion and has the potential to be given in the outpatient setting. The current analysis of the phase III trial assessed the setting of consolidation therapy. Methods: Pts were randomized 1:1 to 1-2 induction cycles of CPX-351 or 7+3; pts with complete remission (CR) or CR with incomplete platelet or neutrophil recovery (CRi) could receive up to 2 consolidation cycles (CPX-351: 65 u/m2 [C 65 mg/m2 + D 28.6 mg/m2] on Days 1 and 3; 7+3: C 100 mg/m2/day x 5 days + D 60 mg/m2 on Days 1 and 2). Site of administration was not protocol defined. Results: Few pts received induction as outpatient therapy (CPX-351 n = 3/153 and 7+3 n = 1/151 in each cycle). 49/153 CPX-351 pts and 32/151 7+3 pts received consolidation, with a substantial proportion of pts receiving CPX-351 as outpatients (consolidation 1: 51%; consolidation 2: 61%). CPX-351 consolidation was associated with substantial improvement in median OS versus 7+3 irrespective of inpatient/outpatient status (Table). Median OS was not diminished with CPX-351 administration in the outpatient versus inpatient setting (consolidation 1: 25.43 and 14.72, respectively; consolidation 2: 26.32 and not reached). Conclusions: Some pts can successfully receive CPX-351 consolidation as outpatients without diminished efficacy, potentially reducing hospitalizations associated with treatment administration. Clinical trial information: NCT01696084. [Table: see text]

Comparison of a pediatric-inspired treatment protocol versus standard-intensity chemotherapy for young adults with standard-risk BCR-ABL negative acute lymphoblastic leukemia

We investigated the utility of a pediatric-inspired protocol in adults aged 18-40 years with standard-risk BCR-ABL negative acute lymphoblastic leukemia (ALL). Retrospective outcomes of 25 patients treated with a pediatric protocol between 2008 and 2014 were compared with 22 similarly aged patients treated with an adult protocol between 2003 and 2008. Twenty-five (100%) and 19 (86%) patients achieved complete remission, respectively. At median follow-up of 36.8 months, 3-year event-free survival was increased in patients on the pediatric protocol at 80% versus 45% (p = .019). There was a trend toward improved overall survival at 80% versus 59% (p = .12). Treatment-related toxicity was not increased despite the increased treatment intensity. Patients with BCR and/or ABL copy number variation demonstrated comparatively poorer outcomes in both cohorts. In our experience with this cohort of patients, pediatric-based protocols are safe and effective, justifying their use in younger adults with ALL.

Vosaroxin plus cytarabine versus placebo plus cytarabine in patients with first relapsed or refractory acute myeloid leukaemia (VALOR): a randomised, controlled, double-blind, multinational, phase 3 study

BACKGROUND

Safe and effective treatments are urgently needed for patients with relapsed or refractory acute myeloid leukaemia. We investigated the efficacy and safety of vosaroxin, a first-in-class anticancer quinolone derivative, plus cytarabine in patients with relapsed or refractory acute myeloid leukaemia.

METHODS

This phase 3, double-blind, placebo-controlled trial was undertaken at 101 international sites. Eligible patients with acute myeloid leukaemia were aged 18 years of age or older and had refractory disease or were in first relapse after one or two cycles of previous induction chemotherapy, including at least one cycle of anthracycline (or anthracenedione) plus cytarabine. Patients were randomly assigned 1:1 to vosaroxin (90 mg/m(2) intravenously on days 1 and 4 in a first cycle; 70 mg/m(2) in subsequent cycles) plus cytarabine (1 g/m(2) intravenously on days 1-5) or placebo plus cytarabine through a central interactive voice system with a permuted block procedure stratified by disease status, age, and geographical location. All participants were masked to treatment assignment. The primary efficacy endpoint was overall survival and the primary safety endpoint was 30-day and 60-day all-cause mortality. Efficacy analyses were done by intention to treat; safety analyses included all treated patients. This study is registered with ClinicalTrials.gov, number NCT01191801.

FINDINGS

Between Dec 17, 2010, and Sept 25, 2013, 711 patients were randomly assigned to vosaroxin plus cytarabine (n=356) or placebo plus cytarabine (n=355). At the final analysis, median overall survival was 7·5 months (95% CI 6·4-8·5) in the vosaroxin plus cytarabine group and 6·1 months (5·2-7·1) in the placebo plus cytarabine group (hazard ratio 0·87, 95% CI 0·73-1·02; unstratified log-rank p=0·061; stratified p=0·024). A higher proportion of patients achieved complete remission in the vosaroxin plus cytarabine group than in the placebo plus cytarabine group (107 [30%] of 356 patients vs 58 [16%] of 355 patients, p<0·0001). Early mortality was similar between treatment groups (30-day: 28 [8%] of 355 patients in the vosaroxin plus cytarabine group vs 23 [7%] of 350 in the placebo plus cytarabine group; 60-day: 70 [20%] vs 68 [19%]). Treatment-related deaths occurred at any time in 20 (6%) of 355 patients given vosaroxin plus cytarabine and in eight (2%) of 350 patients given placebo plus cytarabine. Treatment-related serious adverse events occurred in 116 (33%) and 58 (17%) patients in each group, respectively. Grade 3 or worse adverse events that were more frequent in the vosaroxin plus cytarabine group than in the placebo plus cytarabine group included febrile neutropenia (167 [47%] vs 117 [33%]), neutropenia (66 [19%] vs 49 [14%]), stomatitis (54 [15%] vs 10 [3%]), hypokalaemia (52 [15%] vs 21 [6%]), bacteraemia (43 [12%] vs 16 [5%]), sepsis (42 [12%] vs 18 [5%]), and pneumonia (39 [11%] vs 26 [7%]).

INTERPRETATION

Although there was no significant difference in the primary endpoint between groups, the prespecified secondary analysis stratified by randomisation factors suggests that the addition of vosaroxin to cytarabine might be of clinical benefit to some patients with relapsed or refractory acute myeloid leukaemia.

FUNDING

Sunesis Pharmaceuticals.

MicroRNA-223 dose levels fine tune proliferation and differentiation in human cord blood progenitors and acute myeloid leukemia

A precise understanding of the role of miR-223 in human hematopoiesis and in the pathogenesis of acute myeloid leukemia (AML) is still lacking. By measuring miR-223 expression in blasts from 115 AML patients, we found significantly higher miR-223 levels in patients with favorable prognosis, whereas patients with low miR-223 expression levels were associated with worse outcome. Furthermore, miR-223 was hierarchically expressed in AML subpopulations, with lower expression in leukemic stem cell-containing fractions. Genetic depletion of miR-223 decreased the leukemia initiating cell (LIC) frequency in a myelomonocytic AML mouse model, but it was not mandatory for rapid-onset AML. To relate these observations to physiologic myeloid differentiation, we knocked down or ectopically expressed miR-223 in cord-blood CD34⁺ cells using lentiviral vectors. Although miR-223 knockdown delayed myeloerythroid precursor differentiation in vitro, it increased myeloid progenitors in vivo following serial xenotransplantation. Ectopic miR-223 expression increased erythropoiesis, T lymphopoiesis, and early B lymphopoiesis in vivo. These findings broaden the role of miR-223 as a regulator of the expansion/differentiation equilibrium in hematopoietic stem and progenitor cells where its impact is dose- and differentiation-stage-dependent. This also explains the complex yet minor role of miR-223 in AML, a heterogeneous disease with variable degree of myeloid differentiation.

Deep profiling of multitube flow cytometry data

MOTIVATION

Deep profiling the phenotypic landscape of tissues using high-throughput flow cytometry (FCM) can provide important new insights into the interplay of cells in both healthy and diseased tissue. But often, especially in clinical settings, the cytometer cannot measure all the desired markers in a single aliquot. In these cases, tissue is separated into independently analysed samples, leaving a need to electronically recombine these to increase dimensionality. Nearest-neighbour (NN) based imputation fulfils this need but can produce artificial subpopulations. Clustering-based NNs can reduce these, but requires prior domain knowledge to be able to parameterize the clustering, so is unsuited to discovery settings.

RESULTS

We present flowBin, a parameterization-free method for combining multitube FCM data into a higher-dimensional form suitable for deep profiling and discovery. FlowBin allocates cells to bins defined by the common markers across tubes in a multitube experiment, then computes aggregate expression for each bin within each tube, to create a matrix of expression of all markers assayed in each tube. We show, using simulated multitube data, that flowType analysis of flowBin output reproduces the results of that same analysis on the original data for cell types of >10% abundance. We used flowBin in conjunction with classifiers to distinguish normal from cancerous cells. We used flowBin together with flowType and RchyOptimyx to profile the immunophenotypic landscape of NPM1-mutated acute myeloid leukemia, and present a series of novel cell types associated with that mutation.

A discovery study of daunorubicin induced cardiotoxicity in a sample of acute myeloid leukemia patients prioritizes P450 oxidoreductase polymorphisms as a potential risk factor

Anthracyclines are very effective chemotherapeutic agents; however, their use is hampered by the treatment-induced cardiotoxicity. Genetic variants that help define patient's sensitivity to anthracyclines will greatly improve the design of optimal chemotherapeutic regimens. However, identification of such variants is hampered by the lack of analytical approaches that address the complex, multi-genic character of anthracycline induced cardiotoxicity (AIC). Here, using a multi-SNP based approach, we examined 60 genes coding for proteins involved in drug metabolism and efflux and identified the P450 oxidoreductase (POR) gene to be most strongly associated with daunorubicin induced cardiotoxicity in a population of acute myeloid leukemia (AML) patients (FDR adjusted p-value of 0.15). In this sample of cancer patients, variation in the POR gene is estimated to account for some 11.6% of the variability in the drop of left ventricular ejection fraction (LVEF) after daunorubicin treatment, compared to the estimated 13.2% accounted for by the cumulative dose and ethnicity. In post-hoc analysis, this association was driven by 3 SNPs-the rs2868177, rs13240755, and rs4732513-through their linear interaction with cumulative daunorubicin dose. The unadjusted odds ratios (ORs) and confidence intervals (CIs) for rs2868177 and rs13240755 were estimated to be 1.89 (95% CI: 0.7435-4.819; p = 0.1756) and 3.18 (95% CI: 1.223-8.27; p = 0.01376), respectively. Although the contribution of POR variants is expected to be overestimated due to the multiple testing performed in this small pilot study, given that cumulative anthracycline dose is virtually the only factor used clinically to predict the risk of cardiotoxicity, the contribution that genetic analyses of POR can make to the assessment of this risk is worthy of follow up in future investigations.

Barnacle: detecting and characterizing tandem duplications and fusions in transcriptome assemblies

Background

Chimeric transcripts, including partial and internal tandem duplications (PTDs, ITDs) and gene fusions, are important in the detection, prognosis, and treatment of human cancers.

Results

We describe Barnacle, a production-grade analysis tool that detects such chimeras in de novo assemblies of RNA-seq data, and supports prioritizing them for review and validation by reporting the relative coverage of co-occurring chimeric and wild-type transcripts. We demonstrate applications in large-scale disease studies, by identifying PTDs in MLL, ITDs in FLT3, and reciprocal fusions between PML and RARA, in two deeply sequenced acute myeloid leukemia (AML) RNA-seq datasets.

Conclusions

Our analyses of real and simulated data sets show that, with appropriate filter settings, Barnacle makes highly specific predictions for three types of chimeric transcripts that are important in a range of cancers: PTDs, ITDs, and fusions. High specificity makes manual review and validation efficient, which is necessary in large-scale disease studies. Characterizing an extended range of chimera types will help generate insights into progression, treatment, and outcomes for complex diseases.

Single-nucleotide polymorphisms in reductase genes are not associated with response to daunorubicin-based remission induction

BACKGROUND

To improve the quality of care for patients with acute myeloid leukemia (AML), biomarkers predictive of response to the standard daunorubicin-based induction therapy are needed. Genetic variants affecting daunorubicin metabolism are attractive candidates for such biomarkers.

METHODS

We have previously shown that 13 of the naturally occurring nonsynonymous single-nucleotide polymorphisms (SNP) in the reductase genes affect daunorubicin metabolism in vitro. Here, we test these SNPs individually and jointly for association with response to one cycle of daunorubicin-based chemotherapy in a sample of 189 patients with acute myelogenous leukemia.

RESULTS

Of the 13 SNPs included in this study, only 5 passed quality control filters. No association was found between these 5 SNPs and response to one cycle of daunorubicin-based induction therapy in either individual or joint effect tests.

CONCLUSIONS

Despite their showing in vitro effect on metabolic rate of daunorubicin, the nonsynonymous SNPs in the reductase genes on their own are not significant contributors to the observed variability in response to daunorubicin therapy and thus, as singularities, are not useful biomarkers of this outcome.

IMPACT

The results of this investigation provide important information for studies on personalization of anthracycline-based therapies.

Expression of integrin α2 receptor in human cord blood CD34+CD38-CD90+ stem cells engrafting long-term in NOD/SCID-IL2Rγ(c) null mice

Human hematopoietic stem cells reside in the CD34+CD38-CD90+ population in cord blood and bone marrow. However, this cell fraction is heterogeneous, and the phenotype of the rare primitive stem cells remains poorly defined. We here report that primitive cord blood CD34+CD38-CD90+ stem cells, with the ability to reconstitute NOD/SCID-IL2Rγ(c) null (NSG) mice long-term, at 24 weeks after transplantation, can be prospectively isolated at an increased purity by using integrin α2 receptor as an additional stem cell marker. Using a limiting dilution transplantation assay, we found a highly significant enrichment of multilineage reconstituting stem cells in the CD34+CD38-CD90+ cell fraction expressing the integrin α2 receptor, with a frequency of 1/29 cells, as compared to a frequency of 1/157 in the corresponding integrin α2- cells. In line with this, long-term reconstituting stem cells within the cord blood CD34+CD38- cell population were significantly enriched in the integrin α2+ fraction, while stem cells and progenitors reconstituting short-term, at 8-12 weeks, were heterogeneous in integrin α2 expression. Global gene expression profiling revealed that the lineage-marker negative (Lin-) CD34+CD38-CD90+CD45RA- integrin α2+ cell population was molecularly distinct from the integrin α2- cell population and the more mature Lin-CD34+CD38-CD90-CD45RA- cell population. Our findings identify integrin α2 as a novel stem cell marker, which improves prospective isolation of the primitive human hematopoietic stem cells within the CD34+CD38-CD90+ cell population for experimental and therapeutic stem cell applications.

Activity and tolerability of SL-401, a targeted therapy directed to the interleukin-3 receptor on cancer stem cells and tumor bulk, as a single agent in patients with advanced hematologic malignancies

7029^

Background: SL-401 is a novel biologic targeted therapy directed to the interleukin-3 receptor (IL-3R). IL-3R is overexpressed on cancer stem cells (CSCs) and tumor bulk relative to normal hematopoietic cells in a wide range of hematologic malignancies including AML and blastic plasmacytoid dendritic cell neoplasm (BPDCN). Since SL-401 targets both leukemia blasts and CSCs, tumor regression and improvement in long-term outcome is expected. The clinical activity and side effect profile of SL-401 were evaluated in a multicenter Phase I/II trial of patients with advanced hematologic cancers. Methods: Eighty-one patients with advanced hematologic cancers, including relapsed or refractory AML (n = 59) and heavily pretreated BPDCN (n = 4), have been enrolled. Patients received a single cycle of SL-401 via 15-minute IV infusion to determine the maximum tolerated dose (MTD) and assess antitumor activity. Results: A single cycle of SL-401 demonstrated single agent activity in relapsed or refractory AML patients, including 2 durable CRs of 8 and 25+ months duration and multiple cases of blast reductions. SL-401, when delivered at therapeutically relevant doses, was associated with > 3-fold greater median overall survival (OS) in AML patients who received 2+ prior lines of treatment relative to historical results. In addition, 3 heavily pre-treated patients with BPDCN, an uncommon malignancy that expresses high levels of IL-3R and is ultrasensitive to SL-401 (IC50 values in the femtomolar [10-15 M] range), had CRs, with durations of 5, 3+ and 1+ months. The MTD was 16.6 µg/kg/day; the dose-limiting toxicities of hypoalbuminemia and edema, which are manifestations of capillary leak, occurred at 22.1 µg/kg/day. Other ≥ Grade 3 adverse events included transient transaminase elevations. There was no treatment-related myelosuppression. Conclusions: SL-401 was well tolerated and demonstrated single agent activity in patients with relapsed or refractory AML and BPDCN. Based on these findings, single agent SL-401 given in multiple cycles will be advanced into pivotal studies of AML (3rd-line) and BPDCN. Clinical trial information: NCT00397579.

Multivariate analysis of factors affecting overall survival, event free survival, and 60-day mortality among AML patients treated with CPX-351 or intensive chemotherapy

7100

Background: CPX-351 encapsulates cytarabine (CYT) and daunorubicin (DNR) at a 5:1 molar ratio within liposomes, enabling preferential drug uptake within leukemic blasts and intracellular release, potentially enhancing efficacy in AML. A pair of randomized Phase IIb studies in newly diagnosed older patients (pts) and younger 1st relapse AML pts reported improved rates of morphologic leukemia-free state, CR + CRi, and significant improvements in survival among previously untreated high risk (secondary) pts and among poor-risk 1st relapse pts. This report presents the results of the multivariate analyses performed on all pts treated in both studies. Methods: Patients 60-75 yo with newly diagnosed AML and ≤ 65 yo with 1st relapse AML and ECOG PS= 0-2, SCR < 2.0 mg/dL, total bilirubin < 2.0 mg/dL, ALT/AST <3x ULN, and LVEF ≥ 50% were eligible. Pts with APL, DNR exposure >368 mg/m2, active CNS leukemia, and uncontrolled infections were excluded. Pts were randomized 2:1 to receive up to 2 inductions and 2 consolidations with CPX-351 (100 u/m2; D 1, 3, 5) or CYT + DNR (7+3) for newly diagnosed pts or investigator’s choice of salvage chemotherapy for relapsed pts. Allogeneic transplantation was permitted. Univariate and multivariate Cox and logistic regression were used to assess associations between baseline characteristics and overall (OS) and event-free survival (EFS) and 60-day mortality for all pts. The multivariate employed stepwise selection to identify statistically significant prognostic factors after accounting for potential treatment effects. Results: Patient characteristics including cytogenetics were well balanced. Significant negative prognostic factors affecting OS, EFS, and 60-day mortality included relapsed disease (Study 205 participation, HR=2.13, p<0.001), adverse cytogenetics (HR=1.52, p=0.024), and low (<3g/dL) serum albumin (HR=1.82, p=0.005). CPX-351 treatment was a significant positive factor in EFS (HR=0.62, p=0.006). Conclusions: This analysis identified and quantitated disease specific (adverse cytogenetics) and patient specific (albumin<3gm/dL) factors that can be used to better design future studies. Clinical trial information: NCT00788892 and NCT00822094.

Single-nucleotide polymorphisms in aldo-keto and carbonyl reductase genes are not associated with acute cardiotoxicity after daunorubicin chemotherapy

BACKGROUND

Evidence suggests that interpatient variability in anthracycline metabolic rate may contribute to the cardiotoxicity associated with anthracycline-based chemotherapy. Therefore, polymorphisms in the anthracycline metabolizing enzymes have been proposed as potential biomarkers of anthracycline-induced cardiotoxicity (AIC).

METHODS

We have previously shown that 13 of the naturally occurring nonsynonymous single-nucleotide polymorphisms (nsSNP) in the aldo-keto reductases (AKR) and carbonyl reductases (CBR) reduce anthracycline metabolic rate in vitro. Here, we test these SNPs individually and jointly for association with daunorubicin-induced cardiotoxicity in patients with acute myeloid leukemia (AML).

RESULTS

Five of the 13 nsSNPs exhibiting an in vitro effect on anthracycline metabolism were detected among the 185 patients with AML. No association was found between the SNPs and daunorubicin-induced cardiotoxicity in either individual or joint effect analyses.

CONCLUSIONS

Despite the shown in vitro effect of nsSNPs in reductase genes on anthracycline metabolic rate, on their own these SNPs do not explain enough variability in cardiotoxicity to be useful markers of this adverse event.

IMPACT

The results of this study provide important information for biomarker studies on side effects of anthracycline chemotherapy.

A comparison of CR versus CRi response following CPX-351 treatment of newly diagnosed AML in elderly patients (pts)

6601

Background: A Phase 2b study randomized untreated elderly AML pts to CPX-351 or 7+3. CPX-351 improved leukemia clearance (88% v 71%, <5% marrow blasts), CR+CRi rate (67% v 51%), and was particularly effective in pts with adverse karyotype and antecedent hematologic disorders (sAML). Survival following CRi is usually inferior compared to CR. CPX-351 markedly prolongs plasma drug levels and maintains the 5:1 molar ratio for optimal leukemic cell killing potentially delaying hematologic recovery among CRi patients. Consequently, we compared the characteristics and outcomes of pts achieving CR v CRi. Methods: Untreated AML pts, aged 60-75, PS= 0-2, SCr < 2.0 mg/dL, total bilirubin <2.0 mg/dL, ALT/AST <3 x ULN, and LVEF ≥50% were eligible. Pts were randomized 2:1 to receive up to 2 inductions and 2 consolidations with CPX-351 (100 u/m2; D 1, 3, 5; 90 min infusion) or 7+3 (cytarabine=100 mg/m2 and daunorubicin=60 mg/m2). Consolidation with stem cell transplantation (SCT) was permitted. The 1o endpoint was CR+CRi rate. The 7+3 control arm had only a single CRi among 21 responders. The CPX-351 arm had 15 CRi (27%) and 41 CR (73%) allowing a CR v CRi comparison to be made. Results: CR and CRi pts were balanced by age, race, and PS. The CRi group had more males (87% v 51%), more baseline WBC>20K (27% v 15%), and more adverse karyotype (40% v 27%) and sAML (47% v 29%). A smaller proportion of CRi pts received post-remission chemotherapy (47% v 73%) but had similar rates of SCT (13% v 20%). Most CRi pts had delayed platelet recovery (80%). By 1-year more CRi pts had relapsed (54% v 39%) and more had died (54% v 34%). Contributing causes included: relapsed AML (7 CRi v 10 CR pts), complications post SCT (1 CRi v 1 CR pt), chemotherapy complications (0 CRi v 2 CR pts) and unknown causes (0 CRi v 1 CR pt). The survival curves were not significantly different (p=0.39). Conclusions: More CRi patients had adverse karyotype and sAML and most (53%) received no post remission chemotherapy. Survival was not significantly different compared to CR patients but was markedly better than that of non-responders. These data suggest that CRi following CPX-351 provides clinically meaningful benefit, a finding that needs to be confirmed in a larger randomized study.

Phase 1 trial of linifanib (ABT-869) in patients with refractory or relapsed acute myeloid leukemia

Linifanib, a potent oral inhibitor of fms-like tyrosine kinase 3 (FLT3) and vascular endothelial growth factor receptor tyrosine kinases, has demonstrated promising preclinical single-agent and synergistic anti-leukemic activity in combination with cytarabine. In this phase 1, multicenter, open-label, dose-escalation study, 45 adults with relapsed/refractory acute myeloid leukemia (AML) received linifanib alone in arm A (n = 29) and linifanib plus intermediate-dose cytarabine in arm B (n = 16). Median treatment duration was 21 days (range 5-110). Linifanib was well tolerated overall. The most common grade 3/4 events were fatigue (arm A) and febrile neutropenia (arm B). The recommended phase 2 dose was 15 mg (alone), and 10 mg (with cytarabine). Evidence of on-target kinase inhibition in patients with FLT3-mutant and wild-type AML was seen. Decreased phosphorylated FLT3 was seen in 3/3 patients with FLT3-internal tandem duplication (ITD) with peripheral blast reductions and in 8/24 (33%) patients with wild-type, D835 or unknown FLT3 mutation. Eight/29 (28%) patients had decreased phosphorylated extracellular signal-regulated kinase (ERK).

Cryopreserved mobilized autologous blood progenitors stored for more than 2 years successfully support blood count recovery after high-dose chemotherapy

BACKGROUND AIMS

The ability of hematopoietic progenitor cells-apheresis (HPC-A) that have been stored for many years after cryopreservation to reconstitute hematopoiesis following high-dose chemo/radiotherapy has not been well-documented.

METHODS

In this retrospective study, eight Canadian centers contributed data from 53 autologous stem cell transplants (ASCT) performed using HPC-A that had undergone long-term storage (>2 years, range 2-7 years) and 120 ASCT using HPC-A stored for <6 months (short-term storage).

RESULTS

The doses of nucleated and CD34(+) cells per kilogram recipient weight were similar between the short- (mean ± SD, 4.7 ± 4.9 × 10(8) and 6.8 ± 4.3 × 10(6), respectively) and long- (4.0 ± 4.9 × 10(8) and 6.1 ± 3.4 × 10(6), respectively) term storage groups. The median days to neutrophils (absolute neutrophil count; ANC) >0.5 × 10(9)/L (median 11 days for both short- and long-term storage) and platelets >20 × 10(9)/L (median 12 and 11 for short- and long-term storage, respectively) post-ASCT were not significantly different between the two groups. When ASCT performed with <5 × 10(6)/kg CD34(+) cells was compared there was also no difference in ANC or platelet recovery (median 12 days for both after short-term storage, and 12 and 11 days, respectively, after long-term storage). Fourteen HPC-A products stored for >5 years also showed similar count recoveries as the entire long-term storage group (median 11 days for both ANC and platelets).

CONCLUSIONS

Cryopreserved HPC-A can be stored for at least 5 years with no apparent loss in their ability to support hematopoietic reconstitution after high-dose chemotherapy.

Long-term follow-up of patients undergoing auto-SCT for advanced germ cell tumour: a multicentre cohort study

Failure of cisplatin-based chemotherapy in advanced germ cell tumour (GCT) is associated with a poor outcome. High-dose chemotherapy and auto-SCT is one therapeutic option, although the long-term outcome after this procedure is unclear. We conducted a multicentre cohort study of consecutive patients undergoing a single auto-SCT for GCT between January 1986 and December 2004. Of 71 subjects, median follow-up is 10.1 years. OS at 5 years is 44.7% (95% confidence interval (CI) 32.9-56.5%) and EFS is 43.5% (95% CI 31.4-55.1%). There were seven (10%) treatment-related deaths within 100 days of auto-SCT. Three (4.2%) patients developed secondary malignancies. Of 33 relapses, 31 occurred within 2 years of auto-SCT. Two very late relapses were noted 13 and 11 years after auto-SCT. In multivariate analysis, favourable outcome was associated with IGCCC (International Germ Cell Consensus Classification) good prognosis disease at diagnosis, primary gonadal disease and response to salvage chemotherapy. We conclude that auto-SCT results in successful outcome for a relatively large subgroup of patients with high-risk GCT. Late relapses may occur, a finding not previously reported.

Abstract B77: Ethnicity and hematopoietic stem cell transplantation (HSCT) outcomes in British Columbia, Canada

Purpose: There are documented ethnic disparities in cancer care access, use and clinical outcomes in North America; however, the role of ethnicity on different outcomes of unrelated donor hematopoietic stem cell transplantation (HSCT) as an established treatment for many hematological and non-hematological malignancies has not been studied for Canadian patients.

Patients and Methods: We reviewed the registry data of 395 patients receiving first time unrelated donor HSCT for hematological malignancies at leukemia/BMT center of British Columbia (BC) between 1988 and 2008. They were reported to be white (N=340), Asian (N=32), native (N=8), Hispanic (N=3), black (N=2), mixed (N=9) and other- not specified (N=1) which were further categorized as white (N=340) and non-white (N=55). Different HSCT outcomes were compared by log-rank test and Cox proportional hazard regression adjusting for significant patient, disease and transplant related factors at 95% significance level.

Results: Univariate and multivariate analysis didn't show any statistically significant difference for overall survival, disease-free survival, relapse, acute graft versus host disease (aGVHD) grade 2+ and chronic graft versus host disease (cGVHD) rates between whites and non-whites. We reanalyzed a subset of 115 cases (88 whites and 27 non-whites) who received their HSCT after June 2001 (start date for application of high resolution DNA-based HLA matching in the study center) and their underlying diagnosis was acute myeloid leukemia, acute lymphoid leukemia, chronic myeloid leukemia and myelodysplastic syndrome. The results showed a higher risk of cGVHD for non-whites in univariate analysis (HR1.82, 95% CI1.07-3.12, P=0.03), however; adjusting for covariates in the multivariate analysis resolved this difference (P = 0.09).

Conclusion: According to our data, HSCT clinical outcomes are comparable between white and non-white ethnic minorities in BC. The contrasting result with that of US studies might be due to different ethnic composition of BC and using a heterogeneous non-white ethnic group as the comparator (to increase the power of study) which could mask any unsought differences in the subgroups.

Citation Information: Cancer Epidemiol Biomarkers Prev 2010;19(10 Suppl):B77.

Insights into acute myeloid leukemia via single cell network profiling

Single Cell Network Profiling (SCNP) uses multi-parameter flow cytometry to simultaneously measure resting and evoked intracellular signalling molecules and pathways in distinct cell subsets within a complex tissue sample. This review focuses on the utility of SCNP and its potential applications for chemotherapy selection in Acute Myeloid Leukemia (AML).

Identification of miR-145 and miR-146a as mediators of the 5q- syndrome phenotype

5q- syndrome is a subtype of myelodysplastic syndrome characterized by severe anemia and variable neutropenia but normal or high platelet counts with dysplastic megakaryocytes. We examined expression of microRNAs (miRNAs) encoded on chromosome 5q as a possible cause of haploinsufficiency. We show that deletion of chromosome 5q correlates with loss of two miRNAs that are abundant in hematopoietic stem/progenitor cells (HSPCs), miR-145 and miR-146a, and we identify Toll-interleukin-1 receptor domain-containing adaptor protein (TIRAP) and tumor necrosis factor receptor-associated factor-6 (TRAF6) as respective targets of these miRNAs. TIRAP is known to lie upstream of TRAF6 in innate immune signaling. Knockdown of miR-145 and miR-146a together or enforced expression of TRAF6 in mouse HSPCs resulted in thrombocytosis, mild neutropenia and megakaryocytic dysplasia. A subset of mice transplanted with TRAF6-expressing marrow progressed either to marrow failure or acute myeloid leukemia. Thus, inappropriate activation of innate immune signals in HSPCs phenocopies several clinical features of 5q- syndrome.

Phase I clinical study of diphtheria toxin-interleukin 3 fusion protein in patients with acute myeloid leukemia and myelodysplasia

DT(388)IL3 fusion protein containing the catalytic and translocation domains of diphtheria toxin fused to human interleukin 3 was administered in an inter-patient dose escalation trial by 15 min i.v. infusions every other day for up to 6 doses to patients with chemo-refractory acute myeloid leukemia (AML) and myelodysplasia (MDS). The maximal tolerated dose was >12.5 microg/kg/dose. Transient grade 3 transaminasemia and grade 2 fevers, chills, hypoalbuminemia, and hypotension occurred. Peak DT(388)IL3 levels correlated with dose and day of administration but not antibody titer. Anti-DT(388)IL3 antibodies developed in most patients between day 15 and 30. Of 40 evaluable AML patients, 1 had a CR (8 months) and 1 had PR (3 months). Of 5 MDS patients, 1 had a PR (4 months). Because of the prolonged infusion schedule, many patients failed to receive six doses. DT(388)IL3 produces remissions in patients with relapsed/refractory AML and MDS with minimal toxicities, and alternate schedules of administration are needed to enhance the response rate.

Induction of apoptosis in retinoid-refractory acute myelogenous leukemia by a novel AHPN analog

Acute myelogenous leukemia (AML) is a heterogeneous disease consisting of a variety of different leukemic subtypes. While acute promyelocytic leukemia displays marked sensitivity to the differentiating effects of trans-retinoic acid (tRA), other subtypes of AML display resistance. We now describe a novel compound (E)-4-[3-(1-adamantyl)-4-hydroxyphenyl]-3-chlorocinnamic acid (3-Cl-AHPC/MM002) that induces apoptosis in the tRA-resistant leukemia cell lines M07e, KG-1, and HL-60R, and in tRA-resistant patient leukemic blasts. The 3-Cl-AHPC totally inhibits leukemia colony formation at concentrations that inhibit committed human bone marrow stem cell proliferation, that is, granulocyte/macrophage colony-forming units (CFU-GMs) by only 30%. Exposure to 3-Cl-AHPC results in caspase activation and the cleavage of poly(adenosine diphosphate) (poly(ADP)) ribose polymerase. While activation of the extracellular signal-regulated kinase (ERK) and p38 pathways is not necessary for 3-Cl-AHPC-mediated apoptosis, maximal apoptosis requires c-Jun N-terminal kinase (JNK) activation. The 3-Cl-AHPC-mediated cleavage of the antiapoptotic B-cell leukemia XL (Bcl-XL) protein to a proapoptotic 18-kDa product is found in both the M07e cell line and patient leukemic blasts. The 3-Cl-AHPC treatment of mice bearing the AML 1498 cell line results in a 3.3-log kill in the leukemic blasts. While 3-Cl-AHPC does not activate retinoic nuclear receptors, it is a potent inducer of apoptosis in AML cells and may represent a novel therapy in the treatment of this disease.

Stem cell transplantation for myelofibrosis: a report from two Canadian centers

We describe the course of 25 patients with myelofibrosis (MF) due to agnogenic myeloid metaplasia (n=19) or essential thrombocytosis (n=6) who underwent allogeneic stem cell transplantation (SCT) at one of two Canadian centers. The median age at transplantation was 48.7 (IQR 45.9-50.4) years and transplantation was carried out at a median of 10.7 (IQR 5.67-26.5) months after diagnosis. Granulocyte engraftment (absolute neutrophil count >0.5 x 109/l) occurred at a median of 20 days after transplantation for splenectomized patients, compared with 27.5 days for nonsplenectomized individuals (P=0.03). Increased risk of grade II-IV acute graft-versus-host disease (P=0.04) was noted in patients transplanted after splenectomy. Patients with MF received 0.264+/-0.189 U of packed red blood cells per day over the first 180 days after transplantation, and remained dependent on red blood cell transfusions for a median of 123 (IQR 48-205) days. Complete remission of MF was documented in 33% of evaluable patients. The 1 year cumulative nonrelapse mortality was 48.3%. Median survival for this group of patients was 393 (IQR 109-1014+) days, with a projected 2-year overall survival of 41%. We conclude that allogeneic SCT offers a reasonable chance for prolonged survival in patients with advanced MF, but this occurs at the cost of considerable toxicity and nonrelapse mortality.

Unfulfilled promise of endostatin in a gene therapy-xenotransplant model of human acute lymphocytic leukemia

Retroviral transduction of hematopoietic stem cells (HSCs) offers an attractive strategy for treating malignancies that home to the marrow. This approach should therefore be of interest for evaluating the therapeutic activity of anti-angiogenic agents on hematopoietic malignancies whose growth has been associated with enhanced angiogenesis. A variety of studies have indicated endostatin to be a potent anti-angiogenic agent both in vitro and in vivo, and a human malignancy that might be sensitive to endostatin is human B-lineage acute lymphoblastic leukemia (B-ALL). The demonstrated ability of human B-ALL cells to engraft the marrow of immunodeficient mice suggested the potential of this system for testing an endostatin delivery strategy using co-transplanted non-obese diabetic-scid/scid (NOD/SCID) HSCs engineered to express endostatin. Here we show that, in spite of their mutant scid gene, NOD/SCID HSCs can be transduced with an endostatin-encoding retrovirus at efficiencies that result in a several-fold increase in endostatin serum levels in transplanted recipients. However, this did not alter the regrowth of co-transplanted human B-ALL blasts. These findings validate this gene transfer approach for investigating effects of novel therapeutics on primary human malignant cells that engraft NOD/SCID mice and question the utility of native endostatin for controlling human B-ALL in vivo.

Variable cytotoxicity of diphtheria toxin 388-granulocyte-macrophage colony-stimulating factor fusion protein for acute myelogenous leukemia stem cells

In this study, the utility of DT388-granulocyte-macrophage colony-stimulating factor (GM-CSF) for the ex vivo purging and direct administration to patients with acute myeloid leukemia (AML) is tested using clonogenic assays, long-term cultures (LTC), and NOD/SCID mice as assays for leukemic progenitors. We compare the ability of 24-hour exposure to 0.3 microg/mL (4 nM) DT388-GM-CSF to kill AML colony forming cells (CFC) and the more primitive AML progenitors detected after 6 weeks in stromal cocultures (AML LTC-initiating cells or AML LTC-IC) and after 8 weeks in NOD/SCID mice.AML samples (n = 10), expressing a mean of 35 to 1466 GM-CSF receptors/blast, showed mean (range) percent kills of AML CFC and LTC-IC of 61 (17-98) and 46 (0-94) respectively with a direct correlation (r = 0.69) between the % kills detected in the in vitro assays. Among 5 evaluable samples the percent reduction in AML cell engraftment in NOD/SCID marrow following ex vivo DT388-GM-CSF treatment varied from 38% to 100%. 40% to 56% of normal bone marrow CFC and 31% to 48% of normal LTC-IC survived the same ex vivo treatment (n = 3). In subsequent experiments, NOD/SCID mice received AML blast cell injections intravenously followed in 24 hours by 1.5 microg DT388-GM-CSF daily intraperitoneally for 5 days. A reduction of marrow blast cells was seen with 7 of 9 samples tested 4 to 12 weeks post one course of toxin. Repeating the 5-day course of toxin 2 or 3 times at 4-week intervals did not improve the response, while delaying administration until 4 to 8 weeks post AML cell injection reduced the toxin's effectiveness (n = 5).This fusion toxin may prove useful for in vitro purging of stem cell harvests from selected AML patients and for direct administration to such patients.