Enzalutamide versus flutamide for castration-resistant prostate cancer after combined androgen blockade therapy with bicalutamide: a retrospective study

Abstract

Background: Alternative anti-androgen therapy (AAT) with flutamide after combined androgen blockade (CAB) therapy with bicalutamide for metastatic prostate cancer is common. However, no studies have compared enzalutamide without AAT with enzalutamide after AAT with flutamide as treatment for castration-resistant prostate cancer (CRPC). We aimed to compare the efficacies of flutamide and enzalutamide for CRPC. Methods: In our hospital, 55 patients were diagnosed with CRPC after CAB therapy and administered flutamide or enzalutamide between May 2014 and December 2017. Patients with flutamide failure were administered enzalutamide. We evaluated the prostate-specific antigen (PSA) best response with initial therapy, 2) PSA progression-free survival with initial therapy (PSA-PFS), 3) PSA best response with enzalutamide therapy, 4) PSA-PFS of enzalutamide therapy, and 5) overall survival (OS). Results: As first-line therapy, patients were administered enzalutamide (n = 29) or flutamide (n = 26). In the flutamide group, 18 patients showed disease progression and were administered enzalutamide. PSA best response was statistically higher in the enzalutamide group. PSA-PFS was significantly longer in the enzalutamide group (hazard ratio (HR) 0.42, 95% confidence interval (CI) 0.19-0.92, p = 0.024). However, there was no significant difference in PSA best response with enzalutamide therapy and PSA-PFS between the first-and second-line enzalutamide therapies (HR 0.80, 95% CI 0.33-1.94, p = 0.62). There was no 4 significant difference in OS between enzalutamide and flutamide groups (HR1.85, 95% CI 0.53-6.42, p = 0.33). Conclusions: AAT with subsequent flutamide after CAB therapy with bicalutamide may be suitable for some CRPC patients.

Enzalutamide versus flutamide for castration-resistant prostate cancer after combined androgen blockade therapy with bicalutamide: the OCUU-CRPC study

“…Furthermore, in our previous, retrospective study comparing first-and second-line enzalutamide following flutamide in CRPC after Bic-CAB, the PSA levels decreased in all patients in the second-line enzalutamide group, and there were no significant differences in time to treatment failure of enzalutamide or OS between the two strategies [24]. Since AAT with flutamide prior to enzalutamide initiation is expected to confer economic benefits, future studies will need to establish evidence for the need of sequential therapy including flutamide.…”

Efficacy and Prognostic Factors of Androgen Deprivation Therapy Combined with Radiation Therapy for Prostate Cancer

“…It is demonstrated [ 21 ] that more than 85% of low-risk prostate cancer patients who accepted the androgen castration obtain a 5-year postoperative survival rate; however, some scholars believe that although castration surgery can effectively block testis-derived androgen, the progression of prostate cancer can be promoted by the adrenal gland-secreted androgen. Therefore, most scholars agree that the androgen deprivation therapy with oral drugs is more effective, tolerable, and convenient [ 22 , 23 ].…”

Flutamide as an Alternative Anti-androgen Agent and Predictor of the Efficacy of Novel Androgen Receptor-targeted Agents

“…using flutamide affect the efficacy of novel androgen receptor-targeted agents. Only a few reports have evaluated the relationship between the therapeutic effects of alternative anti-androgen therapy using flutamide and the subsequent treatment effect of novel androgen receptor-targeted agents (12,13). In the present study, we reviewed the clinical characteristics of 79 patients and examined the clinical benefits of flutamide as an alternative anti-androgen agent and as an effective predictor of novel androgen receptortargeted agents.…”

“…Furthermore, patients having a good response to alternative anti-androgen therapy demonstrate a significantly better cancer-specific survival (CSS) rate compared to those without a good response to alternative anti-androgen therapy (9)(10)(11). There exist a few reports showing the effects of novel androgen receptor-targeted agents following anti-androgen therapy using flutamide (12,13). In this study, we evaluated the clinical benefits of flutamide as an alternative anti-androgen agent and examined whether the therapeutic effects of flutamide affect the efficacy of novel androgen receptortargeted agents.…”