Endocrine effects, efficacy and tolerability of a 10.8-mg depot formulation of goserelin acetate administered every 13 weeks to patients with advanced prostate cancer

Objective To determine the endocrine effects, efficacy and tolerability of a 10.8-mg depot formulation of Zoladex(TM) (goserelin acetate, Zeneca Pharm aceuticals, Wilmington, Delaware, USA), a luteinizing hormone-releasing hor mone agonist analogue, when administration was extended from every 12 weeks to every 13 weeks in patients with advanced prostate cancer. Patients and methods Between July 1995 and May 1996, 59 patients with eithe r locally advanced (T3 or T4) or metastatic prostate cancer were enrolled i n an open-label, multicentre trial, Primary efficacy endpoints were testost erone measurements, and assessments of prostate specific antigen (PSA) resp onse, subjective and objective response, Quality of life (QoL) was a second ary efficacy endpoint. Results Mean testosterone concentrations decreased to < 0.3 mu g/L by week 4 and remained so for the duration of treatment, There were no statisticall y significant differences in mean testosterone levels between weeks 12 and 13, or weeks 25 and 26. Serum testosterone suppression was adequate in (98% ) patients at week 26. Of the 58 evaluable patients, 52 (90%) had a PSA res ponse. A subjective response was recorded for six of 11 evaluable patients. Of 58 patients evaluable for objective response, 46 (79%) had a partial re sponse, three (5%) had stable disease and nine (16%) had objective progress ion. Except for a significant (P=0.014) decrease in overall sexual interest , QoL was unchanged during therapy. The most common side-effects, regardles s of causality, were hot flushes (67%), pain (31%) and pelvic pain (22%). M ild injection-site complaints occurred with only three of 221 (1.4%) depot injections. Conclusions Zoladex(TM) 10.8-mg depot, administered every 13 weeks to patie nts with advanced prostatic cancer, is well tolerated, provides adequate su ppression of serum testosterone and produces PSA, subjective and objective responses.