Cooperation of the proapoptotic receptor agonist rhApo2L/TRAIL with the CD20 antibody rituximab against non-Hodgkin lymphoma xenografts

Chemical synthetic approaches to mimic the TRAIL: promising cancer therapeutics

Apoptosis is programmed cell death that eliminates undesired cells to maintain homeostasis in metazoan. Aberration of this process may lead to cancer genesis. The tumor necrosis factor related apoptosis inducing ligand (TRAIL) induces apoptosis in cancer cells after ligation with death receptors (DR4/DR5) while sparing most normal cells. Therefore, strategies to induce apoptosis in cancer cells by mimicking the TRAIL emerge as a promising therapeutic tool. Hence, approaches are taken to develop TRAIL/DR-based cancer therapeutics. The recombinant soluble TRAIL (rhTRAIL) and death receptor agonistic antibodies were produced and tested pre-clinically and clinically. Pre-clinical and clinical trial data demonstrate that these therapeutics are safe and relatively well tolerated. But some of these therapeutics failed to exert adequate efficacy in clinical settings. Besides these biotechnologically derived therapeutics, a few chemically synthesized therapeutics are reported. Some of these therapeutics exert considerable efficacy in vitro and in vivo. In this review, we will discuss chemically synthesized TRAIL/DR-based therapeutics, their chemical and biological behaviour, design concepts and strategies that may contribute to further improvement of TRAIL/DR-based therapeutics.

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.

Midostaurin potentiates rituximab antitumor activity in Burkitt's lymphoma by inducing apoptosis

An intensive short-term chemotherapy regimen has substantially prolonged the overall survival of Burkitt’s lymphoma (BL) patients, which has been further improved by addition of rituximab. However, the inevitable development of resistance to rituximab and the toxicity of chemotherapy remain obstacles. We first prepared two BL cell lines resistant to rituximab-mediated CDC. Using a phosphorylation antibody microarray, we revealed that PI3K/AKT pathway contained the most phosphorylated proteins/hits, while apoptosis pathway that may be regulated by PKC displayed the greatest fold enrichment in the resistant cells. The PI3K/AKT inhibitor IPI-145 failed to reverse the resistance. In contrast, the pan-PKC inhibitor midostaurin exhibited potent antitumor activity in both original and resistant cells, alone or in combination with rituximab. Notably, midostaurin promoted apoptosis by reducing the phosphorylation of PKC and consequently of downstream Bad, Bcl-2 and NF-κB. Therefore, midostaurin improved rituximab activity by supplementing pro-apoptotic effects. In vivo, midostaurin alone powerfully prolonged the survival of mice bearing the resistant BL cells compared to rituximab alone treatments. Addition of midostaurin to rituximab led to dramatically improved survival compared to rituximab but not midostaurin monotherapy. Our findings call for further evaluation of midostaurin alone or in combination with rituximab in treating resistant BL in particular.

Resistance to anticancer immunity in cancer patients: potential strategies to reverse resistance

In the 1990s, the application of immunotherapy approaches to target cancer cells resulted in significant clinical responses in patients with advanced malignancies who were refractory to conventional therapies. While early immunotherapeutics were focused on T cell-mediated cytotoxic activity, subsequent efforts were centered on targeted antibody-mediated anticancer therapy. The initial success with antibody therapy encouraged further studies and, consequently, there are now more than 25 FDA-approved antibodies directed against a range of targets. Although both T cell and antibody therapies continue to result in significant clinical responses with minimal toxicity, a significant subset of patients does not respond to immunotherapy and another subset develops resistance following an initial response. This review is focused on describing examples showing that cancer resistance to immunotherapies indeed occurs. In addition, it reviews the mechanisms being used to overcome the resistance to immunotherapies by targeting the tumor cell directly and/or the tumor microenvironment.

Cancer preventive effect of recombinant TRAIL by ablation of oncogenic inflammation in colitis-associated cancer rather than anticancer effect

The potential of tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) in inducing apoptosis is a hallmark in cancer therapeutics, after which its selective ability to achieve cell death pathways against cancer cells led to hope for recombinant TRAIL in cancer therapeutics. The present data from azoxymethane-initiated, dextran sulfate sodium-promoted colitis associated cancer (CAC) model strongly indicate the potential of rTRAIL in cancer prevention rather than in cancer therapeutics. Early treatment of rTRAIL significantly reduced colitis and CAC by inhibiting the recruitment of macrophages into the damaged mucosa and activating the scavenger activity with efferocytosis and the production of several growth factors. In contrast, late administration of rTRAIL as for anti-cancer effect did not decrease the initiation and development of CAC at all. Significant cancer preventing mechanisms of rTRAIL were identified. In the CAC model, anti-inflammation, regeneration, and efferocytosis was induced by treatment of TRAIL for 6 days, significant inhibitory activity was evident at 4 weeks and anti-oxidative and anti-inflammatory induction were noted at 12 weeks. Most importantly, TRAIL promoted tissue regeneration by enhancing the resolution of pathological inflammation through the activation of the NLRP3 inflammasome pathway. The results indicate that TRAIL reduces the induction of colitis and the initiation of CAC by inhibiting pro-inflammatory signaling and promoting tissue repair to maintain intestinal homeostasis through activation of the NLRP3 inflammasome. Therefore, TRAIL can be used as a chemopreventive agent against CAC, rather than as a therapeutic drug endowing apoptosis.

Apoptosis signaling and BCL-2 pathways provide opportunities for novel targeted therapeutic strategies in hematologic malignances

Apoptosis is an essential biological process involved in tissue homeostasis and immunity. Aberrations of the two main apoptotic pathways, extrinsic and intrinsic, have been identified in hematological malignancies; many of these aberrations are associated with pathogenesis, prognosis and resistance to standard chemotherapeutic agents. Targeting components of the apoptotic pathways, especially the chief regulatory BCL-2 family in the intrinsic pathway, has proved to be a promising therapeutic approach for patients with hematological malignances, with the expectation of enhanced efficacy and reduced adverse events. Continuous investigations regarding the biological importance of each of the BCL-2 family components and the clinical rationale to achieve optimal therapeutic outcomes, using either monotherapy or in combination with other targeted agents, have generated inspiring progress in the field. Genomic, epigenomic and biological analyses including BH3 profiling facilitate effective evaluation of treatment response, cancer recurrence and drug resistance. In this review, we summarize the biological features of each of the components in the BCL-2 apoptotic pathways, analyze the regulatory mechanisms and the pivotal roles of BCL-2 family members in the pathogenesis of major types of hematologic malignances, and evaluate the potential of apoptosis- and BCL-2-targeted strategies as effective approaches in anti-cancer therapies.

Antibody-Based Cancer Therapy: Successful Agents and Novel Approaches

Since their discovery, antibodies have been viewed as ideal candidates or "magic bullets" for use in targeted therapy in the fields of cancer, autoimmunity, and chronic inflammatory disorders. A wave of antibody-dedicated research followed, which resulted in the clinical approval of a first generation of monoclonal antibodies for cancer therapy such as rituximab (1997) and cetuximab (2004), and infliximab (2002) for the treatment of autoimmune diseases. More recently, the development of antibodies that prevent checkpoint-mediated inhibition of T cell responses invigorated the field of cancer immunotherapy. Such antibodies induced unprecedented long-term remissions in patients with advanced stage malignancies, most notably melanoma and lung cancer, that do not respond to conventional therapies. In this review, we will recapitulate the development of antibody-based therapy, and detail recent advances and new functions, particularly in the field of cancer immunotherapy. With the advent of recombinant DNA engineering, a number of rationally designed molecular formats of antibodies and antibody-derived agents have become available, and we will discuss various molecular formats including antibodies with improved effector functions, bispecific antibodies, antibody-drug conjugates, antibody-cytokine fusion proteins, and T cells genetically modified with chimeric antigen receptors. With these exciting advances, new antibody-based treatment options will likely enter clinical practice and pave the way toward more successful control of malignant diseases.

Systems pharmacology and enhanced pharmacodynamic models for understanding antibody-based drug action and toxicity

Pharmacokinetic (PK) and pharmacodynamic (PD) models seek to describe the temporal pattern of drug exposures and their associated pharmacological effects produced at micro- and macro-scales of organization. Antibody-based drugs have been developed for a large variety of diseases, with effects exhibited through a comprehensive range of mechanisms of action. Mechanism-based PK/PD and systems pharmacology models can play a major role in elucidating and integrating complex antibody pharmacological properties, such as nonlinear disposition and dynamical intracellular signaling pathways triggered by ligation to their cognate targets. Such complexities can be addressed through the use of robust computational modeling techniques that have proven powerful tools for pragmatic characterization of experimental data and for theoretical exploration of antibody efficacy and adverse effects. The primary objectives of such multi-scale mathematical models are to generate and test competing hypotheses and to predict clinical outcomes. In this review, relevant systems pharmacology and enhanced PD (ePD) models that are used as predictive tools for antibody-based drug action are reported. Their common conceptual features are highlighted, along with approaches used for modeling preclinical and clinically available data. Key examples illustrate how systems pharmacology and ePD models codify the interplay among complex biology, drug concentrations, and pharmacological effects. New hybrid modeling concepts that bridge cutting-edge systems pharmacology models with established PK/ePD models will be needed to anticipate antibody effects on disease in subpopulations and individual 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.

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.

TRAIL causes deletions at the HPRT and TK1 loci of clonogenically competent cells

When chemotherapy and radiotherapy are effective, they function by inducing DNA damage in cancerous cells, which respond by undergoing apoptosis. Some adverse effects can result from collateral destruction of non-cancerous cells, via the same mechanism. Therapy-related cancers, a particularly serious adverse effect of anti-cancer treatments, develop due to oncogenic mutations created in non-cancerous cells by the DNA damaging therapies used to eliminate the original cancer. Physiologically achievable concentrations of direct apoptosis inducing anti-cancer drugs that target Bcl-2 and IAP proteins possess negligible mutagenic activity, however death receptor agonists like TRAIL/Apo2L can provoke mutations in surviving cells, probably via caspase-mediated activation of the nuclease CAD. In this study we compared the types of mutations sustained in the HPRT and TK1 loci of clonogenically competent cells following treatment with TRAIL or the alkylating agent ethyl methanesulfonate (EMS). As expected, the loss-of-function mutations in the HPRT or TK1 loci triggered by exposure to EMS were almost all transitions. In contrast, only a minority of the mutations identified in TRAIL-treated clones lacking HPRT or TK1 activity were substitutions. Almost three quarters of the TRAIL-induced mutations were partial or complete deletions of the HPRT or TK1 genes, consistent with sub-lethal TRAIL treatment provoking double strand breaks, which may be mis-repaired by non-homologous end joining (NHEJ). Mis-repair of double-strand breaks following exposure to chemotherapy drugs has been implicated in the pathogenesis of therapy-related cancers. These data suggest that TRAIL too may provoke oncogenic damage to the genomes of surviving cells.

ONC201 induces cell death in pediatric non-Hodgkin's lymphoma cells

ONC201/TIC10 is a small molecule initially discovered by its ability to coordinately induce and activate the TRAIL pathway selectively in tumor cells and has recently entered clinical trials in adult advanced cancers. The anti-tumor activity of ONC201 has previously been demonstrated in several preclinical models of cancer, including refractory solid tumors and a transgenic lymphoma mouse model. Based on the need for new safe and effective therapies in pediatric non-Hodgkin's lymphoma (NHL) and the non-toxic preclinical profile of ONC201, we investigated the in vitro efficacy of ONC201 in non-Hodgkin's lymphoma (NHL) cell lines to evaluate its therapeutic potential for this disease. ONC201 caused a dose-dependent reduction in the cell viability of NHL cell lines that resulted from induction of apoptosis. As expected from prior observations, induction of TRAIL and its receptor DR5 was also observed in these cell lines. Furthermore, dual induction of TRAIL and DR5 appeared to drive the observed apoptosis and TRAIL expression was correlated linearly with sub-G1 DNA content, suggesting its potential role as a biomarker of tumor response to ONC201-treated lymphoma cells. We further investigated combinations of ONC201 with approved chemotherapeutic agents used to treat lymphoma. ONC201 exhibited synergy in combination with the anti-metabolic agent cytarabine in vitro, in addition to cooperating with other therapies. Together these findings indicate that ONC201 is an effective TRAIL pathway-inducer as a monoagent that can be combined with chemotherapy to enhance therapeutic responses in pediatric NHL.

Dulanermin with rituximab in patients with relapsed indolent B-cell lymphoma: an open-label phase 1b/2 randomised study

BACKGROUND

Dulanermin-a non-polyhistidine-tagged soluble recombinant human apoptosis ligand 2 (Apo2L) or tumour-necrosis-factor-related apoptosis-inducing-ligand (TRAIL)-has pro-apoptotic activity in a range of cancers and synergistic preclinical activity with rituximab against lymphoma in vivo. We aimed to assess the safety, pharmacokinetics, and efficacy of dulanermin and rituximab in patients with relapsed indolent B-cell non-Hodgkin lymphoma.

METHODS

We did an open-label phase 1b/2 randomised study. Four study centres in the USA enrolled patients into phase 1b, and 27 study centres in the USA, Italy, Australia, France, Czech Republic, New Zealand, and Poland enrolled patients into phase 2. In phase 1b, patients (age ≥18 years) with indolent B-cell non-Hodgkin lymphoma with stable disease or better lasting at least 6 months after the most recent rituximab-containing regimen were included. In phase 2, patients (age ≥18 years) with follicular lymphoma grades 1-3a were included. In phase 1b, patients received 4 mg/kg or 8 mg/kg intravenous dulanermin on days 1-5 of up to four 21-day cycles and intravenous rituximab 375 mg/m(2) weekly for up to eight doses. In phase 2, patients were randomly assigned (1:1:1) centrally by an interactive voice response system to dulanermin (8 mg/kg for a maximum of four 21-day cycles), rituximab (375 mg/m(2) weekly for up to eight doses), or both in combination, stratified by baseline follicular lymphoma International Prognostic Index (0-3 vs 4-5) and geographic site (USA vs non-USA). The primary endpoints of the phase 1b study were the safety, tolerability, and pharmacokinetics of dulanermin with rituximab. The primary endpoint of phase 2 was the proportion of patients who achieved an objective response. All patients who received any dose of study drug were included in safety analyses. Efficacy analyses were per protocol. Treatment was open label; all patients and investigators were unmasked to treatment allocation. This study is registered with ClinicalTrials.gov, NCT00400764.

FINDINGS

Between June 6, 2006, and Feb 15, 2007, 12 patients were enrolled in phase 1b, and between April 4, 2007, and April 20, 2009, 60 patients were enrolled in phase 2, of whom 59 were included in safety analyses and 58 in efficacy analyses. No dose-limiting toxic effects were noted in phase 1b. The most common grade 1-2 adverse events in phase 1b were fatigue (nine; 75%), rash (five; 42%), and chills, decreased appetite, diarrhoea, and nausea (four each; 33%). 19 grade 3 or higher adverse effects were noted in five (42%) patients, with 14 occurring in one patient. After treatment with 8 mg/kg of dulanermin, in six patients the mean serum peak concentration was 80 μg/mL, dropping below the minimum detectable concentration (2 ng/mL) within 24 h after the dose. The mean steady state peak and trough concentrations of rituximab were 461 μg/mL (SD 97.5) and 303 μg/mL (92.8), respectively. In phase 2, eight (14%) of 59 patients experienced 12 grade 3 or higher adverse events. In phase 2, objective responses were noted in 14 of 22 (63.6%, 95% CI 41.8-81.3) patients treated with rituximab only, 16 of 25 (64.0%, 43.1-81.5) treated with dulanermin and rituximab, and one of 11 (9.1%, 0.5-39.0) treated with dulanermin only. The study was terminated early, on May 5, 2010, because of an absence of efficacy in the combination group.

INTERPRETATION

The addition of dulanermin to rituximab in patients with indolent B-cell non-Hodgkin lymphoma was tolerable but did not lead to increased objective responses. This combination is not being developed further in non-Hodgkin lymphoma.

FUNDING

Genentech and Amgen.

Postulated mechanisms of resistance of B-cell non-Hodgkin lymphoma to rituximab treatment regimens: strategies to overcome resistance

Antibody-mediated immunotherapy has gained significant momentum since 1997 when the US Food and Drug Administration approved the first monoclonal antibody (mAb) for the treatment of B-cell non-Hodgkin lymphoma (B-NHL), namely, rituximab (chimeric anti-CD20 mAb). Subsequently, more than 20 approved mAbs have been in use clinically for the treatment of various cancers and several non-cancer-related diseases. Further, the combination treatment of mAbs with chemotherapy, immunotherapy, proteaosome inhibitors, and other inhibitors has resulted in synergistic anti-tumor activity with significant objective clinical responses. Despite their successful clinical use, the underlying mechanisms of rituximab's in vivo activities remain elusive. Further, it is not clear why a subset of patients is initially unresponsive and many responding patients become refractory and resistant to further treatments; hence, the underlying mechanisms of resistance are not known, Attempts have been made to develop model systems to investigate resistance to mAb therapy with the hope to apply the findings in both the generation of new therapeutics and in their use as new prognostic biomarkers. This review focuses on the development of resistance to rituximab treatments and discusses possible underlying mechanisms of action, postulated mechanisms of resistance in model systems, and suggested means to overcome resistance. Several prior reviews on the subject of rituximab resistance have been published and the present review both complements as well as adds new topics of relevance.

Targeting the apoptosis pathway in hematologic malignancies

Apoptosis is a cell death program that is well-orchestrated for normal tissue homeostasis and for removal of damaged, old or infected cells. It is regulated by intrinsic and extrinsic pathways. The intrinsic pathway responds to signals such as ultraviolet radiation or DNA damage and activates "executioner" caspases through a mitochondria-dependent pathway. The extrinsic pathway is activated by death signals induced, for example, by an infection that activates the immune system or receptor-mediated pathways. The extrinsic pathway signals also cascade down to executioner caspases that cleave target proteins and lead to cell death. Strict control of cellular apoptosis is important for the hematopoietic system as it has a high turnover rate. However, the apoptosis program is often deregulated in hematologic malignancies leading to the accumulation of malignant cells. Therefore, apoptosis pathways have been identified for the development of anticancer therapeutics. We review here the proteins that have been targeted for anticancer drug development in hematologic malignancies. These include BCL-2 family proteins, death ligands and receptors, inhibitor of apoptosis family proteins and caspases. Except for caspase activators, drugs that target each of these classes of proteins have advanced into clinical trials.

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.

Death receptor agonist therapies for cancer, which is the right TRAIL?

The activation of cell-surface death receptors represents an attractive therapeutic strategy to promote apoptosis of tumor cells. Several investigational therapeutics that target this extrinsic pathway, including recombinant human Apo2L/TRAIL and monoclonal agonist antibodies directed against death receptors-4 (DR4) or -5 (DR5), have been evaluated in the clinic. Although Phase 1/1b studies provided encouraging preliminary results, findings from randomized Phase 2 studies failed to demonstrate significant clinical benefit. This has raised multiple questions as to why pre-clinical data were not predictive of clinical response. Results from clinical studies and insight into why current agents have failed to yield robust responses are discussed. In addition, new strategies for the development of next generation death receptor agonists are reviewed.

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.

Levels of murine, but not human, CXCL13 are greatly elevated in NOD-SCID mice bearing the AIDS-associated Burkitt lymphoma cell line, 2F7

Currently, few rodent models of AIDS-associated non-Hodgkin’s lymphoma (AIDS-NHL) exist. In these studies, a novel mouse/human xenograft model of AIDS-associated Burkitt lymphoma (AIDS-BL) was created by injecting cells of the human AIDS-BL cell line, 2F7, intraperitoneally into NOD-SCID mice. Mice developed tumors in the peritoneal cavity, with metastases to the spleen, thymus, and mesenteric lymph nodes. Expression of the chemokine receptor, CXCR5, was greatly elevated in vivo on BL tumor cells in this model, as shown by flow cytometry. CXCL13 is the ligand for CXCR5, and serum and ascites levels of murine, but not human, CXCL13 showed a striking elevation in tumor-bearing mice, with levels as high as 200,000 pg/ml in ascites, as measured by ELISA. As shown by immunohistochemistry, murine CXCL13 was associated with macrophage-like tumor-infiltrating cells that appeared to be histiocytes. Blocking CXCR5 on 2F7 cells with neutralizing antibodies prior to injection into the mice substantially delayed tumor formation. The marked elevations in tumor cell CXCR5 expression and in murine CXCL13 levels seen in the model may potentially identify an important link between tumor-interacting histiocytes and tumor cells in AIDS-BL. These results also identify CXCL13 as a potential biomarker for this disease, which is consistent with previous studies showing that serum levels of CXCL13 were elevated in human subjects who developed AIDS-lymphoma. This mouse model may be useful for future studies on the interactions of the innate immune system and AIDS-BL tumor cells, as well as for the assessment of potential tumor biomarkers for this disease.

Targeting of the tumor necrosis factor receptor superfamily for cancer immunotherapy

The tumor necrosis factor (TNF) ligand and cognate TNF receptor superfamilies constitute an important regulatory axis that is pivotal for immune homeostasis and correct execution of immune responses. TNF ligands and receptors are involved in diverse biological processes ranging from the selective induction of cell death in potentially dangerous and superfluous cells to providing costimulatory signals that help mount an effective immune response. This diverse and important regulatory role in immunity has sparked great interest in the development of TNFL/TNFR-targeted cancer immunotherapeutics. In this review, I will discuss the biology of the most prominent proapoptotic and co-stimulatory TNF ligands and review their current status in cancer immunotherapy.

Effects of interleukin-18 on natural killer cells: costimulation of activation through Fc receptors for immunoglobulin

The antitumor activity of monoclonal antibodies is mediated by effector cells, such as natural killer (NK) cells, that express Fc receptors for immunoglobulin. Efficacy of monoclonal antibodies, including the CD20 antibody rituximab, could be improved by agents that augment the function of NK cells. Interleukin (IL)-18 is an immunostimulatory cytokine that has antitumor activity in preclinical models. The effects of IL-18 on NK cell function mediated through Fcγ receptors were examined. Human NK cells stimulated with immobilized IgG in vitro secreted IFN-γ as expected; such IFN-γ production was partially inhibited by blocking CD16 with monoclonal antibodies. IL-18 augmented IFN-γ production by NK cells stimulated with immobilized IgG or CD16 antibodies. NK cell IFN-γ production in response to immobilized IgG and/or IL-18 was inhibited by chemical inhibitors of Syk and several other kinases involved in CD16 signaling pathways. IL-18 augmented antibody-dependent cellular cytotoxicity (ADCC) of human NK cells against rituximab-coated Raji cells in vitro. IL-18 and rituximab acted synergistically to promote regression of human lymphoma xenografts in SCID mice. Inasmuch as IL-18 costimulates IFN-γ production and ADCC of NK cells activated through Fc receptors in vitro and augments antitumor activity of rituximab in vivo, it is an attractive cytokine to combine with monoclonal antibodies for treatment of human cancer.

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.

Liposomes decorated with Apo2L/TRAIL overcome chemoresistance of human hematologic tumor cells

Human Apo2-ligand/TRAIL is a member of the TNF cytokine superfamily capable of inducing apoptosis on tumor cells while sparing normal cells. Besides its antitumor activity, Apo2L/TRAIL is also implicated in immune regulation. Apo2L/TRAIL is stored inside activated T cells in cytoplasmic multivesicular bodies and is physiologically released to the extracellular medium inserted in the internal membrane vesicles, known as exosomes. In this study we have generated artificial lipid vesicles coated with bioactive Apo2L/TRAIL, which resemble natural exosomes, to analyze their apoptosis-inducing ability on cell lines from hematological tumors. We have tethered Apo2L/TRAIL to lipid vesicles by using a novel Ni(2+)-(N-5-amino-1-carboxylpentyl)-iminodiacetic acid, NTA)-containing liposomal system. This lipidic framework (LUVs-Apo2L/TRAIL) greatly improves Apo2L/TRAIL activity, decreasing by around 14-fold the LC50 on the T-cell leukemia Jurkat. This increase in bioactivity correlated with the greater ability of LUVs-Apo2L/TRAIL to induce caspase-3 activation and is probably due to the increase in local concentration of Apo2L/TRAIL, improving its receptor cross-linking efficiency. More important, liposome-bound Apo2L/TRAIL overcame the resistance to soluble recombinant Apo2L/TRAIL exhibited by tumor cell mutants overexpressing Bcl-xL or by a Bax and Bak-defective Jurkat cell mutant (Jurkat-shBak) and are also effective against other hematologic tumor cells. Jurkat-Bcl-xL and Jurkat-shBak cells are resistant to most chemotherapeutic drugs currently used in cancer treatment, and their sensitivity to LUVs-Apo2L/TRAIL could have potential clinical applications.

Intracellular-signaling tumor-regression modeling of the pro-apoptotic receptor agonists dulanermin and conatumumab

Dulanermin (rhApo2L/TRAIL) and conatumumab bind to transmembrane death receptors and trigger the extrinsic cellular apoptotic pathway through a caspase-signaling cascade resulting in cell death. Tumor size time series data from rodent tumor xenograft (COLO205) studies following administration of either of these two pro-apoptotic receptor agonists (PARAs) were combined to develop a intracellular-signaling tumor-regression model that includes two levels of signaling: upstream signals unique to each compound (representing initiator caspases), and a common downstream apoptosis signal (representing executioner caspases) shared by the two agents. Pharmacokinetic (PK) models for each drug were developed based on plasma concentration data following intravenous and/or intraperitoneal administration of the compounds and were used in the subsequent intracellular-signaling tumor-regression modeling. A model relating the PK of the two PARAs to their respective and common downstream signals, and to the resulting tumor burden was developed using mouse xenograft tumor size measurements from 448 experiments that included a wide range of dose sizes and dosing schedules. Incorporation of a pro-survival signal--consistent with the hypothesis that PARAs may also result in the upregulation of pro-survival factors that can lead to a reduction in effectiveness of PARAs with treatment--resulted in improved predictions of tumor volume data, especially for data from the long-term dosing experiments.

TGF-β-induced apoptosis of B-cell lymphoma Ramos cells through reduction of MS4A1/CD20

Transforming growth factor-β (TGF-β) exhibits growth inhibitory effects on various types of tumor cells, including B-cell lymphoma cells. In the present study, the role of TGF-β in the survival of Epstein-Barr virus-negative B-cell lymphoma Ramos cells was investigated. As TGF-β-induced apoptosis of Ramos cells in vitro and in vivo, we attempted to identify novel target gene(s) responsible for their survival. Oligonucleotide microarray analysis and chromatin immunoprecipitation revealed that Smad proteins directly regulated the transcription of membrane-spanning 4-domains, subfamily A, member 1 (MS4A1), also known as CD20, in Ramos cells upon TGF-β stimulation. In addition, immunohistochemical analysis using clinical samples from B-cell lymphoma patients showed an inverse correlation between the expression of MS4A1/CD20 and phosphorylation of Smad3. Although knockdown of MS4A1/CD20 in Ramos cells resulted in an increase of apoptotic cells, Ramos cells stably expressing MS4A1/CD20 were resistant to TGF-β-induced apoptosis. This suggests that MS4A1/CD20 is responsible for TGF-β-induced apoptosis of B-cell lymphoma cells. Moreover, downregulation of MS4A1/CD20 by TGF-β attenuated the effects of the monoclonal anti-MS4A1/CD20 antibody, rituximab, on Ramos cells. Our findings suggest that the sensitivity of B-cell lymphoma cells to rituximab may be affected by TGF-β signaling.

Combinatorial chemotherapeutic efficacy in non-Hodgkin lymphoma can be predicted by a signaling model of CD20 pharmacodynamics

Combination chemotherapy represents the standard-of-care for non-Hodgkin lymphoma. However, the development of new therapeutic regimens is empirical and this approach cannot be used prospectively to identify novel or optimal drug combinations. Quantitative system pharmacodynamic models could promote the discovery and development of combination regimens based upon first principles. In this study, we developed a mathematical model that integrates temporal patterns of drug exposure, receptor occupancy, and signal transduction to predict the effects of the CD20 agonist rituximab in combination with rhApo2L/TNF-related apoptosis inducing ligand or fenretinide, a cytotoxic retinoid, upon growth kinetics in non-Hodgkin lymphoma xenografts. The model recapitulated major regulatory mechanisms, including target-mediated disposition of rituximab, modulation of proapoptotic intracellular signaling induced by CD20 occupancy, and the relative efficacy of death receptor isoforms. The multiscale model coupled tumor responses to individual anticancer agents with their mechanisms of action in vivo, and the changes in Bcl-xL and Fas induced by CD20 occupancy were linked to explain the synergy of these drugs. Tumor growth profiles predicted by the model agreed with cell and xenograft data, capturing the apparent pharmacologic synergy of these agents with fidelity. Together, our findings provide a mechanism-based platform for exploring new regimens with CD20 agonists.

Murine models of B-cell lymphomas: promising tools for designing cancer therapies

Human B-cell lymphomas, the fourth most common hematologic malignancy, are currently the subject of extensive research. The limited accessibility of biopsies, the heterogeneity among patients, and the subtypes of lymphomas have necessitated the development of animal models to decipher immune escape mechanisms and design new therapies. Here, we summarize the cell lines and murine models used to study lymphomagenesis, the lymphoma microenvironment, and the efficacy of new therapies. These data allow us to understand the role of the immune system in the fight against tumors. Exploring the advantages and limitations of immunocompetent versus immunodeficient models improves our understanding of the molecular and cellular mechanisms of tumor genesis and development as well as the fundamental processes governing the interaction of tumors and their host tissues. We posit that these basic preclinical investigations will open up new and promising approaches to designing better therapies.

Update on novel monoclonal antibodies and immunoconjugates for the treatment of lymphoproliferative disorders

The year 1997 was pivotal in lymphoma research, as it was the year that the US FDA approved rituximab. Rituximab significantly altered clinical management and outcomes of patients with B-cell malignancies. Despite a high initial response rate, the majority of patients subsequently develop variable degrees of therapeutic resistance to rituximab. Research attempting to understand the mechanisms of rituximab resistance and potential ways to overcome them has given rise to the development of novel targeted immunotherapeutics. This article will update the readers on advances in bioengineering of monoclonal antibodies and immunoconjugates that target CD20, as well as other surface antigens. Some additional novel immunotherapeutics, including small modular immunopharmaceuticals, bispecific monoclonal antibodies, T-cell engaging antibodies and immunoconjugates, will also be discussed.

Direct Effect of Rituximab in B-Cell–Derived Lymphoid Neoplasias: Mechanism, Regulation, and Perspectives

The anti-CD20 monoclonal antibody rituximab is the backbone of treatment for the B-cell malignancies non-Hodgkin lymphoma and chronic lymphocytic leukemia. However, there is a wide variability in response to rituximab treatment, and some patients are refractory to current standard therapies. Rituximab kills B cells by multiple mechanisms of action, including complement-dependent cytotoxicity and antibody-dependent cellular cytotoxicity, which are immune-mediated mechanisms, as well as by direct effects on cell signaling pathways and cell membranes following CD20 binding. A large number of events that are affected by rituximab binding have been identified, including lipid raft modifications, kinase and caspase activation, and effects on transcription factors and apoptotic/antiapoptotic molecules. Studies on cell lines and isolated tumor cells have shown that by targeting these pathways, it may be possible to increase or decrease susceptibility to rituximab cell killing. An increased understanding of the direct effects of rituximab may therefore aid in the design of new, rational combinations to improve the outcome of CD20-based therapy for patients who currently have suboptimal outcome following standard treatments. Mol Cancer Res; 9(11); 1435–42. ©2011 AACR.

Preclinical studies on the mechanism of action and the anti-lymphoma activity of the novel anti-CD20 antibody GA101

GA101 is a novel glycoengineered Type II CD20 monoclonal antibody. When compared with rituximab, it mediates less complement-dependent cytotoxicity (CDC). As expected for a Type II antibody, GA101 appears not to act through CDC and is more potent than the Type I antibody rituximab in inducing cell death via nonclassical induction of apoptosis cytotoxicity, with more direct cytotoxicity and more antibody-dependent cell-mediated cytotoxicity. We evaluated the antitumor activity of GA101 against the human-transformed follicular lymphoma RL model in vivo in severe combined immunodeficient mice (SCID) mice. GA101 induced stronger inhibition of tumor growth than rituximab. Combination of GA101 with cyclophosphamide in vivo confirmed the superiority of GA101 over rituximab. Neutralizing the complement system with cobra venom factor partially impaired the antitumor activity of rituximab, but had no impact on the efficacy of GA101. In vitro GA101 more potently induced cell death of RL cells than rituximab. The expression of a limited number of genes was found to be induced by both antibodies after exposure in vitro. Among these, early growth response 1 and activation transcription factor 3 were confirmed to be increased at the protein level, suggesting a possible role of these proteins in the apoptotic signalling of anti-CD20 antibodies. These data imply that GA101 is superior to rituximab not only as a single agent, but also in combination with chemotherapy. These data suggest the presence of novel signalization pathways activated after exposure to anti-CD20 antibodies.

Emerging antibody combinations in oncology

The use of monoclonal antibodies (mAbs) has become a general approach for specifically targeting and treating human disease. In oncology, the therapeutic utility of mAbs is usually evaluated in the context of treatment with standard of care, as well as other small molecule targeted therapies. Many anti-cancer antibody modalities have achieved validation, including the targeting of growth factor and angiogenesis pathways, the induction of tumor cell killing or apoptosis, and the blocking of immune inhibitory mechanisms to stimulate anti-tumor responses. But, as with other targeted therapies, few antibodies are curative because of biological complexities that underlie tumor formation and redundancies in molecular pathways that enable tumors to adapt and show resistance to treatment. This review discusses the combinations of antibody therapeutics that are emerging to improve efficacy and durability within a specific biological mechanism (e.g., immunomodulation or the inhibition of angiogenesis) and across multiple biological pathways (e.g., inhibition of tumor growth and induction of tumor cell apoptosis).

Targeting apoptosis proteins in hematological malignancies

The apoptotic machinery plays a key role in hematopoietic cell homeostasis. Terminally differentiated cells are eliminated, at least in part, by apoptosis, whereas part of the apoptotic machinery, including one or several caspases, is required to go through very specific steps of the differentiation pathways. A number of hematological diseases involve a deregulation of this machinery, which in most cases is a decrease in cell sensitivity to pro-apoptotic signals through over-expression of anti-apoptotic molecules. In some situations however, e.g. in the erythroid lineage of low grade myelodysplastic syndromes, cell sensitivity to apoptosis is increased in a death receptor-dependent manner and cell death pathways are inhibited only when these diseases progress into high grade and acute leukemia. Therapeutic strategies targeting the apoptotic machinery specifically block cell death inhibitors that are over-expressed in transformed cells, mainly Bcl-2-related proteins and Inhibitor of Apoptosis Proteins (IAPs). Another strategy is the activation of the extrinsic pathway to apoptosis, mainly through the death receptor agonist Tumor necrosis factor-Related Apoptosis Inducing Ligand (TRAIL) or agonistic antibodies targeting TRAIL receptors. The use of inhibitors of death receptors could make sense when these receptors are involved in excessive cell death or activation of survival pathways. Most of the drugs targeting apoptotic pathways introduced in clinics have demonstrated their tolerability. Their efficacy, either alone or in combination with other drugs such as demethylating agents and histone deacetylase inhibitors, is currently tested in both myeloid and lymphoid hematological diseases.

Novel antibodies against follicular non-Hodgkin's lymphoma

The anti-CD20 monoclonal antibody rituximab has revolutionized the treatment of patients with follicular B-cell lymphoma. With the combination of chemotherapy and rituximab the overall survival rate has increased with approximately 30%. Unfortunately, there is resistance to rituximab with relapse of the disease in about 60% of the patients during the first five years of treatment and eventually in all patients. To this end, there is a need to develop improved anti-CD20 monoclonal antibodies and antibodies that target other attractive molecules expressed on the follicular lymphoma cell. This review describes the development and clinical achievements so far of next generation anti-CD20 and other antibodies in the treatment of follicular B-cell lymphoma.

A potential mechanism of rituximab-induced inhibition of tumor growth through its sensitization to tumor necrosis factor-related apoptosis-inducing ligand-expressing host cytotoxic cells

Rituximab (anti-CD20 mAb) mediates antibody-dependent cell-mediated cytotoxicity (ADCC), complement-dependent cytotoxicity (CDC), and apoptosis in B-NHL cells. The contribution of other host-mediated cytotoxic effects has not been examined. The expression of death-inducing ligands (e.g. TRAIL) by host effector cells may contribute to the mechanism of tumor cell destruction in vivo by rituximab-mediated sensitization of resistant B-cell non-Hodgkin lymphoma (B-NHL) cells. We have examined the sensitizing activity of rituximab on B-NHL cell lines resistant to TRAIL (as model) and natural killer (NK)-induced apoptosis. Treatment of TRAIL-resistant B-NHL cell lines with rituximab sensitized the cells to TRAIL apoptosis and synergy was achieved via activation of the type II mitochondrial pathway for apoptosis. Further, rituximab (Fab')(2)-treated tumor cells were killed by purified peripheral blood-derived NK cells via TRAIL. Treatment of B-NHL cells with rituximab inhibited both YY1 DNA-binding activity and expression. Rituximab-mediated sensitization to TRAIL apoptosis was due, in large part, to rituximab-mediated inhibition of the transcription factor Yin Yang 1 (YY1). The direct role of YY1 in TRAIL sensitization by rituximab was shown in cells transfected with YY1 siRNA, and such cells mimicked rituximab and became sensitive to TRAIL-induced apoptosis. These data suggest that, in vivo, host effector cells expressing TRAIL may contribute to rituximab-mediated depletion of B-NHL cells.

Anti-CD47 antibody synergizes with rituximab to promote phagocytosis and eradicate non-Hodgkin lymphoma

Monoclonal antibodies are standard therapeutics for several cancers including the anti-CD20 antibody rituximab for B cell non-Hodgkin lymphoma (NHL). Rituximab and other antibodies are not curative and must be combined with cytotoxic chemotherapy for clinical benefit. Here we report the eradication of human NHL solely with a monoclonal antibody therapy combining rituximab with a blocking anti-CD47 antibody. We identified increased expression of CD47 on human NHL cells and determined that higher CD47 expression independently predicted adverse clinical outcomes in multiple NHL subtypes. Blocking anti-CD47 antibodies preferentially enabled phagocytosis of NHL cells and synergized with rituximab. Treatment of human NHL-engrafted mice with anti-CD47 antibody reduced lymphoma burden and improved survival, while combination treatment with rituximab led to elimination of lymphoma and cure. These antibodies synergized through a mechanism combining Fc receptor (FcR)-dependent and FcR-independent stimulation of phagocytosis that might be applicable to many other cancers.

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.

Targeted therapies in cancer

Recent advances in understanding the biologic mechanisms underlying cancer development have driven the design of new therapeutic approaches, termed 'targeted therapies', that selectively interfere with molecules or pathways involved in tumor growth and progression. Inactivation of growth factors and their receptors on tumor cells as well as the inhibition of oncogenic tyrosine kinase pathways and the inhibition of molecules that control specific functions in cancer cells constitute the main rational bases of new cancer treatments tailored for individual patients. Small-molecule inhibitors and monoclonal antibodies are major components of these targeted approaches for a number of human malignancies. As the studies of the bio-molecular features of cancer progress, new exciting strategies have arisen, such as targeting cancer stem cells that drive tumor relapses or the selective induction of apoptosis in malignant cells. This article primarily focuses on the biologic bases of the new cancer drugs and summarizes their mechanisms of action, the clinical evidence of their anti-cancer effectiveness as well as the rationale for their use in clinical practice.

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.

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.

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.