Bendamustine: mechanism of action and clinical data

Bendamustine is a chemotherapeutic agent that displays a unique pattern of cytotoxicity compared with conventional alkylating agents. Bendamustine was originally synthesized in the former East German Democratic Republic in the 1960s. It was designed to have both alkylating and antimetabolite properties. The alkylating agent properties are similar to those seen with cyclophosphamide, chlorambucil, and melphalan, and the benzimidazole ring is similar to cladribine. Molecular analyses have revealed that bendamustine differs from other alkylating agents in its mechanism of action. Differences have been observed in regard to its effects on DNA repair and cell cycle progression. Moreover, bendamustine can induce cell death through both apoptotic and nonapoptotic pathways, thereby retaining activity even in cells without a functional apoptotic pathway. Bendamustine has demonstrated significant efficacy in patients with indolent lymphomas and chronic lymphocytic leukemia (CLL), including in patients with disease refractory to conventional alkylating agents and rituximab. The toxicity profile of bendamustine is also superior to that of conventional alkylating agents. Combination therapy with bendamustine and rituximab has demonstrated superior efficacy to a standard rituximab-containing chemotherapy regimen in patients with previously untreated indolent B-cell non-Hodgkin lymphoma, and it is currently being compared against the standard first-line regimen in CLL: fludarabine, cyclophosphamide, and rituximab. Ongoing and planned studies are evaluating new strategies in which bendamustine is being combined with existing agents and with novel therapies to optimize use in different clinical settings.

Efficacy and safety of biologicals against immune-mediated diseases: do benefits outweigh risks?

The success of molecular biology in identifying molecular pathways underlying chronic immune-mediated diseases and the rapid development of gene/cell engineering biotechnologies has resulted in the development of a number of targeted biological drugs, which have revolutionized the therapy of these diseases. Numerous data published over the last 10-15 years demonstrate a dramatic improvement in the clinical efficacy of biologics compared with conventional drugs. However, professional and public concern about serious biological drug-associated adverse events has also been growing steadily. We critically analyze recent literature on the efficacy and safety of biologics in the management of rheumatoid arthritis, psoriasis, psoriatic arthritis and immune thrombocytopenia. Our analysis of benefits, resistance to the therapy, risk of infections, tumors and other serious complications related to chronic administration of biologics is based on the molecular/cellular mechanisms of their interaction with the immune system. We also address whether it is feasible to attenuate the risks associated with biologics without limiting their benefits.

Intravesical Toll-like receptor 7 agonist R-837: optimization of its formulation in an orthotopic mouse model of bladder cancer

OBJECTIVE

To study the immune response caused by the intravesical administration of the immunomodulator R-837 in various formulations and to estimate its therapeutic potential for bladder cancer.

METHODS

Female C57BL/6 mice were intravesically treated with different formulations of R-837, a Toll-like receptor 7 agonist used for treating genital warts and skin malignancy. The tested formulation mixtures contained different ratios of lactic acid, a thermosensitive poloxamer polymer (Lutrol F127) and 2-(hydroxypropyl)-beta-cyclodextrin (HPbetaCD). Induction of tumor necrosis factor alpha (TNFalpha) and keratinocyte-derived chemokine (KC) was analyzed by Luminex microbeads assay. The therapeutic potential of intravesical administration of R-837 was assessed in an orthotopic, syngeneic mouse model of bladder cancer using MB49 cells.

RESULTS

Intravesical administration of R-837 in lactic acid alone induced systemic and bladder TNFalpha and KC in a dose-dependent manner. Formulations including poloxamer decreased systemic absorption of R-837 and significantly reduced systemic and local induction of KC. Addition of HPbetaCD in the poloxamer formulation particularly reversed levels of systemic and local levels of TNFalpha and KC. Histological examination showed that poloxamer-HPbetaCD formulation allowed infiltration of mononuclear cells into urothelium and lamina propria. In studies using orthotopic mouse bladder cancer, the tumor loads in R-837-treated mice were significantly lower than those in vehicle-treated or non-treated mice.

CONCLUSION

The optimized poloxamer-HPbetaCD formulation of R-837 shows therapeutic potential for bladder cancer while avoiding adverse side-effects.

R-Etodolac decreases beta-catenin levels along with survival and proliferation of hepatoma cells

BACKGROUND/AIMS

Inhibition of hepatoma cells by cyclooxygenase (COX)-2-dependent and -independent mechanisms has been shown previously. Here, we examine the effect of Celecoxib, a COX-2-inhibitor and R-Etodolac, an enantiomer of the nonsteroidal anti-inflammatory drug Etodolac, which lacks COX-inhibitory activity, on the Wnt/beta-catenin pathway and human hepatoma cells.

METHODS

Hep3B and HepG2 cell lines were treated with Celecoxib or R-Etodolac, and examined for viability, DNA synthesis, Wnt/beta-catenin pathway components, and downstream target gene expression.

RESULTS

Celecoxib at high doses affected beta-catenin protein by inducing its degradation via GSK3beta and APC along with diminished tumor cell proliferation and survival. R-Etodolac at physiological doses caused decrease in total and activated beta-catenin protein secondary to decrease in its gene expression and post-translationally through GSK3beta activation. In addition, increased beta-catenin-E-cadherin was also observed at the membrane. An associated inhibition of beta-catenin-dependent Tcf reporter activity, decreased levels of downstream target gene products glutamine synthetase and cyclin-D1, and decreased proliferation and survival of hepatoma cells was evident.

CONCLUSIONS

The antitumor effects of Celecoxib (at high concentrations) and R-Etodolac (at physiological doses) on HCC cells were accompanied by the down-regulation of beta-catenin demonstrating a useful therapeutic strategy in hepatocellular cancer.

Pharmacological profiling of novel non-COX-inhibiting indole-pyran analogues of etodolac reveals high solid tumour activity of SDX-308 in vitro

SDX-308 and SDX-309 are potent indole-pyran analogues of SDX-101 (R-etodolac) which has anti-tumour activity unrelated to cyclooxygenase-2 inhibition. Their cytotoxic activity was further studied herein using a well-characterized human tumour cell-line panel containing ten cell lines, as well as in 58 primary tumour cell samples from a variety of diagnoses. The indole-pyran analogues of SDX-101 were in general considerably more active in both cancer cell lines and primary tumour samples. Low cross-reactivity with standard agents was observed, indicating a unique mechanism of action. No apparent influence on efficacy was observed via classical mechanisms of multidrug-resistance. SDX-101 and SDX-309 showed higher relative activity in haematological compared to solid tumour samples, while SDX-308 had pronounced solid-tumour activity. High SDX-308 cytotoxic efficacy was observed in non-small cell lung cancer, renal cancer and ovarian cancer samples, and also in chronic lymphocytic leukaemia. In conclusion, the indole-pyran analogues showed a favourable pharmacological profile and represent a potentially important new class of drugs for cancer treatment.

R-etodolac (SDX-101) and the related indole-pyran analogues SDX-308 and SDX-309 potentiate the antileukemic activity of standard cytotoxic agents in primary chronic lymphocytic leukaemia cells

OBJECTIVE

SDX-101 is the non-cyclooxygenase 2-inhibiting R-enantiomer of the non-steroid anti-inflammatory drug etodolac, and has anti-tumour activity in chronic lymphocytic leukaemia (CLL). SDX-308 and SDX-309 are more potent, structurally related indole-pyran analogues of SDX-101. The current study was performed to investigate and quantify the cytotoxic potentiating effects resulting from a combination of either SDX-101, SDX-308 or SDX-309 with standard cytotoxic agents used in the CLL treatment today.

METHODS

The lymphoma cell line U937-gtb was used, together with primary tumour cells isolated from seven CLL patients. Combinations between chlorambucil and each one of the agents etodolac, SDX-101, SDX-308 and SDX-309 were studied. In addition, SDX-309 was combined with fludarabine, doxorubicin or vincristine. Both simultaneous and sequential exposures were explored using the median-effect method.

RESULTS

Most combinations were additive, which could be of clinical benefit since SDX-101 has been shown to be well tolerated. At the 70% effect level, synergy was observed between SDX-308 and chlorambucil in U937-gtb cells and in two-third of the CLL samples. Since chlorambucil is the most important drug in CLL therapy today and SDX-308 is presently targeted as the lead clinical candidate, this combination would be interesting for further studies. Vincristine and SDX-309 were synergistic in two-fourth of CLL samples.

CONCLUSIONS

To conclude, the non-COX-inhibiting etodolac-derivatives SDX-101, SDX-308 and SDX-309 are potential candidates for combination treatment of CLL. Especially, SDX-308 in combination with chlorambucil warrants further evaluation.

SDX-308, a nonsteroidal anti-inflammatory agent, inhibits NF-kappaB activity, resulting in strong inhibition of osteoclast formation/activity and multiple myeloma cell growth

Multiple myeloma is characterized by increased osteoclast activity that results in bone destruction and lytic lesions. With the prolonged overall patient survival achieved by new treatment modalities, additional drugs are required to inhibit bone destruction. We focused on a novel and more potent structural analog of the nonsteroidal anti-inflammatory drug etodolac, known as SDX-308, and its effects on osteoclastogenesis and multiple myeloma cells. SDX-101 is another structural analog of etodolac that is already used in clinical trials for the treatment of B-cell chronic lymphocytic leukemia (B-CLL). Compared with SDX-101, a 10-fold lower concentration of SDX-308 induced potent (60%-80%) inhibition of osteoclast formation, and a 10- to 100-fold lower concentration inhibited multiple myeloma cell proliferation. Bone resorption was completely inhibited by SDX-308, as determined in dentin-based bone resorption assays. SDX-308 decreased constitutive and RANKL-stimulated NF-kappaB activation and osteoclast formation in an osteoclast cellular model, RAW 264.7. SDX-308 effectively suppressed TNF-alpha-induced IKK-gamma and IkappaB-alpha phosphorylation and degradation and subsequent NF-kappaB activation in human multiple myeloma cells. These results indicate that SDX-308 effectively inhibits multiple myeloma cell proliferation and osteoclast activity, potentially by controlling NF-kappaB activation signaling. We propose that SDX-308 is a promising therapeutic candidate to inhibit multiple myeloma growth and osteoclast activity and that it should receive attention for further study.

Lack of methylthioadenosine phosphorylase expression in mantle cell lymphoma is associated with shorter survival: implications for a potential targeted therapy

PURPOSE

To determine the methylthioadenosine phosphorylase (MTAP) gene alterations in mantle cell lymphoma (MCL) and to investigate whether the targeted inactivation of the alternative de novo AMP synthesis pathway may be a useful therapeutic strategy in tumors with inactivation of this enzyme.

EXPERIMENTAL DESIGN

MTAP gene deletion and protein expression were studied in 64 and 52 primary MCL, respectively, and the results were correlated with clinical behavior. Five MCL cell lines were analyzed for MTAP expression and for the in vitro sensitivity to L-alanosine, an inhibitor of adenylosuccinate synthetase, and hence de novo AMP synthesis.

RESULTS

No protein expression was detected in 8 of 52 (15%) tumors and one cell line (Granta 519). Six of these MTAP negative tumors and Granta 519 cell line had a codeletion of MTAP and p16 genes; one case showed a deletion of MTAP, but not p16, and one tumor had no deletions in neither of these genes. Patients with MTAP deletions had a significant shorter overall survival (mean, 16.1 months) than patients with wild-type MTAP (mean, 63.6 months; P < 0.0001). L-Alanosine induced cytotoxicity and activation of the intrinsic mitochondrial-dependent apoptotic pathway in MCL cells. 9-beta-D-Erythrofuranosyladenine, an analogue of 5'-methylthioadenosine, selectively rescued MTAP-positive cells from L-alanosine toxicity.

CONCLUSIONS

MTAP gene deletion and lack of protein expression are associated with poor prognosis in MCL and might identify patients who might benefit from treatment with de novo AMP synthesis pathway-targeted therapies.

Polyclonal proliferation and apoptosis of CCR5+ T lymphocytes during primary human immunodeficiency virus type 1 infection: regulation by interleukin (IL)-2, IL-15, and Bcl-2

We measured apoptosis of subsets of T lymphocytes by single-cell analysis of caspase activation, to confirm high turnover of chemokine receptor CCR5(+) T cells in subjects with acute, primary human immunodeficiency virus type 1 (HIV-1) infection (PHI). High levels of spontaneous apoptosis, consisting mainly of CD8(+) T lymphocytes, were closely associated with increases in the activation markers Ki-67, CD38, and the HIV coreceptor CCR5 and with decreases in Bcl-2 and the interleukin (IL)-7 receptor at the single-cell level. Increased expression of Ki-67 and CCR5 ex vivo, as well as increased apoptosis, was seen in all T cell receptor beta-chain variable region (TCRBV) subfamilies studied. The addition of IL-2 or IL-15, but not IL-7, significantly inhibited caspase activation, increased Bcl-2 expression, and rapidly initiated proliferation in vitro of CD8(+) T cells expressing CCR5 and multiple TCRBV subfamilies. Furthermore, IL-15 receptor alpha-chain messenger RNA levels were increased in peripheral blood mononuclear cells during PHI. These results suggest that CCR5(+)Ki-67(+)Bcl-2(dim) activated T cells generated during PHI traffic via blood to tissue sites, where the cells may survive and/or further proliferate under the local influence of IL-2 or IL-15. Understanding cytokine effects on CCR5(+) T cells will be important in understanding chronic HIV-1 replication and pathogenesis.

Wnt and frizzled receptors as potential targets for immunotherapy in head and neck squamous cell carcinomas

The diverse receptor-ligand pairs of the Wnt and frizzled (Fz) families play important roles during embryonic development, and thus may be overexpressed in cancers that arise from immature cells. Hence, we investigated the expression and function of five Wnt (Wnt-1, 5a, 7a, 10b, 13) and two Fz (Fz-2, 5) genes in 10 head and neck squamous carcinoma cell lines (HNSCC). In comparison to normal bronchial or oral epithelial cells, all the HNSCC had markedly increased mRNA levels of Wnt-1, 7a, 10b, and 13, as well as Fz-2. Moreover, the levels of Wnt-1, 10b, and Fz-2 proteins were also markedly increased in HNSCC, relative to normal epithelial cells. Treatment of one HNSCC cell line (SNU 1076) with anti-Wnt-1 antibodies reduced the activity of the Wnt/Fz dependent transcription factor LEF/TCF, and diminished the expression of cyclin D1 and beta-catenin proteins. Blocking Wnt-1 signaling also inhibited proliferation and induced apoptosis in these cells. These results show that HNSCC cell lines often overexpress one or more Wnt and Fz genes, and suggest that the growth and survival of a subset of HNSCC may depend on the Wnt/Fz pathway. Hence, the Wnt and Fz receptors may be possible targets for immunotherapy therapy of this common cancer.

Gene expression analysis of osteoblastic cells contacted by orthopedic implant particles

Particles generated from orthopedic implants through years of wear play an essential role in the aseptic loosening of a prosthesis. We have investigated the biocompatibility of these orthopedic particles on different osteoblast-like cells representative of different stages of osteoblast maturation. We found the particles induced a caspase-dependent apoptosis of osteoblasts, with less mature osteoblasts being the most susceptible. An analysis of gene expression was performed on the less mature osteoblasts, which were in contact with the particles. We found that the particles had a profound impact on genes that code for inflammatory cytokines and genes involved in controlling the nuclear architecture. Results from this study suggest that the peri-implant osteolysis after a total joint replacement can be due in part to a decrease of bone formation and not solely to an overstimulation of bone resorption as is generally proposed. Development of new drugs that promote normal bone formation and osteoblast survival would possibly control peri-implant osteolysis, resulting in a better prognosis for patients with orthopedic implants.

Hypoestoxide, a natural nonmutagenic diterpenoid with antiangiogenic and antitumor activity: possible mechanisms of action

We have shown previously that hypoestoxide (HE), a natural diterpenoid [a bicyclo (9, 3, 1) pentadecane], is a potent nonsteroidal anti-inflammatory drug. In this report, we demonstrate that HE also inhibits the growth of a variety of human and murine tumor cell lines in vitro at concentrations ranging from 0.3 to 10 microM and was inactive as a mutagen in the Ames test. HE exhibited highly potent (0.3-10 mg/kg dose ranges) activities against B16 melanoma growth in C57BL/6 mice and P388D1 leukemia in C57BL/6 x DBA/2 F(1) mice, respectively. At a low maximal effective dose of 5 mg/kg, HE induced significant in vivo antitumor activities that were better than or comparable with most of the standard chemotherapeutic antiangiogenic agents tested: cortisone acetate, vincristine, bleomycin, Adriamycin, 5-fluorouracil, cyclophosphamide, and etoposide. All of the agents, except vincristine, had much higher maximal effective doses than HE. HE arrested the growth of human Burkitt lymphoma CA46 cells and HeLa (cervical epitheloid carcinoma) cells in the G2-M phase of the cell cycle, which was caused by interference, either direct or indirect, with actin assembly. Thus, the cell cycle arrest occurred at cytokinesis, as demonstrated by an increase in the number of binucleate cells. Moreover, HE inhibited vascular endothelial growth factor-induced cell proliferation in vitro, with an IC(50) of 28.6 microM, and it significantly inhibited basic fibroblast growth factor-induced angiogenesis on the chick chorioallantoic membrane, with an IC50 of 10 microM. Furthermore, HE inhibited endothelial cell migration on vitronectin, collagen, and fibronectin. Besides its activity as a nonsteroidal anti-inflammatory drug, HE also has promise for the chemotherapy of cancer.

First isolation of rotavirus associated with neonatal diarrhoea in guanacos (Lama guanicoe) in the Argentinean Patagonia region

Group A rotavirus (RV) and coronavirus (CV) are common viral pathogens associated with neonatal diarrhoea in numerous animal species. The purpose of this work was to investigate the presence of these viral agents in two farm populations of captured guanacos (Lama guanicoe) in the Argentinean Patagonia region, that developed severe diarrhoea outbreaks. Stool and serum samples were analysed for RV and bovine CV antigen and antibody by enzyme‐linked immunosorbent assay. Rotavirus was detected in faeces from two new‐born guanacos with acute diarrhoea, one in each farm. After electrophoretic analysis, each isolated strain, showed a distinctive long dsRNA electropherotype characteristic of group A rotaviruses (4:2:3:2). In addition, 95% (38 of 40) of the sampled animals were positive for RV antibodies, suggesting a high prevalence of RV infection in the populations tested. No evidence of CV circulation by antigen or antibody analysis was observed. To our knowledge, this is the first report of the detection and isolation of RV associated with neonatal diarrhoea in Lama guanicoe.

First isolation of rotavirus associated with neonatal diarrhoea in guanacos (Lama guanicoe) in the Argentinean Patagonia region

Group A rotavirus (RV) and coronavirus (CV) are common viral pathogens associated with neonatal diarrhoea in numerous animal species. The purpose of this work was to investigate the presence of these viral agents in two farm populations of captured guanacos (Lama guanicoe) in the Argentinean Patagonia region, that developed severe diarrhoea outbreaks. Stool and serum samples were analysed for RV and bovine CV antigen and antibody enzyme-linked immunosorbent assay. Rotavirus was detected in faeces from two new-born guanacos with acute diarrhoea, one in each farm. After electrophoretic analysis, each isolated strain, showed a distinctive long dsRNA electropherotype characteristic of group A rotaviruses (4:2:3:2). In addition, 95% (38 of 40) of the sampled animals were positive for RV antibodies, suggesting a high prevalence of RV infection in the populations tested. No evidence of CV circulation by antigen or antibody analysis was observed. To our knowledge, this is the first report of the detection and isolation of RV associated with neonatal diarrhoea in Lama guanicoe.

Nanoporous biocapsules for the encapsulation of insulinoma cells: biotransport and biocompatibility considerations

This study investigates whether nanoporous micromachined biocapsules, with uniform membrane pore sizes of 24.5-nm, can be used to encapsulate insulin-secreting cells in vitro. This approach to cell encapsulation is based on microfabrication technology whereby immunoisolation membranes are bulk and surface micromachined to present uniform and well-controlled pore sizes as small as 10 nm, tailored surface chemistries, and precise microarchitectures. This study evaluates the behavior of insulinoma cells with micromachined membranes, the effect of matrix configurations within the biocapsule on cell behavior, as well as insulin and glucose transport through the biocapsule membranes.

Nanoporous anti-fouling silicon membranes for biosensor applications

The ability to create biocompatible well-controlled membranes has been an area of great interest over the last few years, particularly for biosensor applications. The present study describes the fabrication and characterization of novel nanoporous micromachined membranes that exhibit selective permeability and low biofouling. Results indicate that such membranes can be fabricated with uniform pore sizes capable of the simultaneous exclusion of albumin and diffusion of glucose. Compared to polymeric membranes of similar pore size, micromachined silicon membranes allowed more than twice the amount of glucose diffusion after 240 min and complete albumin exclusion. Moreover, membranes exhibit no morphological change or degradability in the presence of biological proteins and fluids at 37 degrees C. The results point to the potential of using such membranes for implantable biosensor applications. With monodisperse pores sizes as small as 10 nm, these membranes offer advantages in their reproducibility, stability, and ability to be integrated in silicon-based biosensing technology.

Temporal Gene Regulation During HIV-1 Infection of Human CD4+ T Cells

CD4+ T-cell depletion is a characteristic of human immunodeficiency virus type 1 (HIV-1) infection. In this study, modulation of mRNA expression of 6800 genes was monitored simultaneously at eight time points in a CD4+ T-cell line (CEM-GFP) during HIV infection. The responses to infection included: (1) >30% decrease at 72 h after infection in overall host-cell production of monitored mRNA synthesis, with the replacement of host-cell mRNA by viral mRNA, (2) suppression of the expression of selected mitochondrial and DNA repair gene transcripts, (3) increased expression of the proapoptotic gene and its gene p53-induced product Bax, and (4) activation of caspases 2, 3, and 9. The intense HIV-1 transcription resulted in the repression of much cellular RNA expression and was associated with the induction of apoptosis of infected cells but not bystander cells. This choreographed host gene response indicated that the subversion of the cell transcriptional machinery for the purpose of HIV-1 replication is akin to genotoxic stress and represents a major factor leading to HIV-induced apoptosis.