zibotentan and Bone-Neoplasms

Patients with prostate cancer who have progression of their disease while on androgen deprivation therapy have limited therapeutic options. Docetaxel is currently the only agent that increases overall survival in patients with metastatic, castration-resistant prostate cancer; additional agents are needed.. This review will describe the importance of endothelin-1 (ET-1) for growth of prostate cancer cells, development of bone metastases, and pain responses; the preclinical data for zibotentan, a specific inhibitor of the ET(A) receptor; and the clinical development of atrasentan, a first-generation ET receptor inhibitor, and zibotentan, a more selective inhibitor of the ET(A) receptor.. Readers will understand the importance of ET-1 as a novel pathway to target for patients with castration-resistant prostate cancer due to its association with prostate cancer growth, metastases to bone, and pain. Readers will learn about the preclinical and clinical development of zibotentan, including the promising Phase II results that have resulted in an extensive Phase III clinical trials program.. Modulating the activity of ET-1 through the ET(A) receptor is a novel target for treating patients with metastatic, castration-resistant prostate cancer. There are currently three ongoing Phase III trials with zibotentan, a selective ET(A) inhibitor, to determine the effect of this agent on overall survival in these patients.

Topics: Animals; Antineoplastic Agents; Bone Neoplasms; Clinical Trials as Topic; Disease-Free Survival; Drug Evaluation, Preclinical; Endothelin A Receptor Antagonists; Endothelin-1; Humans; Male; Molecular Structure; Neoplasms, Hormone-Dependent; Orchiectomy; Prostatic Neoplasms; Pyrrolidines

Overexpression of the endothelin A (ET(A)) receptor has been found in a number of human cancer cell lines. Activation of the ET(A) receptor by endothelin-1 (ET-1) promotes cell proliferation and survival in these tumors, whereas activation of the endothelin B (ET(B)) receptor results in an opposing effect. Therefore, blockade of ET(A) may have antitumor effects, while sparing ET(B)-mediated effects such as induction of apoptosis and clearance of ET-1.. ZD4054 is an orally bioavailable, specific ET(A) antagonist currently being investigated in prostate cancer. In receptor-binding studies, ZD4054 only bound to ET(A), with no binding detected towards ET(B). Prostate cancer cell lines are known to produce ET-1 and there is a relative increase in expression of ET(A) to ET(B) in these cancers. There is also an association of greater ET(A) expression in higher grade versus lower grade tumors, suggesting that ET(A) may be involved in the malignant transformation process. As ET-1 may also mediate nociceptive effects and osteoblastic effects, there is much interest in clinically assessing ZD4054 in prostate cancer.. The data describing the endothelin axis, the role of ET(A) and ET(B) in malignancy, and the effects of ET(A) antagonist ZD4054 in prostate cancer, as demonstrated in preclinical and clinical studies, are reviewed.. Further investigation of ZD4054 in prostate cancer is warranted, and Phase III trials are already planned in patients with non-metastatic castrate-resistant prostate cancer (CRPC) with rising prostate specific antigen values, metastatic (asymptomatic) CRPC, and in metastatic CRPC in combination with docetaxel, assessing either differences in progression-free survival and overall survival or overall survival alone.

Topics: Animals; Antineoplastic Agents; Apoptosis; Bone Neoplasms; Clinical Trials as Topic; Disease-Free Survival; Endothelin A Receptor Antagonists; Humans; Male; Orchiectomy; Prostatic Neoplasms; Pyrrolidines; Receptor, Endothelin A

Recent advances in the understanding of prostate cancer biology and its progression to bone metastasis have led to the development of drugs directed against precise molecular alterations in the prostate tumor cell and host cells in the normal bone environment such as osteoclasts and osteoblasts. Endothelins (ETs) and their receptors have emerged as a potential target in prostate cancer bone metastasis. By activating the ETA receptor, ET-1 is pathogenically involved in facilitating several aspects of prostate cancer progression, including proliferation, escape from apoptosis, invasion, and new bone formation, processes that are general to many malignancies. Notwithstanding, there are a number of features specifically driven by the ET axis in prostate cancer, such as creating and perpetuating a unique interaction between the metastatic prostate cancer cell and the bone microenvironment (osteoblast, osteoclast, and stroma) or altering the equilibrium in pain modulation. These features have led to the preferential clinical evaluation of atrasentan (ABT-627) as a biological therapy in prostate carcinoma, first in hormone-refractory prostate cancer. Biological activity of atrasentan in patients with prostate cancer has been shown by the suppression of biochemical markers of prostate cancer progression in bone, and clinical activity is evidenced by a consistent trend demonstrating a delay in time to disease progression when compared with placebo, especially in patients with bone metastases. Further studies of atrasentan and other selective ET-1 antagonists (ZD4054) are ongoing.

Topics: Antineoplastic Agents; Atrasentan; Bone Neoplasms; Breast Neoplasms; Clinical Trials as Topic; Endothelin Receptor Antagonists; Female; Humans; Male; Prostatic Neoplasms; Pyrrolidines

Endothelin-1 and the endothelin A (ET(A) ) receptor have been implicated in prostate cancer progression in bone. This study aimed to determine whether the specific ET(A) receptor antagonist, zibotentan, prolonged overall survival (OS) in patients with castration-resistant prostate cancer and bone metastases who were pain-free or mildly symptomatic for pain.. Patients were randomized 1:1 to zibotentan 10 mg/day or placebo, plus standard prostate cancer treatment. The primary endpoint was OS. Secondary endpoints included times to pain progression, chemotherapy use, new bone metastases, and safety. Efficacy endpoints were analyzed using a log-rank test.. A total of 594 patients were randomized (zibotentan, n = 299; placebo, n = 295). Median OS was 24.5 months in zibotentan-treated patients versus 22.5 months for placebo, but the difference did not reach statistical significance (hazard ratio, 0.87; 95.2% confidence interval, 0.69-1.10; P = .240). No statistically significant differences were observed for any secondary efficacy endpoints. Peripheral edema (44%) and headache (31%) were the most commonly reported adverse events in the zibotentan group. Cardiac failure events were higher in the zibotentan group than placebo (any grade, 5.7% and 1.7%; Common Terminology Criteria for Adverse Events grade ≥3, 3.0% and 1.0%, respectively); these were manageable and reversible.. In this large, randomized, placebo-controlled phase 3 trial, treatment with zibotentan 10 mg/day did not lead to a statistically significant improvement in OS in this patient population. Zibotentan had an acceptable safety profile.

Topics: Antineoplastic Agents; Bone Neoplasms; Disease-Free Survival; Endothelin A Receptor Antagonists; Endothelin-1; Humans; Male; Orchiectomy; Placebos; Prostatic Neoplasms; Pyrrolidines; Survival; Treatment Outcome

This two-part study assessed the safety and tolerability of combined treatment with zibotentan (ZD4054), a specific endothelin A receptor antagonist, plus docetaxel in patients with metastatic castration-resistant prostate cancer.. Part A was an open-label, dose-finding phase to determine the safety and toxicity profile of zibotentan in combination with docetaxel. Patients received once-daily oral zibotentan 10 mg (initial cohort) or 15 mg in combination with docetaxel 75 mg/m(2) (administered on day 1 of each 21-day cycle) for up to 10 cycles. Part B was a double-blind phase which evaluated the safety and preliminary activity of zibotentan plus docetaxel. Patients were randomized 2:1 to receive zibotentan (at the highest tolerated dose identified in part A) plus docetaxel or placebo plus docetaxel.. Six patients were enrolled in part A (n  = 3, zibotentan 10 mg; n = 3, zibotentan 15 mg). No dose-limiting toxicity was observed, thus zibotentan 15 mg in combination with docetaxel was evaluated in part B (n = 20, zibotentan plus docetaxel; n = 11, placebo plus docetaxel). CTCAE grade ≥3, most commonly neutropenia or leucopenia, were reported in 10 (50%) and nine (82%) patients in the zibotentan and placebo groups, respectively. One (17%) patient receiving placebo achieved complete response, two (22%) patients receiving zibotentan achieved partial response and stable disease occurred in six (67%) and three (50%) patients receiving zibotentan and placebo, respectively.. The tolerability of zibotentan plus docetaxel was consistent with the known profiles of each drug. Sufficient preliminary activity was seen with this combination to merit continued development.

Topics: Adenocarcinoma; Aged; Aged, 80 and over; Antineoplastic Agents; Bone Neoplasms; Cohort Studies; Docetaxel; Dose-Response Relationship, Drug; Double-Blind Method; Drug Therapy, Combination; Endothelin A Receptor Antagonists; Humans; Leukopenia; Male; Middle Aged; Neutropenia; Orchiectomy; Pain; Prostatic Neoplasms; Pyrrolidines; Taxoids; Treatment Outcome

To report the final analysis of a Phase II trial, which investigated the safety and efficacy of the specific endothelin A receptor antagonist zibotentan (AstraZeneca, Macclesfield, UK) in patients with metastatic castration-resistant prostate cancer (CRPC).. Patients with CRPC and bone metastases who were pain free or mildly symptomatic for pain were randomized to receive once-daily oral tablets of zibotentan 10 mg, 15 mg or placebo. The primary endpoint was the time to progression and secondary endpoints included overall survival, change in the number of bone metastases, and safety.. In total, 312 patients were randomized (placebo, n= 107; zibotentan 10 mg, n= 107; zibotentan 15 mg, n= 98). The median duration of study treatment and median follow-up time were 4 and 22 months, respectively. At the final analysis, there were no statistical differences of the primary outcome of time to progression between treatment groups, although an improvement in overall survival was observed in the zibotentan groups compared to placebo. Consistent with the previous analyses for overall survival, hazard ratios (HRs) of less than one were sustained for both zibotentan 15 mg (HR, 0.76; 80% CI, 0.61-0.94; P= 0.103) and 10 mg (HR, 0.83; 80% CI, 0.67-1.02; P= 0.254). The most commonly reported adverse events considered to be related to zibotentan treatment were peripheral oedema, headache and nasal congestion.. The results obtained in the present study support endothelin A receptor antagonism as an approach for treating patients with CRPC. To confirm the survival signal observed in the present study, zibotentan is being investigated further in the ENdoTHelin A USE (ENTHUSE) Phase III clinical trial programme.

Topics: Antineoplastic Agents; Bone Neoplasms; Endothelin A Receptor Antagonists; Epidemiologic Methods; Follow-Up Studies; Humans; Male; Neoplasms, Hormone-Dependent; Orchiectomy; Pain; Prostatic Neoplasms; Pyrrolidines; Treatment Outcome

The endothelin-A receptor (ETAR) has been implicated in the progression of prostate cancer.. To investigate the safety and efficacy of the specific ETAR antagonist ZD4054 in patients with metastatic hormone-resistant prostate cancer (HRPC).. Double-blind, placebo-controlled, randomised, parallel-group, multicentre, phase 2 trial in patients attending cancer centres with HRPC and bone metastases who were pain free or mildly symptomatic for pain.. Patients were randomised to receive once-daily oral tablets of ZD4054 10 mg, or ZD4054 15 mg, or placebo.. The primary end point was time to progression, defined as clinical progression, requirement for opiate analgesia, objective progression of soft-tissue metastases, or death in the absence of progression. Secondary end points included overall survival, time to prostate-specific antigen (PSA) progression, and safety. Statistical significance was preset at 20%.. A total of 312 patients were randomised (ZD4054 10 mg, n=107; ZD4054 15 mg, n=98; placebo, n=107). At the primary analysis, median time to progression was 3.6 mo, 4.0 mo, and 3.8 mo in the placebo, ZD4054 10 mg, and ZD4054 15 mg groups, respectively, with no statistically significant difference between ZD4054 groups and placebo (hazard ratio [HR] vs placebo for the ZD4054 10mg group: 0.88 [80% CI: 0.71-1.09]; HR vs placebo for the ZD4054 15 mg group: 0.83 [80% CI: 0.66-1.03]). However, a signal for prolonged overall survival was observed in the ZD4054 treatment groups versus placebo, based on 40 deaths. At a subsequent analysis after 118 deaths, this survival benefit was confirmed (HR vs placebo for the ZD4054 10 mg group, 0.55 [80% CI: 0.41-0.73], p=0.008; HR vs placebo for the ZD4054 15 mg group, 0.65 [80% CI: 0.49-0.86], p=0.052) but the differences in time to progression remained nonsignificant. Median overall survival was 17.3 mo, 24.5 mo, and 23.5 mo in the placebo group, the ZD4054 10 mg group, and the ZD4054 15 mg group, respectively. Discordance between results for time to progression and overall survival may be due to the sensitivity of the definition of progression. Adverse events were in line with the expected pharmacologic effects of an ETAR antagonist.. The primary end point of time to progression was not achieved in this study, but an improvement was seen in overall survival in both active treatment arms. ZD4054 was well tolerated.. Clinicaltrials.gov NCT00090363.

Topics: Adenocarcinoma; Administration, Oral; Aged; Aged, 80 and over; Antineoplastic Agents, Hormonal; Bone Neoplasms; Dose-Response Relationship, Drug; Double-Blind Method; Drug Administration Schedule; Drug Resistance, Neoplasm; Endothelin A Receptor Antagonists; Humans; Kaplan-Meier Estimate; Male; Maximum Tolerated Dose; Middle Aged; Neoplasm Staging; Pain Measurement; Probability; Prognosis; Prospective Studies; Prostate-Specific Antigen; Prostatic Neoplasms; Pyrrolidines; Receptor, Endothelin A; Risk Assessment; Survival Analysis; Treatment Outcome

Bone metastasis is a painful complication of advanced prostate cancer. Endothelin-1 is a tumor-secreted factor that plays a central role in osteoblast activation and the osteosclerotic response of prostate cancer metastatic to bone. Antagonists that block the activation of the endothelin A receptor (ETAR), located on osteoblasts, reduce osteoblastic bone lesions in animal models of bone metastasis. However, ETAR antagonists demonstrated limited efficacy in clinical trials of men with advanced prostate cancer who also received standard androgen deprivation therapy (ADT). Previous data from our group suggested that, in a mouse model, ETAR antagonists might only be efficacious when androgen signaling in the osteoblast is lowered beyond the ability of standard ADT. This notion was tested in a mouse model of prostate cancer bone metastasis. Castrated and sham-operated male athymic nude mice underwent intracardiac inoculation of the ARCaPM castration-resistant prostate cancer cell line. The mice were then treated with either the ETAR antagonist zibotentan or a vehicle control to generate four experimental groups: vehicle+sham (Veh+Sham), vehicle+castrate (Veh+Castr), zibotentan+sham (Zibo+Sham), and zibotentan+castrate (Zibo+Castr). The mice were monitored radiographically for the development of skeletal lesions. The Zibo+Castr group had significantly longer survival and a single incidental lesion. Mice in the Zibo+Sham group had the shortest survival and the largest number of skeletal lesions. Survival and skeletal lesions of the Veh+Sham and Veh+Castr groups were intermediate compared with the zibotentan-treated groups. We report a complex interaction between ETAR and androgen signaling, whereby ETAR blockade was most efficacious when combined with complete androgen deprivation.

Topics: Animals; Bone Neoplasms; Cell Line, Tumor; Disease Models, Animal; Endothelin A Receptor Antagonists; Endothelin-1; Male; Mice; Orchiectomy; Osteoblasts; Prostatic Neoplasms; Pyrrolidines; Receptor, Endothelin A

Assessment of skeletal metastases' response to therapy is a highly relevant but unresolved clinical problem. The main goal of this work was to compare pharmacodynamic responses to therapy assessed with positron emission tomography-computed tomography (PET/CT) using fluorine-18 sodium fluoride (NaF) and fluorine-18 fluorodeoxyglucose (FDG) as the tracers.. Patients with prostate cancer with known osseous metastases were treated with zibotentan (ZD4054) and imaged with combined dynamic NaF/FDG PET/CT before therapy (baseline), after 4 weeks of therapy (week 4), and after 2 weeks of treatment break (week 6). Kinetic analysis allowed comparison of the voxel-based tracer uptake rate parameter Ki, the vasculature parameters K1 (measuring perfusion/permeability) and Vb (measuring vasculature fraction in the tissue), and the standardized uptake values (SUVs).. Correlations were high for the NaF and FDG peak uptake parameters (Ki and SUV correlations ranged from 0.57 to 0.88) and for vasculature parameters (K1 and Vb correlations ranged from 0.61 to 0.81). Correlation was low between the NaF and FDG week 4 Ki responses (ρ = 0.35; P = .084) but was higher for NaF and FDG week 6 Ki responses (ρ = 0.72; P < .0001). Correlations for vasculature responses were always low (ρ < 0.35). NaF and FDG uptakes in the osseous metastases were spatially dislocated, with overlap in the range from 0% to 80%.. This study found that late NaF and FDG uptake responses are consistently correlated but that earlier uptake responses and all vasculature responses can be unrelated. This study also confirmed that FDG and NaF uptakes are spatially dislocated. Although treatment responses assessed with NaF and FDG may be correlated, using both tracers provides additional information.

Topics: Aged; Aged, 80 and over; Bone Neoplasms; Clinical Trials, Phase III as Topic; Fluorodeoxyglucose F18; Humans; Male; Middle Aged; Positron-Emission Tomography; Prostatic Neoplasms, Castration-Resistant; Pyrrolidines; Sodium Fluoride; Tomography, X-Ray Computed; Treatment Outcome

Despite that greater knowledge of prostate cancer biology has led to the isolation of many new and promising targets, treatment of metastatic prostate cancer is still challenging. New agents targeting these molecules are currently under development in large randomized phase III trials, to improve overall survival and the quality of life of patients with metastatic castrate-resistant prostatic cancer (CRPC). Cytotoxic chemotherapy (docetaxel-based chemotherapy) demonstrated clinical benefit on overall survival, but could be improved. Drugs targeting directly or not the androgen receptor such as abiraterone or new specific peripheral anti-androgens (MDV3100) are very promising. Bone targeted therapies (endothelin1 receptor A inhibitor, RANK ligant, metabolic irradiation) are also very promising and are in development in large phase III trials. Antiangiogenic therapies could also be effective in CRPC. Autologous vaccin against prostatic acid phosphatase seems to prolong overall survival and other vaccin and immunotherapy strategies are in development (anti-CTLA4 antibody). A recent analogue of thalidomide, probably more efficient, lenalidomide is also in development.

Topics: Androgen Antagonists; Androstenes; Androstenols; Angiogenesis Inhibitors; Antibodies, Monoclonal; Antibodies, Monoclonal, Humanized; Antineoplastic Agents, Hormonal; Bone Neoplasms; Castration; Denosumab; Epothilones; ErbB Receptors; Furans; Humans; Immunotherapy; Ketones; Male; Orchiectomy; Prostatic Neoplasms; Pyrrolidines; RANK Ligand