Purpose
Enzalutamide plus ADT has previously been shown to improve clinical outcomes in men with metastatic hormone sensitive prostate cancer (ARCHES; NCT02677896). Here, we assessed if and how the pattern of metastatic spread impacts efficacy of enzalutamide plus ADT in men enrolled in ARCHES.
Materials and Methods
Men with metastatic hormone sensitive prostate cancer were randomized 1:1 to enzalutamide (160 mg/day) plus ADT or placebo plus ADT, stratified by disease volume and prior docetaxel treatment. The primary end point was radiographic progression-free survival. Secondary end points included time to prostate specific antigen progression, initiation of new antineoplastic therapy, first symptomatic skeletal event and castration resistance. Post hoc analyses were performed by pattern of metastatic spread based on study entry imaging.
Results
Of the overall population with metastases identified at enrollment (n=1,146), the largest patient subgroups were those with bone metastases only (n=513) and those with bone plus lymph node metastases (n=351); there were fewer men with lymph node metastases only (n=154) and men with visceral±bone or lymph node metastases (n=128). Enzalutamide plus ADT reduced the risk of radiographic progression versus placebo plus ADT in men with bone metastases only (HR 0.33) and bone plus lymph node metastases (HR 0.31). Similar improvements in secondary end points were also observed in these subgroups.
Conclusions
These findings indicate that treatment with enzalutamide plus ADT provides improvements in men with bone and/or lymph node metastases, but may be less effective in men with visceral patterns of spread.