Intermittent (IAD) versus continuous androgen deprivation (CAD) in hormone sensitive metastatic prostate cancer (HSM1PC) patients (pts) Results of S9346 (INT-0162), an international phase III trial

SUMMARY: Preclinical data had suggested that Intermittent Androgen Deprivation (IAD) could prolong response to therapy and alleviate side effects related to androgen deprivation. In this Phase III trial, 3040 enrolled patients with hormone sensitive metastatic prostate cancer, with PSA ≥ 5 ng/ml, were treated for 7 months with ZOLADEX® (Goserelin) plus CASODEX® (Bicalutamide). After 7 months of this combination therapy, 1535 eligible patients achieved a PSA of ≤4.0 ng/ml. These patients were then randomized to either continue ZOLADEX® plus CASODEX® (Continuous Androgen Deprivation -CAD) or receive this combination intermittently (Intermittent Androgen Deprivation – IAD). The primary endpoint was overall survival. The median Overall Survival from the time of randomization in the CAD group was 5.8 years versus 5.1 years for the IAD group. However, a subset analysis surprisingly revealed that patients with minimal metastatic disease had a statistically significant survival advantage with CAD whereas those with extensive metastatic disease had a better survival with IAD. Counter intuitive as it may be, this study has clearly suggested that the choice of CAD versus IAD should be based on the extent of metastatic disease, in patients with hormone sensitive prostate cancer. Hussain M, Tangen CM, Higano CS, et al. J Clin Oncol 2012; 30, 2012 (suppl; abstr 4)