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.
OBJECTIVE
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).


METHODS
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.


RESULTS
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.


CONCLUSIONS
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.
James
Nicholas D
ND
Division of Cancer Studies, University of Birmingham, Birmingham, UK. n.d.james@bham.ac.uk
Caty
Armelle
A
Payne
Heather
H
Borre
Michael
M
Zonnenberg
Bernard A
BA
Beuzeboc
Philippe
P
McIntosh
Stuart
S
Morris
Thomas
T
Phung
De
D
Dawson
Nancy A
NA
D000970:Antineoplastic Agents / Q000009:adverse effects / Q000627:therapeutic use*; D001859:Bone Neoplasms / Q000188:drug therapy / Q000401:mortality / Q000556:secondary*; D065130:Endothelin A Receptor Antagonists; D004812:Epidemiologic Methods; D005500:Follow-Up Studies; D006801:Humans; D008297:Male; D009376:Neoplasms, Hormone-Dependent / Q000188:drug therapy* / Q000401:mortality / Q000601:surgery; D009919:Orchiectomy; D010146:Pain; D011471:Prostatic Neoplasms / Q000188:drug therapy* / Q000401:mortality / Q000601:surgery; D011759:Pyrrolidines / Q000009:adverse effects / Q000627:therapeutic use*; D016896:Treatment Outcome
D000970:Antineoplastic Agents; D065130:Endothelin A Receptor Antagonists; D011759:Pyrrolidines; C511404:ZD4054