Apo2 ligand/tumor necrosis factor-related apoptosis-inducing ligand cooperates with chemotherapy to inhibit orthotopic lung tumor growth and improve survival

Genetically Modified DR5-Specific TRAIL Variant DR5-B Revealed Dual Antitumor and Protumoral Effect in Colon Cancer Xenografts and an Improved Pharmacokinetic Profile

Despite the weak clinical efficacy of TRAIL death receptor agonists, a search is under way for new agents that more efficiently activate apoptotic signaling. We previously created a TRAIL DR5-selective variant DR5-B without affinity for the DR4, DcR1, DcR2, and OPG receptors and increased proapoptotic activity in tumor cells. Here we showed that DR5-B significantly inhibited tumor growth in HCT116 and Caco-2 but not in HT-29 xenografts. The antitumor activity of DR5-B was 2.5 times higher in HCT116 xenografts compared to TRAIL. DR5-B at a dose of 2 or 10 mg/kg/d for 10 days inhibited tumor growth in HCT116 xenografts by 26% or 50% respectively, and increased animal survival. Unexpectedly, DR5-B at a higher dose (25 mg/kg/d) inhibited tumor growth only during the first 8 days of drug exposure, while at the end of the monitoring, no effect or even slight stimulation of tumor growth was observed. The pharmacokinetic parameters of DR5-B were comparable to those of TRAIL, except that the half-life was 3.5 times higher. Thus, enhancing TRAIL selectivity to DR5 may increase both antitumor and proliferative activities depending on the concentration and administration regimens.

Design and synthesis of a luminescent iridium complex-peptide hybrid (IPH) that detects cancer cells and induces their apoptosis

Tumor necrosis factor related apoptosis inducing ligand (TRAIL) triggers the cell-extrinsic apoptosis pathway by complexation with its signaling receptors such as death receptors (DR4 and DR5). TRAIL is a C₃-symmetric type II transmembrane protein, consists of three monomeric units. Cyclometalated iridium(III) complexes such as fac-Ir(tpy)₃ (tpy = 2-(4-tolyl)pyridine) also possess a C₃-symmetric structure and are known to have excellent luminescence properties. In this study, we report on the design and synthesis of a C₃-symmetric and luminescent Ir complex-peptide hybrid (IPH), which contains a cyclic peptide that had been reported to bind to death receptor (DR5). The results of MTT assay of Jurkat, K562 and Molt-4 cells with IPH and co-staining experiments with IPH and an anti-DR5 antibody indicate that IPH binds to DR5 and induces apoptosis in a manner parallel to the DR5 expression level. Mechanistic studies of cell death suggest that apoptosis and necrosis-like cell death are differentiated by the position of the hydrophilic part that connects Ir complex and the peptide units. These findings suggest that IPHs could be a promising tool for controlling apoptosis and necrosis by activation of the extra-and intracellular cell death pathway and to develop new anticancer drugs that detect cancer cells and induce their cell death.

Luminescent Iridium Complex-Peptide Hybrids (IPHs) for Therapeutics of Cancer: Design and Synthesis of IPHs for Detection of Cancer Cells and Induction of Their Necrosis-Type Cell Death

Death receptors (DR4 and DR5) offer attractive targets for cancer treatment because cancer cell death can be induced by apoptotic signal upon binding of death ligands such as tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) with death receptors. Cyclometalated iridium(III) complexes such as fac-Ir(tpy)₃ (tpy = 2-(4-tolyl)pyridine) possess a C₃-symmetric structure like TRAIL and exhibit excellent luminescence properties. Therefore, cyclometalated Ir complexes functionalized with DR-binding peptide motifs would be potent TRAIL mimics to detect cancer cells and induce their cell death. In this study, we report on the design and synthesis of C₃-symmetric and luminescent Ir complex-peptide hybrids (IPHs), which possess cyclic peptide that had been reported to bind DR5. The results of 27 MHz quartz-crystal microbalance (QCM) measurements of DR5 with IPHs and costaining experiments of IPHs and anti-DR5 antibody, suggest that IPHs bind with DR5 and undergo internalization into cytoplasm, possibly via endocytosis. It was also found that IPHs induce slow cell death of these cancer cells in a parallel manner to the DR5 expression level. These results indicate that IPHs may offer a promising tool as artificial luminescent mimics of death ligands to develop a new category of anticancer agents that detect and kill cancer cells.

TGF3L fusion enhances the antitumor activity of TRAIL by promoting assembly into polymers

TRAIL, a promising antitumor immuno-agent, exerted limited efficacy in clinical trials. The third disulfide loop of TGF-α (TGF3L peptide) with a very low affinity for EGFR has been reported to enhance the activity of fused antigens or cytokines. We wondered whether fusion of this peptide could enhance TRAIL activity and what the underlying mechanism for this enhancement would be. The TGF3L-TRAIL showed greatly enhanced cytotoxicity in a variety of cancer cell lines while spared normal cells unharmed. Typical apoptosis and cellular caspase activation were potently induced by TGF3L-TRAIL at the concentration levels corresponding to its cytotoxicity. TGF3L-TRAIL was able to activate both DR4 and DR5 the same as TRAIL did. It induced complete cell death in Colo205 through only one receptor when the other one was blocked, different from TRAIL-induced cell death (through DR4 dominantly). TGF3L-TRAIL cytotoxicity was not reduced in some cell lines even if both receptors are blocked simultaneously. Surprisingly, TGF3L-TRAIL self-assembled into stable polymers, which was responsible for its enhanced cytotoxicity. In human tumor xenograft mouse models, TGF3L-TRAIL showed anti-tumor activity similar to or better than TRAIL in different cancer cell types, consistent with its differing enhancement of cytotoxicity in vitro. Taken together, TGF3L fusion of TRAIL obviously enhances the anticancer activity of TRAIL by promoting assembly into polymers, which presents a novel fusion strategy for improving TRAIL function.

NanoTRAIL-Oncology: A Strategic Approach in Cancer Research and Therapy

TRAIL is a member of the tumor necrosis factor superfamily that can largely trigger apoptosis in a wide variety of cancer cells, but not in normal cells. However, insufficient exposure to cancer tissues or cells and drug resistance has severely impeded the clinical application of TRAIL. Recently, nanobiotechnology has brought about a revolution in advanced drug delivery for enhanced anticancer therapy using TRAIL. With the help of materials science, immunology, genetic engineering, and protein engineering, substantial progress is made by expressing fusion proteins with TRAIL, engineering TRAIL on biological membranes, and loading TRAIL into functional nanocarriers or conjugating it onto their surfaces. Thus, the nanoparticle-based TRAIL (nanoTRAIL) opens up intriguing opportunities for efficient and safe bioapplications. In this review, the mechanisms of action and biological function of TRAIL, as well as the current status of TRAIL treatment, are comprehensively discussed. The application of functional nanotechnology combined with TRAIL in cancer therapy is also discussed.

TREM-2 serves as a negative immune regulator through Syk pathway in an IL-10 dependent manner in lung cancer

During infection, triggering receptor expressed on myeloid cells-2 (TREM-2) restrains dendritic cells (DCs) and macrophages (MΦs) phagocytosis, as well as reduces pro-inflammatory cytokines release through DNAX-activation protein 12 (DAP12) signaling. However, the role of TREM-2 signaling in cancer has never been elucidated. In the current study, we found that TREM-2 was up-regulated on peripheral blood monocytes in tumor-bearing host. More TREM-2⁺DCs were detected in the lung of 3LL tumor-bearing mice. On the other hand, the level of TREM-2 on pulmonary MΦs positively correlated with the pathological staging of lung cancer. However, surgical or chemotherapeutic reduction of tumor burden led to the obvious decline of TREM-2. In vitro, TREM-2 expression of bone marrow (BM)-derived DCs and MΦs was induced by conditional medium (CM) containing the supernatant of 3LL cells. TREM-2⁺DCs from CM and/or tumor-bearing mice held altered phenotypes (CD80^LowCD86^LowMHCII^Low) and impaired functions, such as, reduced interleukin (IL)-12 secretion, increased IL-10 production, and weakened ovalbumin (OVA)-endocytic capacity; also developed potent inhibitory effect on T cell proliferation that could be partially reversed by TREM-2 blockage. Moreover, spleen tyrosine kinase (Syk) inhibitor restrained IL-10 production of TREM-2⁺DC. Remarkably, IL-10 neutralizing antibody and Syk inhibitor both lowered the suppressive potential of TREM-2⁺DCs in T cell proliferation. Also, adoptive transfer of this TREM-2⁺DCs accelerated the tumor growth rather than jeopardized survival in lung cancer-bearing mice. In conclusion, these results indicate that TREM-2 might act as a negative immuno-regulatory molecule through Syk pathway in an IL-10 dependent manner and partially predicts prognosis in lung cancer patients.

Biomacromolecules based core/shell architecture toward biomedical applications

Polyelectrolyte multilayer capsules have become a novel and promising class of hybrid materials with great potential since they can be applied in various areas, such as pharmaceutical sciences, biotechnology, and biomedicine. The concept of using such carriers for biology application is diagnosis and treatment of diseases for convenience, safety and specific targeting. Therefore, the development of biocompatible, biodegradable and specific characteristic nanostructure material is highly desirable. Much effort has been devoted to exploring innovative and effective techniques to fabricate such materials. Among the available techniques, layer-by-layer (LbL) assembly capsules have attracted considerable attention attributing to the flexibly controlled size, shape, composition, wall thickness and functions. Protein, as the large class of biomacromolecules, was incorporated into capsules for improving the biocompatibility and specific function. In this review we provide an overview of the recent progress in biomacromolecular capsules or core/shell architecture with different diameters for the variety of purposes. The size ranging from micro-, sub-micro to nano scale based on the choice of the template. Their advantages are discussed here. The applications of these biomacromolecular capsules in biotechnological fields have also been summarized, for instance blood substitute, ATP carriers, photodynamic therapy and nanomedicines.

Apoptotic pathways as a therapeutic target for colorectal cancer treatment

Colorectal cancer is the second leading cause of death from cancer among adults. The disease begins as a benign adenomatous polyp, which develops into an advanced adenoma with high-grade dysplasia and then progresses to an invasive cancer. Appropriate apoptotic signaling is fundamentally important to preserve a healthy balance between cell death and cell survival and in maintaining genome integrity. Evasion of apoptotic pathway has been established as a prominent hallmark of several cancers. During colorectal cancer development, the balance between the rates of cell growth and apoptosis that maintains intestinal epithelial cell homeostasis gets progressively disturbed. Evidences are increasingly available to support the hypothesis that failure of apoptosis may be an important factor in the evolution of colorectal cancer and its poor response to chemotherapy and radiation. The other reason for targeting apoptotic pathway in the treatment of cancer is based on the observation that this process is deregulated in cancer cells but not in normal cells. As a result, colorectal cancer therapies designed to stimulate apoptosis in target cells would play a critical role in controlling its development and progression. A better understanding of the apoptotic signaling pathways, and the mechanisms by which cancer cells evade apoptotic death might lead to effective therapeutic strategies to inhibit cancer cell proliferation with minimal toxicity and high responses to chemotherapy. In this review, we analyzed the current understanding and future promises of apoptotic pathways as a therapeutic target in colorectal cancer treatment.

Antitherapeutic antibody-mediated hepatotoxicity of recombinant human Apo2L/TRAIL in the cynomolgus monkey

Apo2L/TRAIL is a member of the tumor necrosis factor superfamily and an important inducer of apoptosis. Recombinant human (rhu) Apo2L/TRAIL has been attractive as a potential cancer therapeutic because many types of tumor cells are sensitive to its apoptosis-inducing effects. Nonclinical toxicology studies were conducted to evaluate the safety of rhuApo2L/TRAIL for possible use in humans. The cynomolgus monkey was chosen for this safety assessment based on high protein sequence homology between human and cynomolgus Apo2L/TRAIL and comparable expression of their receptors. Although hepatotoxicity was observed in repeat-dose monkey studies with rhuApo2L/TRAIL, all animals that displayed hepatotoxicity had developed antitherapeutic antibodies (ATAs). The cynomolgus ATAs augmented the cytotoxicity of rhuApo2L/TRAIL but not of its cynomolgus counterpart. Of note, human and cynomolgus Apo2L/TRAIL differ by four amino acids, three of which are surface-exposed. In vivo studies comparing human and cynomolgus Apo2L/TRAIL supported the conclusion that these distinct amino acids served as epitopes for cross-species ATAs, capable of crosslinking rhuApo2L/TRAIL and thus triggering hepatocyte apoptosis. We describe a hapten-independent mechanism of immune-mediated, drug-related hepatotoxicity – in this case – associated with the administration of a human recombinant protein in monkeys. The elucidation of this mechanism enabled successful transition of rhuApo2L/TRAIL into human clinical trials.

Structural Insight for Roles of DR5 Death Domain Mutations on Oligomerization of DR5 Death Domain-FADD Complex in the Death-Inducing Signaling Complex Formation: A Computational Study

Death receptor 5 (DR5)-induced apoptosis that prioritizes the death of tumor cells has been proposed as one of the promising cancer therapies. In this process, oligomerized DR5 death domain (DD) binding to Fas-associated death domain (FADD) leads to FADD activating caspase-8, which marks the formation of the death-inducing signaling complex (DISC) that initiates apoptosis. DR5 DD mutations found in cancer cells have been suggested to play an important pathological role, the mechanism through which those mutants prevent the DR5-activated DISC formation is not clear yet. This study sought to provide structural and molecular insight for the roles of four selected DR5 DD mutations (E355K, E367K, K415N, and L363F) in the oligomerization of DR5 DD-FADD complex during the DISC formation. Results from the molecular dynamics simulations show that the simulated mutants induce conformational, dynamical motions and interactions changes in the DR5 DD-FADD tetramer complex, including changes in a protein's backbone flexibility, less exposure of FADD DED's caspase-8 binding site, reduced H-bonding and hydrophobic contacts at the DR5 DD-FADD DD binding, altered distribution of the electrostatic potentials and correlated motions of residues, and reduced binding affinity of DR5 DD binding to FADD. This study provides structural and molecular insight for the influence of DR5 DD mutations on oligomerization of DR5 DD-FADD complex, which is expected to foster understanding of the DR5 DD mutants' resistance mechanism against DR5-activated DISC formation.

A Panel of Genetic Polymorphism for the Prediction of Prognosis in Patients with Early Stage Non-Small Cell Lung Cancer after Surgical Resection

Background

This study was conducted to investigate whether a panel of eight genetic polymorphisms can predict the prognosis of patients with early stage non-small cell lung cancer (NSCLC) after surgical resection.

Materials and Methods

We selected eight single nucleotide polymorphisms (SNPs) which have been associated with the prognosis of lung cancer patients after surgery in our previous studies. A total of 814 patients with early stage NSCLC who underwent curative surgical resection were enrolled. The association of the eight SNPs with overall survival (OS) and disease-free survival (DFS) was analyzed.

Results

The eight SNPs (CD3EAP rs967591, TNFRSF10B rs1047266, AKT1 rs3803300, C3 rs2287845, HOMER2 rs1256428, GNB2L1 rs3756585, ADAMTSL3 rs11259927, and CD3D rs3181259) were significantly associated with OS and/or DFS. Combining those eight SNPs, we designed a prognostic index to predict the prognosis of patients. According to relative risk of death, a score value was assigned to each genotype of the SNPs. A worse prognosis corresponded to a higher score value, and the sum of score values of eight SNPs defined the prognostic index of a patient. When we categorized the patients into two groups based on the prognostic index, high risk group was significantly associated with worse OS and DFS compared to low risk group (aHR for OS = 2.21, 95% CI = 1.69–2.88, P = 8.0 x 10⁻⁹, and aHR for DFS = 1.58, 95% CI = 1.29–1.94, P = 1.0 x 10⁻⁵).

Conclusions

Prognostic index using eight genetic polymorphisms may be useful for the prognostication of patients with surgically resected NSCLC.

Apo2L/TRAIL and the death receptor 5 agonist antibody AMG 655 cooperate to promote receptor clustering and antitumor activity

Death receptor agonist therapies have exhibited limited clinical benefit to date. Investigations into why Apo2L/TRAIL and AMG 655 preclinical data were not predictive of clinical response revealed that coadministration of Apo2L/TRAIL with AMG 655 leads to increased antitumor activity in vitro and in vivo. The combination of Apo2L/TRAIL and AMG 655 results in enhanced signaling and can sensitize Apo2L/TRAIL-resistant cells. Structure determination of the Apo2L/TRAIL-DR5-AMG 655 ternary complex illustrates how higher order clustering of DR5 is achieved when both agents are combined. Enhanced agonism generated by combining Apo2L/TRAIL and AMG 655 provides insight into the limited efficacy observed in previous clinical trials and suggests testable hypotheses to reconsider death receptor agonism as a therapeutic strategy.

Influence of the implantation site on the sensitivity of patient pancreatic tumor xenografts to Apo2L/TRAIL therapy

OBJECTIVES

We have previously demonstrated activity of Apo2L/TRAIL against patient pancreatic tumor xenografts. Here, we have examined the influence of the tumor implantation site on therapeutic response of orthotopic tumors and their metastases to Apo2L/TRAIL.

METHODS

Sensitivity of 6 patient pancreatic tumor xenografts to Apo2L/TRAIL was determined in a subcutaneous model. To compare the response of orthotopic tumors, cells from subcutaneous xenografts were injected into the pancreas. Tumor growth was confirmed by histological examination of selected mice, and then treatment was started. When all control mice developed externally palpable tumors, the experiment was terminated, and pancreatic weights compared between control and treated groups. Magnetic resonance imaging was used to quantitate the response of orthotopic and metastatic tumors.

RESULTS

The sensitivity to Apo2L/TRAIL observed in subcutaneous tumors was maintained in orthotopic tumors. Metastatic spread was observed with orthotopic tumor implantation. In an orthotopic model of a sensitive tumor, primary and metastatic tumor burden was significantly reduced, and median survival significantly extended by Apo2L/TRAIL therapy.

CONCLUSIONS

Our data provide evidence that the site of tumor engraftment does not alter the inherent sensitivity of patient xenografts to Apo2L/TRAIL, and these results highlight the potential of Apo2L/TRAIL therapy against primary and metastatic pancreatic cancer.

TRAIL induces apoptosis in oral squamous carcinoma cells--a crosstalk with oncogenic Ras regulated cell surface expression of death receptor 5

TNF-related apoptosis inducing ligand (TRAIL) induces apoptosis through its death receptors (DRs) 4 and/or 5 expressed on the surface of target cells. The selectivity of TRAIL towards cancer cells has promoted clinical evaluation of recombinant human TRAIL (rhTRAIL) and its agonistic antibodies in treating several major human cancers including colon and non-Hodgkin's lymphoma. However, little is known about their ability in killing oral squamous cell carcinoma (OSCC) cells. In this study, we tested the apoptotic responses of a panel of seven human OSCC cell lines (HN31, HN30, HN12, HN6, HN4, Cal27, and OSCC3) to rhTRAIL and monoclonal antibodies against DR4 or DR5. We found that rhTRAIL is a potent inducer of apoptosis in most of the oral cancer cell lines tested both in vitro and in vivo. We also showed that DR5 was expressed on the surface of the tested cell lines which correlated with the cellular susceptibility to apoptosis induced by rhTRAIL and anti-DR5 antibody. By contrast, little or no DR4 was detected on the surface of OSCC3 and HN6 cells rendering cellular resistance to DR4 antibody and a reduced sensitivity to rhTRAIL. Notably, the overall TRAIL sensitivity correlated well with the levels of endogenous active Ras in the cell lines tested. Expression of a constitutively active Ras mutant (RasV12) in OSCC3 cells selectively upregulated surface expression of DR5, but not DR4, and restored TRAIL sensitivity. Our findings could have implications for the use of TRAIL receptor targeted therapies in the treatment of human OSCC tumors particularly the ones harboring constitutively active Ras mutant.

Manipulating the apoptotic pathway: potential therapeutics for cancer patients

This review summarizes the current state of scientific understanding of the apoptosis pathway, with a focus on the proteins involved in the pathway, their interactions and functions. This forms the rationale for detailing the preclinical and clinical pharmacology of drugs that modulate the pivotal proteins in this pathway, with emphasis on drugs that are furthest advanced in clinical development as anticancer agents. There is a focus on describing drugs that modulate three of the most promising targets in the apoptosis pathway, namely antibodies that bind and activate the death receptors, small molecules that inhibit the anti-apoptotic Bcl-2 family proteins, and small molecules and antisense oligonucleotides that inactivate the inhibitors of apoptosis, all of which drive the equilibrium of the apoptotic pathway towards apoptosis. These structurally different yet functionally related groups of drugs represent a promising novel approach to anticancer therapeutics whether used as monotherapy or in combination with either classical cytotoxic or other molecularly targeted anticancer agents.

Aurora and IKK kinases cooperatively interact to protect multiple myeloma cells from Apo2L/TRAIL

Constitutive activation of the canonical and noncanonical nuclear factor-κB (NF-κB) pathways is frequent in multiple myeloma (MM) and can compromise sensitivity to TRAIL. In this study, we demonstrate that Aurora kinases physically and functionally interact with the key regulators of canonical and noncanonical NF-κB pathways IκB kinase β (IKKβ) and IKKα to activate NF-κB in MM, and the pharmacological blockade of Aurora kinase activity induces TRAIL sensitization in MM because it abrogates TRAIL-induced activation of NF-κB. We specifically found that TRAIL induces prosurvival signaling by increasing the phosphorylation state of both Aurora and IKK kinases and their physical interactions, and the blockade of Aurora kinase activity by pan-Aurora kinase inhibitors (pan-AKIs) disrupts TRAIL-induced survival signaling by effectively reducing Aurora-IKK kinase interactions and NF-κB activation. Pan-AKIs consistently blocked TRAIL induction of the antiapoptotic NF-κB target genes A1/Bfl-1 and/or Mcl-1, both important targets for TRAIL sensitization in MM cells. In summary, these results identify a novel interaction between Aurora and IKK kinases and show that these pathways can cooperate to promote TRAIL resistance. Finally, combining pan-AKIs with TRAIL in vivo showed dramatic efficacy in a multidrug-resistant human myeloma xenograft model. These findings suggest that combining Aurora kinase inhibitors with TRAIL may have therapeutic benefit in MM.

Death receptors as targets in cancer

Anti-tumour therapies based on the use pro-apoptotic receptor agonists, including TNF-related apoptosis-inducing ligand (TRAIL) or monoclonal antibodies targeting TRAIL-R1 or TRAIL-R2, have been disappointing so far, despite clear evidence of clinical activity and lack of adverse events for the vast majority of these compounds, whether combined or not with conventional or targeted anti-cancer therapies. This brief review aims at discussing the possible reasons for the lack of apparent success of these therapeutic approaches and at providing hints in order to rationally design optimal protocols based on our current understanding of TRAIL signalling regulation or resistance for future clinical trials.

LINKED ARTICLES

This article is part of a themed section on Emerging Therapeutic Aspects in Oncology. To view the other articles in this section visit http://dx.doi.org/10.1111/bph.2013.169.issue-8.

Induction of death receptor 5 expression in tumor vasculature by perifosine restores the vascular disruption activity of TRAIL-expressing CD34(+) cells

The proapoptotic death receptor 5 (DR5) expressed by tumor associated endothelial cells (TECs) mediates vascular disrupting effects of human CD34(+) cells engineered to express membrane-bound tumor necrosis factor-related apoptosis-inducing ligand (CD34-TRAIL (+) cells) in mice. Indeed, lack of DR5 on TECs causes resistance to CD34-TRAIL (+) cells. By xenografting in nonobese diabetic/severe combined immunodeficient mice the TRAIL-resistant lymphoma cell line SU-DHL-4V, which generates tumors lacking endothelial DR5 expression, here we demonstrate for the first time that the Akt inhibitor perifosine induces in vivo DR5 expression on TECs, thereby overcoming tumor resistance to the vascular disruption activity of CD34-TRAIL (+) cells. In fact, CD34-TRAIL (+) cells combined with perifosine, but not CD34-TRAIL (+) cells alone, exerted marked antivascular effects and caused a threefold increase of hemorrhagic necrosis in SU-DHL-4V tumors. Consistent with lack of DR5 expression, CD34-TRAIL (+) cells failed to affect the growth of SU-DHL-4V tumors, but CD34-TRAIL (+) cells plus perifosine reduced tumor volumes by 60 % compared with controls. In view of future clinical studies using membrane-bound TRAIL, our results highlight a strategy to rescue patients with primary or acquired resistance due to the lack of DR5 expression in tumor vasculature.

Inhibition of the mitochondrial Hsp90 chaperone network: a novel, efficient treatment strategy for cancer?

Research has shown that cancer cells exhibit multiple deregulated pathways, involving proliferation, migration and cell death. Heat-shock-proteins have evolved as "central regulators" and are implicated in the modulation of these pathways and in organelle-specific signaling. In this instance, heat-shock-proteins (Hsps) assist cancer cells in the maturation of proteins. Hsp90 is of particular interest because its enzymatic ATPase activity is elevated in malignant cells as compared to non-neoplastic counterparts. Consistent with its high-activity in cancer cells, Hsp90 stabilizes a considerable number of proteins being instrumental in carcinogenesis and the maintenance and growth of highly malignant cancers. Among its distribution Hsp90 is also localized within mitochondria of neoplastic cells of various origin, interacting with another chaperone, TRAP1 (Tumor necrosis factor type 1 receptor-associated protein or Heat-shock-protein 75) to antagonize the cell death promoting properties of the matrix protein, Cyclophilin-D. Several preclinical studies, including in vivo studies in both orthotopic and genetic animal models, have confirmed that targeting mitochondrial Hsp90 may be a novel efficient treatment method for highly recalcitrant tumors. This review summarizes the most recent findings of mitochondrial Hsp90 signaling and its potential implications for cancer therapy.

Rab25 Small GTPase Mediates Secretion of Tumor Necrosis Factor Receptor Superfamily Member 11b (osteoprotegerin) Protecting Cancer Cells from Effects of TRAIL

BACKGROUND

Expression of Rab25, which is located in the 1q amplicon present at high frequency in many cancer lineages, promotes cancer cell survival under multiple stress conditions. While Rab proteins play essential roles in all stages of vesicle trafficking, the functions and endogenous cargoes for Rab25 remain to be fully elucidated. Osteoprotegerin (OPG) is a secreted glycoprotein that binds the tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) thus preventing it from activating the TNF-family death receptors. In the present study, we demonstrated that Rab25 regulates OPG at both the transcription and secretion level.

METHODS

The effect of Rab25 on OPG expression and its effect on TRAIL-induced cell were examined in both ovarian and breast cells. Signal transduction pathways regulation of OPG expression was examined in cells using pharmacogenetic approaches.

RESULTS

Expression of Rab25 to levels similar to those in tumors with RAB25 amplification, increased OPG mRNA expression and secretion from ovarian and breast cancer cell lines, whereas down regulation with Rab25 specific siRNA decreased OPG secretion and sensitized cells to TRAIL-induced cell death. Critically, exogenous OPG mimicked the effects of Rab25 on cell death supporting the contention that Rab25-induced accumulation of OPG protects cancer cells from the effects of TRAIL. Rab25 cooperates with EGFR-mediated MAPK signaling to increase TRAIL production and release. Importantly, priming cells with EGFR inhibitors increased sensitivity to TRAIL-induced cells death regardless of the Rab25 background.

CONCLUSION

Increased OPG expression induced by Rab25 may provide a mechanistic advantage for cancer development and progression.

Tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) induces death receptor 5 networks that are highly organized

Recent evidence suggests that TNF-related apoptosis-inducing ligand (TRAIL), a death-inducing cytokine with anti-tumor potential, initiates apoptosis by re-organizing TRAIL receptors into large clusters, although the structure of these clusters and the mechanism by which they assemble are unknown. Here, we demonstrate that TRAIL receptor 2 (DR5) forms receptor dimers in a ligand-dependent manner at endogenous receptor levels, and these receptor dimers exist within high molecular weight networks. Using mutational analysis, FRET, fluorescence microscopy, synthetic biochemistry, and molecular modeling, we find that receptor dimerization relies upon covalent and noncovalent interactions between membrane-proximal residues. Additionally, by using FRET, we show that the oligomeric structure of two functional isoforms of DR5 is indistinguishable. The resulting model of DR5 activation should revise the accepted architecture of the functioning units of DR5 and the structurally homologous TNF receptor superfamily members.

Randomized phase II study of dulanermin in combination with paclitaxel, carboplatin, and bevacizumab in advanced non-small-cell lung cancer

PURPOSE

To evaluate the efficacy and safety of dulanermin combined with paclitaxel and carboplatin (PC) and bevacizumab (PCB) as first-line treatment for advanced or recurrent non-small-cell lung cancer (NSCLC).

PATIENTS AND METHODS

Patients with squamous NSCLC and/or CNS metastases received PC every 3 weeks alone (arm 1) or with dulanermin 8 mg/kg for 5 days (arm 2). Patients with nonsquamous NSCLC received PCB alone (arm 3) or with dulanermin 8 mg/kg for 5 days (arm 4) or 20 mg/kg for 2 days (arm 5). The primary end point was the objective response rate (ORR).

RESULTS

Overall, 213 patients were randomly assigned (arm 1, n = 41; arm 2, n = 39; arm 3, n = 42; arm 4, n = 40; arm 5, n = 41). The ORR in arms 1 to 5 was 39% (95% CI, 24% to 56%), 38% (95% CI, 24% to 54%), 50% (95% CI, 35% to 65%), 40% (95% CI, 25% to 56%), and 40% (95% CI, 25% to 56%), respectively. The odds ratio for ORR was 1.04 (P = 1.000) for arm 1 versus arm 2, 1.53 (P = .391) for arm 3 and versus arm 4, and 1.53 (P = .391) for arm 3 versus arm 5. The most common grade ≥ 3 adverse events were neutropenia, asthenia, anemia, thrombocytopenia, and hemoptysis. Of 161 available serum samples, a trend toward increased caspase-cleaved cytokeratin-18 was observed after dulanermin treatment in cycles 1 and 2. Among 84 patients evaluated for GalNT14 expression, there was a trend toward favorable progression-free survival and overall survival with dulanermin treatment in those with high GalNT14 expression.

CONCLUSION

The addition of dulanermin to PC and PCB did not improve outcomes in unselected patients with previously untreated advanced or recurrent NSCLC.

Anticancer efficacy of Apo2L/TRAIL is retained in the presence of high and biologically active concentrations of osteoprotegerin in vivo

Osteoprotegerin (OPG) is a secreted member of the tumor necrosis factor (TNF) receptor superfamily that binds to the ligand for receptor activator of nuclear factor κB (RANKL) and inhibits bone resorption. OPG can also bind and inhibit the activity of the TNF-related apoptosis-inducing ligand (Apo2L/TRAIL), raising the possibility that the anticancer efficacy of soluble Apo2L/TRAIL may be abrogated in the bone microenvironment where OPG expression is high. In this study we used a murine model of breast cancer growth in bone to evaluate the efficacy of recombinant soluble Apo2L/TRAIL against intratibial tumors that were engineered to overexpress native full-length human OPG. In vitro, OPG-overexpressing breast cancer cells were protected from Apo2L/TRAIL-induced apoptosis, an effect that was reversed with the addition of soluble RANKL or neutralizing antibodies to OPG. In vivo, mice injected intratibially with cells containing the empty vector developed large osteolytic lesions. In contrast, OPG overexpression preserved the integrity of bone and prevented breast cancer-induced bone destruction. This effect was due primarily to the complete absence of osteoclasts in the tibias of mice inoculated with OPG-transfected cells, confirming the biologic activity of the transfected OPG in vivo. Despite the secretion of supraphysiologic levels of OPG, treatment with Apo2L/TRAIL resulted in strong growth inhibition of both empty vector and OPG-overexpressing intratibial tumors. While Apo2L/TRAIL-induced apoptosis may be abrogated in vitro by OPG overexpression, the in vivo anticancer efficacy of recombinant soluble Apo2L/TRAIL is retained in the bone microenvironment even in the presence of biologically active OPG at supraphysiologic concentrations.

Combined modality therapy with TRAIL or agonistic death receptor antibodies

Molecularly targeted therapies, such as antibodies and small molecule inhibitors have emerged as an important breakthrough in the treatment of many human cancers. One targeted therapy under development is tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) due to its ability to induce apoptosis in a variety of human cancer cell lines and xenografts, while lacking toxicity in most normal cells. TRAIL and apoptosis-inducing agonistic antibodies to the TRAIL death receptors have been the subject of many preclinical and clinical studies in the past decade. However, the sensitivity of individual cancer cell lines of a particular tumor type to these agents varies from highly sensitive to resistant. Various chemotherapy agents have been shown to enhance the apoptosis-inducing capacity of TRAIL receptor-targeted therapies and induce sensitization of TRAIL-resistant cells. This review provides an overview of the mechanisms associated with chemotherapy enhancement of TRAIL receptor-targeted therapies including modulation of the apoptotic (death receptor expression, FLIP, and Bcl-2 or inhibitors of apoptosis (IAP) families) as well as cell signaling (NFκB, Akt, p53) pathways. These mechanisms will be important in establishing effective combinations to pursue clinically and in determining relevant targets for future cancer therapies.

Lung cancer therapeutics that target signaling pathways: an update

Claiming more than 150,000 lives each year, lung cancer is the deadliest cancer in the USA. First-line treatments in lung cancer include surgical resection and chemotherapy, the latter of which offers only modest survival benefits at the expense of often severe and debilitating side effects. Recent advances in elucidating the molecular biology of lung carcinogenesis have elucidated novel drug targets, and treatments are rapidly evolving into specialized agents that hone in on specific aspects of the disease. Of particular interest is blocking tumor growth by targeting the physiological processes surrounding angiogenesis, pro-tumorigenic growth factor activation, anti-apoptotic cascades and other cancer-promoting signal transduction events. This article looks at several areas of interest to lung cancer therapeutics and considers the current state of affairs surrounding the development of these therapies.

Identification and characterization of a novel agonistic anti-DR4 human monoclonal antibody

The tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) and its functional receptors, DR4 and DR5, have been established as promising targets for cancer treatment. Therapeutics targeting TRAIL and its receptors are not only effective in killing many types of tumors, but they also synergize with traditional therapies and show efficacy against tumors that are otherwise resistant to conventional treatments. We describe here the identification and characterization of two human monoclonal antibodies, m921 and m922, that are specific for human DR4. Both antibodies competed with TRAIL for binding to DR4, but only m921 recognized cell surface-associated DR4 and inhibited the growth of ST486 cells. This antibody may have potential for further development as a candidate therapeutic and research tool.

Tumor Necrosis Factor-related apoptosis-inducing ligand (TRAIL) Receptor-1 and Receptor-2 agonists for cancer therapy

IMPORTANCE OF THE FIELD

Agents that activate the TNF-related apoptosis-inducing ligand death receptors, TRAIL-R1 and TRAIL-R2, have attracted substantial attention and investment as potential anti-cancer therapies. Preclinical studies of TRAIL-R agonists indicate that they may be efficacious in a wide range of tumor types, especially when combined with chemotherapeutic agents.

AREAS COVERED IN THIS REVIEW

The rationale for clinical development of TRAIL-R agonists is described, including the basis for combining these agents with other agents that modulate the 'checks and balances' of the apoptotic pathways. Accruing data that highlight differences between TRAIL-R1 and TRAIL-R2 that could affect the clinical significance of their specific agonists are described. The clinical experience to date with each of the agonists is summarized.

WHAT THE READER WILL GAIN

The reader will gain an understanding of the rationale for the clinical development of TRAIL-R agonists, as well as the current status of clinical trials of these interesting new agents.

TAKE HOME MESSAGE

Ongoing clinical trials will provide important information regarding the future development of TRAIL-R agonists.

Phase I dose-escalation study of recombinant human Apo2L/TRAIL, a dual proapoptotic receptor agonist, in patients with advanced cancer

PURPOSE

Apoptosis ligand 2/tumor necrosis factor-related apoptosis-inducing ligand (Apo2L/TRAIL)-a member of the tumor necrosis factor cytokine family-induces apoptosis by activating the extrinsic pathway through the proapoptotic death receptors DR4 and DR5. Recombinant human Apo2L/TRAIL (rhApo2L/TRAIL) has broad potential as a cancer therapy. To the best of our knowledge, this is the first in-human clinical trial to assess the safety, tolerability, pharmacokinetics, and antitumor activity of multiple intravenous doses of rhApo2L/TRAIL in patients with advanced cancer.

PATIENTS AND METHODS

This phase I, open-label, dose-escalation study treated patients with advanced cancer with rhApo2L/TRAIL doses ranging from 0.5 to 30 mg/kg/d, with parallel dose escalation for patients without liver metastases and with normal liver function (cohort 1) and for patients with liver metastases and normal or mildly abnormal liver function (cohort 2). Doses were given daily for 5 days, with cycles repeating every 3 weeks. Assessments included adverse events (AEs), laboratory tests, pharmacokinetics, and imaging to evaluate antitumor activity.

RESULTS

Seventy-one patients received a mean of 18.3 doses; seven patients completed all eight treatment cycles. The AE profile of rhApo2L/TRAIL was similar in cohorts 1 and 2. The most common AEs were fatigue (38%), nausea (28%), vomiting (23%), fever (23%), anemia (18%), and constipation (18%). Liver enzyme elevations were concurrent with progressive metastatic liver disease. Two patients with sarcoma (synovial and undifferentiated) experienced serious AEs associated with rapid tumor necrosis. Two patients with chondrosarcoma experienced durable partial responses to rhApo2L/TRAIL.

CONCLUSION

At the tested schedule and dose range, rhApo2L/TRAIL was safe and well tolerated. Dose escalation achieved peak rhApo2L/TRAIL serum concentrations equivalent to those associated with preclinical antitumor efficacy.

Identification and functional characterization of a human sTRAIL homolog, CasTRAIL, in an invertebrate oyster Crassostrea ariakensis

Tumor necrosis factor-related apoptosis-inducing ligand (TRAIL/Apo2L) is one of the tumor necrosis factor (TNF) superfamily members, participating in many biological processes including apoptosis and immune responses. In present study, a novel human soluble TRAIL (sTRAIL) homolog, CasTRAIL was identified from the oyster, Crassostrea ariakensis. CasTRAIL has a 99% and 98% similarity to human sTRAIL over the cDNA sequence and the amino acid sequence, respectively. It mostly distributes in tissues of the oyster defense system and was mainly localized at cell membrane, and has no cytotoxicity to normal hemocytes of oyster. The phosphorylation state of MAP kinases revealed that CasTRAIL induced a rapid increase in the phospho-ERK and phospho-p38 levels, which indicated that the MAPK pathway was involved in CasTRAIL-mediated signaling. In addition, CasTRAIL also showed an ability of anti-RLO infection which might be through the p38-MAPK activation pathway. Present studies provide an understanding and insight of the biological functions of CasTRAIL.

Inhibition of NF-kappaB signaling by quinacrine is cytotoxic to human colon carcinoma cell lines and is synergistic in combination with tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) or oxaliplatin

Colorectal cancer is the third most common malignancy in the United States. Modest advances with therapeutic approaches that include oxaliplatin (L-OHP) have brought the median survival rate to 22 months, with drug resistance remaining a significant barrier. Tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) is undergoing clinical evaluation. Although human colon carcinomas express TRAIL receptors, they can also demonstrate TRAIL resistance. Constitutive NF-kappaB activation has been implicated in resistance to TRAIL and to cytotoxic agents. We have demonstrated constitutive NF-kappaB activation in five of six human colon carcinoma cell lines; this activation is inhibited by quinacrine. Quinacrine induced apoptosis in colon carcinomas and potentiated the cytotoxic activity of TRAIL in RKO and HT29 cells and that of L-OHP in HT29 cells. Similarly, overexpression of IkappaBalpha mutant (IkappaBalphaM) or treatment with the IKK inhibitor, BMS-345541, also sensitized these cells to TRAIL and L-OHP. Importantly, 2 h of quinacrine pretreatment resulted in decreased expression of c-FLIP and Mcl-1, which were determined to be transcriptional targets of NF-kappaB. Extended exposure for 24 h to quinacrine did not further sensitize these cells to TRAIL- or L-OHP-induced cell death; however, exposure caused the down-regulation of additional NF-kappaB-dependent survival factors. Short hairpin RNA-mediated knockdown of c-FLIP or Mcl-1 significantly sensitized these cells to TRAIL and L-OHP. Taken together, data demonstrate that NF-kappaB is constitutively active in colon cancer cell lines and NF-kappaB, and its downstream targets may constitute an important target for the development of therapeutic approaches against this disease.

Preclinical evidence that use of TRAIL in Ewing's sarcoma and osteosarcoma therapy inhibits tumor growth, prevents osteolysis, and increases animal survival

PURPOSE

Osteosarcoma and Ewing's sarcoma are high-grade neoplasms typically arising in the bones of children and adolescents. Despite improvement in therapy, the five-year survival rate is only 20% for patients not responding to treatment or presenting with metastases. Among new therapeutic strategies, the efficacy of tumor necrosis factor (TNF)-related apoptosis-inducing ligand (TRAIL), a member of the TNF superfamily with strong antitumoral activity and minimal toxicity to most normal cells and tissues, was investigated by complementary approaches both in vitro and in preclinical models.

EXPERIMENTAL DESIGN

The sensitivity of osteosarcoma and Ewing's sarcoma cell lines to TRAIL was investigated in vitro by determining TRAIL receptor expression together with TRAIL effects on cell viability and apoptosis. Complementary preclinical studies were carried out in respective tumor models by inoculation of osteosarcoma or Ewing's sarcoma tumor cells in paraosseous location. In addition, a model of lung nodule dissemination was developed by i.v. injection of osteosarcoma cells.

RESULTS

In vitro, both osteosarcoma and Ewing's sarcoma cells that express the TRAIL death receptors were highly sensitive to TRAIL-induced caspase-8-mediated apoptosis. TRAIL administered in vivo by nonviral gene therapy inhibited primary bone tumor incidence and growth by 87% and prevented tumor-induced osteolysis, leading to a significant 2-fold increase in animal survival 40 days after tumor induction. Furthermore, TRAIL inhibited tumor nodule dissemination in lungs and increased survival in an osteosarcoma model.

CONCLUSION

These findings suggest that TRAIL is a promising candidate for the development of new therapeutic strategies in the most frequent malignant primary bone tumors.

Tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) and paclitaxel have cooperative in vivo effects against glioblastoma multiforme cells

Tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) in conjunction with microtubule-targeting agents may be a promising novel anticancer treatment strategy. In vitro studies have suggested that relatively low concentrations of TRAIL enhance the lethality of paclitaxel (Taxol) against human cancer cells. The increased efficacy may be due to the triggering of caspase activation, resulting in mitotic checkpoint abrogation and catastrophe. We show here that wild-type p53 protects cells from caspase-dependent death induced by this therapeutic combination in vitro. We have now also developed an imaging-based model system to test the in vivo efficacy of combined TRAIL and Taxol, in which tumor growth and treatment response can be monitored noninvasively and in real-time. We further utilize bioluminescence, F18-fluorodeoxyglucose-positron emission tomography, and microscale computed tomography imaging to confirm the effects of combined treatment on tumors. These studies together provide the first in vivo confirmation that combined TRAIL plus paclitaxel results in better tumor control compared with either TRAIL or paclitaxel alone, and with no discernable increased normal tissue toxicity in the mouse. Interestingly, the in vivo antitumor response elicited by combined treatment was not affected by the p53 status of the tumor cells. These preclinical observations together suggest the therapeutic potential of combining TRAIL plus paclitaxel in cancer treatment, and support further preclinical and future clinical testing.

Human CD34+ cells engineered to express membrane-bound tumor necrosis factor–related apoptosis-inducing ligand target both tumor cells and tumor vasculature

Adenovirus-transduced CD34+ cells expressing membrane-bound tumor necrosis factor–related apoptosis-inducing ligand (CD34-TRAIL+ cells) exert potent antitumor activity. To further investigate the mechanism(s) of action of CD34-TRAIL+ cells, we analyzed their homing properties as well as antitumor and antivascular effects using a subcutaneous myeloma model in immunodeficient mice. After intravenous injection, transduced cells homed in the tumor peaking at 48 hours when 188 plus or minus 25 CD45+ cells per 105 tumor cells were detected. Inhibition experiments showed that tumor homing of CD34-TRAIL+ cells was largely mediated by vascular cell adhesion molecule-1 and stromal cell–derived factor-1. Both CD34-TRAIL+ cells and soluble (s)TRAIL significantly reduced tumor volume by 40% and 29%, respectively. Computer-aided analysis of TdT-mediated dUTP nick end-labeling–stained tumor sections demonstrated significantly greater effectiveness for CD34-TRAIL+ cells in increasing tumor cell apoptosis and necrosis over sTRAIL. Proteome array analysis indicated that CD34-TRAIL+ cells and sTRAIL activate similar apoptotic machinery. In vivo staining of tumor vasculature with sulfosuccinimidyl-6-(biotinamido) hexanoate-biotin revealed that CD34-TRAIL+ cells but not sTRAIL significantly damaged tumor vasculature, as shown by TdT-mediated dUTP nick end-labeling+ endothelial cells, appearance of hemorrhagic areas, and marked reduction of endothelial area. These results demonstrate that tumor homing of CD34-TRAIL+ cells induces early vascular disruption, resulting in hemorrhagic necrosis and tumor destruction.

The efficacy of combination therapy using adeno-associated virus-TRAIL targeting to telomerase activity and cisplatin in a mice model of hepatocellular carcinoma

PURPOSE

TNF-related apoptosis-inducing ligand (TRAIL) functions as a soluble cytokine and has been demonstrated significant antitumor activity against a variety of cancer cell lines without toxicity to most normal cells. Cisplatin is a potent anticancer agent and is widely used in the clinical for treatment of human cancers. Adeno-associated virus (AAV2) is a promising gene delivery vehicle for its advantage of low pathogenicity and long-term gene expression. However, lack of tissue specificity caused low efficiency of AAV transfer to target cells. The promoter of human telomerase reverse transcriptase (hTERT) is a good candidate to enhance targeting efficiency of AAV in cancer cells. Although AAV-mediated TRAIL controlled by hTERT promoter (AAV-hTERT-TRAIL) has obvious antitumor activity, the tumor cannot be completely eradicated. In this study, we first examined the effectiveness of combination therapy of cisplatin and AAV-hTERT-TRAIL on human hepatocellular carcinoma (HCC) in vitro and in vivo.

METHODS

For in vitro experiments, tumor cell lines were treated with cisplatin, virus, or both. The transgene TRAIL expression controlled by hTERT promoter was evaluated in BEL7404 HCC cell line. Cytotoxicity was performed by MTT analysis. Cell apoptosis was detected by flow cytometry analysis. The in vivo antitumor efficacy of combination treatment with cisplatin and AAV-hTERT-TRAIL was assessed in human hepatocellular carcinoma xenografts mouse model.

RESULTS

The enhanced TRAIL expression was observed in BEL7404 cells treated with AAV-hTERT-TRAIL plus cisplatin. Treatment with both AAV-hTERT-TRAIL and cisplatin exhibited stronger cytotoxicity and induced more significant apoptosis in cancer cells compared with AAV-hTERT-TRAIL or cisplatin alone, respectively. Moreover, in animal experiments, the combined treatment greatly suppressed tumor growth and resulted in tumor cell death.

CONCLUSIONS

AAV-mediated therapeutic gene expression in combination with chemotherapy provides a promising therapeutic strategy for human cancers. These data suggest that combined use of AAV-hTERT-TRAIL and cisplatin may have potential clinical application.

Phase 1b study of dulanermin (recombinant human Apo2L/TRAIL) in combination with paclitaxel, carboplatin, and bevacizumab in patients with advanced non-squamous non-small-cell lung cancer

PURPOSE

To determine the safety, pharmacokinetics (PK), and maximum-tolerated dose (MTD) up to a prespecified target dose of dulanermin in combination with paclitaxel, carboplatin, and bevacizumab (PCB) in patients with previously untreated, nonsquamous, stage IIIb (with pleural effusion)/IV or recurrent non-small-cell lung cancer (NSCLC).

PATIENTS AND METHODS

In this phase 1b study, patients (n = 24) received PCB on day 1 of each 21-day cycle then dulanermin at 4 or 8 mg/kg/d for 5 consecutive days or 15 or 20 mg/kg/d for 2 consecutive days per assigned treatment cohort. Incidence of dose-limiting toxicities (DLTs), adverse events, and antidulanermin antibodies were assessed. PK parameters were recorded for each agent. Tumor response was measured by modified Response Evaluation Criteria in Solid Tumors.

RESULTS

Twenty-four patients received at least one dose of dulanermin plus PCB, six in each treatment cohort. There were no DLTs. An MTD was not reached, and the drug combination was well tolerated. Treatment-emergent adverse events were generally as expected for the PCB regimen. Adverse events attributed to dulanermin were grade 1/2; no significant hepatotoxicity occurred. There was minimal impact of PCB on the PK of dulanermin. There was one confirmed complete response and 13 confirmed partial responses. The overall response rate was 58% (95% CI, 37 to 78). Median progression-free survival was 7.2 months (95% CI, 4.7 to 10.3).

CONCLUSION

Dulanermin plus PCB was well tolerated with no occurrence of DLTs and demonstrated antitumor activity in this patient population. Dulanermin at 8 mg/kg/d for 5 days and 20 mg/kg/d for 2 days every 3 weeks in combination with PCB is being studied in a phase II trial.

A phase I safety and pharmacokinetic study of the death receptor 5 agonistic antibody PRO95780 in patients with advanced malignancies

PURPOSE

PRO95780 is a fully human IgG1 monoclonal antibody that triggers the extrinsic apoptosis pathway through death receptor 5. This first-in-human study assessed the safety, tolerability, pharmacokinetics, and any early evidence of efficacy of PRO95780 in patients with advanced malignancies.

EXPERIMENTAL DESIGN

Target concentrations were predicted to occur at 10 mg/kg. Patients received up to eight cycles of PRO95780 i.v. using a 3+3 dose escalation design at 1 to 20 mg/kg every 14 days (every 28 days in cycle 1; stage 1), with cohort expansion at either the maximum tolerated dose or 10 mg/kg, whichever was lower (stage 2). Patients were evaluated for response every other cycle.

RESULTS

The maximum tolerated dose was not reached within this study. Four (8%) of 50 patients reported adverse events of greater than grade 2 at least possibly related to PRO95780, including 2 patients with reversible grade 3 transaminase elevation. The mean terminal half-life was 8.8 to 19.3 days, with dose-dependent increases in exposure (peak plasma concentration and area under the concentration) across 1 to 15 mg/kg. Most patients treated with 10 mg/kg or above achieved trough concentration above the target efficacious concentration at day 15 with moderate accumulation after multiple doses. No objective responses occurred, although three minor responses were observed in patients with colorectal and granulosa cell ovarian cancers (each treated with 4 mg/kg) and chondrosarcoma (10 mg/kg).

CONCLUSIONS

PRO95780 is safe and well tolerated at doses up to 20 mg/kg. Evidence of activity was noted in several different tumor types at 4 and 10 mg/kg. Pharmacokinetic analysis supports a dosing regimen of 10 to 15 mg/kg every 2 to 3 weeks.

Apomab, a fully human agonistic antibody to DR5, exhibits potent antitumor activity against primary and metastatic breast cancer

Apomab, a fully human agonistic DR5 monoclonal antibody, triggers apoptosis through activation of the extrinsic apoptotic signaling pathway. In this study, we assessed the cytotoxic effect of Apomab in vitro and evaluated its antitumor activity in murine models of breast cancer development and progression. MDA-MB-231-TXSA breast cancer cells were transplanted into the mammary fat pad or directly into the tibial marrow cavity of nude mice. Apomab was administered early, postcancer cell transplantation, or after tumors progressed to an advanced stage. Tumor burden was monitored progressively using bioluminescence imaging, and the development of breast cancer-induced osteolysis was measured using microcomputed tomography. In vitro, Apomab treatment induced apoptosis in a panel of breast cancer cell lines but was without effect on normal human primary osteoblasts, fibroblasts, or mammary epithelial cells. In vivo, Apomab exerted remarkable tumor suppressive activity leading to complete regression of well-advanced mammary tumors. All animals transplanted with breast cancer cells directly into their tibiae developed large osteolytic lesions that eroded the cortical bone. In contrast, treatment with Apomab following an early treatment protocol inhibited both intraosseous and extraosseous tumor growth and prevented breast cancer-induced osteolysis. In the delayed treatment protocol, Apomab treatment resulted in the complete regression of advanced tibial tumors with progressive restoration of both trabecular and cortical bone leading to full resolution of osteolytic lesions. Apomab represents a potent immunotherapeutic agent with strong activity against the development and progression of breast cancer and should be evaluated in patients with primary and metastatic disease.

Bifidobacterium longum as a delivery system of TRAIL and endostatin cooperates with chemotherapeutic drugs to inhibit hypoxic tumor growth

In our previous study, we have shown that vector pBV22210 containing a chloramphenicol resistance and a cryptic plasmid pMB1 from Bifidobacterium longum strain could stably replicate and did not significantly affect the biological characteristics of B. longum. In this study, B. longum was transfected by electroporation with pBV22210 encoding the extracellular domain of TRAIL (B. longum-pBV22210-TRAIL) and its carbohydrate fermentation and growth curve were determined, and its location and inhibitory effect on tumor xenografts in mice were also examined. The results further proved that gene transfection did not change the main biochemical characteristics of B. longum. The results also showed that B. longum-pBV22210-TRAIL resulted in selective location in tumors and exhibited a definite antitumor effect on S180 osteosarcoma. In addition, when a low dosage of Adriamycin (5 mg kg(-1)) or B. longum-pBV22210-endostatin was combined, the antitumor effect was significantly enhanced. The successful inhibition of S180 tumor growth suggested a stable vector in B. longum for transporting anticancer genes combined with low-dose chemotherapeutic drugs or other target genes is a promising approach in cancer gene therapy.