Enzalutamide

Enzalutamide is a novel anti-androgen agent that has significant antitumour activity in patients with castrate-resistant prostate cancer who have progressed after previous chemotherapy. In the AFFIRM study, patients who had previously received docetaxel chemotherapy were randomised to enzalutamide or placebo.10The median overall survival was 18.4 months (95% CI, 17.3 to not yet reached) in the enzalutamide group versus 13.6 months (95% CI, 11.3 to 15.8) in the placebo group (HR for death in the enzalutamide group = 0.63; 95% CI, 0.53 to 0.75; P <0.001). Treatment was well tolerated. However, seizures were reported in 0.6% of patients who received enzalutamide and none with placebo. In addition, there was improvement in time to first skeletal-related event, time to pain progression, and quality of life in patients who received enzalutamide.11,12The role of enzalutamide in chemotherapy-nave patients was evaluated in the PREVAIL study.13Eligible patients had not received cytotoxic chemotherapy, ketoconazole or abiraterone. At the planned interim analysis, there was a median duration of follow-up of 22 months. At that point, overall survival was significantly increased with enzalutamide compared with placebo (estimated median 32.4 vs 30.2 months, HR = 0.71; 95% CI, 0.60 to 0.84). An updated analysis of overall survival with 116 additional deaths showed that 82% of patients in the enzalutamide group and 73% of those in the placebo group were alive at 18 months. There was a significant decrease in the risk of radiographic progression with enzalutamide compared with placebo (12 month PFS 65 vs 14%, HR = 0.19; 95% CI, 0.15 to 0.23). One patient in each study group experienced a seizure. Patients who received enzalutamide also reported significantly improved patient-related outcomes, with delays in the occurrence of first skeletal-related event.14

There have been no cost-effectiveness analyses on enzalutamide performed using local cost data and Singaporean societal norms. On 23 July 2014, NICE recommended enzalutamide for the treatment of metastatic hormone-relapsed prostate cancer that has progressed during or after docetaxel-containing chemotherapy.15The NICE Committee determined a probable pairwise ICER of USD $22,213 per QALY for enzalutamide versus abiraterone and USD $78,391 per QALY for enzalutamide versus best supportive care. For patients who had received 2 or more previous courses of cytotoxic chemotherapy, the NICE Committees estimated ICER for enzalutamide compared with best supportive care was USD $73,600 per QALY gained.