James ND, Caty A, Payne H, et al. Final safety and efficacy analysis of the specific endothelin A receptor antagonist zibotentan (ZD4054) in patients with metastatic castration-resistant prostate cancer and bone metastases who were pain-free or mildly symptomatic for pain: a double-blind, placebo-controlled, randomized Phase II trial
Division of Cancer Studies, University of Birmingham, Birmingham, UK. BJU International
(Impact Factor: 3.53).
10/2010; 106(7):966-73. DOI: 10.1111/j.1464-410X.2010.09638.x
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.
Available from: PubMed Central
- "Zibotentan is an oral ETA specific antagonist shown to inhibit cell invasion, proliferation, and metastasis.57 A phase II trial of patients with CRPC bone metastasis showed improvements in overall survival.57 The current and potential therapeutic targets for PC bone metastasis are discussed in Table 4. "
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ABSTRACT: Prostate cancer (PC) is one of the most common cancers arising in men and has a high propensity for bone metastasis, particularly to the spine. At this stage, it often causes severe morbidity due to pathological fracture and/or metastatic epidural spinal cord compression which, if untreated, inevitably leads to intractable pain, neurological deficit, and paralysis. Unfortunately, the underlying molecular mechanisms driving growth of secondary PC in the bony vertebral column remain largely unknown. Further investigation is warranted in order to identify therapeutic targets in the future. This review summarizes the current understanding of PC bone metastasis in the spine, highlighting interactions between key tumor and bone-derived factors which influence tumor progression, especially the functional roles of osteoblasts and osteoclasts in the bone microenvironment through their interactions with metastatic PC cells and the critical pathway RANK/RANKL/OPG in bone destruction.
Available from: Manon Buist-Homan
- "Interestingly, GPCRs antagonists have shown excellent therapeutic benefits in clinical trials in controlling tumor growth and apoptosis . For example, an endothelin A receptor antagonists ZD4054, has been shown to improve the overall survival and reduce the risk of death and bone metastasis in patients with resistant prostate cancer . Therefore, GPCR-based drugs may also show therapeutic benefits in regulation of apoptosis and/or survival in liver diseases. "
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Excessive hepatocyte apoptosis is a common event in acute and chronic liver diseases leading to loss of functional liver tissue. Approaches to prevent apoptosis have therefore high potential for the treatment of liver disease. G-protein coupled receptors (GPCR) play crucial roles in cell fate (proliferation, cell death) and act through heterotrimeric G-proteins. G(αi)PCRs have been shown to regulate lipoapoptosis in hepatocytes, but their role in inflammation- or bile acid-induced apoptosis is unknown. Here, we analyzed the effect of inhibiting G(αi)PCR function, using pertussis toxin (PT), on bile acid- and cytokine-induced apoptosis in hepatocytes. Primary rat hepatocytes, HepG2-rNtcp cells (human hepatocellular carcinoma cells) or H-4-II-E cells (rat hepatoma cells) were exposed to glycochenodeoxycholic acid (GCDCA) or tumor necrosis factor-α (TNFα)/actinomycin D (ActD). PT (50-200 nmol/L) was added 30 minutes prior to the apoptotic stimulus. Apoptosis (caspase-3 activity, acridine orange staining) and necrosis (sytox green staining) were assessed. PT significantly reduced GCDCA- and TNFα/ActD-induced apoptosis in rat hepatocytes (-60%, p<0.05) in a dose-dependent manner (with no shift to necrosis), but not in HepG2-rNtcp cells or rat H-4-II-E cells. The protective effect of pertussis toxin was independent of the activation of selected cell survival signal transduction pathways, including ERK, p38 MAPK, PI3K and PKC pathways, as specific protein kinase inhibitors did not reverse the protective effects of pertussis toxin in GCDCA-exposed hepatocytes.
Pertussis toxin, an inhibitor of G(αi)PCRs, protects hepatocytes, but not hepatocellular carcinoma cells, against bile acid- and cytokine-induced apoptosis and has therapeutic potential as primary hepatoprotective drug, as well as adjuvant in anti-cancer therapy.
Available from: ncbi.nlm.nih.gov
- "Interestingly, the study did not meet its primary endpoint of time to progression. Moreover, at the final analysis (median follow-up of 22 months), the absolute OS benefit diminished down to 3.6 months from 7.2 months. Based on the initial OS benefit, an expanded phase III program was launched and included three trials (ENTHUSE M0, ENTHUSE M1, and ENTHUSE M1c) in disease ranging from non-metastatic CRPC (M0) to mCRPC (M1 and M1c), evaluating either single-agent zibotentan (M0 and M1) or in combination with docetaxel (M1c) . "
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ABSTRACT: Men with metastatic castration-resistant prostate cancer (mCRPC) carry poor prognosis despite the use of docetaxel-based regimens which has modest survival benefit shown by randomized clinical trials. Significant progress in the discovery of novel therapeutic agents has been made in the past few years. While sipuleucel-T, cabazitaxel, and abiraterone gained regulatory approval in 2010 and 2011, several highly promising candidates/regimens have failed in large scale clinical trials. Challenges remain to optimize the design and interpretation of clinical trial results and develop more effective strategies for mCRPC. In this review, we examined the positive and negative clinical trials in mCRPC in the past and discussed the various aspects of clinical trial design including selection of targets and appropriate outcome measures, biomarker development and implementation, and strategies for combination therapy.
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