Combination of YM155, a Survivin Suppressant, with Bendamustine and Rituximab: A New Combination Therapy to Treat Relapsed/Refractory Diffuse Large B-cell Lymphoma

Bendamustine: A review of pharmacology, clinical use and immunological effects (Review)

Bendamustine is an alkylating agent classified into the group of nitrogen mustard analogues, synthesized almost sixty years ago. It was registered in former East Germany in 1971 and approved by the US Food and Drug Administration in 2008 for treatment of chronic lymphocytic leukemia and indolent B-cell non-Hodgkin lymphoma. Considering its beneficial properties in the therapy of relapsed or refractory hematological malignancies, synergistic effects with other antineoplastic agents and increasing recent reports on its immunomodulatory effects, bendamustine has once again gained its justified attention. The uniqueness of bendamustine-mediated effects should be observed keeping in mind its distinctive structure with structural similarities to both alkylating agents and purine analogs. In the present review, the current knowledge on the use of bendamustine in oncology, its pharmacokinetics, mechanism of action and toxicity was summarized. In addition, its immune-modulating effects that have not been fully elucidated so far are emphasized, hoping to encourage further investigations of this unique drug.

Altered pathways and targeted therapy in double hit lymphoma

High-grade B-cell lymphoma with translocations involving MYC and BCL2 or BCL6, usually referred to as double hit lymphoma (DHL), is an aggressive hematological malignance with distinct genetic features and poor clinical prognosis. Current standard chemoimmunotherapy fails to confer satisfying outcomes and few targeted therapeutics are available for the treatment against DHL. Recently, the delineating of the genetic landscape in tumors has provided insight into both biology and targeted therapies. Therefore, it is essential to understand the altered signaling pathways of DHL to develop treatment strategies with better clinical benefits. Herein, we summarized the genetic alterations in the two DHL subtypes (DHL-BCL2 and DHL-BCL6). We further elucidate their implications on cellular processes, including anti-apoptosis, epigenetic regulations, B-cell receptor signaling, and immune escape. Ongoing and potential therapeutic strategies and targeted drugs steered by these alterations were reviewed accordingly. Based on these findings, we also discuss the therapeutic vulnerabilities that coincide with these genetic changes. We believe that the understanding of the DHL studies will provide insight into this disease and capacitate the finding of more effective treatment strategies.

High ETV6 Levels Support Aggressive B Lymphoma Cell Survival and Predict Poor Outcome in Diffuse Large B-Cell Lymphoma Patients

The identification of prognostic factors for aggressive B-cell lymphomas still represents an unmet clinical need. We used forward phase protein arrays (FFPA) to identify proteins associated with overall survival (OS) from diagnostic formalin-fixed paraffin-embedded material of diffuse large B-cell lymphoma (DLBCL) patients (n = 47). Univariate Cox regression analysis identified numerous proteins, including immune check-point molecules (PDCD1, PDCD2 and PD1L2) and BCL2 to be significantly associated with OS. However, only ETV6 and PIM2 proteins persisted following multivariate Cox analysis. Independent validation studies by immunohistochemistry and analysis of public gene expression profiles of DLBCL confirmed a prognostic role for high ETV6 and ETV6/PIM2 ratios in DLBCL. ETV6 is a recurrently mutated/deleted gene in DLBCL for which its function in this disease entity is currently unknown. We find that ETV6 is upregulated during oncogenic transformation of germinal center B-cells and that it regulates DLBCL survival, as its acute loss results in marked apoptosis. Fluctuations in survivin (BIRC5) expression levels were associated with this phenomenon. Furthermore, an inverse correlation between ETV6 and BIRC5 expression levels was found and correlated with a response to the BIRC5 inhibitor, YM155. In conclusion, we present evidence for an oncogenic function of ETV6 in DLBCL.

MnO2 nanosheets as a carrier and accelerator for improved live-cell biosensing application of CRISPR/Cas12a

Besides gene-editing, the CRISPR/Cas12a system has also been widely used in in vitro biosensing, but its applications in live-cell biosensing are rare. One reason is lacking appropriate carriers to synchronously deliver all components of the CRISPR/Cas12a system into living cells. Herein, we demonstrate that MnO₂ nanosheets are an excellent carrier of CRISPR/Cas12a due to the two important roles played by them. Through a simple mixing operation, all components of the CRISPR/Cas12a system can be loaded on MnO₂ nanosheets and thus synchronously delivered into cells. Intracellular glutathione (GSH)-induced decomposition of MnO₂ nanosheets not only results in the rapid release of the CRISPR/Cas12a system in cells but also provides Mn²⁺ as an accelerator to promote CRISPR/Cas12a-based biosensing of intracellular targets. Due to the merits of highly efficient delivery, rapid intracellular release, and the accelerated signal output reaction, MnO₂ nanosheets work better than commercial liposome carriers in live-cell biosensing analysis of survivin messenger RNA (mRNA), producing much brighter fluorescence images in a shorter time. The use of MnO₂ nanosheets might provide a good carrier for different CRISPR/Cas systems and achieve the rapid and sensitive live-cell biosensing analysis of different intracellular targets, thus paving a promising way to promote the applications of CRISPR/Cas systems in living cells.

Herein, we demonstrate that MnO₂ nanosheets are an excellent carrier of CRISPR/Cas12a due to the two important roles played by them.

Facile Strategy To Enhance Specificity and Sensitivity of Molecular Beacons by an Aptamer-Functionalized Delivery Vector

To enhance the specificity and sensitivity of molecular beacons (MBs) in detecting mRNA in living tumor cells, we introduced an aptamer (AS1411) to the delivery system of MBs to form an aptamer-decorated nanoprobe (ANP), which was prepared through self-assembly between AS1411-conjugated carboxymethyl chitosan (ACMC) with protamine sulfate (PS)/CaCO₃/MB cores. Owing to the specific binding of AS1411 to nucleolin, which is overexpressed in tumor cell membranes and nuclei, an AS1411-decorated MB-delivery system leads to dramatically increased cell uptake of MBs for probing survivin mRNA and thus induces strong intracellular fluorescence emission in targeted tumorous cells and cell nuclei. Furthermore, we demonstrate that ANP can efficiently detect survivin mRNA in mitochondria. In other words, the effective delivery of MBs ensures the precise detection of mRNA distribution in diverse organelles. In addition, we evaluated the efficiency of ANP in probing tumor cells in simulated blood as well as in peripheral blood from a healthy donor and found that the nanoprobe can specifically deliver MBs to tumor cells and identify tumor cells in blood. The targeting delivery system we constructed holds promising applications in precise detection of subcellular distribution of mRNA in living tumor cells as well as in fluorescence-guided cancer detection in liquid biopsy technology. This study provides a facile strategy to effectively improve the specificity and sensitivity of conventional molecular beacons.

Survivin is a prognostic marker and therapeutic target for extranodal, nasal-type natural killer/T cell lymphoma

Background

The relationship between survivin and extranodal, nasal-type natural killer/T cell lymphoma (ENKTCL) was unclearly established yet. We here studied the potential prognostic roles of survivin and its implication as a target in ENKTCL therapy.

Methods

ENKTCL patients' peripheral blood were collected and tested by ELISA. ENKTCL cell lines were cultured with or without survivin inhibitor and tested by MTT and Flow cytometry. According to the gene expression profiles from the ArrayExpress Archive under E-TABM-702, survivin co-regulated cluster was established by Coupled Two-way Clustering Algorithm.

Results

Seventeen point six percent of total 17 ENKTCL patients were serum survivin-positive. These patients had poorer outcome than that of negative cases (P<0.01). Analysis of survivin co-regulation genes in ENKTCL revealed that survivin was significantly involved in pluripotency, drug resistance, cell cycle and proliferation, indicating that it should be one of key regulators in ENKTCL and might be a latent therapeutic target. Our results just showed that YM155, a survivin inhibitor, had strong anti-tumor effect on ENKTCL cell lines in a dose dependent manner. It increased sub-G1 phase population and reduced G1- and G2-M phase populations (P<0.05). In addition, combining YM155 with DDP induced a larger decrease in cell viability than either agent alone and had a higher inhibition rate than Bliss index, suggesting their synergistic inhibition.

Conclusions

We concluded that survivin was a potential prognostic marker and a critical regulatory molecule in the pathological process of ENKTCL. It would be a promising target in drugs discovery for ENKTCL therapy.

Survivin at a glance

Survivin (also known as BIRC5) is an evolutionarily conserved eukaryotic protein that is essential for cell division and can inhibit cell death. Normally it is only expressed in actively proliferating cells, but is upregulated in most, if not all cancers; consequently, it has received significant attention as a potential oncotherapeutic target. In this Cell Science at a Glance article and accompanying poster, we summarise our knowledge of survivin 21 years on from its initial discovery. We describe the structure, expression and function of survivin, highlight its interactome and conclude by describing anti-survivin strategies being trialled.

Evaluation of gilteritinib in combination with chemotherapy in preclinical models of FLT3-ITD+ acute myeloid leukemia

Activating internal tandem duplication (ITD) and tyrosine kinase domain (TKD) point mutations in Fms-like tyrosine kinase 3 (FLT3) occur in approximately 30% of patients with acute myeloid leukemia (AML), and confer a poor prognosis with standard cytarabine/anthracycline or azacitidine-based chemotherapy regimens. Gilteritinib is a highly-specific, potent FLT3/AXL inhibitor with demonstrated activity against FLT3-ITD and FLT3-TKD mutations. Compared with salvage chemotherapy, treatment with once-daily oral gilteritinib demonstrated a clinical benefit in patients with FLT3-mutated relapsed/refractory AML, which led to its recent approval in Japan and the United States. We investigated the effects of gilteritinib combined with cytarabine plus daunorubicin/idarubicin, or combined with azacitidine in human FLT3-ITD–positive (FLT3-ITD⁺) AML cell lines and xenografted mouse models. Gilteritinib induced G₁ arrest and apoptosis in a dose-dependent manner. The addition of cytarabine, daunorubicin, idarubicin, or azacitidine potentiated apoptosis. Gilteritinib alone or combined with cytarabine, daunorubicin, idarubicin, or azacitidine, inhibited anti-apoptotic protein expression in MV4-11 cells. In xenografted mice, administration of cytarabine, idarubicin, or azacitidine in combination with gilteritinib had little impact on plasma or intratumor PK profiles of gilteritinib, cytarabine, idarubicin, or azacitidine. Gilteritinib combined with chemotherapy reduced tumor volume to a greater extent than either gilteritinib or chemotherapy alone. Of note, the addition of cytarabine plus daunorubicin/idarubicin led to tumor regression in mice, with complete regression observed in six out of eight mice in both triple combination groups. These findings support the investigation of gilteritinib combined with chemotherapy in patients with FLT3-ITD⁺ AML, including those who are ineligible for intensive chemotherapy.

Predicting response to sepantronium bromide (YM155), a survivin suppressant, by PET imaging with [11C]YM155

INTRODUCTION

Sepantronium bromide (YM155) is a survivin suppressant that induces apoptosis in tumor cells. Although YM155 induces tumor regression in various tumor types in vivo, phase I and II studies demonstrated responding and non-responding patient populations. We investigated ¹¹C-labeled YM155 ([¹¹C]YM155) used as a positron emission tomography (PET) tracer to assess whether tumor uptake of [¹¹C]YM155 correlated with its anti-tumor effect, thereby allowing identification of patients who would respond to YM155 treatment.

METHODS

(1) Uptake of YM155 was measured in 39 human cancer cell lines in vitro using liquid chromatography coupled with tandem mass spectrometry (LC-MS/MS). (2) In vivo tumor uptake was assessed in xenografted mice and total body distribution was evaluated in a cynomolgus monkey using [¹¹C]YM155 with PET/computed tomography (CT) (mice) and PET (monkey) imaging.

RESULTS

Intracellular uptake of YM155 in human cancer cell lines correlated well with its in vitro efficacy measured by GI₅₀ (Pearson's r = -0.5709). Similarly, in vivo studies using tumor xenografted mice showed that tumors sensitive to YM155 demonstrated robust uptake of [¹¹C]YM155, whereas insensitive tumors demonstrated low uptake. In the monkey, the biodistribution of [¹¹C]YM155 indicated low accumulation in lung, breast, head, and neck and was only significant in organs involved with drug clearance: i.e. liver, kidneys, and bladder.

CONCLUSIONS

Robust uptake of [¹¹C]YM155 by a tumor appears to be a positive predictive marker for a good response to YM155. The findings suggest the potential utility of PET/CT imaging with [¹¹C]YM155 for selection of patients whose tumors are likely to respond to YM155.

ADVANCES IN KNOWLEDGE

YM155 efficacy correlated closely with its in vitro intracellular uptake and uptake on [¹¹C]YM155 PET imaging. [¹¹C]YM155 PET may predict tumor sensitivity to YM155.

IMPLICATIONS FOR PATIENT CARE

The concept that tumor response can be accurately predicted prior to chemotherapy should be exploited to improve cancer treatment outcomes through judicious patient selection. The small molecule sepantronium bromide (YM155), a survivin suppressant, has been developed for the treatment of several cancers, including non-Hodgkin lymphoma, lung cancer, and breast cancer. The preferentially high in vitro uptake of YM155 by YM155-sensitive cancer cells and the high in vivo uptake of [¹¹C]YM155 in YM155-sensitive tumors demonstrated by PET imaging suggest the potential utility of performing [¹¹C]YM155 PET to allow the identification of patients with YM155-sensitive tumors.

HIF-2α dictates the susceptibility of pancreatic cancer cells to TRAIL by regulating survivin expression

Cancer cells develop resistance to therapy by adapting to hypoxic microenvironments, and hypoxia-inducible factors (HIFs) play crucial roles in this process. We investigated the roles of HIF-1α and HIF-2α in cancer cell death induced by tumor necrosis factor (TNF)-related apoptosis-inducing ligand (TRAIL) using human pancreatic cancer cell lines. siRNA-mediated knockdown of HIF-2α, but not HIF-1α, increased susceptibility of two pancreatic cancer cell lines, Panc-1 and AsPC-1, to TRAIL in vitro under normoxic and hypoxic conditions. The enhanced sensitivity to TRAIL was also observed in vivo. This in vitro increased TRAIL sensitivity was observed in other three pancreatic cancer cell lines. An array assay of apoptosis-related proteins showed that knockdown of HIF-2α decreased survivin expression. Additionally, survivin promoter activity was decreased in HIF-2α knockdown Panc-1 cells and HIF-2α bound to the hypoxia-responsive element in the survivin promoter region. Conversely, forced expression of the survivin gene in HIF-2α shRNA-expressing Panc-1 cells increased resistance to TRAIL. In a xenograft mouse model, the survivin suppressant YM155 sensitized Panc-1 cells to TRAIL. Collectively, our results indicate that HIF-2α dictates the susceptibility of human pancreatic cancer cell lines, Panc-1 and AsPC-1, to TRAIL by regulating survivin expression transcriptionally, and that survivin could be a promising target to augment the therapeutic efficacy of death receptor-targeting anti-cancer therapy.

Induction of autophagy and autophagy-dependent apoptosis in diffuse large B-cell lymphoma by a new antimalarial artemisinin derivative, SM1044

Diffuse large B-cell lymphoma (DLBCL) is the most common form of non-Hodgkin's lymphoma. R-CHOP is currently the standard therapy for DLBCL, but the prognosis of refractory or recurrent patients remains poor. In this study, we synthesized a new water-soluble antimalarial drug artemisinin derivative, SM1044. The treatment of DLBCL cell lines with SM1044 induces autophagy-dependent apoptosis, which is directed by an accelerated degradation of the antiapoptosis protein Survivin, via its acetylation-dependent interaction with the autophagy-related protein LC3-II. Additionally, SM1044 also stimulates the de novo synthesis of ceramide, which in turn activates the CaMKK2-AMPK-ULK1 axis, leading to the initiation of autophagy. Our findings not only elucidate the mechanism of autophagy-dependent apoptosis in DLBCL cells, but also suggest that SM1044 is a promising therapeutic molecule for the treatment of DLBCL, along with R-CHOP regimen.

Association of rituximab with graphene oxide confers direct cytotoxicity for CD20-positive lymphoma cells

Non-Hodgkin lymphoma (NHL) is one of the most common hematologic malignancies among adults for which the chimeric monoclonal anti-CD20 antibody (Ab) rituximab (RTX) is used as first-line therapy. As RTX itself is not directly cytotoxic but relies on host immune effector mechanisms or chemotherapeutic agents to attack target cells, its therapeutic capacity may become limited when host effector mechanisms are compromised. Currently, refractory disease and relapse with NHL are still common, highlighting the need for novel anti-CD20 antibody strategies with superior therapeutic efficacy over current protocols. We hypothesized that making RTX directly cytotoxic might improve the therapeutic efficacy. Graphene oxide (GO) has recently emerged as a highly attractive nanomaterial for biomedical applications; and several studies have reported cytotoxic effect of GO on benign and malignant cells in vitro. Herein, we report that RTX can be stably associated with GO, and that GO-associated RTX (RTX/GO) demonstrates remarkably high avidity for CD20. Binding of GO-associated RTX to CD20-positive lymphoma cells induces CD20 capping and target cell death through an actin dependent mechanism. In vivo, GO-associated RTX, but not free RTX, quickly eliminates high-grade lymphomas in the absence of host effector mechanisms in a xenograft lymphoma mouse model. Our findings represent the first demonstration of using GO-associated antibody as effective cytotoxic therapy for human B cell malignancies in the absence of chemotherapy, and these findings could have important clinical implications.

YM155 exerts potent cytotoxic activity against quiescent (G0/G1) multiple myeloma and bortezomib resistant cells via inhibition of survivin and Mcl-1

YM155, a novel small molecule inhibitor of survivin, shows broad anticancer activity. Here, we have focused on the cytotoxic activity of YM155 against multiple myeloma (MM) including cytokinetically quiescent (G₀/G₁) cells and bortezomib resistant cells. YM155 strongly inhibited the growth of MM cell lines with the IC₅₀ value of below 10 nM. YM155 also showed potent anti-myeloma activity in mouse xenograft model. YM155 suppressed the expression of survivin and rapidly directed Mcl-1 protein for proteasome degradation. YM155 abrogated the interleukin-6-induced STAT3 phosphorylation, subsequently blocked Mcl-1 expression and induced apoptosis in MM cells. Triple-color flow cytometric analysis revealed that YM155 potently induced cell death of MM cells in G₀ phase. Quiescent primary MM cells were also sensitive to YM155. We established bortezomib-resistant MM cell line, U266/BTZR1, which possess a point mutation G322A. YM155 exhibited similar cytotoxic potency against U266/BTZR1 compared with parental cells. Interestingly, survivin expression was markedly elevated in U266/BTZR1 cells. Treatment with YM155 significantly down-regulated this increased survivin and Mcl-1 expression in U266/BTZR1 cells. In conclusion, our data indicate that YM155 exhibits potent cytotoxicity against quiescent (G₀/G₁) MM cells and bortezomib-resistant cells. These unique features of YM155 may be beneficial for the development of new therapeutic strategies to eliminate quiescent MM cells and overcome bortezomib resistance.

Clinical impact of serum survivin positivity and tissue expression of EBV-encoded RNA in diffuse large B-cell lymphoma patients treated with rituximab-CHOP

Survivin is an inhibitor of apoptosis and is upregulated by Epstein–Barr virus (EBV) latent genes. Given the frequent association of EBV with lymphoid malignancies, survivin is expected to have prognostic value in diffuse large B-cell lymphoma (DLBCL). Thus, we measured the pretreatment serum level of survivin in DLBCL patients and analyzed its association with survival outcome and EBV status, as represented by EBV-encoded RNA (EBER) in DLBCL. Pretreatment serum survivin level was measured in patients registered in a prospective cohort study (n = 210), and serum survivin-positivity was defined as any detectable level of survivin. EBV status was determined using EBER in situ hybridization, and EBER-positivity was defined as 20% of examined cells showing nuclear positivity. Mean serum survivin level was higher in patients with relapsed or refractory disease than with responsive disease (59.89 pg/mL versus 17.34 pg/mL, P = 0.041). Serum survivin-positive patients had worse overall and progression-free survival (P = 0.023 and 0.022, respectively). Serum survivin positivity was associated with unfavorable characteristics including stage. In patients with non-germinal center B-cell type DLBCL, serum survivin-positive patients also had significantly worse survival than serum survivin-negative patients (P < 0.001). EBER-positivity was found in 6.7% (14/210) of patients, and EBER-positive patients had worse survival (P < 0.05). Patients having concomitant positivity for serum survivin and EBER expression (2.8%, 6/210) showed extremely poor prognosis. In the present era of rituximab in DLBCL, DLBCL with serum survivin positivity showed adverse clinical features and followed worse clinical course, especially in non-GCB subtype DLBCL. EBER-positivity was still associated with worse outcomes in DLBCL.

Action of YM155 on clear cell renal cell carcinoma does not depend on survivin expression levels

The dioxonapthoimidazolium YM155 is a survivin suppressant which has been investigated as an anticancer agent in clinical trials. Here, we investigated its growth inhibitory properties on a panel of immortalized and patient derived renal cell carcinoma (RCC) cell lines which were either deficient in the tumour suppressor von Hippel-Lindau (VHL) protein or possessed a functional copy. Neither the VHL status nor the survivin expression levels of these cell lines influenced their susceptibility to growth inhibition by YM155. Of the various RCC lines, the papillary subtype was more resistant to YM155, suggesting that the therapeutic efficacy of YM155 may be restricted to clear cell subtypes. YM155 was equally potent in cells (RCC786.0) in which survivin expression had been stably silenced or overexpressed, implicating a limited reliance on survivin in the mode of action of YM155. A follow-up in-vitro high throughput RNA microarray identified possible targets of YM155 apart from survivin. Selected genes (ID1, FOXO1, CYLD) that were differentially expressed in YM155-sensitive RCC cells and relevant to RCC pathology were validated with real-time PCR and western immunoblotting analyses. Thus, there is corroboratory evidence that the growth inhibitory activity of YM155 in RCC cell lines is not exclusively mediated by its suppression of survivin. In view of the growing importance of combination therapy in oncology, we showed that a combination of YM155 and sorafenib at ½ x IC50 concentrations was synergistic on RCC786.0 cells. However, when tested intraperitoneally on a murine xenograft model derived from a nephrectomised patient with clear cell RCC, a combination of suboptimal doses of both drugs failed to arrest tumour progression. The absence of synergy in vivo highlighted the need to further optimize the dosing schedules of YM155 and sorafenib, as well as their routes of administration. It also implied that the expression of other oncogenic proteins which YM155 may target is either low or absent in this clear cell RCC.

Japanese apricot extract (MK615) potentiates bendamustine-induced apoptosis via impairment of the DNA damage response in lymphoma cells

Bendamustine, a hybrid molecule of a purine analog and alkylator, induces cell death by the activation of apoptosis and the DNA damage response. The agent MK615 is produced from Japanese apricot and contains a number of cyclic triterpenes that exhibit antitumor activities. In the present study, the combined effects of bendamustine and MK615 on lymphoma cells were investigated. The combined compounds synergistically induced apoptosis in all lymphoid cell lines examined. MK615 inhibited the bendamustine-induced phosphorylation of checkpoint kinase 1 and 2. As ataxia telangiectasia mutated (ATM) and ataxia telangiectasia- and Rad3-related (ATR) kinases are key mediators of the DNA damage response, the effects of the combination of bendamustine and ATM/ATR inhibitors (KU-60019 and VE-821) on lymphoma cells were investigated. KU-60019 and/or VE-821 potentiated bendamustine activity in all cell lines tested, but did not affect MK615 activity, suggesting that these inhibitors have the same underlying mechanism of action as that of MK615. The results of the present study suggest that it may be feasible to use ATM/ATR inhibitors in combination with bendamustine for treating malignant lymphoma.

Dihydromyricetin Induces Apoptosis and Reverses Drug Resistance in Ovarian Cancer Cells by p53-mediated Downregulation of Survivin

Ovarian cancer is one of the leading causes of death in gynecological malignancies, and the resistance to chemotherapeutic agents remains a major challenge to successful ovarian cancer chemotherapy. Dihydromyricetin (DHM), a natural flavonoid derived from Ampeopsis Grossdentata, has been widely applied in food industry and medicine for a long time. However, little is known about the effects of DHM on ovarian cancer and the underlying mechanisms. In this study, we demonstrated that DHM could effectively inhibit the proliferation of ovarian cancer cells and induce cell apoptosis. Survivin, an inhibitor of apoptosis (IAPs) family member, exhibited a decreased expression level after DHM treatment, which may be attributed to the activation of p53. Moreover, DHM markedly sensitized paclitaxel (PTX) and doxorubicin (DOX) resistant ovarian cancer cells to PTX and DOX by inhibiting survivin expression. Collectively, our findings highlight a previously undiscovered effect of DHM, which induces apoptosis and reverses multi-drug resistance against ovarian cancer cells through downregulation of survivin.

Diffuse large B-cell lymphoma: R-CHOP failure-what to do?

Although rituximab plus cyclophosphamide, doxorubicin, vincristine, and prednisone (R-CHOP) is the standard treatment for patients with diffuse large B-cell lymphoma (DLBCL), ∼30% to 50% of patients are not cured by this treatment, depending on disease stage or prognostic index. Among patients for whom R-CHOP therapy fails, 20% suffer from primary refractory disease (progress during or right after treatment) whereas 30% relapse after achieving complete remission (CR). Currently, there is no good definition enabling us to identify these 2 groups upon diagnosis. Most of the refractory patients exhibit double-hit lymphoma (MYC-BCL2 rearrangement) or double-protein-expression lymphoma (MYC-BCL2 hyperexpression) which have a more aggressive clinical picture. New strategies are currently being explored to obtain better CR rates and fewer relapses. Although young relapsing patients are treated with high-dose therapy followed by autologous transplant, there is an unmet need for better salvage regimens in this setting. To prevent relapse, maintenance therapy with immunomodulatory agents such as lenalidomide is currently undergoing investigation. New drugs will most likely be introduced over the next few years and will probably be different for relapsing and refractory patients.

ON 01910.Na inhibits growth of diffuse large B-cell lymphoma by cytoplasmic sequestration of sumoylated C-MYB/TRAF6 complex

Diffuse large B-cell lymphoma (DLBCL), the most common lymphoma, shows either no response or development of resistance to further treatment in 30% of the patients that warrants the development of novel drugs. We have reported that ON 01910.Na (rigosertib), a multikinase inhibitor, is selectively cytotoxic for DLBCL and induces more hyperphosphorylation and sumoylation of Ran GTPase-activating protein 1 (RanGAP1) in DLBCL cells than in non-neoplastic lymphoblastoid cell line. However, the exact mechanism of rigosertib-induced cell death in DLBCL remains to be clarified. Here, we analyzed the efficacy of rigosertib against DLBCL cells in vitro and in vivo and its molecular effects on tumor biology. We found for the first time that rigosertib attenuated expression of unmodified and sumoylated tumor necrosis factor receptor-associated factor 6 (TRAF6) and c-Myb and inhibited nuclear entry of sumoylated RanGAP1, TRAF6, and c-Myb that was confirmed by immunofluorescence. Moreover, co-immunoprecipitation showed that rigosertib induced sequestration of c-Myb and TRAF6 in the cytoplasm by stimulating their sumoylation through the RanGAP1*SUMO1/Ubc9 pathway. Specific knockdown of c-Myb and TRAF6 induced tumor cell apoptosis and cell cycle arrest at G1 phase. Xenograft mice bearing lymphoma cells also exhibited effective tumor regression on rigosertib treatment along with cytoplasmic expression of c-Myb and TRAF6. Nuclear expression of c-Myb in clinical cases of DLBCL correlated with a poor prognosis. Thus, suppression of c-Myb and TRAF6 activity may have therapeutic implication in DLBCL. These data support the clinical development of rigosertib in DLBCL.

Functional imaging of pharmacological action of SGLT2 inhibitor ipragliflozin via PET imaging using 11C-MDG

Sodium‐dependent glucose cotransporter 2 (SGLT2) is a pharmacological target of type 2 diabetes mellitus. The aim of this study was to noninvasively visualize the pharmacological action of a selective SGLT2 inhibitor ipragliflozin in the kidney using positron emission tomography (PET) imaging with ¹¹C‐methyl‐d‐glucoside (¹¹C‐MDG), an SGLT‐specific radio‐labeled substrate. PET imaging with ¹¹C‐MDG in vehicle‐treated rats demonstrated that intravenously injected ¹¹C‐MDG substantially accumulated in the renal cortex, reflecting that the compound was reabsorbed by SGLTs. In contrast, ipragliflozin‐treated rats showed significantly lower uptake of ¹¹C‐MDG in renal cortex in a dose‐related manner, suggesting that ipragliflozin inhibited the renal reabsorption of ¹¹C‐MDG. This method of visualizing the mode of action of an SGLT2 inhibitor in vivo has demonstrated the drug's mechanism in reducing renal glucose reabsorption in kidney in living animals.

Tetravalent anti-CD20/CD3 bispecific antibody for the treatment of B cell lymphoma

Bispecific antibodies (bsAbs) are second generation antibodies for therapeutic application in immunotherapy. One of the major strategies of the bsAb platform is the recruitment of immune effector T cells by incorporating an anti-CD3 domain. A bispecific T-cell engager (BiTE), with one end having an affinity for CD3 and the other end with affinity for CD19, has been approved in the US and Europe for the treatment of acute lymphoblastic leukemia. However, due to their small size and lack of Fc region, these single-chain variable fragment (scFv) bsAbs have short half-lives in vivo. Additionally, poor solubility, structural instability, and low production yields have also become major challenges in the bulk production process. To overcome these challenges, we have engineered a tetravalent bsAb with bivalent binding specificity for the CD20 and CD3 antigen in an immunoglobulin G (IgG) format. The fusion of the anti-CD3 scFvs to the CD20 antibody via a linker-hinge domain (LHD) results in improved antibody stabilization and properties. Here we demonstrate this antibody's highly efficient cancer cell elimination in a dose-dependent manner in a CD20-expressing B lymphoblastoid cell line in vitro. Our data suggest the potential clinical application of this bsAb for the treatment of CD20-expressing B cell malignancies.

Essential Role for Survivin in the Proliferative Expansion of Progenitor and Mature B Cells

Survivin is a member of the inhibitor of apoptosis family of proteins and a biomarker of poor prognosis in aggressive B cell non-Hodgkin's lymphoma. In addition to its role in inhibition of apoptosis, survivin also regulates mitosis. In this article, we show that deletion of survivin during early B cell development results in a complete block at the cycling pre-B stage. In the periphery, B cell homeostasis is not affected, but survivin-deficient B cells are unable to mount humoral responses. Correspondingly, we show that survivin is required for cell division in response to mitogenic stimulation. Thus, survivin is essential for proliferation of B cell progenitors and activated mature B cells, but is dispensable for B cell survival. Moreover, a small-molecule inhibitor of survivin strongly impaired the growth of representative B lymphoma lines in vitro, supporting the validity of survivin as an attractive therapeutic target for high-grade B cell non-Hodgkin's lymphoma.

Prognostic and biological significance of survivin expression in patients with diffuse large B-cell lymphoma treated with rituximab-CHOP therapy

Survivin, a member of the inhibitor of apoptosis protein family, is overexpressed in a variety of human neoplasms. The prognostic significance of survivin expression in diffuse large B-cell lymphoma patients treated with rituximab plus cyclophosphamide, doxorubicin, vincristine and prednisone (R-CHOP) is unclear. We used standard immunohistochemistry methods to quantify survivin expression in 463 patients with de novo diffuse large B-cell lymphoma who received the R-CHOP. Of the 463 patients, 269 (58%) had survivin overexpression with a cutoff of >25%, associated with an International Prognostic Index score of >2 (P=0.015), disease in ≥2 extranodal sites (P=0.011), and a high Ki-67 index (P<0.0001). Among patients with activated B cell-like disease, the overall survival rate of survivin-positive patients was significantly lower than that of survivin-negative patients (P=0.033); multivariate analysis confirmed that in these patients, survivin overexpression was an independent prognostic factor for survival. Among patients with wild-type p53 overexpression, the overall survival and progression-free survival rates of the survivin-positive group were significantly lower than those of the survivin-negative group (P=0.035 and P=0.04 respectively). In STAT3-positive patients, survivin overexpression was associated with significantly better survival. Among patients with activated B cell-like disease, survivin-positive compared with survivin-negative groups had significantly different gene expression signatures, including genes involved in mitosis or tumor cell proliferation. Our results indicate that survivin is an independent prognostic factor for poor outcome in patients with activated B cell-like disease treated with the R-CHOP regimen, and patients with survivin-positive activated B cell-like diffuse large B-cell lymphoma seem to benefit less from this treatment and may require additional novel agents.

Hyperthermia induces apoptosis by targeting Survivin in esophageal cancer

Hyperthermia is considered the fifth pillar of cancer treatment. It induces cancer cell apoptosis, however, its molecular mechanisms remain unclear. In the present study, the role of Survivin in hyperthermia-induced apoptosis in esophageal cancer was investigated. Different temperatures were used to treat EC109 esophageal cancer cells, and their viability was found to be significantly inhibited with a concomitant increase in apoptosis and necrosis. Necrosis increased in a temperature‑dependent manner, whereas peak apoptosis was reached at 43˚C. The hyperthermia-induced apoptosis was due to the inhibition of Survivin and the activation of caspase-3. Subsequently, overexpression of Survivin inhibited the activation of caspase-3 and hyperthermia-induced apoptosis, however, this inhibition was reversed in the absence of XIAP. Immunoprecipitations showed that Survivin did not directly bind to caspase-3, whereas XIAP interacted with Survivin and caspase-3. Immunohistochemistry was performed to detect the expression of Survivin in esophageal cancer patient samples. A higher expression of Survivin in esophageal cancer tissues compared to normal tissues was observed, and a high expression correlated with poor prognosis. The results indicated that hyperthermia decreases the expression of Survivin, prevents its binding to XIAP, activates caspase-3 and induces apoptosis. Due to its correlation with poor prognosis, Survivin may be a target for hyperthermia in the treatment of esophageal cancer.

Silencing of survivin by YM155 induces apoptosis and growth arrest in hepatocellular carcinoma cells

Survivin overactivation is a frequent event in human hepatocellular carcinoma (HCC), due to its function in the induction of hepatocyte proliferation and apoptotic dysfunction. Recently, a novel survivin inhibitor named YM155, has demonstrated broad antitumor effects against various malignant tumors. Therefore, the present study aimed to explore how this agent may impact on HCC and elucidate its underlying mechanism of action. Immunohistochemical analysis was performed on 8 specimens of human HCC, to assess the protein expression of survivin and phosphorylated retinoblastoma tumor suppressor (p-Rb). In addition, in vitro, HepG2 and Huh7 human HCC cell lines were exposed to 100 µM YM155 for up to 72 h and the cell viability was subsequently determined using MTT assay. Furthermore, the apoptotic status of YM155-treated HCC cells was investigated by flow cytometry, and the protein levels of survivin, procaspase-3 and p-Rb in YM155-treated HCC cells were assessed by immunoblotting analysis. The results demonstrated that HCC specimens expressed high levels of survivin and p-Rb protein compared with those of adjacent noncancerous liver tissues. In vitro, YM155 significantly induced HCC cell apoptosis and growth arrest. At the protein level, YM155 markedly inhibited survivin and p-Rb expression, and elevated procaspase-3. YM155 demonstrated significant antitumor effects on HCC cells in the present study. These effects were associated with its anti-proliferative and apoptosis-induction activities. YM155 requires further investigation as a novel agent for potential use as a therapeutic strategy for the treatment of HCC.

AML sensitivity to YM155 is modulated through AKT and Mcl-1

HL60 and U937 (acute myeloid leukemia (AML) cell lines) were assessed for sensitivity to YM155, and found to have distinct sensitive and resistant phenotypes, respectively. In HL60 cells, YM155 inhibition of growth proliferation was due to apoptosis which was measured by annexin V/PI staining. YM155 induced apoptosis through activation of intrinsic and extrinsic pathways that also culminated in caspase-3 activity and PARP cleavage. YM155 sensitivity was partially associated with this compound's ability to down-regulate survivin transcription since this was more pronounced in the HL60 cell line. However, marked differences were also observed in XIAP, Bcl-2, and Mcl-1L, and Mcl-1s. Furthermore, YM155 treatment completely inhibited production of total Akt protein in HL60, but not U937 cells. Importantly, Akt activity (pAkt-Ser473) levels were maintained in YM155 treated U937 cells which may help stabilize other anti-apoptotic proteins. Combination treatments with an Akt inhibitor, MK-2206, reduced levels of pAkt-Ser473 in U937 cells and synergistically sensitized them to YM155 cytotoxicity. Collectively our results indicate that Akt signaling may be an important factor mediating YM155 response in AML, and combinatorial therapies with Akt inhibitors could improve treatment efficacy in YM155-resistant cells.

Dual induction of apoptotic and autophagic cell death by targeting survivin in head neck squamous cell carcinoma

Survivin is ubiquitously expressed in patients with head neck squamous cell carcinoma (HNSCC) and is associated with poor survival and chemotherapy resistance. Sepantronium bromide (YM155) is a selective survivin suppressant that exhibits potent antitumor activities by inducing apoptosis and autophagy in various types of cancer. However, the curative effects and underlying mechanisms of YM155 in HNSCC remain unclear. This study showed that survivin overexpression positively correlated with p-S6, p-Rb and LAMP2 but negatively correlated with the autophagic marker LC3 in human HNSCC tissues. In vitro studies revealed that YM155 triggered apoptosis of HNSCC cells in mitochondria and death receptor-dependent manner. The treatment also significantly enhanced autophagy by upregulating Beclin1, which led to cell death. YM155 not only downregulated the expression of survivin but also remarkably suppressed the activation of the mTOR signaling pathway in vitro and in vivo. YM155 displayed potent antitumor activities in both CAL27 xenograft and transgenic HNSCC mice models by delaying tumor onset and suppressing tumor growth. Furthermore, YM155 combined with docetaxel promoted tumor regression better than either treatment alone without causing considerable body weight loss in the HNSCC xenograft models. Overall, targeting survivin by YM155 can benefit HNSCC therapy by increasing apoptotic and autophagic cell death, and suppressing prosurvival pathways.

Examination of survivin expression in 50 chordoma specimens--A histological and in vitro study

Chordomas mainly arise along the axial skeleton and are characterized by their slow but destructive growth. Prognosis and quality of life are poor because treatment options are mainly limited to surgery and radiotherapy. Survivin, a member of the apoptosis inhibitor protein family, functions as a key regulator of mitosis and programmed cell death, and is overexpressed in many tumor types. The aim of this study was to determine the role of survivin in chordomas. Survivin expression was investigated in 50 chordoma samples and three chordoma cell lines using immunohistochemistry. The intensity of immunostaining was evaluated in regard to the development of recurrences. The immunohistochemical results were correlated with clinical parameters like gender, age, tumor size, and location and were performed in primary chordomas as well as in recurrent lesions. Furthermore, survivin knockdown experiments on chordoma cell lines were performed. YM155 decreased the growth behavior of chordoma cells dose- and time dependently. Transient knockdown of survivin led to a G2/M arrest, decreased proliferation, consistently induced an increase of polyploidy and morphological changes, and induced apoptosis. The resultant data from this study suggest that survivin plays a cell cycle-progressive role in chordomas. Hence, regulation of survivin by YM155 is a promising new target for the development of new therapeutic drugs.

Small molecule inhibitor YM155-mediated activation of death receptor 5 is crucial for chemotherapy-induced apoptosis in pancreatic carcinoma

Despite much effort, pancreatic cancer survival rates are still dismally low. Novel therapeutics may hold the key to improving survival. YM155 is a small molecule inhibitor that has shown antitumor activity in a number of cancers by reducing the expression of survivin. The aim of our study is to understand the mechanisms by which YM155 functions in pancreatic cancer cells. We established the antitumor effect of YM155 with in vitro studies in cultured cells, and in vivo studies using a mouse xenograft model. Our data demonstrated that YM155 reduced the expression of survivin; however, downregulation of survivin itself is insufficient to induce apoptosis in pancreatic cancer cells. We showed for the first time that treatment with YM155 increased death receptor 5 (DR5) expression in pancreatic cancer cells. We found that YM155 induced apoptosis by broad-spectrum inhibition of IAP family member proteins (e.g., CIAP1/2 and FLIP) and induced proapoptotic Bak protein upregulation and activation; the antitumor effect of YM155 treatment with either the DR5 agonist lexatumumab or gemcitabine on pancreatic cancer cells was synergistic. Our data also revealed that YM155 inhibits tumor growth in vivo, without apparent toxicity to the noncancerous human pancreatic ductal epithelial cell line. Together, these findings suggest that YM155 could be a novel therapeutic agent for pancreatic cancer.

Small Molecule Inhibitor YM155-Mediated Activation of Death Receptor 5 Is Crucial for Chemotherapy-Induced Apoptosis in Pancreatic Carcinoma

Despite much effort, pancreatic cancer survival rates are still dismally low. Novel therapeutics may hold the key to improving survival. YM155 is a small molecule inhibitor that has shown antitumor activity in a number of cancers by reducing the expression of survivin. The aim of our study is to understand the mechanisms by which YM155 functions in pancreatic cancer cells. We established the antitumor effect of YM155 with in vitro studies in cultured cells, and in vivo studies using a mouse xenograft model. Our data demonstrated that YM155 reduced the expression of survivin; however, downregulation of survivin itself is insufficient to induce apoptosis in pancreatic cancer cells. We showed for the first time that treatment with YM155 increased death receptor 5 (DR5) expression in pancreatic cancer cells. We found that YM155 induced apoptosis by broad-spectrum inhibition of IAP family member proteins (e.g., CIAP1/2 and FLIP) and induced proapoptotic Bak protein upregulation and activation; the antitumor effect of YM155 treatment with either the DR5 agonist lexatumumab or gemcitabine on pancreatic cancer cells was synergistic. Our data also revealed that YM155 inhibits tumor growth in vivo, without apparent toxicity to the noncancerous human pancreatic ductal epithelial cell line. Together, these findings suggest that YM155 could be a novel therapeutic agent for pancreatic cancer. Mol Cancer Ther; 14(1); 80–89. ©2014 AACR.