Venous thromboembolism prevention during asparaginase-based therapy for acute lymphoblastic leukemia.

BACKGROUND: Venous thromboembolism (vte) is a recognized complication in patients treated with asparaginase-containing chemotherapy regimens; the optimal preventive strategy is unclear. We assessed the safety and efficacy of prophylaxis using low-dose low molecular weight heparin in adult patients with acute lymphoblastic leukemia in complete remission treated with an asparaginase-based post-remission chemotherapy regimen. METHODS: As part of the intensification phase of the Dana-Farber Cancer Institute 91-01 regimen, asparaginase was administered weekly to 41 consecutive patients for 21-30 weeks; these patients also received prophylaxis with enoxaparin 40 mg daily (60 mg for patients ≥80 kg). Outcomes were assessed against outcomes in a comparable cohort of 99 patients who received the same chemotherapy regimen without anticoagulation prophylaxis. RESULTS: The overall rate of symptomatic venous thrombosis was not significantly different in the prophylaxis and non-prophylaxis cohorts (18.92% and 21.74% respectively). Among patients receiving prophylaxis, vte occurred in higher proportion in those who weighed at least 80 kg (42.86% vs. 4.35%, p = 0.0070). No major bleeding complications occurred in the prophylaxis group (minor bleeding: 8.1%). CONCLUSIONS: Prophylaxis with low-dose enoxaparin during the intensification phase was safe, but was not associated with a lower overall proportion of vte.

The repositioning of the anti-fungal agent ciclopirox olamine as a novel therapeutic agent for the treatment of haematologic malignancy.

WHAT IS KNOWN AND OBJECTIVE: 6-Cyclohexyl-1-hydroxy-4-methyl-2(1H)-pyridone (ciclopirox) and specifically its olamine salt 6-cyclohexyl-1-hydroxy-4-methyl-2(1H)-pyridone 2-aminoethanol salt (ciclopirox olamine) are anti-fungal agents currently used for the treatment of mild to moderate cutaneous fungal infection. Our objective is to comment on the opportunity to rapidly reposition ciclopirox and its olamine for the treatment of haematologic malignancy by leveraging its prior published toxicology and pharmacology data. COMMENT: Ciclopirox olamine chelates intracellular iron and displays preclinical efficacy in the treatment of haematologic malignancy. Currently, an ongoing study is evaluating topical ciclopirox olamine for the treatment of cervical cancer. Doses of ciclopirox olaine required for a systemic anti-cancer effect appear pharmacologically achievable. However, caution is required as at the highest doses tested in animal toxicology studies, irreversible cardiac degeneration was observed. WHAT IS NEW AND CONCLUSION: The existing pharmacology and toxicology data suggest that systemic ciclopirox olamine could be repositioned as a new investigational anti-cancer agent. The available pharmacology and toxicology data should aid in the design of phase I clinical trials of this agent in patients with refractory haematologic malignancies.

Effect of an antimicrobial stewardship programme on antimicrobial utilisation and costs in patients with leukaemia: a retrospective controlled study.

OBJECTIVES: To examine the effectiveness of an antimicrobial stewardship programme on utilization and cost of antimicrobials in leukaemia patients in Canada. METHODS: We conducted a multisite retrospective observational time series study from 2005 to 2013. We implemented academic detailing as the intervention of an antimicrobial stewardship programme in leukaemia units at a hospital, piloted February-July 2010, then fully implemented December 2010-March 2013, with no intervention in August-November 2010. Internal control was the same hospital's allogeneic haematopoietic stem-cell transplantation unit. External control was the combined leukaemia-haematopoietic stem-cell transplantation unit at another hospital. Primary outcome was antimicrobial utilization (antibiotics and antifungals) in defined daily dose per 100 patient-days (PD). Secondary outcomes were antimicrobial cost (Canadian dollars per PD); cost and utilization by drug class; length of stay; 30-day inpatient mortality; and nosocomial Clostridium difficile infection. We used autoregressive integrated moving average models to evaluate the impact of the intervention on outcomes. RESULTS: The intervention group included 1006 patients before implementation and 335 during full implementation. Correspondingly, internal control had 723 and 264 patients, external control 1395 and 864 patients. Antimicrobial utilization decreased significantly in the intervention group (p <0.01, 278 vs. 247 defined daily dose per 100 PD), increased in external control (p = 0.02, 237.4 vs. 268.9 defined daily dose per 100 PD) and remained stable in internal control (p = 0.66). Antimicrobial cost decreased in the intervention group (p = 0.03; $154.59 per PD vs. $128.93 per PD), increased in external control (p = 0.01; $109.4 per PD vs. $135.97 per PD) but was stable in internal control (p = 0.27). Mortality, length of stay and nosocomial C. difficile rate in intervention group remained stable. CONCLUSIONS: The antimicrobial stewardship programme reduced antimicrobial use in leukaemia patients without affecting inpatient mortality and length of stay.

Targeting XIAP for the treatment of malignancy.

X-linked inhibitor of apoptosis protein (XIAP) is a member of the inhibitor of apoptosis proteins family of caspase inhibitors that selectively binds and inhibits caspases-3, -7 and -9, but not caspase-8. As such, XIAP blocks a substantial portion of the apoptosis pathway and is an attractive target for novel therapeutic agents for the treatment of malignancy. Antisense oligonucleotides directed against XIAP are effective in vitro and are currently being evaluated in clinical trials. Small molecule XIAP inhibitors that target the baculovirus IAP repeat (BIR) 2 or BIR 3 domain are in preclinical development and are advancing toward the clinic. This review will discuss the progress being made in developing antisense and small-molecule XIAP inhibitors.

Biological and clinical consequences of NPM1 mutations in AML.

Acute myeloid leukemia (AML) is characterized by accumulation of myeloid cells in the bone marrow because of impaired differentiation and proliferation, resulting in hematopoietic insufficiency. NPM1 is one of the most commonly mutated genes in AML, present in 20-30% of cases. Mutations in NPM1 represent a distinct entity in the World Health Organization (WHO) classification and commonly indicate a better risk prognosis. In this review, we discuss the many functions of NPM1, the consequence of mutations in NPM1 and possible mechanisms through which mutations lead to leukemogenesis. We also discuss clinical consequences of mutations, associated gene expression patterns and the role of NPM1 mutations in informing prognosis and therapeutic decisions and predicting relapse in AML.

Expression of CD4 is correlated with an unfavorable prognosis in wild-type NPM1, FLT3-ITD-negative cytogenetically normal adult acute myeloid leukemia.

INTRODUCTION: In the cytogenetically normal population of AML (CN-AML), FLT3-ITD-positive and wild-type NPM1 is correlated with a worse outcome, and FLT3-ITD-negative with NPM1-mut is correlated with a better outcome. This leaves a large subpopulation of CN-AML patients without NPM1 or FLT3-ITD mutations with heterogeneous outcomes with overall survivals (OS) ranging from several weeks to years. Therefore, new prognostic markers are needed to better risk stratify this subset of patients. METHODS: The retrospective study included 60 de novo adult AML patients diagnosed at our institution with normal karyotype, no FLT3-ITD or NPM1 mutations, and who did not receive allogeneic hematopoietic stem cell transplantations. We investigated the prognostic significance of immunophenotypic markers and clinical laboratory features in this double-negative population. RESULTS: Older age (>60) and CD4 expression (14%) were significantly correlated with shorter event-free survival (EFS) (P < 0.001, P = 0.016, respectively). Expression of CD56 (12%), as well as lack of CD34 expression (19% of the cases), was also associated with a worse EFS (P = 0.048, P = 0.028, respectively). On multivariable analysis, CD4 expression and old age (>60) were identified as independent predictors for worse EFS (P = 0.016; P = 0.001, respectively) and OS (P = 0.048; P = 0.028, respectively). CONCLUSIONS: Our results indicate that CD4 expression and older age are adverse prognostic factors in wild-type NPM1, FLT3-ITD-negative CN-AML.

The BH3 domain of BAD fused to the Antennapedia peptide induces apoptosis via its alpha helical structure and independent of Bcl-2.

Since the over-expression of Bcl-2 is a common cause of multi-drug resistance, cytotoxic peptides that overcome the effects of Bcl-2 may be clinically useful. We harnessed the death-promoting alpha helical properties of the BH3 domain of BAD by fusing it to the Antennapedia (ANT) domain, which allows for cell entry (ANTBH3BAD). Treatment of 32D cells with the ANTBH3BAD peptide results in a 99% inhibition of colony formation. No significant toxicity is observed after treatment with ANT or BH3BAD alone. A mutant fusion peptide unable to bind Bcl-2 induces cell death as effectively as the wild-type ANTBH3BAD. Furthermore, 32D cells over-expressing Bcl-2 show no resistance to the ANTBH3BAD peptide. Therefore, the toxicity of the peptide was independent of the Bcl-2 pathway. We demonstrate that the toxicity of the peptide is due to its alpha helicity that disrupts mitochondrial function. Since this peptide overcomes major forms of drug resistance, it may be therapeutically useful if appropriately targeted to malignant cells.

Ovarian function after autologous bone marrow transplantation.

PURPOSE: To determine the frequency of return of ovarian function after autologous bone marrow transplantation (ABMT), and the major factors that predict recovery. PATIENTS AND METHODS: Records of 200 consecutive women who underwent ABMT at the University of Toronto Autologous Blood and Marrow Program (Toronto, Canada) were reviewed. Seventeen patients met the inclusion criteria, which were (1) alive at the time of evaluation, (2) disease-free at least 18 months after transplantation, (3) age younger than 50 years at transplantation, and (4) premenopausal before transplantation. Recovery of ovarian function was determined by pregnancy or regular menses, with no menopausal symptoms and an estradiol level greater than 20 pmol/L off hormonal therapy. RESULTS: All 17 patients became menopausal immediately after ABMT. Five patients (29%) recovered ovarian function a median of 24 months post-ABMT (range, 6 to 48 months). The median age at transplantation of women with restored ovarian function was 19 years (range, 19 to 28 years) versus 30 years (range, 22 to 48 years) for those who did not regain function. Younger age at transplantation predicted ovarian recovery (P = .03) by means of a log-rank test. Only one of five women who regained ovarian function received total-body irradiation (TBI) compared with five of 12 women who did not. Univariate analysis suggested a trend for TBI to predict a sustained loss of ovarian function (P = .067). The number of regimens of induction or salvage chemotherapy that contained an alkylating agent ranged from none to five and was not predictive (P = .45). CONCLUSION: All women became menopausal after ABMT but 29% recovered ovarian function. Younger age at transplantation predicted return of ovarian function, whereas TBI may have had a negative effect.

Treatment of elderly patients with acute lymphoblastic leukemia--evidence for a benefit of imatinib in BCR-ABL positive patients.

All patients with acute lymphoblastic leukemia (ALL) over age 60 years seen at Princess Margaret Hospital over an 11-year period were analysed retrospectively. Of 53 patients, 45 received multiagent induction chemotherapy using a variety of regimens. There were 13 BCR-ABL positive patients, 9 of who received imatinib mesylate, either during induction or post-remission therapy. The overall complete remission (CR) rate of all 45-induction patients was 56%, with a 27% induction-related mortality rate. The CR rate was not influenced by induction regimen, age, initial WBC, LDH or BCR-ABL status. The median overall survival of the induction patients was 9 months, while the median progression-free survival (PFS) of the patients achieving CR was 10 months. The estimated overall survival (OS) at 3 years was 18.4% (95% CI: 9.8-34.3%). Age and initial WBC did not significantly predict for OS when evaluating the entire group of induction patients. However, there was a strong trend for BCR-ABL status to favorably predict for PFS, and for OS when only patients treated after July 2000 (when imatinib became available) were evaluated. The results indicate that ALL remains a poor prognosis disease in elderly patients, and that aggressive induction regimens designed for younger patients are very toxic for these patients. These data suggest that BCR-ABL+ ALL is becoming a relatively more favorable prognosis disease in the elderly, likely due to the influence of imatinib therapy. Further regimens should explore the use of less aggressive regimens in elderly patients and should evaluate the optimal way of combining imatinib with conventional agents in BCR-ABL+ patients.

Synthetic triterpenoids activate a pathway for apoptosis in AML cells involving downregulation of FLIP and sensitization to TRAIL.

Acute myelogenous leukemia (AML) remains a deadly disease for most adult patients, due primarily to the emergence of chemoresistant cells. Defects in apoptosis pathways make important contributions to chemoresistance, suggesting a need to restore apoptosis sensitivity or to identify alternative pathways for apoptosis induction. Triterpenoids represent a class of naturally occurring and synthetic compounds with demonstrated antitumor activity, including 2-cyano-3,12-dioxoolean-1,9-dien-28-oic acid (CDDO) and its methyl ester (CDDO-m). We explored the effects of CDDO and CDDO-m in vitro on established AML cell lines (HL-60, U937, AML-2) and on freshly isolated AML blasts. CDDO and CDDO-m reduced the viability of all AML cell lines tested in a dose-dependent manner, with effective doses for killing 50% of cells (ED(50)) within 48 h of approximately 1 and 0.5 muM, respectively. CDDO or CDDO-m also induced substantial increases in cell death in five out of 10 samples of primary AML blasts. Cell death induced by CDDO and CDDO-m was attributed to apoptosis, based on characteristic cell morphology and evidence of caspase activation. Immunoblot analysis demonstrated proteolytic processing of caspase-3, -7, and -8, but not caspase-9, suggesting the involvement of the 'extrinsic' pathway, linked to apoptosis induction by TNF-family death receptors. Accordingly, CDDO and CDDO-m induced concentration-dependent reductions in the levels of FLIP protein, an endogenous antagonist of caspase-8, without altering the levels of several other apoptosis-relevant proteins. Reductions in FLIP were rapid, detectable within 3 h after exposure of AML cell lines to CDDO or CDDO-m. CDDO and CDDO-m also sensitized two of four leukemia lines to TRAIL, a TNF-family death ligand. The findings suggest that synthetic triterpenoids warrant further investigation in the treatment of AML, alone or in combination with TRAIL or other immune-based therapies.

FV-162 is a novel, orally bioavailable, irreversible proteasome inhibitor with improved pharmacokinetics displaying preclinical efficacy with continuous daily dosing.

Approved proteasome inhibitors have advanced the treatment of multiple myeloma but are associated with serious toxicities, poor pharmacokinetics, and most with the inconvenience of intravenous administration. We therefore sought to identify novel orally bioavailable proteasome inhibitors with a continuous daily dosing schedule and improved therapeutic window using a unique drug discovery platform. We employed a fluorine-based medicinal chemistry technology to synthesize 14 novel analogs of epoxyketone-based proteasome inhibitors and screened them for their stability, ability to inhibit the chymotrypsin-like proteasome, and antimyeloma activity in vitro. The tolerability, pharmacokinetics, pharmacodynamic activity, and antimyeloma efficacy of our lead candidate were examined in NOD/SCID mice. We identified a tripeptide epoxyketone, FV-162, as a metabolically stable, potent proteasome inhibitor cytotoxic to human myeloma cell lines and primary myeloma cells. FV-162 had limited toxicity and was well tolerated on a continuous daily dosing schedule. Compared with the benchmark oral irreversible proteasome inhibitor, ONX-0192, FV-162 had a lower peak plasma concentration and longer half-life, resulting in a larger area under the curve (AUC). Oral FV-162 treatment induced rapid, irreversible inhibition of chymotrypsin-like proteasome activity in murine red blood cells and inhibited tumor growth in a myeloma xenograft model. Our data suggest that oral FV-162 with continuous daily dosing schedule displays a favorable safety, efficacy, and pharmacokinetic profile in vivo, identifying it as a promising lead for clinical evaluation in myeloma therapy.

Busulfan and cyclophosphamide as a preparative regimen for allogeneic blood and marrow transplantation in patients with non-Hodgkin's lymphoma.

This study reports on overall and recurrence-free survival (OS and RFS) of 37 consecutive patients with low- and intermediate-grade NHL receiving a related donor allogeneic BMT using a nonradiation-containing preparative regimen. In addition, transplant-related toxicity and factors influencing outcome are discussed. The preparative regimen consisted of busulfan and cyclophosphamide. Median patient age was 44 years (range 20-55). In all, 18 were female. Median follow-up of surviving patients from BMT was 4.2 years. A total of 25 patients had low-grade, and 12 intermediate grade NHL. Most patients (89%) were treated with at least two different chemotherapy regimens prior to BMT. In all, 22 patients (59%) were transplanted in partial remission, 15 (41%) in complete remission. OS at 12 months was 89% (95% confidence interval (CI) of 79-99%) and 79% (64-93%) at 60 months. RFS at 12 months was 86% (75-97%) and at 5 years 70% (54-86%). Four patients (11%) relapsed. Seven patients (19%) died, six because of treatment-related toxicity and one with relapse. Univariate analysis showed improved OS for younger patients and patients of female gender, suggesting that allogeneic BMT using busulfan-cyclophosphamide as a preparative regimen can achieve disease control and possibly cure patients with NHL particularly younger ones.

Decreased bone mineral density is common after autologous blood or marrow transplantation.

Survivors of autologous blood or marrow transplantation (ABMT) are predisposed to decreased bone mineral density (BMD), but data are lacking on the incidence and risk factors for this condition. Therefore, we measured BMD in 64 of 68 consecutive ABMT survivors (35 men and 29 women) attending the University of Toronto ABMT long-term follow-up clinic. Patients were evaluated a median of 4.2 years (range: 4.9 months-11.4 years) after ABMT. Median age at evaluation was 49.6 years (range: 23.5-68.2 years). At the L1-L4 vertebrae, 17 (26%) patients (eight men and nine women) had osteopenia and one male (2%) had osteoporosis. Mean BMD at L1-L4 did not differ from healthy young adults or age and sex matched controls. At the femoral neck, 30 patients (46%) (18 men and 12 women) had osteopenia and five (8%) (two men and three women) had osteoporosis. Mean BMD at the femoral neck was significantly lower than in healthy young adults and age- and sex-matched controls. By regression analysis, patients with decreased BMD were older than those with normal BMD (P = 0.02). Gender, body mass index, time from BMT to evaluation and presence of hypogonadism were not associated with decreased BMD. Treatment of decreased bone density was instituted and follow-up data were obtained 1 year after treatment in 22 of 39 patients with reduced BMD. Nineteen (86%) patients had stabilization or improvement of their bone density at follow-up. We conclude that, after ABMT, over half of the patients have evidence of osteopenia or osteoporosis. Men and women were equally affected. In our study, only older age at evaluation was predictive for loss of BMD. We recommend the measurement of BMD as an integral component to the follow-up of ABMT patients.

Safety of therapeutic anticoagulation in patients with multiple myeloma receiving autologous stem cell transplantation.

The use of autologous stem cell transplantation (ASCT) for the treatment of multiple myeloma is increasing. Anticoagulation may be required during ASCT for conditions such as Hickman line thrombosis. The safety of anticoagulation in patients receiving ASCT is unknown. We report a retrospective case-control study of the safety of therapeutic anticoagulation in patients with multiple myeloma receiving ASCT. We identified 10 patients who received therapeutic anticoagulation during ASCT. For each of the 10 cases identified, two matched controls were selected. As a primary endpoint, bleeding complications were assessed. Secondary endpoints included survival, length of hospital stay, transfusion requirements, grade 4 toxicity, and days to platelet engraftment. Bleeding complications were not significantly different between patients receiving anticoagulation and controls (P = 0.3). Three of 10 anticoagulated patients and two of 20 controls had a bleeding complication. Mortality during admission was similar (P = 1.0); one anticoagulated patient and one control died of sepsis. A trend towards increased median number of platelet transfusions in the heparinized patients was seen (27 vs 12 units, P = 0.055), reflecting the higher transfusion threshold chosen for the anticoagulated patients. The other secondary endpoints did not differ between patients and controls. In this case control study, bleeding was not significantly increased in the group receiving anticoagulation during ASCT. This group electively received more units of platelets than controls. Thus, therapeutic anticoagulation can be managed with minimal increased toxicity during ASCT.

Allogeneic or autologous bone marrow transplantation (BMT) for non-Hodgkin's lymphoma (NHL): results of a provincial strategy. Ontario BMT Network, Canada.

In 1986, the bone marrow transplant centers in Ontario agreed to a strategy for the treatment of patients with NHL. Suitable patients would undergo autotransplant but be referred for allotransplant if they had persistent marrow involvement or an inadequate marrow/stem cell harvest. Data of all patients were recorded in a database. We reviewed this database to compare these transplant modalities with respect to overall survival, rate of relapse and treatment-related mortality. Between January 1986 and August 1997, 429 patients underwent BMT for NHL - 385 autotransplants and 44 allotransplants. Sixty-eight percent of patients received their transplant for aggressive NHL, while the others had indolent lymphoma. Three-year actuarial survival did not differ between allogeneic and autologous BMT: 71% vs 62%, respectively (P = 0.5330 by log-rank testing). Three-year actuarial rate of relapse was lower after allotransplant than autotransplant: 6% vs 41%, respectively (P = 0.0006 by log-rank testing). Treatment-related mortality was higher after allotransplant than autotransplant: 23% vs 6%, respectively (P = 0.001 by chi2 analysis). For further comparison, autotransplant patients were randomly matched 2:1 with the allotransplant patients for age +/- 5 years, disease status at BMT, disease histology, and year of BMT. In the matched comparison, survival did not differ (relative risk of death after allotransplant: 0.711 (95% CI: 0.309-1.637)). Relapse rate was significantly lower in the allotransplant group (relative risk of relapse for allotransplant: 0.190 (95% CI: 0.043-0.834)) and treatment-related mortality was not significantly different (relative risk for allotransplant: 1.425 (95% CI: 0.527-3.851)). In conclusion, a review of a provincial strategy for treatment of NHL, shows that survival is not different after allogeneic or autologous BMT, but the rate of relapse is lower after allotransplant. These data support continuing the current provincial strategy.

BAD induces apoptosis in cells over-expressing Bcl-2 or Bcl-xL without loss of mitochondrial membrane potential.

Inhibitors of Bcl-2 may be useful therapeutic agents for the treatment of a wide variety of malignancies including leukemia. A potential prototype of such a compound is the endogenous Bcl-2 and Bcl-xL binding protein BAD. Previous reports indicate that BAD can overcome the anti-apoptotic effect of Bcl-xL but not Bcl-2. If BAD cannot induce apoptosis in cells over-expressing Bcl-2, it would limit the application of molecules like BAD as novel anti-tumor agents. We report that transient transfection of BAD induced cell death in cells with and without over-expression of Bcl-2 or Bcl-xL. Forty-eight hours after transfection, BAD increased cell death in COS, COS Bcl-2, and COS Bcl-xL cells as demonstrated by decreased GFP expression, and an increase in the number of number of floating cells. In addition, BAD induced cell death in leukemic cell lines over-expressing Bcl-2 and Bcl-xL as determined by changes in luciferase activity. BAD-induced apoptosis was not accompanied by loss of mitochondrial membrane potential. Therefore, we conclude that transient transfection of BAD directly induces apoptosis in cells over-expressing Bcl-2 or Bcl-xL and validates the pursuit of molecules like BAD as novel therapeutic agents.

Mitochondrial matrix proteases as novel therapeutic targets in malignancy.

Although mitochondrial function is often altered in cancer, it remains essential for tumor viability. Tight control of protein homeostasis is required for the maintenance of mitochondrial function, and the mitochondrial matrix houses several coordinated protein quality control systems. These include three evolutionarily conserved proteases of the AAA+ superfamily-the Lon, ClpXP and m-AAA proteases. In humans, these proteases are proposed to degrade, process and chaperone the assembly of mitochondrial proteins in the matrix and inner membrane involved in oxidative phosphorylation, mitochondrial protein synthesis, mitochondrial network dynamics and nucleoid function. In addition, these proteases are upregulated by a variety of mitochondrial stressors, including oxidative stress, unfolded protein stress and imbalances in respiratory complex assembly. Given that tumor cells must survive and proliferate under dynamic cellular stress conditions, dysregulation of mitochondrial protein quality control systems may provide a selective advantage. The association of mitochondrial matrix AAA+ proteases with cancer and their potential for therapeutic modulation therefore warrant further consideration. Although our current knowledge of the endogenous human substrates of these proteases is limited, we highlight functional insights gained from cultured human cells, protease-deficient mouse models and other eukaryotic model organisms. We also review the consequences of disrupting mitochondrial matrix AAA+ proteases through genetic and pharmacological approaches, along with implications of these studies on the potential of these proteases as anticancer therapeutic targets.

Inhibition of intracellular dipeptidyl peptidases 8 and 9 enhances parthenolide's anti-leukemic activity.

Parthenolide is selectively toxic to leukemia cells; however, it also activates cell protective responses that may limit its clinical application. Therefore, we sought to identify agents that synergistically enhance parthenolide's cytotoxicity. Using a high-throughput combination drug screen, we identified the anti-hyperglycemic, vildagliptin, which synergized with parthenolide to induce death of the leukemia stem cell line, TEX (combination index (CI)=0.36 and 0.16, at effective concentration (EC) 50 and 80, respectively; where CI <1 denotes statistical synergy). The combination of parthenolide and vildagliptin reduced the viability and clonogenic growth of cells from acute myeloid leukemia patients and had limited effects on the viability of normal human peripheral blood stem cells. The basis for synergy was independent of vildagliptin's primary action as an inhibitor of dipeptidyl peptidase (DPP) IV. Rather, using chemical and genetic approaches we demonstrated that the synergy was due to inhibition of the related enzymes DPP8 and DPP9. In summary, these results highlight DPP8 and DPP9 inhibition as a novel chemosensitizing strategy in leukemia cells. Moreover, these results suggest that the combination of vildagliptin and parthenolide could be useful for the treatment of leukemia.

The prognostic impact of FLT3-ITD and NPM1 mutations in patients with relapsed acute myeloid leukemia and intermediate-risk cytogenetics.

Internal tandem duplication of the fms-like tyrosine kinase-3 gene (FLT3-ITD) and nucleophosmin-1 (NPM1) mutations have prognostic importance in acute myeloid leukemia (AML) patients with intermediate-risk karyotype at diagnosis, but less is known about their utility to predict outcomes at relapse. We retrospectively analysed outcomes of 70 patients with relapsed, intermediate-risk karyotype AML who received a uniform reinduction regimen, with respect to FLT3-ITD and NPM1 mutation status and first complete remission (CR1) duration. CR1 duration, but not molecular status, was significantly correlated with CR2 rate. On univariate analysis, patients with mutated FLT3-ITD (FLT3+) had significantly worse overall survival (OS) compared with those with neither an NPM1 nor FLT3-ITD mutation (NPM1-/FLT3-). On multivariate analysis, shorter CR1 duration was significantly correlated with inferior OS at relapse (P<0.0001), while FLT3 and NPM1 mutation status and age were not significantly correlated with OS. Patients who subsequently underwent allogeneic stem cell transplant (alloSCT) had a superior OS regardless of CR1 duration, but outcomes were better in patients with CR1 duration>12 months. In intermediate-risk karyotype AML patients receiving reinduction, CR1 duration remains the most important predictor of OS at relapse; FLT3-ITD and NPM1 status are not independent predictors of survival.