A patch of positively charged residues regulates the efficacy of clinical DR5 antibodies in solid tumors

Receptor clustering is the first and critical step to activate apoptosis by death receptor-5 (DR5). The recent discovery of the autoinhibitory DR5 ectodomain has challenged the long-standing view of its mechanistic activation by the natural ligand Apo2L. Because the autoinhibitory residues have remained unknown, here we characterize a crucial patch of positively charged residues (PPCR) in the highly variable domain of DR5. The PPCR electrostatically separates DR5 receptors to autoinhibit their clustering in the absence of ligand and antibody binding. Mutational substitution and antibody-mediated PPCR interference resulted in increased apoptotic cytotoxic function. A dually specific antibody that enables sustained tampering with PPCR function exceptionally enhanced DR5 clustering and apoptotic activation and distinctively improved the survival of animals bearing aggressive metastatic and recurrent tumors, whereas clinically tested DR5 antibodies without PPCR blockade function were largely ineffective. Our study provides mechanistic insights into DR5 activation and a therapeutic analytical design for potential clinical success.

Perspective of clinical research in follicular NHL: interaction between science and industry

Despite advancements in the treatment of follicular lymphoma (FL), curative therapy remains an elusive unmet medical need. Improvements in progression-free survival result in new logistical and financial challenges to clinical investigation and drug development in this indolent disease. Surrogate endpoints that utilize imaging and sensitive markers of treatment effect may serve to address this problem. Additionally, alternative trial designs may help to bypass some of the logistical hurdles.

TRAIL receptor signaling and therapeutics

IMPORTANCE OF THE FIELD

TNF-related apoptosis-inducing ligand (TRAIL) is a member of the TNF family of cytokines, which can induce apoptotic cell death in a variety of tumor cells by engaging specific death receptors, TRAIL-R1 and TRAIL-R2, while having low toxicity towards normal cells. There is interest in cancer therapy inducing cell death by activation of the death-receptor-mediated apoptotic pathway while avoiding decoy-receptor-mediated neutralization of the signal. This has led to the development of a number of receptor-specific TRAIL-variants and agonistic antibodies. Some of these soluble recombinant TRAIL and agonist antibodies targeting TRAIL-R1 and/or TRAIL-R2 are progressing in clinical trials. In addition, TRAIL-resistant tumors can be sensitized to TRAIL by a combination of TRAIL or agonistic antibodies with chemotherapeutic agents, targeted small molecules or irradiation.

AREAS COVERED IN THIS REVIEW

Recent advances in developing TRAIL or its agonist receptor antibodies in cancer therapy. We also discuss combination therapies in overcoming TRAIL resistance in cancer cells.

WHAT THE READER WILL GAIN

Knowledge of current clinical trials, the promise and obstacles in the future development of therapies affecting TRAIL signaling pathways.

TAKE HOME MESSAGE

Cancer therapeutics targeting the TRAIL/TRAIL receptor signaling pathway hold great promise for molecularly targeted pro-apoptotic anti-cancer therapy.

Outcomes of patients with advanced non-small cell lung cancer treated in a phase I clinic

BACKGROUND

The outcomes of patients with advanced non-small cell lung cancer (NSCLC) treated in phase I clinical trials have not been systematically analyzed.

METHODS

We reviewed the records of consecutive patients with advanced/metastatic NSCLC who were treated in the Phase I Clinical Trials Program at MD Anderson from August 2004 to May 2009.

RESULTS

Eighty-five patients (51 men, 34 women) treated on various phase I protocols were identified. The median age was 62 years (range, 30-85). The median number of previous systemic therapies was two (range, 0-5). A partial response was observed in eight patients (9.5%) and stable disease lasting >4 months was observed in 16 patients (19%). The median overall survival time was 10.6 months and median progression-free survival (PFS) time was 2.8 months, which was 0.6 months shorter than the median PFS of 3.4 months following prior second-line therapy. Factors predicting longer survival in the univariate analysis were an Eastern Cooperative Oncology Group performance status (PS) score of 0-1, no prior smoking, two or fewer organ systems involved, a hemoglobin level ≥ 12 g/dL, liver metastases, a history of thromboembolism, and a platelets count > 440 × 10(9)/L. In the multivariate analysis, a PS score of 0-1 and history negative for smoking predicted longer survival. Sixty-two (73%) patients had grade ≤ 2 toxicity, and there were no treatment-related deaths.

CONCLUSION

Phase I clinical trials were well tolerated by selected patients with advanced NSCLC treated at M.D. Anderson. Nonsmokers and patients with a good PS survived longer. PFS in our population was shorter in smokers/ex-smokers and patients with a PS score of 2. It is reasonable to refer pretreated patients with a good PS to phase I clinical trials.

TNF-related apoptosis-inducing ligand (TRAIL): a new path to anti-cancer therapies

Since its discovery in 1995, tumor necrosis factor-related apoptosis-inducing ligand (TRAIL), a member of the tumor necrosis factor super family, has been under intense focus because of its remarkable ability to induce apoptosis in malignant human cells while leaving normal cells unscathed. Consequently, activation of the apoptotic signaling pathway from the death-inducing TRAIL receptors provides an attractive, biologically-targeted approach to cancer therapy. A great deal of research has focused on deciphering the TRAIL receptor signaling cascade and intracellular regulation of this pathway, as many human tumor cells possess mechanisms of resistance to TRAIL-induced apoptosis. This review focuses on the current state of knowledge regarding TRAIL signaling and resistance, the preclinical development of therapies targeted at TRAIL receptors and modulators of the pathway, and the results of clinical trials for cancer treatment that have emerged from this base of knowledge. TRAIL-based approaches to cancer therapy vary from systemic administration of recombinant, soluble TRAIL protein with or without the combination of traditional chemotherapy, radiation or novel anti-cancer agents to agonistic monoclonal antibodies directed against functional TRAIL receptors to TRAIL gene transfer therapy. A better understanding of TRAIL resistance mechanisms may allow for the development of more effective therapies that exploit this cell-mediated pathway to apoptosis.

Apo2L/TRAIL inhibits tumor growth and bone destruction in a murine model of multiple myeloma

PURPOSE

Multiple myeloma is an incurable disease, for which the development of new therapeutic approaches is required. Here, we report on the efficacy of recombinant soluble Apo2L/tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) to inhibit tumor progression and bone destruction in a xenogeneic model of human multiple myeloma.

EXPERIMENTAL DESIGN

We established a mouse model of myeloma, in which Apo2L/TRAIL-sensitive RPMI-8226 or KMS-11 cells, tagged with a triple reporter gene construct (NES-HSV-TK/GFP/Luc), were transplanted directly into the tibial marrow cavity of nude mice. Tumor burden was monitored progressively by bioluminescence imaging and the development of myeloma-induced osteolysis was measured using high resolution in vivo micro-computed tomography.

RESULTS

Tumor burden increased progressively in the tibial marrow cavity of mice transplanted with Apo2L/TRAIL-sensitive RPMI-8226 or KMS-11 cells associated with extensive osteolysis directly in the area of cancer cell transplantation. Treatment of mice with recombinant soluble Apo2L/TRAIL reduced myeloma burden in the bone marrow cavity and significantly protected against myeloma-induced osteolysis. The protective effects of Apo2L/TRAIL treatment on bone were mediated by the direct apoptotic actions of Apo2L/TRAIL on myeloma cells within the bone microenvironment.

CONCLUSIONS

This is the first in vivo study that investigates the efficacy of recombinant Apo2L/TRAIL on myeloma burden within the bone microenvironment and associated myeloma-induced bone destruction. Our findings that recombinant soluble Apo2L/TRAIL reduces myeloma burden within the bone microenvironment and protects the bone from myeloma-induced bone destruction argue against an inhibitory role of osteoprotegerin in Apo2L/TRAIL-induced apoptosis in vivo and highlight the need to clinically evaluate Apo2L/TRAIL in patients with multiple myeloma.

The TRAIL to targeted therapy of breast cancer

Breast cancers can be classified into those which express the estrogen (ER) and progesterone (PR) receptors, those with HER-2 amplification, and those without expression of ER, PR, or amplified HER-2 (referred to as triple-negative or basal-like breast cancer). Tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) activates apoptosis upon binding to its receptors in many tumor types and the ligand and agonist antibodies are currently being studied in patients in clinical phases I and II trials. Cell line studies suggest that many breast cancer cell lines are very resistant to TRAIL-induced apoptosis. However, recent data suggest that a subset of triple-negative/basal-like breast cancer cells is sensitive to TRAIL as a single agent. In addition, many studies have demonstrated that resistance to TRAIL-mediated apoptosis in breast cancer cells can be overcome by combinations of TRAIL with chemotherapy, radiation, and various targeted agents. This chapter will discuss the current understanding of the mechanisms, which control TRAIL-mediated apoptosis in breast cancer cells. The preclinical data supporting the use of TRAIL ligands and agonistic antibodies alone and in combination in breast cancer will also be discussed.

Death receptors as targets for anti-cancer therapy

Human tumour cells are characterized by their ability to avoid the normal regulatory mechanisms of cell growth, division and death. The classical chemotherapy aims to kill tumour cells by causing DNA damage-induced apoptosis. However, as many tumour cells possess mutations in intracellular apoptosis-sensing molecules like p53, they are not capable of inducing apoptosis on their own and are therefore resistant to chemotherapy. With the discovery of the death receptors the opportunity arose to directly trigger apoptosis from the outside of tumour cells, thereby circumventing chemotherapeutic resistance. Death receptors belong to the tumour necrosis factor receptor superfamily, with tumour necrosis factor (TNF) receptor-1, CD95 and TNF-related apoptosis-inducing ligand-R1 and -R2 being the most prominent members. This review covers the current knowledge about these four death receptors, summarizes pre-clinical approaches engaging these death receptors in anti-cancer therapy and also gives an overview about their application in clinical trials conducted to date.

Chemotherapeutic management of soft tissue sarcoma

Soft tissue sarcomas are a heterogeneous group of connective tissue tumors, with more than 50 different subtypes. Given the heterogeneity, and the relative small numbers of patients, performing large adequately powered clinical trials in which one can glean any overall broad treatment decisions based on outcome is difficult at best. There is controversy on which chemotherapeutic agents to use in the adjuvant and metastatic settings, or even if to use chemotherapy in the adjuvant setting. In the metastatic setting, doxorubicin and ifosfamide have remained the standards of care for more than 20 years. This review discusses the data on chemotherapy for treatment of metastatic sarcomas and the utility of chemotherapy in the adjuvant and neoadjuvant settings. In addition, the utility of newer biologic agents in the treatment for sarcomas is considered.

Identifying breast cancer druggable oncogenic alterations: lessons learned and future targeted options

Although the introduction of novel therapies and drug combinations has improved the prognosis of metastatic breast cancer, this disease remains incurable. It is therefore important to develop additional novel therapeutic strategies and agents. Increased understanding of the biology and the molecular alterations present in breast cancer is facilitating the design of targeted therapies directed to oncogenic proteins. Here, we review the signaling pathways and proteins that participate in breast cancer proliferation and survival, with special emphasis in those that are druggable. We will also comment on how the knowledge on the basic pathogenetic processes is translated into drug development strategies that are reaching the breast cancer clinic.

Targeting the extrinsic apoptosis pathway in cancer

Mutational inactivation of the p53 tumor-suppressor gene, which regulates apoptosis mainly via the cell-intrinsic pathway, reduces the sensitivity of many cancers to conventional treatments. Targeting the cell-extrinsic pathway, which triggers p53-independent apoptosis, offers a unique therapeutic strategy to induce apoptosis in cancer cells. This article focuses on two proapoptotic receptor agonists, recombinant human Apo2-ligand/TNF-related apoptosis-inducing ligand (rhApo2L/TRAIL) and Apomab, which activate death receptor (DR) 4 and/or DR5, thus stimulating the cell-extrinsic pathway. These agents are under investigation for the treatment of solid tumor and hematologic malignancies. Preclinical data indicate that both molecules cause significant regression or growth inhibition of malignant tumors without significant toxicity. Initial data on rhApo2L/TRAIL and Apomab from phase 1 safety trials also confirm that these agents are suitable for further clinical investigation.

TRAIL-receptor antibodies as a potential cancer treatment

Increasing attention has been focused on the use of agonistic monoclonal antibodies against TNF-related apoptosis-inducing ligand (TRAIL) death receptors DR4 or DR5 as a potential cancer treatment. These antibodies have strong apoptosis-inducing activity against cancer cells and potent antitumor activity against tumor xenografts in preclinical models that are enhanced by combination chemotherapy treatment. There are several agonistic humanized or human monoclonal antibodies against DR4 and DR5 that have been tested in Phase I and II trials in patients with advanced cancer. These trials have demonstrated these antibodies to be well tolerated, and to produce prolonged stable disease, which is the best antitumor effect in patients with advanced cancer. Clinical studies in which TRAIL-receptor antibodies are being investigated in combination treatment regimens in patients with advanced cancer are ongoing. It is anticipated that the results from a broad spectrum of cancer therapy clinical trials will identify the activity and toxicity profiles of TRAIL death-receptor antibodies as a single agent, or in combination with chemotherapy agents or radiation therapy.