P676Percutaneous coronary intervention and clinical outcomes in patients with lymphoma: a 10-year period United States nationwide inpatient sample (NIS) analysis

Background

Clinical outcomes and characteristics of patients with lymphoma undergoing percutaneous coronary intervention (PCI) are unknown.

Purpose

To describe clinical characteristics and procedural outcomes in patients that underwent PCI and had a concurrent diagnosis of Hodgkin (HL) or non-Hodgkin (NHL) lymphoma and compare risks of complications and in-hospital mortality in lymphoma subtypes to patients without lymphoma.

Methods

A total of 6,413,175 PCI procedures undertaken in the United States between 2004 and 2014 in the Nationwide Inpatient Sample were included in the analysis. Multivariable regression analysis was performed in order to examine the association between lymphoma diagnosis and clinical outcomes post-PCI including complications and in-hospital mortality.

Results

Patients with lymphoma generally had a significantly higher incidence of post-PCI complications and in-hospital mortality compared to patients without lymphoma (Figure 1). Patients with lymphoma were more likely to experience in-hospital mortality (OR 1.34, 95% CI 1.20–1.49), stroke or transient ischemic attack (TIA) (OR 1.59, 95% CI 1.47–1.73), and any in-hospital complication (OR 1.19, 95% CI 1.14–1.25), following PCI. In the lymphoma subtype-analysis, diagnosis of HL was associated with an increased likelihood of in-hospital death (OR 1.31, 95% CI 1.17–1.48), any in-hospital complication (OR 1.20, 95% CI 1.14–1,26), bleeding complications (OR 1.12 95% CI 1.05–1.19) and vascular complications (OR 1.10 95% CI 1.03–1.17) while these risks were not significantly associated with NHL diagnosis. Finally, both types of lymphoma were associated with an increased likelihood of stroke/TIA following PCI, with this effect being twice greater for HL than NHL diagnosis (OR 1.66, 95% CI 1.52–1.81 and OR 1.33, 95% CI 1.06–1.66, respectively) (Table 1).

Table 1. ORs for clinical outcomes Variable HL vs. No Lymphoma NHL vs. No Lymphoma Bleeding complications 1.12 (1.05–1.19) 1.07 (0.89–1.27) Vascular complications 1.10 (1.03–1.17) 1.13 (0.92–1.27) Cardiac complications 0.94 (0.85–1.03) 0.86 (0.68–1.11) Post-procedural stroke/TIA 1.66 (1.52–1.81) 1.33 (1.06–1.66) Any complication 1.20 (1.14–1.26) 1.04 (0.91–1.18) In-hospital mortality 1.31 (1.17–1.48) 0.89 (0.65–1.21) HL, Hodgkin's Lymphoma; NHL, non-Hodgkin's Lymphoma; TIA, Transient Ischemic Attack.

Figure 1. Type of lymphoma and outcomes

Conclusions

While the incidence of lymphoma in the observed PCI cohort was low, a diagnosis of lymphoma was associated with an adverse prognosis following PCI, primarily in patients with a diagnosis of HL.

A phase II study of decitabine and gemtuzumab ozogamicin in newly diagnosed and relapsed acute myeloid leukemia and high-risk myelodysplastic syndrome

Decitabine may open the chromatin structure of leukemia cells making them accessible to the calicheamicin epitope of gemtuzumab ozogamicin (GO). A total of 110 patients (median age 70 years; range 27-89 years) were treated with decitabine and GO in a trial designed on model-based futility to accommodate subject heterogeneity: group 1: relapsed/refractory acute myeloid leukemia (AML) with complete remission duration (CRD) <1 year (N=28, 25%); group 2: relapsed/refractory AML with CRD ⩾1 year (N=5, 5%); group 3: untreated AML unfit for intensive chemotherapy or untreated myelodysplastic syndrome (MDS) or untreated myelofibrosis (MF; N=57, 52%); and group 4: AML evolving from MDS or relapsed/refractory MDS or MF (N=20, 18%). Treatment consisted of decitabine 20 mg/m(2) daily for 5 days and GO 3 mg/m(2) on day 5. Post-induction therapy included five cycles of decitabine+GO followed by decitabine alone. Complete remission (CR)/CR with incomplete count recovery was achieved in 39 (35%) patients; group 1= 5/28 (17%), group 2=3/5 (60%), group 3=24/57 (42%) and group 4=7/20 (35%). The 8-week mortality in groups 3 and 4 was 16% and 10%, respectively. Common drug-related adverse events included nausea, mucositis and hemorrhage. Decitabine and GO improved the response rate but not overall survival compared with historical outcomes in untreated AML ⩾60 years.

FOXP3 is a direct target of miR15a/16 in umbilical cord blood regulatory T cells

Exact mechanism of action of umbilical cord blood (CB)-derived regulatory T cells (Tregs) in the prevention of GVHD remains unclear. On the basis of selective overexpression of peptidase inhibitor 16 in CB Tregs, we explored the related p53 pathway, which has been shown to negatively regulate miR15a/16 expression. Significantly lower levels of miR15a/16 were observed in CB Tregs when compared with conventional CB T cells (Tcons). In a xenogeneic GVHD mouse model, lower levels of miR15a/16 were also found in Treg recipients, which correlated with a better GVHD score. Forced overexpression of miR15a/16 in CB Tregs led to inhibition of FOXP3 and CTLA4 expression and partial reversal of Treg-mediated suppression in an allogeneic mixed lymphocyte reaction that correlated with the reversal of FOXP3 demethylation in CB Tregs. On the other hand, miR15a/16 knockdown in CB Tcons led to expression of FOXP3 and CTLA4 and suppression of allogeneic lymphocyte proliferation. Using a luciferase-based mutagenesis assay, FOXP3 was determined to be a direct target of miR15a and miR16. We propose that miR15a/16 has an important role in mediating the suppressive function of CB Tregs and these microRNAs may have a 'toggle-switch' function in Treg/Tcon plasticity.

Final results of phase I and pharmacokinetic study of SJG-136 administered on a daily x 5 schedule

e13506

Background: SJG-136 is a pyrrolobenzodiazepine dimer that forms covalent DNA crosslinks in a sequence-specific manner in the minor groove. In vitro testing demonstrated a broad pattern of antitumor activity in sub-nmol concentrations. A phase I study in patients (pts) with solid tumors revealed clinical activity, defined MTD as 30 mg/m2/d administered on daily x 3 schedule, and confirmed manageable toxicity. Here we report the results of a CTEP-sponsored phase I trial of SJG-136 administered on a daily x 5 schedule in pts with relapsed or refractory (R/R) leukemias. Methods: Previously treated pts with R/R acute leukemias (AML, ALL, high risk MDS, CML blast phase) or R/R CLL with adequate organ function and ECOG performance status of ≤ 2 were eligible for the study. The starting dose level was 6 mcg/m2 given intravenously daily x 5 days on a 21 day cycle. Pts were sequentially enrolled in cohorts of 3 and the dose was escalated in a classic 3+3 schema at the dose levels: 6, 12, 24, and 36 mcg/m2. Repeat courses and intrapatient dose escalation were allowed. Results: Sixteen pts (11M, 5 F) were enrolled on the study. The median age of the patients was 53 (21–84). Thirteen (81%) pts had R/R AML, and 3 (19%) had R/R ALL of which 5 (31%) had diploid and 6 (38%) had adverse cytogenetics. Median number of prior therapies was 3 (2–6). Pts enrolled at each dose level (mcg/m2) were: 6 (3 pts), 12 (5 pts), 24 (4 pts), 36 (4 pts). The median number of cycles delivered was 1 (0–5). The dose of 36 mcg/m2 was found to be above the MTD, with the DLT being grade 3 soft tissue edema. Other manifestations of vascular leak including grade I, II hypoalbuminemia, edema, and pleural effusions were seen in a number of patients starting at dose level 24 mcg/m2 and above. Other non-dose limiting toxicities included nausea, dyspnea, fatigue, bloating, and insomnia. One pt had a PR, 8 pts had stable disease, and 6 had progression. Pharmacokinetic characteristics in this population will be reported. Conclusions: SJG-136 is safe and active in patients with advanced leukemias. Edema and other vascular leak syndromes are characteristic toxicities of the agent at higher dose levels. 24 mcg/m2 is the recommended phase II dose for the daily x 5 schedule.

No significant financial relationships to disclose.

Phase II study of vorinostat (V) in combination with idarubicin and high-dose cytarabine (IA) as front-line therapy in patients (pts) with high-risk myelodyplsatic syndrome (MDS) or acute myeloid leukemia (AML)

7004

Background: Standard induction therapy for pts with AML has not changed over the last 2 decades nor has the outcome of these pts. We demonstrated in vitro and ex vivo that the combination of an histone deacetylase inhibitor with anthraycline is synergistic (Blood 2006;108:1174); an effect that could be mediated by activation of DNA damage/repair pathways, and found that such combination is safe in phase 1 trial (Blood 2007;110:1842). We designed a phase II study of V with IA as front-line therapy for MDS/AML. Methods: Pts with untreated int-2/high-risk MDS or AML ages 15–65 with adequate liver and renal functions and PS, and EF ≥ 50% were eligible. Pts with CBF were excluded. Initial dose of V was 500 mg orally TID for 3 days followed on day 4 by IA (I:12 mg/m2/dx3; A:1.5g/m2/dx4 over 24 hrs). After induction and if in CR, pt can receive 5 cycles of consolidation with V at the same dose and IA (I:8 mg/m2/dx2; A:0.75g/m2/dx3 over 24 hours) followed by 1 year of maintenance with V. The study was powered to demonstrate improvement in PFS at 7 months and acceptable toxicity. Prior to formal initiation of the phase II, the study had a “run-in” phase to confirm the safety of the triple combination. Correlative studies include analysis of DNA repair/damage pathways. Results: 22 pts have been registered. 3 pts with relapsed/refractory AML were treated in the run-in phase. No excess toxicity was observed; 2 achieved CR and 1 CRp. Following these, 19 pts were enrolled on the phase 2 portion. 17 pts were evaluable. Median age was 49 years. Median WBC at presentation was 12.75 x 109/L. Cytogenetic analysis were abnormal in 12 (71%), complex in 10 (59%). 8 (47%) had secondary disease. 4 (23%) were Flt-3 positive. No unexpected grade 3/4 toxicities have been observed. The CR rate was 82%. 1 pt acheived a marrow CR and 2 pts died during induction. CR were universally associated with CG response. All Flt-3+ pts achieved a CR. Only 2 pts (14%) have relapsed (4 and 5 months). The median PFS has not been reached. Conclusions: The combination of IA and V is safe and active in AML/MDS. No stopping rule has been met. Results will be compared with those of a parallel IA study at MDACC. Correlative analysis are ongoing.

[Table: see text]

The dual PI3 kinase/mTOR inhibitor PI-103 prevents p53 induction by Mdm2 inhibition but enhances p53-mediated mitochondrial apoptosis in p53 wild-type AML

Activation of the phosphatidylinositol-3 kinase/Akt/mammalian target of the rapamycin (PI3K/Akt/mTOR) pathway and inactivation of wild-type p53 by murine double minute 2 homologue (Mdm2) overexpression are frequent molecular events in acute myeloid leukemia (AML). We investigated the interaction of PI3K/Akt/mTOR and p53 pathways after their simultaneous blockade using the dual PI3K/mTOR inhibitor PI-103 and the Mdm2 inhibitor Nutlin-3. We found that PI-103, which itself has modest apoptogenic activity, acts synergistically with Nutlin-3 to induce apoptosis in a wild-type p53-dependent fashion. PI-103 synergized with Nutlin-3 to induce Bax conformational change and caspase-3 activation, despite its inhibitory effect on p53 induction. The PI-103/Nutlin-3 combination caused profound dephosphorylation of 4E-BP1 and decreased expression of many proteins including Mdm2, p21, Noxa, Bcl-2 and survivin, which can affect mitochondrial stability. We suggest that PI-103 actively enhances downstream p53 signaling and that a combination strategy aimed at inhibiting PI3K/Akt/mTOR signaling and activating p53 signaling is potentially effective in AML, where TP53 mutations are rare and downstream p53 signaling is intact.

Apoptosis effector mechanisms: a requiem performed in different keys

Apoptosis is the regulated form of cell death utilized by metazoans to remove unneeded, damaged, or potentially deleterious cells. Certain manifestations of apoptosis may be associated with the proteolytic activity of caspases. These changes are often held as hallmarks of apoptosis in dying cells. Consequently, many regard caspases as the central effectors or executioners of apoptosis. However, this "caspase-centric" paradigm of apoptotic cell death does not appear to be as universal as once believed. In fact, during apoptosis the efficacy of caspases may be highly dependent on the cytotoxic stimulus as well as genetic and epigenetic factors. An ever-increasing number of studies strongly suggest that there are effectors in addition to caspases, which are important in generating apoptotic signatures in dying cells. These seemingly caspase-independent effectors may represent evolutionarily redundant or failsafe mechanisms for apoptotic cell elimination. In this review, we will discuss the molecular regulation of caspases and various caspase-independent effectors of apoptosis, describe the potential context and/or limitations of these mechanisms, and explore why the understanding of these processes may have relevance in cancer where treatment is believed to engage apoptosis to destroy tumor cells.

Phase I trial of intermittent administration of sorafenib (BAY 43–9006) for patients (pts) with refractory/relapsed acute myelogenous leukemia (AML)

7018

Background: Fms-like tyrosine kinase 3 (FLT3) mutations, both internal tandem duplication (ITD) and point mutations, occur in approximately 30% of pts with AML and confer poor prognosis. Sorafenib is an oral multi-kinase inhibitor highly potent against mutant FLT3 (IC50 1–3 nM). Based on preclinical data, this study was initiated to assess two intermittent administration schedules of sorafenib. Methods: This phase I trial evaluated the safety and efficacy of sorafenib in 15 pts with refractory/relapsed AML (n=14) or high-risk myelodysplastic syndrome (n=1). Pts were randomized to sorafenib for 5 days per week (arm A; n=8) or for 14 days every 21 days (arm B; n=7). In both arms, dose level (DL) 1 was 200 mg twice daily in 21-day cycles. Successive DLs were 600, 800, and 1,200 mg daily on a standard 3+3 design. Pre- and post-treatment peripheral blood (PB) and bone marrow (BM) samples were obtained for evaluation of FLT3 status and phospho and total FLT3 and ERK expression. Results: 10 (67%) of 15 pts (all with AML) received at least 1 cycle of sorafenib (5 in arm A, 5 in arm B) and 5 discontinued sorafenib (3 in arm A, 2 in arm B): 3 due to disease progression, and 2 due to infectious complications. Pts who received at least 1 cycle were treated at DL-1 (n=4) or DL-2 (n=6). Median age was 61 years (range, 51–81), number of prior therapies 4 (range, 1–6), and time from diagnosis to sorafenib 9 months (range, 5–46). Sorafenib was well tolerated; the MTD has not been reached. Six (60%) of 10 pts receiving at least 1 cycle of sorafenib (3 in arm A, 3 in arm B) responded. Responses were transient and only occurred in pts with FLT3-ITD mutation. The median blast percentage before and after sorafenib start was 59% and 0% in PB (p=0.008) and 66% and 32% in BM (p=0.03). Serial determinations of phosphorylation status following sorafenib (at 0, 2, 24,120 hours) in pts with FLT3-ITD, demonstrated inhibition of phospho-FLT3 in 3/3 and phospho-ERK in 5/5 pts. Conclusions: Sorafenib is safe in AML and has encouraging activity at the relatively low doses tested thus far, particularly in pts with FLT3-ITD mutation. Clinical studies of sorafenib in combination with chemotherapy or other targeted agents are warranted in pts with AML expressing this abnormality.

[Table: see text]

Interim results of a phase I trial with a novel orally administered synthetic triterpenoid RTA 402 (CDDO-Me) in patients with solid tumors and lymphoid malignancies

14101

Background: RTA 402 (CDDO-Me) is a novel synthetic triterpenoid with potent anticancer and anti-inflammatory activity through selective modulation of proteins that respond to changes in oxidative stress, including NF-κB, JNK, and STAT3. Based on preclinical data demonstrating effects on tumors and associated stroma, a Phase 1 dose-finding and pharmacokinetic study was initiated. Methods: RTA 402 is administered orally once a day for the first 21 days of a 28-day cycle. Dose escalation is proceeding according to an accelerated titration design until an MTD is reached. Results: RTA 402 has been administered to 11 patients at 7 dose levels (5 to 300 mg/day). Cycle 1 data are available for 8 patients. No significant drug-related toxicity has been reported and dose escalation continues in 100% increments. The median biological half-life of RTA 402 was 49 h (range, 18–67 h), and all patients receiving doses >20 mg/day were continuously exposed to plasma levels of the drug exceeding 1 ng/mL. Evidence of antitumor and biological activity has been observed in initial patients. A patient with medullary thyroid carcinoma treated at 5 mg/day has received eight cycles of therapy and has had stable disease with a 70% reduction of calcitonin levels. A patient with metastatic melanoma has experienced disease stabilization through four cycles and remains on study. A second melanoma patient has also experienced disease stabilization through two cycles and remains on study. Radiographic evidence of regressing lesions has been observed in both melanoma patients. Additionally, significant reductions in circulating VEGF, MMP-9, TNF, IL-8, and IL-10, up to 65%, 91%, 90%, 73%, and 70%, respectively, have been observed in at least half of patient samples. Cytokine suppression has correlated with improvements in reported pain and fatigue. Conclusions: Orally administered RTA 402 appears well tolerated up to 150 mg/day and with prolonged exposure up to 8 months. Data from initial patients indicate biological activity and suggest clinical benefit, with disease stabilization in several patients who had rapidly progressing disease with high tumor burden. Phase 2 trials are planned.

No significant financial relationships to disclose.

Hyperglycemia and obesity in patients (pts) with acute lymphoblastic leukemia (ALL): Association with prevalence, response, and survival

7074

Increasing evidence suggests associations between obesity, diabetes and/or hyperglycemia (DM/HG) and solid tumors. Less is known about the relationship of these metabolic factors to the hematologic malignancies. To determine the prevalence of DM/HG and obesity in pts with ALL and whether these are predictors of response and survival, we conducted a retrospective chart review of 299 pts with newly diagnosed ALL, who were evaluated at our institution between November 1999 and May 2005 and received hyper-CVAD therapy: fractionated cyclophosphamide, vincristine, doxorubicin, dexamethasone alternating with methotrexate and high-dose cytarabine. Median age was 43 yrs (range 15–83). Sixty-one percent of pts were male, and 39% female. Seventy-four percent had a diagnosis (dx) of precursor B cell ALL (22% Ph+), 18% Burkitt's ALL, 6% lymphoblastic lymphoma, 2% other. Prior to therapy, the overall prevalence of DM/HG (diabetes based on reported dx prior to ALL-dx, and hyperglycemia based on baseline serum glucose ≥200 mg/dL) was 16%. Pts with DM/HG were significantly older than those without DM/HG (median age 57 yrs vs. 40 yrs, p<0.001). Complete remission (CR) rate and the CR duration (CRD) were similar in the DM/HG vs. non-DM/HG group. However, the mean CRD was 80 wks in the HG separately group and 121 wks in the non-HG group (p=0.04). The mean CRD was 102 wks in the obese pts and 124 wks in the non-obese pts (p=.04). In univariate analysis, DM/HG, obesity, and older age were associated with shorter overall survival (OS). Mean OS of pts with DM/HG was 134 vs. 194 wks for pts without DM/HG, (p=0.2). Mean OS of obese pts was 136 vs. 199 wks for non-obese pts, (p=0.01). In a multivariable Cox regression model, the only factors that remained significant for survival were age, obesity, and white blood cell count (WBC). There was no significant difference in OS by leukemia diagnosis. In conclusion, the prevalence data suggests that DM/HG may be involved in the development of ALL. However, DM/HG has no impact on survival, probably because of its strong correlation with age. The association of obesity with shorter OS warrants further investigation.

No significant financial relationships to disclose.

Novel role of HDAC inhibitors in AML1/ETO AML cells: activation of apoptosis and phagocytosis through induction of annexin A1

The chimeric fusion protein AML1-ETO, created by the t(8;21) translocation, recruits histone deacetylase (HDAC) to AML1-dependent promoters, resulting in transcriptional repression of the target genes. We analyzed the transcriptional changes in t(8;21) Kasumi-1 AML cells in response to the HDAC inhibitors, depsipeptide (FK228) and suberoylanilide hydroxamic acid (SAHA), which induced marked growth inhibition and apoptosis. Using cDNA array, annexin A1 (ANXA1) was identified as one of the FK228-induced genes. Induction of ANXA1 mRNA was associated with histone acetylation in ANXA1 promoter and reversal of the HDAC-dependent suppression of C/EBPalpha by AML1-ETO with direct recruitment of C/EBPalpha to ANXA1 promoter. This led to increase in the N-terminal cleaved isoform of ANXA1 protein and accumulation of ANXA1 on cell membrane. Neutralization with anti-ANXA1 antibody or gene silencing with ANXA1 siRNA inhibited FK228-induced apoptosis, suggesting that the upregulation of endogenous ANXA1 promotes cell death. FK228-induced ANXA1 expression was associated with massive increase in cell attachment and engulfment of Kasumi-1 cells by human THP-1-derived macrophages, which was completely abrogated with ANXA1 knockdown via siRNA transfection or ANXA1 neutralization. These findings identify a novel mechanism of action of HDAC inhibitors, which induce the expression and externalization of ANXA1 in leukemic cells, which in turn mediates the phagocytic clearance of apoptotic cells by macrophages.

Quantitative single cell determination of ERK phosphorylation and regulation in relapsed and refractory primary acute myeloid leukemia

We investigated the constitutive activation of the MEK/ERK pathway in acute myelogenous leukemia (AML) via a flow cytometric technique to quantitate expression of phosphorylated ERK (p-ERK). A total of 42 AML samples (16 newly diagnosed, 26 relapsed/refractory) were analyzed. Normal bone marrow CD34+ cells (n = 10) had little or no expression of p-ERK, while G-CSF-mobilized CD34+ cells exhibited enhanced p-ERK levels. Markedly elevated p-ERK levels were found in 83.3% of the AML samples, with no differences observed between the newly diagnosed and relapsed/refractory samples. Treatment with a MEK inhibitor resulted in significantly decreased p-ERK levels in both the newly diagnosed and relapsed/refractory samples, which was associated with growth arrest, but not apoptosis induction. In summary, we defined conditions for the analysis of MAPK signaling in primary AML samples. Normal CD34+ cells expressed very low levels of p-ERK, and increased p-ERK levels were found in normal G-CSF-stimulated circulating CD34+ cells. Constitutively high p-ERK levels observed in the majority of AML samples suggest deregulation of this pathway that appears to be independent of disease status. The ability of ERK inhibition to promote growth arrest rather than apoptosis suggests that clinical trials of MEK/ERK inhibitors may be more effective when combined with chemotherapy.

The novel triterpenoid CDDO-Me suppresses MAPK pathways and promotes p38 activation in acute myeloid leukemia cells

Development of novel therapeutic strategies is a continuing challenge for the treatment of acute myeloid leukemia (AML). The novel triterpenoid, C-28 methyl ester of 2-cyano-3,12-dioxoolen-1,9-dien-28-oic acid (CDDO-Me), induces apoptosis in myeloid leukemic cell lines and in primary AML samples. In this report, the effects of CDDO-Me on CD34(+) AML progenitor cells in vitro were examined. CDDO-Me induced apoptosis in all but one of ten AML samples. CDDO-Me is known to inhibit the activation of ERK1/2. In this series of primary AML samples, ERK was expressed and phosphorylated in all patient samples studied and CDDO-Me inhibited ERK phosphorylation in five of 10 samples. However, CDDO-Me induced apoptosis in four of five samples without decreasing pERK levels, suggesting that pERK is not the sole target of the compound. CDDO-Me induced phosphorylation of p38 in AML-derived U937 cells. Pretreatment of U937 cells with a p38 inhibitor protected cells from the cyto-toxic effects of CDDO-Me. These findings suggest a role for p38 in CDDO-Me-induced apoptosis. In preliminary studies, CDDO-Me induced p38 phosphorylation in seven of eight primary AML samples. These findings suggest that CDDO-Me treatment shifts cell signaling away from cyto-protective pathways and thus CDDO-Me may be effective for the treatment of AML.

Leukotriene B4 receptor inhibitor LY293111 induces cell cycle arrest and apoptosis in human anaplastic large-cell lymphoma cells via JNK phosphorylation

Anaplastic large-cell lymphoma (ALCL) is a heterogeneous lymphoma category in which a subset of cases carry the t(2;5)(p23;q35) or variant translocations resulting in overexpression of anaplastic lymphoma kinase (ALK). LY293111 (2-[2-propyl-3-[3-[2-ethyl-4-(4-fluorophenyl)-5-hydroxyphenoxy]-propoxy]-phenoxy] benzoic acid sodium salt) is a leukotriene B4 receptor antagonist, which was found to be safe and tolerable in Phase I clinical trials. In this study, we investigated the potential therapeutic effects and mechanisms of action of LY293111 in ALCL cell lines. LY293111 inhibited proliferation of both ALK(+) and ALK(-) ALCL cell in a dose-dependent fashion and induced complete G(1)-S cell cycle arrest, which was accompanied by upregulation of p27 and downregulation of cyclin E. Pretreatment with LY293111 for 4 h resulted in profound inhibition of serum-induced phosphorylation of extracellular-regulated kinases-1 and 2 and Akt and a concomitant increase in the phosphorylation of the stress-activated kinase c-jun N-terminal kinases (JNK). Simultaneously, LY293111 induced caspase-dependent apoptosis via activation of the intrinsic pathway, including early loss of mitochondrial inner transmembrane potential and the production of reactive oxygen species (ROS), cleavage of caspases-9, -3, poly ADP-ribose polymerase (PARP) and X-linked inhibitor of apoptosis. The phospho-JNK inhibitor SP600125 partially protected Sup-M2 cells from LY293111-induced apoptosis, PARP cleavage and ROS generation, suggesting a role for JNK in LY293111-induced cell death. These results warrant further studies of LY293111 in ALCL.

PKC α mediates chemoresistance in acute lymphoblastic leukemia through effects on Bcl2 phosphorylation

Overexpression of protein kinase C alpha (PKC alpha) promotes Bcl2 phosphorylation and chemoresistance in human acute leukemia cells. The contribution of non-Bcl2 mechanisms in this process is currently unknown. In this report, overexpression of PKC alpha was found not to affect cell proliferation, cell cycle, or activation of mitogen-activated protein kinases. The failure of PKC alpha overexpression to activate non-Bcl2 survival pathways suggested that PKC alpha-mediated chemoresistance requires Bcl2. Supporting this notion, REH/PKC alpha transfectants were found to be as sensitive to HA14-1 (a drug that targets Bcl2 function) as parental cells. In addition, HA14-1 abrogated PKC alpha's ability to protect REH cells from etoposide. These findings suggested that Bcl2 is necessary for the protective function of PKC alpha in REH cells. Since Bcl2 phosphorylation status is negatively regulated by protein phosphatase 2A (PP2A) and PP2A regulates PKC alpha, we investigated whether PKC alpha can conversely regulate PP2A. Overexpression of PKC alpha was found to suppress mitochondrial PP2A activity by a mechanism that, at least in part, involves suppressed expression of the regulatory subunit comprising the Bcl2 phosphatase (ie the PP2A/B56 alpha subunit). The ability of PKC alpha to target both Bcl2 and the Bcl2 phosphatase represents a novel mechanism for chemoresistance.

Inhibition of phosphatidylinositol 3-kinase dephosphorylates BAD and promotes apoptosis in myeloid leukemias

The phosphatidylinositol 3-kinase (PI3K)/AKT protein kinase pathway is involved in cell growth, proliferation, and apoptosis. The functional activation of PI3K/AKT provides survival signals and blockade of this pathway may facilitate cell death. Downstream targets of PI3K-AKT include the proapoptotic protein BAD, caspase-9, NF-kappaB, and Forkhead. We have previously reported that BAD is constitutively phosphorylated in primary acute myeloid leukemia (AML) cells, a post-transcriptional modification, which inactivates its proapoptotic function. In this study, we tested the hypothesis that the inhibition of PI3K by LY294002 results in the dephosphorylation of AKT and BAD, and thus promote leukemia cell apoptosis. We investigated the effects of LY294002 in megakaryocytic leukemia-derived MO7E cells, primary AML and normal bone marrow progenitor cells. In MO7E cells, LY294002 reduced AKT kinase activity, induced dephosphorylation of AKT and BAD, and increased apoptosis. Concomitant inhibition of mitogen-activated protein kinase signaling or combination with all-trans retinoic acid further enhanced apoptosis of leukemic cells. In primary AML samples, clonogenic cell growth was significantly reduced. Normal hematopoietic progenitors were less affected, suggesting preferential targeting of leukemia cells. In conclusion, the data suggest that the inhibition of the PI3K/AKT signaling pathway restores apoptosis in AML and may be explored as a novel target for molecular therapeutics in AML.

Stromal cells prevent apoptosis of AML cells by up-regulation of anti-apoptotic proteins

The aim of this study was to study interactions between stromal bone marrow microenvironment and leukemic cells. We tested the hypothesis that stromal cells prevent apoptosis of AML cells by up-regulating anti-apoptotic proteins in leukemic blasts. In HL-60 and NB-4 cells, serum deprivation- and ara-C-induced apoptosis was diminished when cells were cocultured with murine MS-5 stromal cells (P < 0.02). This effect was reproduced with conditioned medium from MS-5 cells. Cocultivation with stromal cells induced Bcl-2 expression levels, both by PCR analysis and flow cytometry. In primary AML (n = 14), ara-C-induced apoptosis was significantly lower in cells cocultured with MS-5 cells than in controls (P < 0.001). This effect was partially preserved when leukemic cells were separated from stromal cells by a microporous insert (in 5/9 samples, P = 0.04). In addition, Bcl-2 levels were significantly higher in stroma-supported than in control CD34(+) AML cells (P < 0.01). Bcl-X(L) levels were higher in 5/7 samples grown on stromal layers. Of note, in AML patients resistant to induction chemotherapy (n = 6), Bcl-2 increased significantly after cultivation with stromal cells, but no such increase was noted in cells from chemotherapy-sensitive patients. In conclusion, MS-5 stromal cells prevented apoptosis in HL-60 cells and in primary AML blasts via modulation of Bcl-2 family proteins. The observed association of high Bcl-2 expression in stroma-supported AML blasts in vitro with resistance to chemotherapy in vivo suggests that the same mechanisms may be operational in vivo.

Therapeutic targeting of the MEK/MAPK signal transduction module in acute myeloid leukemia

The mitogen-activated protein kinase (MAPK) pathway regulates growth and survival of many cell types, and its constitutive activation has been implicated in the pathogenesis of a variety of malignancies. In this study we demonstrate that small-molecule MEK inhibitors (PD98059 and PD184352) profoundly impair cell growth and survival of acute myeloid leukemia (AML) cell lines and primary samples with constitutive MAPK activation. These agents abrogate the clonogenicity of leukemic cells but have minimal effects on normal hematopoietic progenitors. MEK blockade also results in sensitization to spontaneous and drug-induced apoptosis. At a molecular level, these effects correlate with modulation of the expression of cyclin-dependent kinase inhibitors (p27(Kip1) and p21(Waf1/CIP1)) and antiapoptotic proteins of the inhibitor of apoptosis proteins (IAP) and Bcl-2 families. Interruption of constitutive MEK/MAPK signaling therefore represents a promising therapeutic strategy in AML.

Liposomal Bcl-2 antisense oligonucleotides enhance proliferation, sensitize acute myeloid leukemia to cytosine-arabinoside, and induce apoptosis independent of other antiapoptotic proteins

The antiapoptotic proteins, Bcl-2 and Bcl-X(L), are expressed in most cases of acute myeloid leukemia (AML) and may contribute to drug resistance in AML. We tested the hypothesis that down-regulation of Bcl-2 alone by antisense oligodeoxynucleotides (Bcl-2-AS) induces apoptosis, even in the presence of other antiapoptotic genes. We tested Bcl-2-AS in myeloid leukemic HL-60 cells, in Bcl-2 and Bcl-X(L) overexpressing HL-60-DOX cells, and in primary AML samples. Down-regulation of Bcl-2 by Bcl-2-AS reduced the viability of HL-60 cells and, less effectively, HL-60-DOX cells and increased ara-C cytotoxicity in both cell lines. Incubation of primary AML blasts with Bcl-2-AS decreased Bcl-2 expression in CD34(+) blast cells after induction of apoptosis and enhancement of ara-C cytotoxicity in 11 of 19 primary AML samples. In 8 samples in which Bcl-2-AS did not induce apoptosis, baseline Bcl-2 levels were found to be strikingly high. The expression of other antiapoptotic proteins (Bcl-X(L), Bag-1, A1, and Mcl-1) did not prevent Bcl-2-AS-induced apoptosis. Bcl-2-AS also inhibited colony formation of AML progenitor cells. Low concentrations of Bcl-2-AS induced significant increases in S-phase cells (P =.04). Results establish Bcl-2 as a critical target for AS strategies in AML in which the baseline levels predict response to Bcl-2-AS. Bcl-2 exerts both antiapoptotic and antiproliferative functions in AML. Because early normal hematopoietic stem cells do not express Bcl-2, Bcl-2-AS therapy should be highly selective for AML cells. (Blood. 2000;95:3929-3938)

Expression of Bcl-2-related genes in normal and AML progenitors: changes induced by chemotherapy and retinoic acid

The expression of Bcl-2 family members was examined in normal and leukemic hematopoietic cells. Immature hematopoietic progenitor cells (CD34+/33-/13-) did not express Bcl-2 but Bcl-XL, the majority of CD34 cells expressed Bcl-2, Bcl-XL and BAD, and normal promyelocytes (CD34-/33+) lacked expression of both Bcl-2 and Bcl-XL, while leukemic CD34+progenitors and promyelocytes expressed these anti-apoptotic proteins. In AML, Bcl-2 expression was higher on CD34+ than on all AML cells, however, expression of Bcl-2 or Bcl-XL did not predict achievement of complete remission. Surprisingly, low Bcl-2 content was associated with poor survival in a group of patients with poor prognosis cytogenetics. The anti-apoptotic BAD protein was found to be expressed in AML, but was phosphorylated in 41/42 samples. Phosphorylation was found at both sites, Ser 112 and Ser 136. During induction chemotherapy, Bcl-2 levels of CD34 cells increased significantly. In the context of evidence for small numbers of leukemic CD34+ cells expressing very high levels of Bcl-2 prior to therapy, this finding is interpreted as a survival advantage of Bcl-2 overexpressing progenitors and rapid elimination of cells with low Bcl-2. Bcl-2 and Bcl-XL were both expressed in minimal residual disease cells. Downregulation of Bcl-2 mRNA and protein was observed by ATRA and the combination of Ara-C, followed by ATRA, resulted in markedly increased cytotoxicity in HL-60 cells, as compared to Ara-C alone or ATRA followed by Ara-C. Implications of these findings for the development of new therapeutic strategies for AML are discussed.

Apoptosis. Molecules and mechanisms

This review of the molecules and pathways involved in programmed cell death (apoptosis) discriminates triggers of apoptosis (e.g. chemotherapy, radiation, Fas ligation), modulators of apoptosis (e.g. Bcl-2 family members, Bcl-2 interacting proteins, Apafs, IAPs, and Fas/FasL modulators including FLICE and FLIPs), effectors (caspases 1-13) and cleavage substrates (e.g. PARP). Special consideration is given to the structure-function relationship of Bcl-2 family members and to their post-transcriptional modification. Brief references are made to the role of apoptotic pathway in leukemias and lymphomas and to strategies of modulating apoptotic pathways.

Expression and function of leptin receptor isoforms in myeloid leukemia and myelodysplastic syndromes: proliferative and anti-apoptotic activities

The receptor for the gene product of the obesity gene, leptin, was recently reported to be expressed on murine and human hematopoietic progenitor cells. Therefore, we studied the expression of the leptin receptor, OB-R, in normal myeloid precursors, human leukemia cell lines, and primary leukemic cells using reverse-transcriptase polymerase chain reaction. In normal hematopoiesis, OB-R was expressed in CD34(+) cells. Normal promyelocytes (CD34(-)33(+) and CD34(-)13(+)) expressed only very low levels of the short, presumably nonsignaling isoform. Both the long and short isoforms of OB-R were expressed in 10 of 22 samples from patients with newly diagnosed primary or secondary acute myeloid leukemia (AML), with a higher incidence of the long isoform in primary AML (87.6% v 28.6%; P =.01). The incidence of OB-R expression was higher in recurrent than in newly diagnosed AML (P <.001), and samples from four patients with refractory AML showed strong expression of both isoforms. Both OB-R isoforms were also expressed in newly diagnosed and recurrent acute promyelocytic leukemia cells but were essentially absent in samples of chronic or acute lymphocytic leukemia. In vitro growth of myeloid leukemic cell lines and of blasts from 14 primary AMLs demonstrated that recombinant human leptin alone induced low level proliferation, significantly (P <.05) increased proliferation induced by recombinant human granulocyte colony-stimulating factor, interleukin 3, and stem cell factor in a subset of AML and increased colony formation (P <.005). Also, leptin reduced apoptosis induced by cytokine withdrawal in MO7E and TF-1 cells. Serum leptin levels correlated only with body mass index (P <. 001) and gender (P =.03). Results confirm the reported expression of leptin receptor in normal CD34(+) cells and demonstrate the frequent expression of leptin receptors in AML blasts. While normal promyelocytes lack receptor expression, leukemic promyelocytes express both isoforms. We also demonstrate proliferative effects of leptin alone and in combination with other physiologic cytokines, and anti-apoptotic properties of leptin. These findings could have implications for the pathophysiology of AML.

Ligation of cell surface CD38 protein with agonistic monoclonal antibody induces a cell growth signal in myeloid leukemia cells

CD38 is expressed during early stages of differentiation in normal and leukemic myeloid cells. Recently, CD38 has been shown to participate in intracellular signal transduction pathways following its ligation with CD38-specific mAbs. In this study we report that ligation of CD38 by one such agonistic mAb (IB4) induced proliferation of cultured leukemic cells in vitro. In HL-60, KG-1A, NB4, and OCI-AML-3 myeloid leukemia cell lines, IB4 mAb induced an increase in the proliferating cell fraction as determined by cell number, clonogenic assay, and flow cytometric analysis. The presence of Ab caused a dose-dependent increase in the number of CFU and an increase in cell divisions. HL-60-Dox cells (a HL-60-doxorubicin-resistant cell line), which have no detectable CD38 expression, failed to respond to IB4 mAb. The effect of CD38 ligation on cell growth was also evaluated in freshly isolated leukemic cells from patients with acute myelogenous leukemia (AML). A significant increase in the proliferating cell fraction (S+G2M) was observed in 50% of the patients incubated with IB4 mAb. In five of the six AML patients, anti-CD38 mAb stimulated the proliferation of AML colony-forming cells. These results suggest that ligation of CD38 can induce the proliferation of leukemic cells and may play a role in the propagation of leukemic cell clones in certain cohorts of AML patients.