PSA declines and survival in patients with metastatic castration-resistant prostate cancer treated with enzalutamide

RATIONALE: PSA responses have been associated with a survival benefit in patients treated with enzalutamide in retrospective analyses. PATIENT CONCERNS: However the prognostic value of PSA declines in highly pretreated patients receiving enzalutamide remains to be defined. DIAGNOSES AND INTERVENTATIONS: Medical records of patients with documented mCRPC treated with enzalutamide between September 2011 and August 2016 were reviewed at multiple participating centers and assessed for overall survival (OS), PSA variations, and other variables of interest. Univariable and multivariable analyses were conducted. OUTCOMES: A total of 129 patients received enzalutamide. PSA response rates (>50% PSA declines) were 58/119 (48.7%), 58/115 (50.4%), 54/110 (49.1%), and 47/91 (51.7%) at weeks 4, 8, 12, and 16, respectively. Having a PSA response was a statistically significant prognostic factor of improved OS at 8 and 12 weeks in univariable analysis, whereas it was significant at 12 weeks in the multivariable analysis. Patients treated with enzalutamide had a median OS of 7.8 months. LESSONS: Our study supports the prognostic value of PSA declines in heavily treated patients receiving enzalutamide.